.22 rounds exploding

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TheNeko
Posts: 4
Joined: Fri Oct 30, 2020 7:14 pm

.22 rounds exploding

Post by TheNeko »

I had 2 rounds blow up upon firing on 2 separate days. Fired hundreds of rounds between the 2 events.
All my ammo is Federal, CCI, Gemtech, etc. no cheap stuff. I think it was a Federal round that blew each time.
I did put in the BB advanced firing pin and spring - could this be the cause?
Gun is DoubleStar lower and CMMG dedicated .22 upper. Also using the BB carrier weight with 1 aluminum weight.

Any suggestions as to the cause?


Thx,
Neko
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Renaissanceman
Posts: 46
Joined: Thu Sep 10, 2020 4:38 pm

Re: .22 rounds exploding

Post by Renaissanceman »

Out of battery discharges are not uncommon with the Ciener style bolt, the firing pin and weight are not the cause. Make sure your chamber stays clean and the bullets are seating fully, and stop and clean when you start to have issues chambering. Federal ammo is often especially waxy and may not reliably chamber on a dirty rifle. How many rounds had you shot before this started to happen?

See this thread for many, many instances of OOB and the ammo and parts in use at the time of OOB:
https://www.ar15.com/forums/ar-15/Have_ ... 15-333407/?
TheNeko
Posts: 4
Joined: Fri Oct 30, 2020 7:14 pm

Re: .22 rounds exploding

Post by TheNeko »

Thanks for the reply. I cleaned it after the last event so I had only fired 4 or 5 mags so 120-150 rounds max.
I thought the adjustable weight system would improve the ability of the bolt to go into battery ? Like I say, new to this AR-22 stuff.
I will read up on OOB issues at the link you provided. Thx
Thx,
Neko
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Renaissanceman
Posts: 46
Joined: Thu Sep 10, 2020 4:38 pm

Re: .22 rounds exploding

Post by Renaissanceman »

It generally does. The springs in the 22lr BCG wear out and get weaker over time, so I can also suggest this spring kit if you're having trouble with consistent chambering:
http://blackdogmachinellc.net/ciener-la ... g-kit.aspx

I run the heavy spring in one of my rifles, and it really sends the bolt into battery with authority. Just replacing my recoil spring after about 4000 rounds made a big difference. I replaced it after finding a severely bulged casing when cleaning up my brass, and I haven't found one since. I'll have to dig up that photo -- it fired about 1/16" out of battery and was right on the edge of a rupture. There were probably 200 rounds down the pipe at that point.
TheNeko
Posts: 4
Joined: Fri Oct 30, 2020 7:14 pm

Re: .22 rounds exploding

Post by TheNeko »

I ordered the spring kit then it went OOS so I guess I got the last one (sorry guys).
My original spring shouldn't have that much use on it - less than 500 rounds I would think. If CMMG would get the auto sear trip kit in stock then that would be a different matter :D I am trying to get it working well and see what ammo it likes in preparation for some full auto fire but at this point I don't trust it. I don't really watch the bolt when firing so I don't know if its bouncing or how it is allowing OOB detonations. I disassembled and cleaned the whole thing, installed the pressure plug and will try again tomorrow. Will skip the Federal and just use CCI (clean-22). This is suppressed by the way so I now wonder if the back pressure could be causing problems ...??
Thx,
Neko
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Renaissanceman
Posts: 46
Joined: Thu Sep 10, 2020 4:38 pm

Re: .22 rounds exploding

Post by Renaissanceman »

Back pressure doesn't cause these problems, ruptured cases are almost always OOB issues. Suppressors do cause everything in these 22lr guns to get much dirtier, much faster, however. A hundred or two with a can may create about the same amount of grime as many hundreds of rounds in a 16" non-suppressed.

I like to run the bolt rails, bolt and the sliding surfaces of the weight wet with lubricant to reduce friction. This is even more important with a 4.5" barrel, as you're dealing with a much reduced impulse to the bolt, even with high velocity ammo -- it's like shooting subs in a rifle.

I have a buddy who runs a 4.5 exclusivity and I've found that the cheap 36gr Armscor ammo cycles it very well. I think they use a much faster powder than other 22lr -- despite only reading 1120fps out of my 16" upper, it will cycle the adjustable weight with 4 tungsten weights. other bulk HV ammo reads around 1250fps (Federal, Aguila, Winchester 555, etc) but will not consistently cycle with 4 tungsten weights.
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