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Posted: 12/30/2004 4:19:51 PM EDT
[Last Edit: 12/30/2004 5:10:47 PM EDT by airbiscuit]
Just got back from the range today with the M1A and had my first (and hopefully last) out of battery failure. The rifle, an SA 38xxx 1986 vintage factory NM, was rebarreled with a Barnett medium weight and this was my first time out with it with the new barrel. I wore the other one out, never a failure, never a problem. Ammo was Radway Green '88 or '85 vintage. The extractor and ejector were blown out and sitting on the shooting mat a foot away. The magazine floorplate blew out and magwell split on all sides like a banana, cutting my elbow through a long sleeve t-shirt. I'm stripping it to figure out what happened. The guy spotting for me looked at the separated case head and said he couldn't see anything wrong with it until I reminded him that a 7.62 NATO is not a belted round. 2004 was not my year for firearms. News at 11............with pics.
Link Posted: 12/30/2004 4:27:21 PM EDT
Damn, atleast you didnt get badly hurt.
Link Posted: 12/30/2004 5:53:18 PM EDT
Happened to me with a 5.56 not too long ago. It was nasty.

-Cap'n
Link Posted: 12/30/2004 6:44:02 PM EDT
So far the autopsy shows the bolt parts apparently OK. The firing pin tail and receiver contact should not allow this to happen unless something is broken. The is a circular broken piece of metal that I am trying to ID where it came from. I think it is a piece of the bolt roller and I'm having a helluva time getting the oprod out. I'll post what happened as soon as I figure it out. Note that that banana peeled mag is STEEL. The sides of the splitting mag are what cut up the back of my arm through my shirt.

Link Posted: 12/30/2004 6:50:30 PM EDT
Glad you are ok!
Link Posted: 12/30/2004 7:03:12 PM EDT
Thanks. It sucked. I had an idea what happened immediately. If I would have been gripping the mag, or a lefty, I would have had problems. Worse than that, a number of fellows at the range had commented favorably on the rifle and hovering about asking questions (McMillan stocked, NM / M25 mods, BPT mount, Leupold LRM3, etc. etc.). How embarrasing. It was partly my bad because you know how you know something is wrong but you don't know what it is? I got that odd, mild feeling an instant before I pulled the trigger. I've always caught such things before, but everything looked good, no real indication, so........It really is a good idea to wear shooting glasses!


Originally Posted By 700_5R:
Glad you are ok!

Link Posted: 12/30/2004 7:07:57 PM EDT

Originally Posted By 700_5R:
Glad you are ok!



That just sucks. Hope you find out what happened, so it won't happen again.
Link Posted: 12/30/2004 7:17:41 PM EDT
glad you are ok. Sucks to have a nice rifle out of commision.
Link Posted: 12/30/2004 9:03:11 PM EDT
Damn man, I'm glad you're allright.
Link Posted: 12/30/2004 9:16:46 PM EDT
What can cause a rifle to do that?
Link Posted: 12/30/2004 9:37:52 PM EDT
[Last Edit: 12/30/2004 9:42:56 PM EDT by airbiscuit]
Thanks guys. Green, it is caused when the cartridge is not fully seated in the chamber, yet the hammer strikes the firing pin causing the weapon to discharge. Thus, the bolt is not locked into the breach and some of the cartridge by the head is outside the chamber. Firing a rifle is simply a controlled and contained explosion which has nowhere to go but to push the bullet down the barrel. In the case of an out of battery (the bolt lugs are not locked into the chamber, and not "in battery") that explosion, which is alot of PSI, gets out quickly and violently and the path of least resistance is usually right down through the magwell and mag. Since the mag was locked in by the catch, it blew 15 cartridges down until the floorplate blew out, with the pressure being sufficient to peel back all four steel magazine walls where the pressure released. When functioning properly, the hammer should not be released until the bolt is in battery, and a portion of the receiver (theoretically) in an M1 and M1A will not allow the hammer to strike the firing pin (it has a tail on it that must clear a cutout inside the receiver) until the bolt and bolt lugs are rotated into locked battery. Something broke here (it isn't the receiver) or lodged in the mechanism which disrupted or over-rode this. It may have been that the roller broker off, allowing the bolt to wobble and have enough play to bounce over the receiver cutout for the bolt / firing pin tail, and/or disrupted the sear. Something is up with the roller because I cannot get the op rod out of its track. It's a crappy feeling right after that happens feeling around to see if anything is stuck in you. Be careful and wear shooting glasses. I wasn't and could have lost my vision. It is very stupid of me not to do so. Life is hard anyway, but it's a real bitch when you're blind. One funny thing was after several rounds this thing blew up and my spotter didn't know it and was looking through the spotting scope telling me "OK go ahead, next shot, go ahead, you can go" and I'm feeling around for shrapnel, feeling my face, counting fingers, and policing up gun parts.


Originally Posted By Green95LX:
What can cause a rifle to do that?

Link Posted: 12/30/2004 10:32:27 PM EDT
All I can say is WOW.

I'm not expert on KB's, but here's a guess: Something in the chamber preventing complete chambering? Check out everything that is inside that barrel.

Link Posted: 12/31/2004 12:22:46 AM EDT
I'm glad that you are OK. I'm going to show this to my son who does not like to wear shooting glasses.
Link Posted: 12/31/2004 4:33:48 AM EDT
Look a bit further than an OOB ignition.

You do not mention the ammunition used. Could be a factor. Also headspace.

Could be an OOB due to a slamfire caused by a high primer, or something wedged in the firing pin hole, including a broken firing pin.

Could be ammo reloaded once to often causing case seperation.

Could also be due to excess headspace.

More than a few possibilities, and I'm only an Armchair Commando guessing.

Glad you weren't seriously hurt.



Lonny
Link Posted: 12/31/2004 4:34:14 AM EDT
Andreuha, yep, could have something to do with the match chamber on the Barnett, but I doubt it. In any event, it SHOULD not have fired until the bolt was in battery. We all have instances from time to time when a cartridge won't chamber fully (reason for a forward assist on an AR, and the heal of your hand on an M1A), but that and something else occurred to allow the hammer to fall on the firing pin. Raptor, I hope it helps him to understand and that he is smarter than me. Your face and eyes are right next to a contained explosion every time you pull the trigger. For the failure of perhaps a cheap bolt roller that lodged in my firecontrol parts I could have lost my eyesight. Even a cheap (I get them free) pair of safety glasses could save your vision.
Link Posted: 12/31/2004 4:44:28 AM EDT
[Last Edit: 12/31/2004 4:45:20 AM EDT by airbiscuit]
Originally Posted By xcpd69:
Look a bit further than an OOB ignition.

You do not mention the ammunition used. Could be a factor. Also headspace.
I mentioned it earlier. Radway Green, '88 date. Always had great results with several thousand rounds of this stuff fired.

Could be an OOB due to a slamfire caused by a high primer, or something wedged in the firing pin hole, including a broken firing pin.
Could be, but we'll never know as the extractor, ejector, were blown out the front (curiously ended up sitting one inch from each other, on my mat, a foot to the immediate right of the breach). The firing pin was blown out the back and held inside the weapon.

Could be ammo reloaded once to often causing case seperation.
Factory, NATO spec, nice brass, anneeled, etc. I will say this, I had already fired about 150 rounds of Portugese NATO, and was only into the third round of RG when this happened, so you may have somthing.

Could also be due to excess headspace.
It was just rebarreled by a well known and very very good smith. I'm not going to mention his name and company as it may have had nothing to do with him.

More than a few possibilities, and I'm only an Armchair Commando guessing.
Me too, but I appreciate your guesses, they are solid and one likely explains it or played a part.

Glad you weren't seriously hurt.
Thanks. Please let your buddies know they need to wear safety glasses.


Lonny
Link Posted: 12/31/2004 6:14:51 AM EDT
[Last Edit: 12/31/2004 7:08:03 AM EDT by airbiscuit]
I think I've ID'd part (or all) of the problem as a short chamber on the Barnett barrel. On a stripped bolt, the Portugese and commercial .308 chambers and the bolt goes into battery fine. Not so on the RG '88. It might need a chamber reaming......................

Update: Bolt and bolt parts removed, no problems, not a broken roller. the KB was DEFINITELY caused by a short chamber in the Barnett barrel in which the RG 88 ammunition will not seat. I used two stripped bolts, both headspaced to this weapon, and neither will close. The cases also exhibit contact points at the mouth and shoulder. The barrel is a .308 medium weight match and undoubtedly tighter and shorter than the RG specs, which was meant for an FN / L1A1, not an M14 or commercial .308. The Portugese FNMI is no problem. The previous barrel was an SA NM and obviously reamed looser for commercial ammo. If you look in the pics there is a little c shaped piece of metal that broke off something and was in the trigger group. I have yet to ID where it came from, but I'm still looking.
Link Posted: 12/31/2004 7:32:21 AM EDT
[Last Edit: 1/2/2005 6:43:06 PM EDT by olephart]
I'm assuming that the gunsmith reamed to chamber to close on a commercial GO gauge. Most of the .308 military surplus rounds that I have measured are .003 to .005 shorter than the headspace dimension found on a military nogo gauge. This is fine in a military chamber. It insures reliability and headspace is well within limits.

I understand you to say that you think the Radway is longer than spec. That is quite possible, but fairly rare. I think it would be worth it to find a case gauge and measure the ammo the see for sure.

When using a custom (non military) reamer, the headspace dimension may be minimum using the HS gauge, but usually the diameter at the case neck and length of the throat where bullet diameter equals throat diameter is tighter/shorter. This may be worth checking.

Using military ammo in a .308 match chamber (cut to .000 headspace on the gauge) will usually result in headspace of +.003 to .005, and the cartridge may be tight (or jam) at the case neck or have premature contact of the bullet at the throat. Often, the force of chambering a semi-auto will force the slightly oversize round into battery.

Match chambers can be just a little tighter in the neck/throat area (like the Wylde 5.56 chamber) or they can be rather precisely fitted for a particular case/bullet combination. Your gunsmith really needs to tell you the max case neck diameter and OAL to bore diameter for your chamber. You can check your ammo to see if it will work in your custom chamber.

You can ream it out to mil spec, and all the surplus ammo should be fine. That would be the end of your "march" grade rifle. Better to find out what your chamber dimensions are and use ammo that fits.
Link Posted: 12/31/2004 7:53:02 AM EDT
[Last Edit: 12/31/2004 7:56:47 AM EDT by airbiscuit]
That's the info I needed Olephart. Many thanks. Looks like RG is out for this, unless the chamber is reamed, which, as you say pretty much nullifies the usefulness of a match barrel. Crap. I've got about a thousand rounds or more of RG left. My SA and Port. chambers fine, as does the commercial. This RG simply will NOT chamber. I don't know that it is bad, just bad for this rifle (much like Sanchez mags + my [name omitted to save this thread] lower). That's why I've got 1000+ of it because it previously worked so well. What are we going to do without Saban and quarterbacks? Run alot I guess Thanks again for the great info and HNY.


Originally Posted By olephart:
I'm assuming that the gunsmith reamed to chamber to close on a commercial GO gauge. Most of the .308 military surplus rounds that I have measured are .003 to .005 shorter than the headspace dimension found on a commercial gauge (specifically the Forester gauge). This is fine in a military chamber. It insures reliability and headspace is well within limits.

I understand you to say that you think the Radway is longer than spec. That is quite possible, but fairly rare. I think it would be worth it to find a case gauge and measure the ammo the see for sure.

When using a custom (non military) reamer, the headspace dimension may be minimum using the HS gauge, but usually the diameter at the case neck and length of the throat where bullet diameter equals throat diameter is tighter/shorter. This may be worth checking.

Using military ammo in a match chamber (cut to .000 headspace on the gauge) will usually result in headspace of .003 to .005, but the cartridge may be tight (or jam) at the case neck or have premature contact of the bullet at the throat. Often, the force of chambering a semi-auto will force the slightly oversize round into battery.

Match chambers can be just a little tighter in the neck/throat area (like the Wylde 5.56 chamber) or they can be rather precisely fitted for a particular case/bullet combination. Your gunsmith really needs to tell you the max case neck diameter and OAL to bore diameter for your chamber. You can check your ammo to see if it will work in your custom chamber.

You can ream it out to mil spec, and all the surplus ammo should be fine. That would be the end of your "march" grade rifle. Better to find out what your chamber dimensions are and use ammo that fits.

Link Posted: 12/31/2004 8:24:51 AM EDT
Don't assume that another batch of SA or Port will be OK. I have seen fairly wide ranging dimensions on military cartridges as to HS dimensions and bullet seating depth from the same manufacturer - all OK in a mil spec chamber. Maybe not OK in a custom chamber. I forget the actual dimensions, but HS in a military chamber is a bit more generous than a commercial chamber. Another factor that indicates caution when using GI ammo in a commercial chamber.

I believe a military round that was in spec and at the greatest allowable dimensions would be a very difficult fit in a minimum dimension commercial chamber. Fortunately for most of us, the military ammo is usually a bit smaller than max spec.

I would check to see just what the chamber dimensions are - you can measure the reamer if the guy will let you. Make a cast if he won't. At least check headspace and OAL for the bullet you are using. You can do that by pulling a bullet, making some slits on the case neck and chambering the round letting the barrel seat the bullet. Remove and measure OAL. This will be the length for that bullet design that touches the lands. Subtract about .010 and use this as the max OAL for rounds loaded with this bullet. That will get you everything you need to know except case neck diameter.

Many times you will get a much tighter chamber than indicated by the reamer specs. That is because reamers cost a lot and people cut more chambers than they should before replacing them. The more they wear, the smaller the chamber will be. I think this is what caused the rash of "tight" DPMS chambers a few months ago.

Link Posted: 12/31/2004 8:29:15 AM EDT
a little longer headspace will not necessarily degrade the accuracy of your rifle. it is not a foregone conclusion.

btw, the firing pin and/or receiver bridge geometry MUST be checked as that was not supposed to happen. you need to pull the powder from some of that RG ammo and try and duplicate what happened with primers and bullets only. a short chamber, by itself, is not supposed to cause a kB.

until you can duplicate what happened, you may never get rid of a certain flinch. I know I could not.
Link Posted: 12/31/2004 8:53:11 AM EDT
I agree w/caser. We are just speculating about the problem. You really need to know exactly what happened or I wouldnt shoot it again. The next kaboom may not be so mild.

The fact that RG would not chamber is a clue, but ya still don't know what the problem is. I'm not sure that it was out of battery. Seems like the bolt would have slammed back causing more damage. Could be a bullet set back with tight neck causing major over pressure or several other things.

Keep us posted.
Link Posted: 12/31/2004 9:19:02 AM EDT
[Last Edit: 12/31/2004 9:34:13 AM EDT by tangeant]
The Hammer on an M14/ M1 cannot hit the firing pin untill the bolt fully rotates into the locked position. The only way the hammer can hit the firing pin out of battery is with both the firing pin toe broken off and the safety projection on the hammer broken off at the same time. Your firing pin looks fine and should have been held back by reciever web if the bolt wasn't in battery.

From the case it looks more like you ran into a RG round with soft/defective brass and had a case seperation with enough residual pressure to blow out the seperated section as it extracted. Put your bolt back together, get a new mag and stock if it broke and press on.

BTW Match M1A chambers are 308 Win not 7.62 NATO.
Link Posted: 12/31/2004 11:07:35 AM EDT
Link Posted: 12/31/2004 1:28:28 PM EDT
[Last Edit: 12/31/2004 1:30:55 PM EDT by tangeant]
This is the bolt full forward not rotated into battery. Along with firing pin totally blocked by receiver web the safety nose on the hammer hits the flat back of the bolt preventing it from even coming close to touching the firing pin.




Pic 2; Even if the bolt is not quite fully closed but lugs engaged, the hammer safety nose WILL CAM THE BOLT CLOSED closed as it hits.





As a note never ever fire an M1 -M14/1A with a broken firing pin or hammer with the safety nose broken off !
Link Posted: 12/31/2004 1:40:43 PM EDT
Thanks for sharing airbiscuit

This thread is a great way to take a lousy event and trun it into something positive and educational.
Link Posted: 12/31/2004 2:23:25 PM EDT
I'll own a malfunction if I did it, but how is this my error? Everything was going fine, then bam. I don't stop and check my action after every pull of the trigger on a semi anything. I checked everything out this AM, disassembled and reassembled the bolt, checked for damage, and took it back out today putting about 350 rds through it. Portugese FNM was easy 1 MOA or less at 100 yds. and SA was crappy at about 3 MOA. RG will not fully chamber and the bolt will not go into battery on RG assembled, stripped, and with a bit of force. After I send a rifle to a custom gunmaker and smith, who knows what I shoot (surplus to match ammo) do I need to headspace and mic all of my ammunition?


Originally Posted By Chuck:
Unless unless you can close the bolt on a commercial NO-GO gage a M14 rifle is too tight. Commercial NO-GO is the same as M14 GO. These are self loading rifles, not hunting bolt guns. There's nothing wrong with a M14 rifle which will close on a commercial FIELD gage unless is also closes on a M14 FIELD gage.

These problems are caused by a misunderstanding of minimum headspace specifications for the M14 rifle and the attempt to induce "match" chambers into general purpose rifles. Match chambered rifles require match ammunition.

While the firing pin should not have struck the primer until the bolt was fully closed this remains an owner-operator induced failure.

-- Chuck

Link Posted: 12/31/2004 2:25:56 PM EDT
Mostly likely guess is that there was foreign material on your bolt face, then. Did OOB occur during cycling, or had you paused after the previous round and the kaboom occured when you pressed the trigger again?

You've got a tight match chamber. If the OOB occured during cycling, your tight chamber may have been producing excess pressure, causing previous round to bulge or pop primers. The primer from your previous round might have flowed or popped, and either stuck to the bolt face or left some debris around the firing pin hole in the bolt, which could have been enough to hit the primer of the kaboom round before the bolt was fully closed. This same scenario would govern if you had a high primer that was ignited by contact with the bolt face.

If the OOB occured after cycling, on pressing the trigger, the analysis is back to square one.
Link Posted: 12/31/2004 2:39:22 PM EDT
To be honest, I think it may have been the FIRST round out the magazine. I had run a couple 10 rd. mags of FNM through it getting on paper. This was the first of the RG mags because it was a 20. I let the oprod go, got a funny feeling, bumped the back of the oprod handle with my palm, settled in, squeezed the trigger, and BAM, pieces of mag everyhere. Today I have a tiny very purple bruise right under my left eyelid. Had my eye been open it would have been bad. Again, hate to sound like a broken record, but wear those shooting glasses. At the range today only 3 of 6 were wearing them (including me). What I need to do is look at the receiver again and tail of the firing pin. Nothing looks unusual, so I'm having a hard time figuring it out, more so with the great pics tangeant posted. I like to think that I have a detailed understanding of the operation of the M1 / M14 system, which I do, which makes it more perplexing. The round definitely discharged out of battery as RG will not chamber in this rifle fully. Also, the case head is bulged and separated at the point that the remainder was left in the chamber. I keep a seperated case extractor with my weapon, along with rod sections. That and a combo tool are must have M1A items.


Originally Posted By Circuits:
Mostly likely guess is that there was foreign material on your bolt face, then. Did OOB occur during cycling, or had you paused after the previous round and the kaboom occured when you pressed the trigger again?

You've got a tight match chamber. If the OOB occured during cycling, your tight chamber may have been producing excess pressure, causing previous round to bulge or pop primers. The primer from your previous round might have flowed or popped, and either stuck to the bolt face or left some debris around the firing pin hole in the bolt, which could have been enough to hit the primer of the kaboom round before the bolt was fully closed. This same scenario would govern if you had a high primer that was ignited by contact with the bolt face.

If the OOB occured after cycling, on pressing the trigger, the analysis is back to square one.

Link Posted: 12/31/2004 2:45:44 PM EDT

Originally Posted By airbiscuit:
I'll own a malfunction if I did it, but how is this my error? Everything was going fine, then bam. I don't stop and check my action after every pull of the trigger on a semi anything. I checked everything out this AM, disassembled and reassembled the bolt, checked for damage, and took it back out today putting about 350 rds through it. Portugese FNM was easy 1 MOA or less at 100 yds. and SA was crappy at about 3 MOA. RG will not fully chamber and the bolt will not go into battery on RG assembled, stripped, and with a bit of force. After I send a rifle to a custom gunmaker and smith, who knows what I shoot (surplus to match ammo) do I need to headspace and mic all of my ammunition?


Originally Posted By Chuck:
Unless unless you can close the bolt on a commercial NO-GO gage a M14 rifle is too tight. Commercial NO-GO is the same as M14 GO. These are self loading rifles, not hunting bolt guns. There's nothing wrong with a M14 rifle which will close on a commercial FIELD gage unless is also closes on a M14 FIELD gage.

These problems are caused by a misunderstanding of minimum headspace specifications for the M14 rifle and the attempt to induce "match" chambers into general purpose rifles. Match chambered rifles require match ammunition.

While the firing pin should not have struck the primer until the bolt was fully closed this remains an owner-operator induced failure.

-- Chuck



Thats what I'd like to know.
Link Posted: 12/31/2004 5:01:06 PM EDT
Only error was using Foreign surplus ammo .

Very lucky the receiver wasn't damaged, I've seen atleast One NM m14 that someone fired a Bubba 180 grain homebrew magnum untin 308 win load in. It punch a bolt shaped hole out the back of the receiver tang
Link Posted: 12/31/2004 5:47:20 PM EDT
Re reading this entire thread, including pieces posted after mine, I have another thought.

In one posting at least you state that it "felt funny" when chambering and you pushed the op-rod the rest of the way home. Then when the trigger was pulled "KA-BOOM."

If you pushed the op-rod home, then the bolt HAD to be in battery.

I'm now thinking short chamber, with inadequate leade or throat, allowing the bullet and/or case to contact the lands. This would add resistance, and boost chamber pressure. Obviously, If my theory is correct, with the increase in pressure, the bullet gets down the barrel faster, gas hits the port quicker and with more pressure, causing the bolt to unlock while the gas pressure is still unacceptably high in the cartridge case. This started extraction and the unsupported portion of the case, when withdrawn from the chamber, blew.

I've no education or experience in this field, but it SEEMS feasable to me.



Lonny
Link Posted: 1/1/2005 6:42:52 AM EDT
Link Posted: 1/1/2005 8:19:21 AM EDT
[Last Edit: 1/1/2005 8:28:54 AM EDT by airbiscuit]
(1) "Deliberately had the rifle barrelled out of spec."
You really don't know what my instructions were to my smith nor whether I asked questions about shooting high end milspec 7.62 NATO out of the rifle. That would be speculation on your part, and the speculation is incorrect. Chambers can be lengthened and modified by a good smith (and he is) without destroying accuracy. It is done all the time in custom calibers. What barrel did I get? What are the specs on the barrel? Chamber? Does such a Barnett barrel come from the maker set up to accept and fire NATO milspec ammo? Go check this out Chuck re .308 in 7.62 and vice versa:
www.fulton-armory.com/308.htm

(2) "and then used military spec ammo in a rifle with a sub-minimum sized chamber."
Faulty premise based upon the above speculation. It was military spec ammo. But do you know that the chamber was "sub-minimum sized"? What size is the chamber? What is the case length? The bullet length? The overall round length? What marks is the chamber making on the bullet or case if any? Did the smith ream the chamber? What does the receiver look like? What does the tail on the firing pin look like? etc. etc. Have you pulled bullets and tested the primer hardness? Have you tried to replicate the event? Do you know if the ammo was out of spec or a bad lot?

I think emphatic pronouncements without all the facts are improper and can be misleading. I met this problem recently with the [name withheld to save this thread] lower not dropping mags. The facts proved different than alot of the abusive pronouncements. The facts will show what happened, not conjecture. Conjecture may ultimately prove correct. I don't mind admitting error if it will help us learn. I don't like it, but if I'm wrong I'll say so. Please also note that the tired phrase "sh!t happens" is sometimes true. Fortuitous events can compound that alone would be innocuous, but together make for a crap filled day. Wear your shooting glasses.

After going through everything today (with a hangover, HNY everybody), pulling bullets, testing hammer drop, etc., this is what I think: I got a combo out of battery and slam fire which produced a KB. The chamber is tight, but it should be. Curiously, it chambers another box of RG from the same lot no problem. I tried on five cartridges, numerous times on each, to replicate the event in my backyard (pulled bullets and dumped powder) without success, various stages of bolt battery. No luck. Observed the rear of the firing pin, hammer, and all seemed to work as designed. Some notes of interest:
1) There was a small piece of broken metal (that spec in the pic above) in the trigger group at the time of the kb. Did it interfere with anything? Where did it come from?
2) The firing pin tail has wear, as does the receiver, but nothing that would interfere with its proper functioning that I can see. Pics to follow for your assessment.

Guys, the pics below may help and I welcome commentary. Did I remind ya'll to wear your shooting glasses




Originally Posted By Chuck:
Its primarily an owner/operator error because the owner/operator deliberately had the rifle (1) barrelled out of spec and then (2) used military spec ammo in a rifle with a sub-minimum sized standard chamber.

Minimum headspace for the M14 rifle -- which shoots 7.62mm NATO ammunition -- is 1.634". This is the same as a commercial bolt gun NO-GO gage. The bolt must close on a commercial NO-GO gage to meet M14 specifications. If your rifle doesn't have a large enough chamber you should not fire 7.62mm NATO ammunition.

Anyone who insists on a M14 with a .308 bolt gun chamber -- sub-minimum headspace -- should not be surprised when there are problems with ammunition not matching that specification. Match chambers will work, but they require match-sized ammunition.

This rifle has other problems either in the bolt or receiver because the firing pin should not be able to touch the primer until the bolt is rotated into battery -- but this is all acerbated by a deliberate combination of headspace and ammo.

-- Chuck

Link Posted: 1/1/2005 8:34:25 AM EDT
Looks like the same thing that happened to my Poly tech M14 back in 92. I had a round of surplus (cant remember what specifically) that apparently had the bullet setback in the case while feeding. This caused a case rupture and split my mag dropping the rounds and parts on the ground below. My bolt lugs were in rough shape as well. I sold that rifle to a gunsmith shortly thereafter.
Link Posted: 1/1/2005 9:04:14 AM EDT

I got that odd, mild feeling an instant before I pulled the trigger. I've always caught such things before, but everything looked good, no real indication, so........It really is a good idea to wear shooting glasses!


You pulled the trigger and gun went off hence the rifle was in battery and no slamfire. This is just a simple case of bad ammo. Hot over-pressure ammo + seperated case will do this and worse to an M1a. I don't think you have a chamber/ headspace problem, if the round will chamber it will fire.
Link Posted: 1/1/2005 9:27:29 AM EDT
Tangeant, those were my thoughts as well. My smith is good, very good, and works on M1A's and is known for such work. I am NOT going to even hint as to who it is lest this accident be attributed to him in any way. After going through everything today, again, I think this is what happened, subject to what ya'll come up with after viewing the pics: The round did not chamber fully for whatever reason. It was out of battery. When I pulled the trigger the hammer struck the rear of the bolt, as it will at that position, and the impact cause the pin to move forward, lightly striking the primer, but enough to cause the round to discharge. As you will see, the primer dent is light and it looks like a heavier strike because it blew back against the pin. Pics at halftime.....


Originally Posted By tangeant:

I got that odd, mild feeling an instant before I pulled the trigger. I've always caught such things before, but everything looked good, no real indication, so........It really is a good idea to wear shooting glasses!


You pulled the trigger and gun went off hence the rifle was in battery and no slamfire. This is just a simple case of bad ammo. Hot over-pressure ammo + seperated case will do this and worse to an M1a. I don't think you have a chamber/ headspace problem, if the round will chamber it will fire.

Link Posted: 1/1/2005 9:32:34 AM EDT
Airbiscuit,
Just a theory here - the dirth of good quality parts availibity for the M14 is a fact of life. It is too bad, but M14 shooters are are being forced to use aftermarket parts (repro's) more and more. Not a bad thing but caution is always a prudent stance - ie do a good QC checks on replacement parts. That being said, an even more alarming situation is where worn out surplus parts are "refurbished" with new parkerizing and sold as new - ala gunshow parts dealers.
All of this leads me to this - there was a modification waaaay back in the M14 days when it was in use (circa early 60's-ish) that was made in production of the extractors. The problem (the details are fuzzy - because I am still fuzzy after last night....) was related to extractors that were popping out of the bolts - the fix was a bevel on the bottom edge of the extractor. Investiagte the chance of having an unmodifed extractor - because if the extractor rode up a bit, it would definitely prevent the bolt from going into battery.
Also - another trick that good M14 plumbers employ is to trim the ejector spring to tune the ejection pattern. As the ejector is not the primary means of retaining the extractor, the spring and detent (again a worn part or replacement that doesn't have a deep enough detent may contribute) may lessen the force on the extractor shaft enough to contribute to a less than perfect retention system. A trimmed spring, coupled with an early - unmodified extractor may have allowed the extractor to ride up.

Just a thought but worth checking.

Ditto on the glasses - we had a shooter who had a K-BOOM with an 03 shooting cast lead bullets - completely grenaded the rifle and a chuck of the recvr went THROUGH his right eye and lodged in the back of his eye socket - surgeons said that another 1/8" and it would have penetrated into his brain housing unit and more than likely would have killed him.
Took him a year to learn to shoot lefty......

HNY
1SGA
Link Posted: 1/1/2005 10:01:48 AM EDT

Glad you're okay, Airbiscuit.

Link Posted: 1/1/2005 10:47:45 AM EDT
Tks DrMark. Below is a pic of primer indents. The first is what a normal one looks like on RG. The second is the KB, the third is me attempting to replicate the kb. Note the kb strike was light, but the exploding cartridge forced the primer back. I believe this makes it look like more of a strike.

Here is the rifle
Link Posted: 1/1/2005 10:51:03 AM EDT
Here is the rear of the firing pin out of battery. Note the notch in the receiver at the 3 o'clock from the pin tail. The tail drops in this notch with the bolt in battery so that the hammer can strike it.


This is the same pic, IN battery, bolt locked:
Link Posted: 1/1/2005 10:52:38 AM EDT
[Last Edit: 1/1/2005 10:52:58 AM EDT by caser]

Originally Posted By tangeant:
You pulled the trigger and gun went off hence the rifle was in battery and no slamfire. This is just a simple case of bad ammo. Hot over-pressure ammo + seperated case will do this and worse to an M1a. I don't think you have a chamber/ headspace problem, if the round will chamber it will fire.



You are right that it was not a slamfire, but you might not be right about the gun being fully in battery. Airbiscuit, did you smack the op rod handle and assume the gun went into battery (like about 99.999% of us do, not a dig at you), or did you visually verify that the bolt rolled all the way over? usually, most of us don't pay such close attention to every single detail.

you might have bumped the op rod forward all right, but maybe not enough. if that is true, then you really must verify the receiver bridge/bolt/firing pin relationship. an easy way to do that is to dump the powder from some RG ammo, and try and set off a primer when the bolt is not fully closed. if you can ignite a primer that way, you need to figure out why.
Link Posted: 1/1/2005 10:53:41 AM EDT
This is the pin with the bolt partially out of battery. The pic below it shows what the bolt lug looks like and the positioning topside:

Link Posted: 1/1/2005 10:55:42 AM EDT
[Last Edit: 1/1/2005 10:56:35 AM EDT by airbiscuit]
Here is the firing pin tail:


Another pic of the round:
Link Posted: 1/1/2005 11:06:14 AM EDT
[Last Edit: 1/1/2005 11:07:41 AM EDT by airbiscuit]
Caser, the operator error was what you just identified, and I don't think what Chunk said. I made the silly mistake of ASSUMING. That is, chamber the round, bump the back of the oprod handle, squeeze, it won't go off if it isn't in battery (great anime for what I just said). As I stated, I got a brief weird feeling right before squeezing the trigger. Guys, most of us still have vestiges of caveman in us. Women hate certain aspects of this (my wife rolls her eyes and sighs alot), but it is something that can save your life (or eyesight). I did three things wrong I can ID: 1) No shooting glasses at that time; got lazy. 2) Didn't trust that funny feeling and STOP EVERYTHING AND DO A WTF CHECK. 3) Assumed the system would not fail.

After testing pulled bullet rounds earlier this morning per suggestions here, consistent with yours, I could not replicate the kb, only a slight slight primer indent as shown. I think a number of things came into play: 1) Me doing the three things wrong; 2) Tight (but in spec) chamber / round not chambering fully; 3) Sensitive primer; 4) Possible chamber debris, firing pin hole debris that kept the pin forward; 5) The hammer hitting the rear of the bolt, but not pin, and driving the pin against the primer with just enough force to detonate the cartridge. I welcome suggestions and criticisms as you guys have been alot of help in sorting this out.


Originally Posted By caser:

Originally Posted By tangeant:
You pulled the trigger and gun went off hence the rifle was in battery and no slamfire. This is just a simple case of bad ammo. Hot over-pressure ammo + seperated case will do this and worse to an M1a. I don't think you have a chamber/ headspace problem, if the round will chamber it will fire.



You are right that it was not a slamfire, but you might not be right about the gun being fully in battery. Airbiscuit, did you smack the op rod handle and assume the gun went into battery (like about 99.999% of us do, not a dig at you), or did you visually verify that the bolt rolled all the way over? usually, most of us don't pay such close attention to every single detail.

you might have bumped the op rod forward all right, but maybe not enough. if that is true, then you really must verify the receiver bridge/bolt/firing pin relationship. an easy way to do that is to dump the powder from some RG ammo, and try and set off a primer when the bolt is not fully closed. if you can ignite a primer that way, you need to figure out why.

Link Posted: 1/1/2005 12:14:18 PM EDT
[Last Edit: 1/1/2005 12:38:36 PM EDT by tangeant]
Deff time for a new firing pin. Do you have a pic of the hammer face ? A pic of the primer on the seperated case ?

You can check the web by putting forward pressure on the firng pin with a finger as you ride the bolt forward, firing pin should not move forward enough to clear bolt face untill lugs begin to engage.
Link Posted: 1/1/2005 12:44:28 PM EDT
Very good tip tangeant. Thanks. It does not move forward until the lugs lock. The wear looks worse than it is on the pin. This ole girl has been through alot. I've sold several M1A's and kept her, almost 20 years now. The round count is high and parts have been refinished. The hammer was replaced a couple years ago just because, with the new trigger job. I keep the old one as a spare / emergency. I'll get a pic of the hammer face for you. 1SGA, I'm pretty finicky about parts and everything except the receiver and barrel is USGI milspec, as new as I can get. Good advice re refurbed and refinished parts. I bought CMP M14 spare parts (complete oprod, guide, sping, complete trigger set, bolt) when they were available. They were nice, but used. I had them refinished with my custom work and they look like new parts. I probably could not tell the difference if you handed them to me.


Originally Posted By tangeant:
Deff time for a new firing pin. Do you have a pic of the hammer face ?

You can check the web by putting forward pressure on the firng pin with a finger as you ride the bolt forward, firing pin should not move forward enough to clear bolt face untill lugs begin to engage.

Link Posted: 1/1/2005 1:22:23 PM EDT
Airbiscuit
The more I think about it, the more I think that your extractor may have popped up and prevented the bolt from fully entering the breach recess.
See if you can pop the extractor up and put the kboom case back in the chamber and see if the rupture lines up with the unsupported area.

Have you checked the extractor for the bevel? It could have been a new USGI part that did not have the bevel revision.

1SGA
Link Posted: 1/1/2005 1:53:25 PM EDT
[Last Edit: 1/1/2005 1:54:06 PM EDT by tangeant]
Didn't catch this pic.



Pic is more evidence of just a seperated case from a hot overpressured round, primer has flowed back into the primer hole. You must remember that an M14 is very hard on brass because there is still significant pressure holding the case against the chamber walls and the gas sytem is trying to pull the case out before the pressure has completely dropped. When a case seperates as badly as this one there is still enough pressure to blowout the seperated case rear section as it extracted.

Really if all the moons were alingned and you did mysteriously have an OOB the primer wouldn't look like that and you would still have a bullet stuck in the barrel.
Link Posted: 1/1/2005 3:14:29 PM EDT
Tangeant, guys, I went through more RG chambering and the majority of it will NOT seat correctly. I never had this problem with my previous match barrel (SA) with this same ammo. It shows contact at the case shoulder and on the bullet. I believe the chamber needs to be reamed further to take it and is short. 7.62 NATO is a tad longer chamber spec. Most of the time the diff is so insignificant that the bolt in an M1A just "crushes" it in. Likely not the case here (no pun intended).
Link Posted: 1/1/2005 3:20:06 PM EDT
A4/A1818 1989-vintage Radway Green. I just ran 60 or so rounds of this through my Bush rifle yesterday, thankfully with no surprises I think I'll be taking some and running it through my case gauge ASAP, just because

Thank you for sharing airbiscuit, and glad you are good to go.
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