Herter's .308 steel cased ammo failure (ruined my rifle)

[Slamfire]

Case head separation or rupture is exactly what you get with excessive headspace, it's the classic sign.

When a cartridge is fired, the thinner parts of the case expand, gripping the chamber walls. At the back, where the case is thicker, it can't expand easily so it stretches to the rear. Normally the bolt face limits that rearward movement. If the headspace is too long that rear movement will go beyond the limits of the case's ability to stretch, and it will rupture. And, since the base of the case is not in contact with the bolt, you get the primer pushed out then flattened since there is nothing back there to stop it initially, if at all.

These are classic signs of case head separation. Stretching in the side wall. Cases are a lot thinner and weaker in the sidewalls.

The extractor groove has lots of brass. So why should the thickest, strongest part of the case break first, if headspace is the issue

 

[FlyinBryan]

yep. what slamfire said.

looks like defective case more than a headspace issue to me.

texas rifleman is correct that case heads will seperate with excessive h.s., but not where 1k's photos suggest.

 

[jungle]

I agree with the above two posts in that a head failure in the extraction groove is not normal, but how do you explain the backed out primers in the other cases and how do you account for the case heads movement out of square on the failed example-where did that head find room to move? If not in excess headspace, where?

A look at sectioned steel cases will show you more of a 90 degree corner at the base of the inner shell cavity. A section in this case might prove enlightening.

Whould you really continue to shoot this rifle without a headspace check?
Do you feel lucky?

 

[Maverick223]

[Would] you really continue to shoot this rifle without a headspace check?
Do you feel lucky?

Exactly. If it were an autoloader it would be a more complex diagnosis...but this one is simple: Unless you can manage to make that bolt move mighty fast (I'm being facetious), the primers have nowhere to go in a properly headspaced manually operated rifle. Be it the only problem or not, headspace is almost certainly an issue (unless the cartridge case was improperly sized/formed and I highly doubt that). I'd be willing to bet that a thin washer could fit between a loaded cartridge and the breachface.

Time to check the headspace followed by an order for a bolt head a little larger.

 

[1KPerDay]

I can't check headspace until the bolt head is fixed (or whatever's blocking it) as noted... so the question is moot. Based on what I've read I'm pretty confident the headspace will be (would be) close to max or above. However, I'm not convinced that the case failure was caused by excessive headspace. It seems to be in the wrong spot. But I guess it doesn't matter, as either way my rifle is out of commission.

That's a good idea about a cross section... I'll see if I can figure out how to do it without cutting my fingers off.

 

[Jeff F]

Well you have an Enfield that probably has a generous chamber to begin with, head space is probably on the long side but still in Mil Spec and your shooting steel cased ammo. Probably not a good combination. Steel is not going to stretch like brass. I shoot a couple of No4 Enfields in .303 and have had a number of case head separations but they have never done any damage. I'm curious as to what was damaged keep us updated.

 

[TexasRifleman]

The extractor groove has lots of brass. So why should the thickest, strongest part of the case break first, if headspace is the issue

Again, because we also have primers not flush with the pockets which indicates the brass was not contacting the bolt face when fired, only slammed back into it later. That means there was some extra room from something, and it's important to not ignore that and go straight to the case itself being a problem.

Remember also this is not brass ammo, this is steel cased ammo which does not stretch as well as brass.

If this was brass as in your picture, and no primer indications, we wouldn't be as suspicious of headspacing, but we have TWO indications of headspace, which means it's worth looking into.

As I said, it may not be excessive headspace alone but there is enough evidence to suggest it at least contributed to this and shooting a rifle with those indications might not be safe.

 

[rikman]

I'm a relatively new reloader and not a gunsmith...but based on your excellent pics and before I read others posts, I guessed excessive headspace as a most likely culprit. Glad you guys are ok.

Rikman

 

[1KPerDay]

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=487530&catid=5830

according to numrich, the NO 1 MKIII, and NO 2A MKIII have the same bolt head... isn't the No 1 MKIII a .303? Can someone please confirm they use the same bolt head?

 

[OhioChief]

I'm not sure why you ask a great question, then not listen to the really great answers. Ya gotta head space problem! maybe other things, but that's your biggest one.

 

[Maverick223]

according to numrich, the NO 1 MKIII, and NO 2A MKIII have the same bolt head... isn't the No 1 MKIII a .303? Can someone please confirm they use the same bolt head?

Not certain, but I believe the extractor is the only difference. The bolt head should be the same. However, you really need to find and fix the problem with your existing bits and get the rifle to function on some level (without firing) in order to determine which bolt head you need for proper headspacing as well as identify what the inherent problem is to compile an accurate parts list (could need more than just the bolt head, or perhaps no bolt head at all).

 

[Slamfire]

Again, because we also have primers not flush with the pockets which indicates the brass was not contacting the bolt face when fired, only slammed back into it later. That means there was some extra room from something, and it's important to not ignore that and go straight to the case itself being a problem.

Remember also this is not brass ammo, this is steel cased ammo which does not stretch as well as brass.

Could be an indication of low pressure. The primer backs out on ignition. Then if pressures are high enough, the case stretched back to the bolt face stuffing the primer back in the pocket.

If pressures are not high enough to stretch the case, the primer stays backed out.

Could there be excessive headspace, yes. But backed out primers are an indication of low pressures.

 

[1KPerDay]

I'm not sure why you ask a great question, then not listen to the really great answers.

What makes you think I'm not listening?

Have you read my replies? I believe there is a headspace problem. I'm trying to get the rifle running so I can check it.

What am I missing here?

 

[1KPerDay]

Well I removed the extractor and the bolt closes perfectly. You smart folks that suggested it may have been the extractor... thank you.

I can't see any damage to either the extractor or the bolt head, other than some scorch marks... There is a noticeable "groove" in the rear of the barrel, in the extractor channel, that looks like the tip of the extractor is hitting and (I assume) getting hung up, rather than springing outward as it should.

I can't figure out why this would have changed due to a case failure; I suppose it may be coincidence.

I also assume that extractor ramp could be polished a bit to remove the 'step' caused by the nose of the extractor?

I also assume that it may feed properly with rounds in the mag, rather than closing the bolt without a case in place. But I haven't tried that yet.

I definitely will not fire this rifle again without it being checked for proper headspace (7.62X51) and I'm going to stick with lighter handloads and/or 7.62x51 BRASS ammo (assuming headspace is within specs).

Thanks to all, again, for your excellent feedback and advice. And let me know what you think about the extractor ramp, etc.

 

[buckfynn]

I've also read quite a bit of very passionate stuff here and elsewhere saying that .308 and 7.62 are identical for all intents and purposes.

Nope, not true. Read the articles in the links below to see the differences between the NATO 7.62X51 and .308 Win.

7.62x51mm NATO or 308 Winchester? What's the Difference?

And also.

.308 Win vs. 7.62x51--The Straight Scoop
Before we go much further, we want to address the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge.

http://www.6mmbr.com/308win.html

 

[Maverick223]

The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi.

That is just further proof that someone failed basic reading comprehension...NATO is measured in CUP (copper units of pressure) NOT PSI. The pressure (when put in the same units of measure) is near identical (as it was designed to be when Winchester asked to make a commercial copy of the 7.62NATO), the ONLY difference is the thickness of the brass. SAAMI says the two are completely interchangeable, but what do they know about sporting arms and ammunition?

 

[buckfynn]

I was pointing out the difference in head space between the NATO 7.62X51 and the .308 Win which could very well cause the problems the OP encountered.

...the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge.

 

[1KPerDay]

Yeah, but you also said this.

The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi.

I personally think the case failure (where it occurred) was ammo related. However, I also think the evidence so far suggests the rifle has generous and/or excessive headspace, which MAY have somehow contributed to the case failure (hard to say exactly, but it can't help).

It was my fault for not checking the rifle for headspace beforehand. But I still feel the case shouldn't have failed where it did. In case the .308/7.62 issue is indeed an issue in this rifle, I'm going to avoid shooting factory-loaded .308 in it in the future. 7.62 is generally cheaper anyway, and I can always handload lighter loads.

Anyone know a good source for enfield bolt heads?

 

[Maverick223]

I was pointing out the difference in head space between the NATO 7.62X51 and the .308 Win which could very well cause the problems the OP encountered.

They even misspelled SAAMI, that alone makes it a worthless source for gathering reliable information IMO. As far as the difference in chamber specifications, as I said before that changes in accordance to the firearm. A MG will have a very large clearance, a standard FA/SA autoloader will have a generous headspace, and a sporting bolt rifle/sniper rifle will have a tight headspace for precision. There is no clear-cut standard that every NATO/SAAMI chamber religiously follows.

Now back to the topic at hand...

1KPerDay, I think you are on the right track with reshaping the extractor groove (which was, in my unprofessional opinion, the result of escaping superheated gases cutting their way through the point of least resistance while exiting the breach), but it is a heck of a difficult place to get to with a dremel (or other similar grinding tool). Take it slow and easy and it will probably turn out okay. I, not having performed any work like this, am eager to hear how it does, but believe it to be at the very least safe (just wonder if it will work properly post-reshaping).

I personally think the case failure (where it occurred) was ammo related. However, I also think the evidence so far suggests the rifle has generous and/or excessive headspace, which MAY have somehow contributed to the case failure (hard to say exactly, but it can't help).

Headspace is almost certainly an issue, but I suspect you are right about the case. That said, the case will likely rupture on the exposed/unsupported part of the case (which stretches too much; something easy to do with steel cases), despite the thicker brass (in your case malleable steel) in this area. If you would like, you can send me the case and I'll section it for you so you can see what was going on inside (PM me for details). Running a bent paper clip (to feel for grooves/malformation/anomaly) inside it might also tell you if there is a deformity in the case.

Anyone know a good source for enfield bolt heads?

Try the guys mentioned in this handy list.

 

[jungle]

"Well I removed the extractor and the bolt closes perfectly. You smart folks that suggested it may have been the extractor... thank you.

I can't see any damage to either the extractor or the bolt head, other than some scorch marks... There is a noticeable "groove" in the rear of the barrel, in the extractor channel, that looks like the tip of the extractor is hitting and (I assume) getting hung up, rather than springing outward as it should.

I can't figure out why this would have changed due to a case failure; I suppose it may be coincidence.

I also assume that extractor ramp could be polished a bit to remove the 'step' caused by the nose of the extractor?

I also assume that it may feed properly with rounds in the mag, rather than closing the bolt without a case in place. But I haven't tried that yet.

I definitely will not fire this rifle again without it being checked for proper headspace (7.62X51) and I'm going to stick with lighter handloads and/or 7.62x51 BRASS ammo (assuming headspace is within specs).

Thanks to all, again, for your excellent feedback and advice. And let me know what you think about the extractor ramp, etc."
1KPerDay

Now that you have isolated the problem to the extractor you would do well to remember the axiom that one should always fit the cheapest part. Keep that dremel away from the extractor groove.

It is likely the gas changed the shape of the extractor in a way you can't detect, would it not be better to reshape the outer forward edge of the extractor until it fits? It looks as if the area to be altered is now clearly marked for you.
You may not need a new bolt head, headspace is best measured without the extractor in place.

The extractor on the 7.62 version is different than the .303, and you may end up having to alter a .303 extractor to fit in any event.

If the chamber is cut too deep, a bolt head won't fix it. People who did it for a living used a lathe to turn back the barrel breeching surface, a breeching washer and/or possible rechambering.

Go here and scroll down to the articles on breeching up and cartridge headspace. This gentleman knows his stuff and all of his articles are worth reading if you are an Enfield fan. http://www.milsurps.com/showthread.php?t=16948

 

[1KPerDay]

Thanks. The reason I was thinking of trying to polish the extractor groove is that I can see a visible "dent" there where the tip of the extractor is contacting it... but I suppose it's possible that it's just normal wear, and with an in-spec bolt head and extractor it may not be an issue. I cleaned and reassembled the bolt head today and it does the same thing... the pointed tip of the extractor seems to be contacting the rear of the barrel inward of the extractor groove.

As I suspected, it does chamber and close properly with a case in place (to hold the extractor away from the bore far enough to contact the ramp/groove properly).

You who have suggested the extractor may have changed shape due to gas contacting it have me thinking... I wonder if the escaping gas may have 'bent' it or heated it so the spring tension could push inward on the tip and reshape it or something... or perhaps the gas merely blew the cosmoline/crap out from the bolt head innards near the extractor, which allowed the extractor to move fully inward for the first time, where it may not have been able to before due to crud or something. I'd never disassembled the bolt head before.

In any case, thanks again for your excellent advice. I'll let you know what I find out if I can track down a set of headspace gauges.

Maverick, I may take you up on that offer to section the case (and maybe one of the others that didn't rupture but has obvious "stretch marks" and primer backing).

 

[SaxonPig]

Herter's went under 40+ years ago. How old is that ammo, anyway? Where was it manufactured? I associated steel cased ammo with China.

 

[Jeff F]

Herter's went under 40+ years ago. How old is that ammo, anyway? Where was it manufactured? I associated steel cased ammo with China.

Herter's is re boxed Wolf ammo made in Russia, anyways their .223 and 7.62x39 is. Cabela's sells a lot of it and I have shot a few thousand rounds of their .223 with no issues other then some rounds that had their primers set in sideways.

 

[Maverick223]

Maverick, I may take you up on that offer to section the case (and maybe one of the others that didn't rupture but has obvious "stretch marks" and primer backing).

No problem, PM inbound...

 

[marinville]

Herter's is re boxed Wolf ammo made in Russia, anyways their .223 and 7.62x39 is. Cabela's sells a lot of it and I have shot a few thousand rounds of their .223 with no issues other then some rounds that had their primers set in sideways.

Actually it's re-boxed Ulyanovsk, not Wolf.