Broken Shell- Danger, Must Read!

This is a must read for all SKS'ers.

A friend of mine was asked to extract a broken Remmington brass from his neighbor's Chinese SKS. He placed a wooden dowel down the barrel and tapped the piece of the broken case out. Good so far.

http://www.hunt101.com/data/500/medium/broken_shell_001.jpg
http://www.hunt101.com/data/500/medium/broken_shell_002.jpg

Knowing that the SKS had fired milsurp ammo (steel case) with no problems, he measured the milsurp casings against the Remmington brass and found no appreciable difference in dimensions. So he loaded one Remmington and fired. No problem yet. He loaded two Remingtons and fired.

The first shot broke a case (as above) and the next round chambered leaving the bolt open and jammed about a 1/4" from full battery. He could not hand "eject" the live round, as it was pressed into the broken case.

Now before the experts (myself included 8) ) start crying "foul! ignorance! idiot!", we must all remember that when we first were becoming familiar with the SKS, we did not know that the safety was only a trigger block and not a hammer block. And for all who still do not know this fact, please read carefully.

My friend took the SKS into his basement work room and placed it on the bench, removed the rear cover and spring and then took two light taps on the bolt handle....... and the hammer released.

The resulting discharge sent the bullet through the siding of his work bench, the wall paneling and stopped at the cement. The bolt and carrier flew off the back of the gun. His right arm, neck and face were sprayed with burning powder and very serious situation resulted in no serious injury.

http://www.hunt101.com/data/500/medium/broken_shell_003.jpg

A reminder to all of us who love the SKS:

Negative or Neutral sear engagement is a DANGEROUS SITUATION that could lead to serious harm. Thanks for giving your attention.

I'm trying to figure out a way to avoid that situation incase I see it one day.

with the receiver cover off you could block the hammer fall with something perhaps?? prior to pulling the trigger group??? then pound away on the bolt carrier?

I think it would dawn on me that I have a hammer waiting to fall on a firing pin with an open battery....a huge recipe for some shit cake. at least i would hope so....I don't think I would go tapping on a cocked weapon .... first priority before removing the jam would be to render safe somehow...

that's all arm chair quarterbacking though... thank goodness no serious damage occured....as powder burns suck big time in their own right....

I tested my Tula for sear engagemnet and I think it was just neutral....I'll look at it again.

thanks for the warning.

With some more time to think this one through, it would also be very easy to remove the trigger group altogether and eliminate the threat entirely before attempting removal of a live round that is stuck in the chamber.

I hope that I will remember that if the need ever arises.

since I'm guessin that getting a live round stuck will occur while I'm at the range...only

I'll take you guys suggestions and remove the trigger group before attempting to clear the chamber

I have some dummy 7.62x39 FMJ rounds that I loaded to use whilst I was building my AK's..I use these whenever I have feeding/chambering problems

This and my electronic reloading scale have saved me from most dumbass mistakes(but not all of them)

Having never owned an sks I have never disasembled one.... is the FCG similar to the semi auto ak ?

Seems like common sence to remove the hammer or block it somehow if there is a round in the chamber and the weapon is "cocked"

Ouch! Thanks for the info Martin. Which brings a question to mind that Dad and I have discussed before. American made 7.62 x 39 such as the Remmington's, Are they different than com bloc ammo? I think I remember many years ago when I had my first SKS a friend gave me some Remmington ammo that would not feed into my SKS. I've never compared the two side by side.:confused:

I had a CETME 308 once that blew up on me and I'll never forget it. The sides of the receiver were swelled out like an egg and the blast blew the guts of the magazine and the remaining rounds onto my stomach and legs. Luckily I wasn't injured in any way but it was a sobering experience. I always wear safety glasses when I shoot now!

Here's a link to the SKS Boards thread that talks about SAMMI vs. CPI ammo on the second page.

http://www.sksboards.com/smf/index.php?topic=59164.0

Knall...the whole trigger/hammer group drops out of the bottom of the rifle..kind of like an M1 carbine

doesn't take long to drop the whole assy, but can sometimes be a bitch to reinstall without a lil wood chiselng and judicius dremeling

My 16" barrel SKS with the hi tech rifle sites is waaay more accurate than any of my AK's with the same ammo...which is why I usually shoot it for other than just blasting purposes

I think we should affirm the hammer blocking prior to flipping the rifle over and prying on the FCG removal button. it could be OK...but I wouldn't take any chances with a potential brass firecracker...

the rifle is ready to fire....there are threads on the danger of that positive / negative thingy... allong with drop testing to test for sear engagement....

in the scenario where the rifle is cocked with partial in-battery I think it's real important to ensure the hammer doesn't have a clear shot at the firing pin before phuqing with the rifle in any way.

Another excellent point, Bounce.

Would you recommend a wooden block? Thick rubber?

I would have to look at it, as I've been talking out my ass without consulting my SKS.... but I would think the Mark 1 Mod zero thumb or hand might do the trick while popping the release with a pointy object.

Thanks for the link Martin, Interesting!

I hope to get my hands on the gun tomorrow and do some inspection.

I've checked the bolt carrier, bolt, disconnector and hammer function on one of my guns and it just doesn't seem possible that a hammer to pin contact could happen unless the round is in full battery.

One thing for certain, the pin did strike the primer.

http://www.hunt101.com/data/500/medium/broken_shell_1.jpg

Having never owned an sks I have never disasembled one.... is the FCG similar to the semi auto ak ?

Seems like common sence to remove the hammer or block it somehow if there is a round in the chamber and the weapon is "cocked"

KNALL the SKS was designed to be field stripped with nothing but a live 7.62X39 round.The trigger mechanism comes out in one piece by depressing a spring loaded pin behind the trigger gaurd and lifting up on the trigger gaurd.Below is a link if you want to read up on the SKS disassembly/reassembly,td

PS if you like the AK the SKS IMO ranks right up there with shooting fun.IMO they are more accurate than the AK,td



http://www.surplusrifle.com/sks/carbine/index.asp


http://i198.photobucket.com/albums/aa278/tdbrown1969/skstrigger.jpg

Check out SKS trigger job on YouTube by Sailorcurt. There are 5 video's that go into detailed explanation of negative, neutral, and positive sear engagement and how to remedy the problem. I followed his instructions to correct the negative engagement on my Romy SKS.

I was not able to procure the rifle this weekend, my friend's neighbor was out of town. I did get some more information.

1. The bolt was definitely "out of battery", as the jammed live round was visible.

2. The firing pin was free in the block, but noted after the discharge. There was no way to tell if the pin was stuck and the primer already struck before the attempted removal.

3. The removal attempt with a dead blow was just that, my friend directed his blows toward the rear of the gun.

I'm still in hopes to see the gun, because I'm having difficulty picturing the scenario that a hammer release caused the discharge. There still may be a faulty disconnector in the trigger group... but that is speculation at this point.

Any ideas are welcome as to how the primer was struck. i.e. could the round that was captured by the extractor and bolt face keep enough downward pressure to depress the disconnector????

Here is the result.

Side of work bench and wall.

http://www.hunt101.com/data/500/medium/hole_in_wall_001.jpg

http://www.hunt101.com/data/500/medium/hole_in_wall_002.jpg

Maybe it all could have been prevented is he had put the weapon on 'safe'???

The original post states that the safety is only a trigger safety and does not prevent the hammer from dropping.

That is one reason I sold off my SKS collection, not a safe weapon, even with the "safety" on. NTM the firing pin issues. My thoughts on this is your friend might have been safe if he had given the bolt carrier one strong whack enough to send it to the rear of the receiver. I read this as he hit it a couple of times and maybe the bolt carrier moved forward on the rebound from the hammer blow just enough to allow the hammer to drop. I could be wrong. And another reason I shoot steel case ammo out of Combloc weapons.

PS if you like the AK the SKS IMO ranks right up there with shooting fun.IMO they are more accurate than the AK,td




I really enjoy the SKS too,I kinda like 'em alot.

It sounds to me as if there is a problem with trigger engagement.

Now that is not the only problem with this rifle, or the ammo used possibly, but if the safety is engaged then it is unlikely there is much surface engagement between trigger and hammer.

Other than that, a good examination of the chamber, including headspace, is in order.



I would also wonder about the ammo. Might be reloads. You're getting the information but it sure ain't first hand.

Scary, glad your friend wasn't seriously hurt.

martin: You go to a lot of trouble to blame the discharge on trigger engagement, SAAMI specs, blah, blah. I can only say that your 'friend/neighbor' is a fool, and technically insane.

You do know that repeat behavior - expecting different results - is one definition of insanity. Or do you? [Testing Rem ammo after problems with Rem ammo? Hello -- Another broken case? Why not 'single-shot' in ALL follow-up tests? ]

-The SKS hammer CAN reach the end of the firing pin while slightly out of battery.

-Trigger block safety's: AREN'T.

-Hammer block safety's: ARE.

In your 'friends' case, ANYTHING jammed between the hammer and the bolt could have 'safed' the rifle. (ie toothbrush, rag, dog toy, cardboard)

-Hammers (as in the tool) are not to be used on 'fubared firearms' at the brink of disaster. Tell your 'friend'.

-SKS designers knew it could fire out of battery. The disconnector is pushed down by the bolt itself, going into battery. "Hammering" apparently defeated this design feature.

-"Chamber polishing" is not always a good thing. In this case, it may have contributed to the case breakage at the shoulder. Some designs (HK) flute the chamber walls to retard the case movement to the rear. Polishing would hasten it -- Leaving only the thinnest section of the case stuck to the chamber walls. [If anyone has questions here, consult a good reloading manual.]

Last but not least, most homestyle gunsmithing takes place on inexpensive firearms. This will not reduce the actual cost of freelance tinkering. Those costs will often exceed simple wall repairs, and ringing eardrums.

-"Chamber polishing" is not always a good thing. In this case, it may have contributed to the case breakage at the shoulder. Some designs (HK) flute the chamber walls to retard the case movement to the rear. Polishing would hasten it -- Leaving only the thinnest section of the case stuck to the chamber walls. [If anyone has questions here, consult a good reloading manual.]


HK rifles with fluting use the flutes to direct gas around the cartridge case, "floating" it in the chamber instead of allowing the case to stick to the walls as is normal. This is required because the HK design is a roller delayed blowback, if the case wasn't free to push against the bolt when fired it won't cycle. Aftermarket bbls with incorrect fluting are famous for causing failures to cycle.

Now, some .22 magnum blowback designs do use a ring or similar cut into the chamber to delay blowback, the case swells into it and adds friction so the opening of the bolt is delayed. But normally you want a smooth chamber, not a rough one.

I'm aware of the HK operating principles, thanx.

At what point does GAS flow backward past the case in that fluted chamber? Would that be after the pressure drops in the barrel, and the brass has released it's grip on the fluted chamber walls?

Thanks for the comment.

[Edited some possible confusion out of the last line. The part above it is fact. Pressure should (and does) press the case to the chamber -- which seals against gas leakage. ]

The fluting in the chamber extends past the case mouth. At the moment of firing the gas flows from the bore back through the flutes and keeps the case from sticking to the chamber walls. It also impacts the shoulder, adding some force rearward. At least that's what HK says, I would think they would know how their system works.

http://www.hkpro.com/index.php?option=com_content&view=article&id=133:technical-engineering-detail-of-the-g3&catid=4:special-topics&Itemid=5


"The gas force (Max. 1.570 kg/460 lbs.) resulting from the burning powder acts upon both the bullet F4 and, within the cartridge case through the cartridge case base, the bolt head face. In addition to this momentum, almost simultaneously a second impact, F5, is created which acts between the shoulder of the chamber andthe shoulder of the cartridge case because of the fluting in the chamber. "

"Cartridge case obturation, the greatest uncertainty factor in every automatic weapon, is reduced so much by the introduction and further development of the fluted chamber and has become uniform for all types of cartridge cases, including lacquered steel cases, that operation is reliable in every situation, even under the most adverse firing conditions."

I stand corrected. Again, thanks for your comments.

I am shocked that HK leeches gas back past the case neck to help with extraction. Look at the soot in the photo.

When the HK 91's were introduced into the US, the fluting was said to slow the unlocking of the action; Now I know they have other 'corrective' properties.

HK style 'chamber fluting' in the neck and shoulder area might solve the broken case problem in this thread. There's a revolting, but hilarious thought.



At any rate; Altering the chamber of any firearm without a damn good reason is a recipe for disaster. Polishing a chrome chamber is silly, and hammering on a loaded, out-of-battery rifle is formal application for a Darwin award.

I must live a charmed life. I've owned a dozen or so SKSs over the years and I've never had one burp. This must make them an eqaully ungodly nightmare when you come upon one that has something strange whacked on it.