Lee Enfield headspace issues

[msuspartan]

Bought a SMLE no1 mkIII for my son. everything works well BUT a couple of rounds, .303 British, were split around the base. It had a headspace gauge on it but......
Also the person I bought it from thought but was not certain, it may have been rechambered in .308. Did not find any proof there.

From what I have read and researched it may be a headspace issue. Looking for a gunsmith or experienced Lee Enfield person to help out. Thoughts and advice are appreciated.
PM me please if you are gunsmith familiar with Enfields, Thank you.

 

[Wolfhound]

It might help to list what ammo you were shooting and pictures of the split brass if possible.

 

[msuspartan]

It might help to list what ammo you were shooting and pictures of the split brass if possible.

Thank you and updated the post.

 

[Wolfhound]

I will wait for others to respond but that looks like typical case head separation. Usually the result of reloading rifle brass too many times. Where did you get the ammo?

 

[jcj54]

The Enfields headspace on the case rim. A .303 headspace gauge is required to properly determine headspace. This was enough of an issue that various length bolt heads were made to bring headspace into tolerance. If your ammo was new manufacture it is likely a rifle problem. If it is old military surplus it may be brittle cases. If it is old surplus ammo it may be corrosive primed as well.

 

[Basher]

I seem to recall reading about folks using paper shims to check headspace, the idea being that you use them to see how much excess headspace you may have. You remove the firing pin from the bolt, insert a cartridge, then insert the bolt back into the receiver, adding one shim at a time until you feel light resistance while fully closing the bolt handle. Once you get that resistance, you use calipers to measure the stack of shims, and there’s a spec for what’s allowable. Then swap bolt heads until you’re in spec.

All of this assumes the chambering is correct, though I think you’d have a hard time closing the bolt on a .303 if it was rechambered to .308, and you’d see a much sharper shoulder on the fired case. That, and with .308 being shorter, you probably wouldn’t have seen the case separation you have there. My money’s on excess headspace. What number is stamped on the bolt head? It should range from 0 to 3.

 

[Wolfhound]

Here is some relevant info on Enfield headspace and how to measure it.

How to Properly measure Enfield 303 Headspace

Lots of research went into this and finally I have found the way to do this. First SAAMI specs are too tight from and always have been. This has been stated by numerous Enfield experts and differ from the arsenal specs given by the manufacturers of Enfields. That being said the proper...

forum.full30.com

 

[Basher]

Here is some relevant info on Enfield headspace and how to measure it.

How to Properly measure Enfield 303 Headspace

Lots of research went into this and finally I have found the way to do this. First SAAMI specs are too tight from and always have been. This has been stated by numerous Enfield experts and differ from the arsenal specs given by the manufacturers of Enfields. That being said the proper...

forum.full30.com

Hey, I was pretty close lol! I forgot you remove the extractor, not the FP. And the idea of using some solder as a compressible shim kind of like a plastigage is much better than fiddling with pieces of paper, too!

 

[92FSTech]

Is that factory ammo or a reload that experienced the case head separation? Enfields are notoriously hard on brass. The bolt has it's locking lugs at the rear, so the brass can stretch to fill any space produced by flex along the entire bolt body when fired. If it's doing that to factory ammo with brand new brass, I'd say you have a definite headspace problem with your rifle. If it's a reload, more than likely it's just an Enfield being an Enfield.

I've found that I absolutely have to neck-size for mine, and keep brass specific to each rifle, otherwise I was only getting one or two full-power reloads per case before it started doing exactly what yours did. I've also started shooting mostly light, powder-coated and gas-checked cast-bullet reloads through them in order to maximize my brass life. .303 brass is hard to find and expensive.

 

[msuspartan]

I will wait for others to respond but that looks like typical case head separation. Usually the result of reloading rifle brass too many times. Where did you get the ammo?

Brand new ammo, no reloads. From what I have gathered it is headspace but fixing is another thing.

 

[msuspartan]

I seem to recall reading about folks using paper shims to check headspace, the idea being that you use them to see how much excess headspace you may have. You remove the firing pin from the bolt, insert a cartridge, then insert the bolt back into the receiver, adding one shim at a time until you feel light resistance while fully closing the bolt handle. Once you get that resistance, you use calipers to measure the stack of shims, and there’s a spec for what’s allowable. Then swap bolt heads until you’re in spec.

All of this assumes the chambering is correct, though I think you’d have a hard time closing the bolt on a .303 if it was rechambered to .308, and you’d see a much sharper shoulder on the fired case. That, and with .308 being shorter, you probably wouldn’t have seen the case separation you have there. My money’s on excess headspace. What number is stamped on the bolt head? It should range from 0 to 3.

According to Lee Enfield people it is on the mk4's and the Mk3's have no number. I wish it did as getting one would be easier...lol

 

[msuspartan]

Is that factory ammo or a reload that experienced the case head separation? Enfields are notoriously hard on brass. The bolt has it's locking lugs at the rear, so the brass can stretch to fill any space produced by flex along the entire bolt body when fired. If it's doing that to factory ammo with brand new brass, I'd say you have a definite headspace problem with your rifle. If it's a reload, more than likely it's just an Enfield being an Enfield.

I've found that I absolutely have to neck-size for mine, and keep brass specific to each rifle, otherwise I was only getting one or two full-power reloads per case before it started doing exactly what yours did. I've also started shooting mostly light, powder-coated and gas-checked cast-bullet reloads through them in order to maximize my brass life. .303 brass is hard to find and expensive.

The other issue is how to find out if it is .308 as many were rechambered but not sure where that would be found.

 

[Squirt239]

The other issue is how to find out if it is .308 as many were rechambered but not sure where that would be found.

Calipers to measure the muzzle

 

[jcj54]

.303 cannot fit in .308 chamber .308 case length is 2.015 and .303 is 2.222.

 

[92FSTech]

The other issue is how to find out if it is .308 as many were rechambered but not sure where that would be found.

Re-chambered or re-barelled? I know the Indians made some SMLEs chambered in .308/7.62 Nato, but I've not heard of anybody re-chambering a .303 rifle to .308. I supposed it could be done, but you'd need some kind of machined insert, and the bore diameter would still be wrong as .303 is .311" (and many are even larger...I have a couple that are as wide as .314"), while .308 is, well, .308".

Regardless, you're not getting the bolt closed on a .303 Brit round in a .308 Win chamber. It's just not dimensionally possible. In the pic below, that a .303 Brit on the left and a .308 on the right. If by some miracle you did manage to force the bolt closed and fire it, your brass would have come out looking much different than your pic above!

 

[Greffy]

I also have a 1918 Enfield and have pondered the 'loose' chamber thing. They have loose chambers because wartime ammo (WW1) had a tendency to not be made to specifications. The workaround was to make the chambers sloppy to work with the potentially 'bad' ammo. Haven't got to it yet, but I've thought about taking new brass and expanding the necks to .35 cal and then slowly form the necks back to the .310-.311 size to fit the chamber well. Fortunately my rifle has not ruined the cases (PPU) on the few that I fired to check rifle for function. BTW, it is recognized that S&B ammo is particularly prone to poor brass performance with many reports of case head separation on the first firing. I have other 'wild'($) ideas to make brass that fits the chamber, but....

 

[Stengun]

You can fire form brass to Chamber. The headspace problem goes away for that combination of brass and chamber

I have quite a few enfields so that is not practical for me.

I have had a number necks and body splits on the brass over the years. A few primer leaks but not many

 

[Squid556]

I really love enfields… but honestly their bolt / headspace arrangement is a dumpster fire. Theres multiple variables going on in there.

Headspace tends to grow slowly on enfields. Very unlikely a spare bolt head will work properly. They have to be clocked correctly as well as be the right length. Otherwise headspace will grow much faster.

I’ve learned it may be best just to send it to someone who’s got the info to fix it right. I’ve had some correspondence with this fella. He seems to be one of the few enfield experts stateside.

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