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Using another bolt assembly to fix headspace?

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Kurt
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Using another bolt assembly to fix headspace?

#1 Post by Kurt » Tue Jul 25, 2017 3:29 pm

Please discuss how trying another bolt in a No4 Mk1 to remedy headspace issue could be or likely be problematic. Thank you

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Re: Using another bolt assembly to fix headspace?

#2 Post by DaleH » Tue Jul 25, 2017 5:26 pm

FWIW a friend is going through this (has a #3 bolt, wants a #4, but can't find one ...) and from reading on here and other milsurp or Enfield-specific sites, they advise to replace the bolt body, as those have been proven to 'shorten' through 1,000s of rounds (their position - not my words, just going from recollection here).

Have also read that if you use the O-Ring trick to blow the shoulder forward on new/newer brass ... that you may not need to be concerned about it.

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Re: Using another bolt assembly to fix headspace?

#3 Post by Tommy Atkins » Tue Jul 25, 2017 6:10 pm

The originals were (to a point) hand-fitted to individual receivers. This was one reason for the need for matching serial numbers.
Assuming you swap a bolt body (for a No4 the No1 is a little different). If the "old" bolt is too short you could try fitting a longer one as a remedy, BUT this might change the other fitting points meaning a cascade swap!
There are 3 critical fitting points:

The bolts recoil lugs, 2 of them. They need to be both equally engaged so they share the firing stresses as designed. This is done by stoning the bolts rear faces of the lugs & using "dykem" engineers blue or something similar to show the contact & removal areas.

The bolt head has to "clock" (rotationally position) correctly so the shoulder takes the firing shock, not the screw threads.

The bolt HEAD has to be the correct length (noted by numbers 0~4) to set up head space to less than 0.074". NOTE: bold HEADS are numbers 0~4, not bolt bodies, you have to mic them.

The firing pin at rest must protrude between 0,040~0.050".

Now it gets a tad tricky.
As you stone the locking lugs the bolt can seat further back, this changes head-space & protrusion slightly.
Now you may need to change the bolt head to remedy this, but it must also clock correctly.
Finally you adjust the firing pin for correct protrusion.

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Re: Using another bolt assembly to fix headspace?

#4 Post by Kurt » Tue Jul 25, 2017 8:06 pm

Thanks for the replies and information. I thought there was more to it and quite a bit more! Thanks again.

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Re: Using another bolt assembly to fix headspace?

#5 Post by 72 usmc » Wed Jul 26, 2017 8:59 am

If your bolt matches I would switch the bolt heads and then it may take 5 or so to find one that actually times in. Not all bolt heads are the same measurement, you can actually find a #2 that is longer than#3. The rifle may just be too far gone and you have to set the barrel back. At one time there was a chart showing ranges in bolt head size. Lost in the old forum???? So if you get a longer bolthead and it measures what you may need; it most likely will not/does not time in correctly. That is bad news. So it is a costly adventure. I would headspace the rifle and see if it passes on a FIELD gauge if it does you are ready to go. Leave well enough alone. If it fails, you can fire form brass for that rifle and reload those boxes and then just neck size the reloads. If I had a common dog Enfield that did not headspace i'd dump it on a dealer and buy a matching bolt, Enfield that you headspaced with a FIELD gauge prior to its purchase so you are not stuck with a dog. Even a bolt that already times in, may take 2 or 3 to get the rifle to headspace and have contact with the lugs. At $80-100 per bolt????? If it takes that much work and it a treasure I would let a gunsmith mess with it so all is correct-- but I bet that is going to be around $200-300. Hence, always headspace an Enfield prior to purchase to have a nice problem free shooter. Parts like boltheads are no longer $10 bucks each when us old guys had a cigar box full to fit and find a larger head. Some guys will tell you headspace does not matter???? But I always test rifles with FIELD gauges prior to purchase; why buy a dog when you can pay the same price and get a surplus rifle that passes a FIELD test. Lots of luck on your adventure-- a nice but expensive learning process.
Last edited by 72 usmc on Wed Jul 26, 2017 11:20 am, edited 2 times in total.
To old to fight and to old to run, a Jar head will just shoot and be done with you.

72 usmc
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Re: Using another bolt assembly to fix headspace?

#6 Post by 72 usmc » Wed Jul 26, 2017 9:05 am

To old to fight and to old to run, a Jar head will just shoot and be done with you.

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