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IMR-7383...don't overlook this powder

Posted: Sat Jun 09, 2018 6:08 pm
by Rapidrob
IMR-7383 or RAD-78 was used in the ,50 caliber spotting gun used to zero the 105mm Recoilless Rifle. The powder is a medium slow powder and not a .50 BMG powder.
Over the years this powder has proven to be outstanding in many centerfire cartridges. It is easy to light and even in my desert climate seems to be very stable.
The powder loves an over-bored cartridge with a heavy bullet. The 6.5 Swede and the 7.5 Swiss are my most accurate cartridges using this powder. ( 2-3 MOA at any range)
A few of the small bore calibers do very well. .22-250 is a great cartridge for this powder. So far, I have not found a military caliber of .264 or larger that does not shoot well using this powder*. Are there cons using this powder, yes but their not that bad as long as you remember what they are.
Never TIGHTLY compress this powder. A mild compression is fine. Crushing the powder grains is a no-no. Doing so and pressures will go through the roof.
Use a heavy bullet. In .30 cal rifles, 150 grain is OK, 175 grain is awesome.
Same in your Russian or English rifles.
Large bore rifles with a heavy bullet do well with long bullets. You may have to use a filler in some cases to prevent a flash-over .
Many cast bullet loaders have had good luck using this powder.Once you find your pet load, do not change it. Going one full grain over could get you into trouble.
You will know when you found the "sweet Spot" load as the fired case will have no soot on the case neck. Primer will look normal.
Recoil will feel the same as will the rifles report.
Can you use it in a gas-gun? Yes. But it depends on the gas system type. The dwell time is just slightly long. But not so long as to do damage with a NORMAL load.
My Jlungman AG-42B loves this powder. The brass is not damaged at all and the bullet is hauling butt.
Really large cases using this powder will not have 100% case density. Because of this accuracy will be very good but not outstanding. You'd think you could fill the case with powder. Not true. After 70 grains of powder has been loaded,the pressure curve really goes off the chart. Rifles where I could Load 90 grains of powder went nuts after 72 grains.
Burn rate started to increase and pressures wanted to spike.
So far I have loaded:
.22 PPC ( over bore caliber)
6.5 Jap
6.5 Carcano
6.5 MS
6.5 Dutch
6.5 Swede ( over bore caliber) this caliber is stupid accurate using this powder.
.25-06 with a 120 grain bullet load is just nuts. Another perfect cartridge for this powder.
7mm Mauser ( 160 grain bullet is hard to beat)
7.5 Swiss- WOW! a 175 bullet is amazing with this powder.
7.5 French has not been tried due to their light normal bullet.
,30-40 Krag w/ 220 grain RN bullet, is amazing.
7.62x51 / .308 with 175 grain and a good crimp is a very good accurate load.
.30-06 with 175 does very well. I do not recommend it for the M1 rifle though. You decide. Some shooters swear by it.
.303 Britt with 175/80 grain bullet is a very good shooter.
7.65 Argy Another WOW loading with a 170 grain bullet
7.62x54R- This cartridge eats this powder up. With the "Heavy Ball" bullet in a Mosin is a very good loading. Very clean burning. I do not feel it is safe fired out of the SVT-40 rifle. Dwell time is too long for this rifle.You will get powder bast in the face. PSL with a 150 grain bullet is OK to use.
8mm Mauser with a 198 grain bullet is crazy accurate.
8mm Lebel is another great cartridge for this powder
8x56R is another "why didn't I try this before" cartridge. With a 208 grain bullet it is sleeper shooter. In the long barreled rifle the powder really gets the bullet moving.
The powder is not a " fire ball" thrower. Even in carbines.
The powder is cheap to buy. It is much faster than .50 BMG powder,do not substitute it for a .50 BMG loading.
* many reloaders have used this powder from .17 on up with good results. I'm not crazy about it out of an AR15 but guys using a HK love it.
I have many loads for this powder. I have not had any "bad things" happen to any of my brass or rifles using this powder with my loads.
Guys have pushed beyond safe loads and damaged their rifles. This powder is no more "scary" than H-335 or IMR-3031. Push them,compress them and bad things happen.
Try this powder. It works well. More bang for your buck.

Re: IMR-7383...don't overlook this powder

Posted: Sat Jun 09, 2018 9:35 pm
by professrh
I'm glad to see this post! I experimented some with 7383 back before the site went down, and had great results with 8x57 and 7.62x54R. Had some fun with 8x89R, too.

Other hobbies have been usurping my reloading time lately, but I do plan to do some new tests with 7383 this summer: 7x57 and 175-grain RNSPs, 7.5x55 using 180-grain PSPs, Speer 200-grain PSPs in 8x57. I also want to refine my 8x56R load with this powder in anticipation of tricking out my m95 with Mojo Sights for hog hunting.

Thanks for posting this, Rapidrob.


Re: IMR-7383...don't overlook this powder

Posted: Sun Jun 10, 2018 5:43 pm
by Rapidrob
I just fired 100 rounds of 6.5x55mm Swede out of my Jlungman rifle. I'm using the Privi 140 grain SPBT bullet over 37 grains of IMR7383. The load is very accurate and clean burning. No unburnt powder is left in the bore. The load is very good in the rifle and carbine.

Re: IMR-7383...don't overlook this powder

Posted: Thu Jun 21, 2018 10:02 pm
by jardows
Having trouble finding places online that are selling this. Do you have any good links or sources where I could buy it to try?

Re: IMR-7383...don't overlook this powder

Posted: Fri Jun 22, 2018 11:07 am
by Rapidrob

Re: IMR-7383...don't overlook this powder

Posted: Fri Jun 22, 2018 6:31 pm
by Smokey
Rapidrob, I might try your supplier, being a disabled vet.

I've bought a lot of stuff from this guy and been happy with him: