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Are mismatched bolts a safety issue in a Lee Enfield No 1 MK3?
I know mismatched bolts reduce the collector value, but assuming the headspace checks out are they safe to fire? Are there any safety implications?
I want to buy a friend's rifle as a shooter, but I need to check with you experts first.
Any advice would be greatly appreciated!
Thanks.
Smoothbore
Hi Smootbore,
Good question about the mismatch of an bolt.
First the easy part: yes, if the headspace is correct then the rifle is safe to fire.
Now the difficult part: who checked the headspace after installing the "new" bolt? Only an qualified armourer should do these sort of things!!
Presuming that the new bolt was checked/installed by an qualified person you can always ask your friend to show you some empty cases. If they are fine, and not bulged (I hope I spelled it right) then you have an good indication of the headspace.
You have to imagine that most of the rifles we buy are mass produced. The factory just took an reciever, barrel and bolt+bolthead (with the correct headspace) and put them together. So almost all of them are interchangable.
There are an few Enfields on the lose that have not interchangable parts but they are marked ith an A in thier serial number.
Do a search for the phrase "headspace" on here. There are a number of threads relating to discussions about it on Enfields specifically.
Also, Parashooter published a good article in the Technical Articles for Milsurp Collectors and Re-loaders(click here)
Headspace 101 for .303's (click here)
Regards,
Badger
Hi Guys,
Good article on head spacing and it explained a few things in a slightly differant manner to what I have been thinking of.
I have another quirry similar to Smoothbores.
I have seen several shell cases (not all) from a mates No1 Mk3 that show very fine cracks about 2 to 3mm long and a bee's pecker wide, running parrallel with the case. these cracks appear just were the shoulder starts to roll over and down to the projectile.
There is no sign of the stressing spoken about in the above article back further along the case, only the cracks at the front.
I always assumed this sort of case damage was attributed to head spacing, ie the case moves back in the chamber the shoulder distance is increased and when the case expands after firing it stretchs beyond its brittle failure point and the cracks appear.
but if I reading the article above correctly its saying the for end of the case should be locked in place by the expanding cases contact with the breach at the point of detination, which means the case couldnt slide back and open up the gap enough for the cracks to develope as I had been thinking.
if that is indeed the case than maybe my friends rifle has a more serious problem, like excesive were, which accounts for the expansion failures I'm speaking of??
to look at it by eye, all looks to be in pretty good shape, no pitting etc.
any thoughts most welcome,
regards Rob.
PS using 1940's and 1950s surplus mil ammo, and the rifles certified for the later ammo (HV stamp on barrel).
OK, here's the best answer from this thread. Bring the gun to your local gunsmith. Most smiths will pop in a gauge and check your headspace for free. If there's a problem, however, the fix won't be as cheap ;)
I would suspect that longitudinal cracking in the shoulder area is an ammunition issue. The ammunition showing these cracks after firing is 50-60 years old. Does it happen with fresh commercial ammunition?
Off_Winters... your mate's problem with cases splitting from the shoulder forward is because the brass is too brittle. There has been some milisurp ammo more noted for this than others, but generally it is a storage problem over a long period. I have some cases here that have split the same way and the projectiles fell out without it having ever been near a rifle.
With the "generous" dimensions of an Enfield chamber, it will "work" the brass a lot on firing. They were never designed to be kind to the cases so they could be re-loaded. Compare the length at the shoulder of a fired case to a new one of the same lot. You'll see what I mean. When you realise how far the shoulder gets blown forward, you'll understand why a couple of thou headspace isn't the cause for damaged cases.
As tiriaq suggested, treat yourself to some new commercial ammo and check out the cases.
I cannot understand the rabid fascination everybody has with headspace. It isn't going to blow up if it is a bit out of spec. It isn't going to destroy your cases if it is a bit out of spec. And to look at fired cases for bulges to indicate headspace problems-:slap: ! With the taper of a Lee Enfield chamber, it would need to be 1/4" out of spec to show a visible bulge. What you are seeing is the thin part of the case (just beyond the solid section of the base) expanding to the chamber wall. It may be very slightly larger than the solid part, and will probably show "stretch marks" at this point. This is normal. If the case fails around this line (case head seperation- it WILL happen after enough reloads, but shouldn't with new brass) the brass may be brittle or perhaps the chamber is oversize in diameter- maybe the previous owner polished out some pitting....
Smoothbore, the problem with a miss-matched bolt isn't headspace- headspace can be fixed with a change of bolthead. The problem could be equal pressure on the lugs. On assembly, the bolt body was lapped to the receiver to ensure equal presure on the lugs. Then a bolthead was fitted and adjusted for headspace. Then a proof round was fired- this ensured the rifle wouldn't blow up, but also seated the lugs with the over-pressure recoil. It was then re-checked for headspace, adjusted if needed and sent out.
A missmatched bolt may have only one lug in contact. If so, it will pound that lug with all the pressure untill it allows the other lug to come in contact. This may cause excessive headspace (which isn't a life-ending drama) in a shorter period of time. In extreme cases, if the small lug is in contact, it could shear off. I have only seen one such bolt, and it looked as if the other lug had been ground back. I would suggest you go ahead and use it, but check the lugs periodically. If you are concerned, mark the lug surfaces with a texta, and cycle the bolt a few times to see if the ink is polished off....
In service the rifles were gauged every 5000 rounds or so, with the view to changing the bolthead every 10,000 IF it was needed.
Here's a pic showing a fired case next to a new case from the same lot and a set of headspace gauges. Note the fired case is visibly longer at the neck and shoulder. This is because on firing it has expanded outward and forward to the chamber walls. Look closely- there is a feint line about 1/4" forward of the rim. This is where the stretching begins, and this is where the case will fail eventually after many re-loads. It is not a sign of excessive headspace.