How to restore accuracy to the Russian Capture K98

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AGB-1
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How to restore accuracy to the Russian Capture K98

Post by AGB-1 »

https://forums.gunboards.com/showthread ... ost9940499

good info here. AGB-1

Start at post#68.
72 usmc
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Re: How to restore accuracy to the Russian Capture K98

Post by 72 usmc »

More info on making a K98 a bit more accurate.

https://www.milsurpaccuracyinc.com/mauser-accurizing

The kit of shims & shim material sold here: https://www.victory-arms.com/Mauser-Accurizing-Shim-Kit
To old to fight and to old to run, a Jar head will just shoot and be done with you.
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Re: How to restore accuracy to the Russian Capture K98

Post by 72 usmc »

I found this a useful write up:
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Default Here is an article I wrote on K98K shooting for our local club newsletter
Technical article Accuracy and the Kar98K

At the present time the Kar98K and rifles derived from it are not particularly popular in vintage rifle matches. Considering that over 13.5 million were produced in Germany, and variants such as the Spanish model 43, 44, Portuguese model 37 and the Yugoslavian model 48 are but derivations of the Kar98K, this is surprising, as many of these rifles that survived the ravages of time ultimately ended up on America's shores. Certainly in the past 10 years Yugoslavian model 48 and Soviet rebuilt Kar98K rifles have been plentiful and cheap, with the ammunition amongst the cheapest surplus available. Many a shooter has one or more of these rifles tucked away in their gun room.

Perhaps one of the reasons that these rifles are not more commonly seen in vintage rifle events is due to their reputation for variable accuracy between rifles, along with what is seen as a generally lower accuracy level when compared to the Swedish model 96 / 38 or Swiss K31 rifles. Given that the 7.92x57 mm is not known as a world class match rifle cartridge (compared to the 6.5 x 55 or the 7.5 x 55), it is still capable of fine accuracy given good quality bullets. As far as the rifles themselves, the Kar98K and its derivatives were in fact very carefully engineered for repeatable accuracy under varying climatic conditions. In point of fact, well preserved factory assembled Kar98K rifles are capable of a uniformly high level of accuracy, how accurate to be discussed in the latter portion of this article.

It is the author's contention that much of the reputation of the Kar98K rifles for questionable accuracy is due to wear and storage abuse, incorrect assembly of rebuilt guns and poor ammunition choices. If all of these issues are dealt with and if the bore is in good condition, the Kar98K design is not only very accurate in terms of group size, but one of the best bolt action designs with regards to repeatability of accuracy, that is the ability of the rifle to retain its zero under all conditions.

Given the potential defects in assembly that may plague many of the rifles available on the secondary market and in shooters hands, perhaps some attention to the correct bedding and other related accuracy topics is in order. This article will attempt to detail the official build requirements of this model as well as some of more subtle issues that the accuracy minded shooter is likely to encounter in competitive shooting.


Bedding and Stock Issues:

The official Mauser bedding specifications are well documented. These specifications not only apply to the Kar98K, but also largely cover the following designs: VZ-24 (any caliber), G24(t), FN model 50, Spanish model 43 and 44, Portuguese model 37, Mauser "banner" models, Yugoslav models 98, 48, 24/47 and 24/52. The requirements for any of these stock assemblies and their fit to the barreled action, starting at the front of the rifle and working backwards are as follows:

1) The bayonet lug must be firmly assembled to the stock with no play whatsoever. When assembled to the barreled action, the bayonet lug must clear the barrel bottom by at least .2 mm.

2) When assembled to the stock, the forward part of the stock channel, between the middle and forward band is to bear upward against the barrel lightly. In practical terms this means that with the barreled action correctly assembled to the stock, the force required to lift the barrel off of this forward barrel seat will be no less than .75 Kg to no more than 1.25 Kg. The fit of the barrel to the stock channel should be near 90 percent on the bottom 180 degrees of the barrel, with no side-to-side play.

3) The coned sections of the barrel and the corresponding shoulders on the stock should not contact, the clearance between these two surfaces must be at .5 to 1 mm for all these surfaces.

4) The rear cylindrical portion of the barrel behind the tapers noted in (3) to the receiver face must not contact the barrel channel on either side of the stock barrel channel. The clearance is to be a minimum of .5mm. The stock may contact the very bottom of the barrel in this section, or contact the bottom of the rear sight base, but any contact must be very slight, with no upward force applied to the barrel and have a maximum contact on the bottom 10 degrees of the barrel. If stock contact is made, it must be dead center with the barrel, any off centered contact will affect zero as the barrel heats up.

5) The front of the sight base projection which retains the handguard must clear the top of the stock by 0.3 mm.

6) The recoil shoulder in the stock must contact the recoil lug of the action firmly and with a uniform pressure along the entire recoil lug surface. Ideally the contact between these two surfaces will exceed 90 %. The flat bottom surface of the action forward of the magazine must contact the top seating surface of the stock uniformly. The barreled action will sit within the stock with no side to side play, though .2 mm forward movement from the final seat is allowed when the action screws are not tight.

7) At the rear of the stock, the tang of the receiver should have firm contact with the stock, with a minimum of the rear 20 mm of the tang having full contact with the stock.

8) The trigger guard should fit in the stock cutout like a glove in both the forward and aft screw hole regions. When assembled with screws to the action it should bear firmly against the stock 25 mm at the rear screw and 20 mm at the front screw. When assembled with the screws tight but without the bands mounted it should be impossible to move the action within the stock. However the rear of the magazine well in the stock should have a slight gap between it and the triggerguard.

9) The top hand guard should be a glove like fit between the rear sight base projection and the middle band. The hand guard should be able to be moved fore and aft by a minimum of .2 mm. The handguard may be tight fit in the rear sight retaining projection, but when inserted into the rear sight band projection it should not require any force in order to lay flat on the top of the stock. The fit at the middle band should be firm enough so that the middle band is not loose but just firmly held in place. The hand guard barrel channel should clear the barrel by a minimum of .1 mm except at the channel underneath the middle band, where the barrel should lightly touch but not exert a binding force on the barrel.

That is as far as the official documentation goes into the bedding of the Kar98K. Having had an opportunity to study numerous correctly assembled matching rifles and troubleshooting other examples the following points seem to be equally important as regards to the fit of the stock and hand guards.

10) The front band should have a glove like fit on the front bayonet lug and stock when assembled without the barreled action. When the barreled action is included, the front band must not exert downward force on the barrel in area of the bayonet lug. The fit must be like that of a glove, with the ideal being the very top of the band in contact the very top of the barrel, but with minimal downward force exerted. A slight gap may exist, such that the barrel may be moved up approximately .1 mm if an upward force is applied to the barrel without any effect on accuracy.

11) The interior of the front band contacting the barrel and the top barrel surface have no burs or rough portions that might interfere with the forward and rearward movement of the barrel during recoil.

If the rifle is fitted as above, then one can expect the rifle to shoot well, hot or cold, as long as the bolt, action and barrel assembly is correct and free of wear. These are our next areas to consider:

Actions and bolt concerns:

The two front locking lugs should both firmly seat on the receiver locking lugs, with a minimum of 70 % contact on each lug. The headspace measured from the index of the case shoulder to the front of the bolt face should be no less than 1.896 ", or any longer than 1.901". The protrusion of the firing pin should be no less than .045 " nor more than .065 " when the firing pin is in its de-cocked state. The ideal firing pin protrusion is .060 with the bolt at or under maximum headspace. The rear safety bolt lug should be clear of the locking surface within the receiver by a minimum of .15 mm. With the firing pin spring removed the reassembled firing pin assembly should move through the bolt without any perceivable drag or roughness. The trigger should release the firing pin with no creep or any grittiness.


Barrel concerns:

The crown on the front of the barrel should be perfect, with the exposed lands having square edges with no wear on the top of any individual land when observed with an inspection glass of between 4 and 10 X magnification. Of course the barrel should be smooth and bright. Fine pitting in the grooves might be acceptable, but pitting or roughness on the lands is unacceptable. The throat of the K98K is of particular importance, with any asymmetric wear within the throat being a cause for barrel condemnation.


Sight concerns:

Both the front and rear sight assemblies should be soldered to the barrel with no play between the barrel and sight bands. The rear leaf must be a firm fit on the sight band, with no side to side movement when the tangent sight is moved up and down. Both the barleycorn front sight and the rear v notch should be examined with an inspection glass. The edges of both should be distinct and not rounded. The front barleycorn sight should not end in a point, but should have a flat top edge with a width of .045~.055". Finally all sighting surfaces should be fully blued, including all edges.


Practical troubleshooting:

A non-specialized reader may well comment that the above information is fine and dandy, but what sort of practical use can be made of this information? Hopefully the following will help:

First and foremost it must be remembered that in this day and age an unaltered Kar98K with matching numbers is a valuable collector's item. Just as a like an excellent condition Colt single action or early correct M1903 is of such value that few will consider shooting such a firearm, so too it would seem that excellent quality Kar98K rifles have reached values sufficiently high to preclude a wise owner from doing any modifications or heavy shooting with same. In addition, practically speaking an excellent condition Kar98K with all matching parts made before 1945 is unlikely to have any serious defect in its construction requiring any real accuracy overhaul. Such samples should not be modified or shot heavily if the owner wishes to retain the value and collectability of such arms.

That leaves the many recently imported castoffs of the ex-Soviet republics. There have been numerous imports of ex-Soviet and Yugoslavian rebuilt Kar98K rifles, rebuilt VZ-24 and G 24(t) rifles from Romania, Czech 98K post war copies from Slovakia and the former East Germany in the last 10 years. Many of these rifles do not have all of the stock fits correct and if rebuilt or mismatched are not considered all that valuable. On the secondary market, though there is the occasional matched mint rifle, past observations indicate the rifles put up for sale are more often than not rifles that have miss-matched bolts, parts and suffer from accuracy problems that the former owners did not care to or know how to resolve. Any such miss-matched rifles and ex east-bloc imports often have some assembly problems that can be rectified with knowledge and attention to detail. It is to these rifles that the following is addressed.

Prior to any shooting the wise shooter will first of course check the screws to ensure they are tight; make sure the bore is clean, etc. A range session with appropriate ammunition is next in order. Assume the results are ragged groups ranging from 4 inches to distressingly larger. What to do?

We can tell a lot about potential problems from examining of the group. If it is horizontally strung, with no significant vertical dispersion, then it is a sign that one of the front two bolt lugs is not bearing or is possibly one is bearing much less than the other lug.

This can be verified by clearing the bolt lugs and then using a permanent magic marker to blacken the rear locking surfaces. Working the bolt about 20 times will indicate the degree of contact between these lugs and the action (good idea to check the third reserve lug on the rear of the bolt as well). If contact is missing on one lug, then most likely the bolt is defective and another bolt body must be procured. Past experience has indicated that the Germans were fairly careful in their set up of bolts dimensionally, most mismatched bolts will show correct headspace and bolt lug engagement when assembled to a correctly dimensioned action. Of course when changing the bolt body, be sure to check headspace (after lug engagement is checked) and also check firing pin protrusion. There were examples of bolts that were out of specification that made it onto the surplus market, for this reason when a bolt lug engagement problem is found it is better to replace the bolt that to attempt to lap the bolt into the action.

In the case where one lug has over 60 percent engagement and the other less than 20 percent, a small amount of judicious lapping using JB bore paste can resolve the problem. In most cases such lapping will allow the loose lug to achieve over 70 percent engagement in short order with negligible effect on the headspace. In such cases, the lapping is meant to remove a very small amount of metal, less than 1/1000 of an inch. Removal of more metal than that is not advised, due to heat treatment concerns.

If the group is strung out vertically with little evidence of horizontal stray shots, this can be a sign of the following defects:

a) The front band is too tight on the barrel and it is binding the barrel.

b) The portion of wood bearing on the barrel between the upper and middle band is not correct, most likely there is insufficient wood supporting the barrel. In such cases the middle band/handguard assembly may be pressing down on the barrel with resultant stringing.

c) The trigger guard screw(s) are not tight, allowing the action to flex up and down during firing.

d) Primer ignition is inconsistent resulting in inconsistent peak chamber pressures; this is the result of firing pin protrusion being insufficient.

All of these potential issues should be checked. This will require a full disassembly and careful reassembly of the rifle. It has been noted that ex-Soviet rifles have at times had red varnish built up in the barrel channel that causes some barrel binding; such build-up should be carefully removed with acetone or varnish thinner. The firing pin protrusion, though in theory a possible cause, will in all likelihood not be an issue, as once again the Germans maintained very tight dimensional control over these parts. If the firing pin protrusion is incorrect, a used German made replacement part will most likely solve the issue; if it does not the problem likely lies in the bolt body itself.
One other thing that can, in theory (though the author has rarely seen it) provide vertical stringing is an incorrectly fit handguard that is either binding the barrel or too long between the front sight rail and the middle band. In this case the handguard is a very tight fit and is pushing back on the sight base and forward on the middle band. As the rifle heats up and the barrel elongates, the tension is removed and the group will begin to move higher on the target. The cure for this is to relieve the handguard band fits slightly so that the fit is as specified in the bedding guide, items #9 and #10

If the group is two grouping, forming two separate groups that may or may not overlap it is indicative of the following:

In most cases "two-grouping" is evidence of a barreled action to stock stiction fit, which is causing the action to shift position within the stock shot to shot. Typical examples of this defect are as follows:

a) The action body is loose within the action seat in the stock. Typically the problem is the tension beneath the front action ring; the stock does not have the correct degree of "crush".

b) The front trigger guard screw is not tight, which gives a similar effect as in "a".

c) The fit of the barrel within the forward barrel channel of the stock is not correct, with the barrel having side to side play within the channel. This is often combined with the area to the rear middle barrel band (where there should be no contact) making contact on one side of the stock.

d) The recoil reinforce within the stock is not firmly in contact with the recoil support surface of the action along its full length.

e) If the two groups are in a horizontal line, then it is evidence of the rear sight not being tight within the sight base, or "c"

In all cases except "a" the problem can typically be corrected by disassembly and careful relief of the stiction fits. In cases such as "a", where it truly is a stock to action seat miss fit, then the wood must be either built up underneath the forward action ring, or the forward trigger guard support on the action and trigger guard must be shaved down slightly to allow the flat underside of the action to firmly grip the stock surface once again. Past experience indicates adjusting this can affect the fit of the barrel in the forward barrel channel and require additional adjustments; as such this modification is not for those who has not previous experience in stock fitting. In all cases make very slight changes prior to retest.

If the rifle is grouping relatively well, but is occasionally, throwing flyers in a random direction, it is indicative of the following:

a) Mild stiction fit problem (as above)

b) Crown problem on the barrel.

c) Heavy built up of fouling within the bore

In cases where the rifle throws flyers, the most common problem is "b" and "c", though "a" cannot be ruled out prior to examining all of the fits on the rifle. In most cases, it is a worn crown or heavy built up fouling. Let us first deal with the fouling issue: Many of these surplus rifles were never cleaned that well in post WW II service, especially if they were second line reserve rifles in any of the eastern bloc nations. The combination of heavy carbon build up intermixed with copper can produce rather frustrating groups, with flyers coming at an unexpected rates as the fouling build up waxes and wanes. The only fix for this is to thoroughly clean out the bore, removing both the carbon and copper build up. While beyond the scope of this article, a simple cleaning with Hoppes # 9 will not suffice, something more aggressive such as JB, wire brushes, a carbon specific cleaner and a copper specific cleaner may well be required. The author has seen what appeared to be shallow grooves become more predominate when the fouling was removed. Such cleaning should not be omitted if accuracy is erratic.

Once the bore is spotlessly clean, the next step is to carefully examine the crown with a fine inspection glass of between 4 and 10 x magnification. The crown must be perfect if the shooter hopes to get repeatable accuracy. This means the circumference of the crown is a fine line with no rounding at the bore/crown interface, and that the rifling lands are square at the crown. If not, mild wear can be corrected with a re-crowning. In those cases where there is evidence of cleaning rod wear in the bore, such that it cannot be removed with a simple re-crown, the barrel must be discarded. For more detail on what would be grounds for condemnation of the barrel, the interested reader is referred to "Barrel troubleshooting" in Volume II, #10.

In most cases fixing the crown and cleaning the bore will resolve this condition. One aspect of the Kar98K that does merit special mention is the throat. The Kar98K has a more gradual throat taper than most other military rifles (more on this in the section on ammunition). It would appear from anecdotal evidence that the Kar98K throat is more sensitive to asymmetrical wear on the lands than other more sharp throated leads on such cartridges as the 7.62 NATO or 30-06. Though not documented by any known authority, the author has seen a Kar98K rifle bore that produced flyers with known quality ammunition that seemed to have no other defect than that. Of course any single rifle is not sufficient to generalize, but it is worth considering that the gradual taper of the K98K throat simulates the effect of a heavily worn US pattern throat, which is generally what produces flyers in match barrels once that wear becomes excessive. While not definitive it is something to keep in mind if one has a rifle with such wear.

The final case to be considered is where the rifle will not put in any sort of group at all, just some sort of random distribution of shots. In most cases the first thing to check is the bore. If the throat and crown pass muster than the bore pitting should be checked. Rather than go into the specifics of bore inspection, the interested reader is referred to the article referenced above. In most cases observed, when a rifle will not even put in the semblance of a group, the cause is the overall barrel condition.

If the bore, crown and throat seem to be acceptable, the shooter must go back to square one. Here the shooter will have to start at the top of the bedding list and check each and every item to see if the fundamental cause can be determined. All of the fits mentioned above are critical, inspection and correction of each fit should be attempted. One minor point sometimes over looked is the fit of the action screws. The Kar98K has small locking screws to ensure that the action screws do not come undone. These were hand selected in assembly to ensure correct fit, such that when fully tightened the locking cut lined up with the small retention screws. That is why the action screws had the last two digits of the rifle serial numbers applied. In rifles that were assembled from parts or had these screws replaced, the screws may have to be backed up 1/2 of a turn or more in order to get the locking screw to fit. The ideal solution is to not use the locking screw in its intended function, relying on blue locktite instead (which is provided for in the design, as the locking screws have a quarter moon cut out in them).

The main point to take from this is the necessity of getting the bedding correct according to the German stocking specifications. Many a shooter familiar with regulating lee Enfields is used to a variety of non military tweaks to get the rifle to shoot, with the Mauser it is strict adherence with assembly specifications, which somehow seems appropriate considering the Teutonic nature of this design.

What if in the end all of the fits seem correct and the barrel condition shows no sign of defect? At that point the shooter should turn a wary eye to his ammunition, the next topic of concern.
Ammunition selection and awareness:

A correctly assembled Kar98K with an excellent bore does not assure one of acceptable accuracy, especially if one is using surplus ammunition or older American hunting ammunition. This is because of a twist of fate in the history of the 8mm Mauser cartridge. It turns out that there are really three bore/groove sizes one might come across in surplus M88/M98 pattern arms. These are:

1) The original "I" (or J) bore which was used from 1888 to approximately 1905 for military arms, and until 1939 for commercial hunting arms. This design specified a 7.80 mm bore (.3071") and an 8.21 mm groove diameter (.323"). The standard bullet diameter to be used with this bore was an 8.10 mm, (3188~.3189 ") diameter bullet.

2) In 1905 the German arm adopted the "S projectile, which featured a sharp nosed hollow based bullet of 154 grains. The barrel bore diameter was altered to a nominal 7.90 mm (.311") and the groove diameter specified at minimum depth of 8.21 mm and a maximum depth of 8.228 mm (.3233~.324"). The nominal bullet diameter was 8.16 mm (.3215") for the German "S' and 8.20mm (.323") for the post WW I "SS" bullets. These bore dimensions were retained for the remainder of German military production and civilian production after 1939. When FN and Radom produced 8mm ammunition and barrels for this caliber, they followed the German S specifications.

3) In between 1918 and 1924 the Czech factory at Brno made their M88 replacement barrels to a third specification. The Czech dimensions specified a bore of 7.82 mm diameter (.308 ") with a groove diameter of 8.08 mm diameter (.318"). These rifles were used with Czech made "G-88" pattern ammunition, which had a nominal diameter of 8.03 mm (.316"). It would also appear that some of the commercial German sporters made between the wars used this bore size. The Czech barrels were sold to South American counties for use on M1888 rifles and as such it is possible to find them in the US of A.

The end result of this third Czech specification was that when US ammunition manufacturers started to make hunting ammunition between WWI and WWII that they utilized bullets of .321 diameter and loaded the cartridges to no more than 37,000 PSI pressure. Sometime after WWII, the bullet diameters were increased to between .322 and .323 inch diameter, though to this day commercial loading made in the US of A restrict the pressure to below 42,000 PSI.

When one considers surplus military ammunition that has been imported during the last 20 years, the situation become more complex, as there have been essentailly three types that were common:

1) S Cartridge: This was a 154 grain projectile with a nominal .321 bullet diameter that could be fired in either of the first two bores. The base of the bullet was slightly concave; so that it could expand to fill the groove diameter of the larger .323 bore barrels. Typical examples of this cartridge were the imported Turk, and Chinese surplus. The nominal velocity of the S was 2,854 fps in a 23.62 inch barrel. A variant of this was the 1970s Romania load that had a .3215 diameter, but had a boat-tail mild steel core bullet.

2) SS Cartridge: This was the standard German load for the Kar98K from 1935 on. It featured a lead core, FMJ 197 gr. projectile with a .323" diameter. Examples imported include Yugoslavian, Portuguese, and Egyptian ammunition. The nominal velocity of the SS load was 2,476 fps in a 23.62 inch barrel.

3) SME Cartridge. This was an early WWII replacement for the SS cartridge and featured a 178 mild steel core FMJ-BT projectile with a nominal diameter of .323". Two variants of this exist, one made by Canada and one by Winchester, both of which used a 170 gr. FMJ with a concave base. Both used a bullet with a nominal .3215 diameter bullet. The nominal velocity of the SME was 2,526 fps in a 23.62 inch barrel. The above loads comprise the majority of loads that have been imported in the last 20 years.
Many folks assume any surplus military ammunition will offer them a similar accuracy potential, and that if the rifle does not shoot it is likely the rifles fault. This is not the case.

The Kar98K was designed and the rifling throat optimized for the SS cartridge with a long bearing surface and a .323 diameter bullet. The best accuracy will be achieved with surplus ammunition that utilized this bullet; especially if loaded on machinery set up to German specifications, such as Yugoslavian, Portuguese and Egyptian ammunition. Of the lots available in normal trade, any of these loads give superb accuracy, with the exception of the 1950's Yugo surplus (which seems to have been substandard, as the next available years are in the 1970s and 1980s, all of which offer superb accuracy).

The SME bullet was a war time adaptation that enhanced penetration, reduced recoil and maintained the same trajectory at the price of lower accuracy on some lots. Generally the Germans found that while the SME gave close to SS accuracy when made out of dies that were like new, once the machinery ran for a period of time the accuracy of SME bullet dropped off considerably, most likely due to problems with centering the mild steel core within the lead jacket. Post-war ammunition of this type was loaded by the Czechs, and generally shows mediocre accuracy, though some good lots do exist.

The earlier S projectile, while it can be safely fired in the Kar98K, was never a primary cartridge intended for use in the Kar98K, nor in general is it considered to provide the best accuracy, due to its smaller than nominal groove size. (For more detail on the relationship between bullet diameter and accuracy, see Volume II, # 4 "Bullet Diameter and Accuracy"). Some lots with open bullet bases will shoot quite well and should not be discounted without testing. The Romanian ammunition, with its SME type steel core, FMJ boat-tail bullet of .3215 diameter offers the worst of all worlds, even though the ammunition is quite well made. These 1970s loaded cartridges were for use in reserve VZ 24 rifles, which featured wider lands with a different throat and will shoot quite well in the Vz24. In the Kar98K with its SS optimized throat and bore, such ammunition will rarely shoot better than mediocre accuracy.

In any situations steel cased WWII German ammunition should not be used under any circumstances, as this ammunition generally suffers from interior case rust and powder deterioration. Firing such ammunition can score the barrel in only 15 to 20 shots from iron oxide abrasion.

For the handloader that is considering what bullets to use, most will find that heavier projectiles with longer bearing surfaces give better accuracy at moderate velocities than lighter and shorter bearing surface bullets driven at higher speeds. This is because of the gradual lead of the throat referenced earlier. The longer bearing surface bullets seem to make the jump into the rifling throat with more consistency. In all cases the bullet diameter of any jacketed base bullets should be .323 to .3235. In practical terms the 175 to 200 gr. spitzer soft tip hunting bullets will generally offer relatively good results with the flat based bullet variants showing some superiority in bores that show wear or slight pitting.

Rifles with like new bores and throats will often shoot the lighter 150 gr. bullets quite well with moderate loads, past experience has indicated that once the loads get close to the S velocity the accuracy deteriorates, as the soft common hunting bullets do not handle the relatively long jump into the rifling all that well. In such cases, powders such as Varget, IMR4895 are about as slow as one should consider, with moderately faster powders such as IMR3031 being good choices. These faster powders seem in limited testing to give more consistent pressure profiles during the vital interval during which the bullet makes the long jump into the rifling. Further it must be keep in mind that while the 8mm Mauser is similar to the 30-06 cartridge, the larger bullet diameter means the volume of the combustion chamber increases as the bullet travels down the bore at a higher rate than on any of the .30 cal cartridges. This implies that for a given bullet weight the 8mm Mauser will likely require a faster grade of powder than a .30 caliber would require to obtain similar pressure profiles.

So what can one expect as regards accuracy?

So what sort of accuracy can one expect out of a correctly bedded Kar98K that has had all of the above areas of concern properly adjusted and fired with appropriately dimensioned ammunition? Let us start by examining the accuracy specifications for the Kar98K. We shall consider two aspects, group size, and accuracy in terms of zero stability relative to a fixed aiming mark.

Group size:

Throughout WWII the standard specification for acceptance of the Kar98K was a 5 shot group of 120 mm or less @ 100 meters. This correlates to a maximum 5 shot group of 4.32 inches @ 100 yards. This was with SS ammunition, not the more common SME load. By all measures the latter cartridge was not as accurate, with 5 shot groups on the order of 5 to 5.5 inches at 100 meters with some lots not being unheard of. Such accuracy is not all that impressive if one considers the M1903A3 was required to put 5 shots in a 3 inch group @ 100 yards with average grade 30-06 M2 ball rifle cartridges.

However the documentation that exists from the factories indicates the average rifle could produce much better accuracy. Rifles selected for optical conversion, either as marksman's rifles (ZF-41, 1.75 x) or sniper rifles (all other 4x to 6x power scopes) was 5 shots in a group under 60 mm @ 100 meters (no shot not contained within the scoring template), corresponding to a maximum 5 shot group of 2.05" center to center @ 100 yards. Rifles were not specially built up or bedded for sniper use; rather the most accurate production rifles based on acceptance testing were put aside and then fitted with telescopic sights as they became available. According to the surviving documents (many have been published in the last few years) the supply of accurate rifles was never an issue but rather the supply of telescopic sights.

Most interesting in examination of these documents is that the factory test was not sufficient to select the very best rifles, as a 5 shot group at 100 meters was not sufficiently discriminating, the Army weapons office preferring 10 shot groups @ 300 meters. The documentation indicates that a reasonable percentage of rifles could pass the 60 mm requirement and that given the number of shots there was no real way of assuring that the most accurate rifles were in fact being built up as sniper/marksman's rifles. The preponderance of evidence (including modern firing tests) indicates that the "average" Kar98K would produce groups well under 3 MOA with good ammunition, and that a good percentage of rifles off of the production line were capable of well under 2 MOA. While by no means National Match quality, such accuracy is sufficient to clean the SR 200 yard target, which is used in vintage rifle competition.

Stability of zero relative to a fixed aiming mark:

While the grouping ability of most Kar98K is sufficiently accurate to clean the SR target used in vintage competition, a second aspect of the accuracy; the ability of the rifle to retain its zero relative to a fixed aiming mark must be considered. That is where the K98K has a particular niche. The pre war German army made accurate rifle fire a fundamental point of doctrine, and with typical German thoroughness, kept in mind zero stability of their rifles far more than any of their foes (including the US of A). Indeed while little remains of German ordnance manuals or overhaul procedures, the instructions to armourers regarding stock warping and tests for same stand out in marked contrast to US and British manuals attention to this topic. The German instructions are very detailed and require replacement and destruction of any stock found to have any sort of weather induced movement that might affect weapons zero or stability of same. When the ability of industry to supply suitable well cured wood became a problem in the late 1930's, Mauser developed the first laminated wooden stocks, which for all practical purposes resolved the problem for the rest of the war. Correctly fitted, Kar98K rifles show a remarkable ability to maintain zero over varying conditions of humidity and rifle firing temperature, especially the laminated stock variants (With the possible exception of some 1945 production rifles).
In contrast to issued M1 Garands with any degree of stock crush, M1903A3 rifles from 1943 on, 1891/30 rifles with wartime stocks and many of the war time produced No 4 Mk I rifles this stability is quite marked, both in terms of zero maintenance day to day and its ability maintain its zero within a target string, without any tendency of the group to rise or fall on target as the rifle barrel warms up. Of course this presupposes that the shooter has a Kar98K that has been correctly assembled, which is not always the case, especially with recent imports over the past decade.


Use as a vintage competition rifle

Given the above, the next obvious question becomes; what sort of use can be made of these rifles in vintage competition? Because of the crude barleycorn front sight and v notch rear, older shooters find the sights to be very difficult to use. The interested reader is referred back to Volume III, # 3 for the article "Competitive Shooting with the Open Sight". By the suitable use of an orthoptic on one's glasses, this problem can be largely resolved. One aspect of the sight that should not be ignored is the flat .050 top surface of the front barleycorn sight, ensuring that it has shape edges will help with sight alignment.

Of course in order for the orthoptic to work throughout all stages it requires the shooter to maintain a similar head position on the rifle stock. Here the shooter of average build between 5' 7" and 5' 10" is going to find that the German stock design has some utility, as with relatively little practice he will discover that the German stock design aids in achieving this, especially if he adopts some of the positions taught in the German marksmanship manuals of the period. In particular a light stock weld in comparison to US practices seems to help in all positions. Individual shooter body structure may negate this, so the shooter is left to his conscious and inventiveness for position refinement.

While the German Soldat was taught to use the rifle san sling support, most competitive shooters prefer the use of one. The side mounted narrow sling of the Kar98K is not ideal for this, but most find that with a little bit of effort it can be configured quite comfortably as a hasty sling, as long as the shooter utilizes what would be considered to be light sling tension as compared to common US competitive practice. The essence of the principle being that the rifle must be steady in the position without the sling, the hasty sling being used to just slightly tighten up the position and by so doing remove that small degree of wobble present. This takes some getting used to by a shooter trained in the standard US positions, but once mastered is quite sufficient to shoot cleans on the 3.5 moa SR center.

One final area that the competitive shooter who is serious about competing with the Kar98K might want to consider is the trigger. In general the K98K seems to have a heavy pull, and in examples that have mismatched or force matched bolts some creep and grittiness. This can be cleaned up by the least mechanically inclined shooter through the use of a small amount of JB bore cleaner. Placing a small amount on the trigger sear and bolt sear surfaces, dry firing between 20 and 40 times will result in a smoother, creep free trigger. If the shooter uses a firm grip, as is required with the lesser stock weld supported position, one will find that such a trigger is good enough for vintage competitive use.

The last question of course is "why bother when one can shoot the K31, Swede model 96 or better yet, that superlative example of rifle technology that is the envy of the western democracies, the Short Magazine Lee Enfield and its derivatives?" The answer is as follows: The Kar98K rifles in the US are but the detritus of battle taken from the defeated Hun. In that defeat much of the knowledge of the finer points of this rifle's accuracy potential were lost. What draws people to vintage rifle shooting is the limits of the sport, attempting to extract the best performance out of a stock item. A correctly assembled Kar98K with appropriate ammunition is a fine choice for a vintage match shooter, and one that offers the shooter an opportunity to make use of all of his mechanical, handloading and shooting skills.
source of quote: https://forums.gunboards.com/showthread ... 8-accurcey
To old to fight and to old to run, a Jar head will just shoot and be done with you.
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