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Page AR-15 » Rimfire and Pistol Calibers
AR Sponsor: bravocompany
Posted: 12/19/2014 2:59:33 PM EDT
I got my RRA 9mm Carbine in last Saturday and have shot it off the back deck several times but yesterday I decided to shoot a few reloads through it. They were 115 gr bullets with 4.2 gr of Universal Clays, I shot some over the weekend and they all shot fine. This is the first three I shot today today, the second one looks a little funny.Looks like it fired without the round being chambered all the way. Not sure if it being a blowback action has anything to do with it. What caused it is what I don't know, they all seemed to sound the same.</a>" />
Link Posted: 12/19/2014 3:07:32 PM EDT
[#1]
Do you have a case gauge? I was having the same problem with my 40 S&W, got a case gauge and threw away the ones that didn't pass and ended my problem.
Link Posted: 12/19/2014 3:09:53 PM EDT
[#2]
Yikes! What was your OAL?
Link Posted: 12/19/2014 3:13:22 PM EDT
[#3]
I don't have a case gauge (yet) and the o.a.l. was 1.098, book said 1.100.

Steve.........
Link Posted: 12/19/2014 3:15:33 PM EDT
[#4]
Did you crimp them?
Link Posted: 12/19/2014 3:17:53 PM EDT
[#5]
Just a taper crimp,  the same die I use for my 9mm pistol loads, didn't change any settings.

Steve.........
Link Posted: 12/22/2014 12:50:42 AM EDT
[#6]
If your talking about the reloading manual saying C.O.L is 1.100 that's what the Hornady manual states and that is too short
I just helped a friend get his press setup and we compared that to a blazer factory round (it was about 1.153) and it looked like it was set way too deep
Try taking them out to 1.150
Max oal is 1.169 if memory serves right. Just check the lenght next to a factory one or in your magazine.

I've also seen that type of case damage on blowback rifles using too slow of a powder, basically pressure is still high with the slower burning powder when the action starts to open. That's why the case is belled  out at the base like that.
Try a faster powder or put more weight in your system (bolt, buffer, stiffer xp spring) to counter a slower burning powder.

Link Posted: 12/22/2014 11:22:18 AM EDT
[#7]
First....you are lucky not to have a case burst on you. If  you have never experienced that you are lucky!  Its not pretty or fun.

What loads are you using?
What buffer and spring did you use in the rifle?
Have you tried dropping a new factory round in the chamber and checked for it sitting at the right depth?
Does your bolt easy move completely forward and sit nice and firm against the breech?

As mentioned, the problem is you have too much pressure in the casing with the bolt not fully in battery. The rear of the case is not supported and you have pressure expanding the case. If you do this on a case that is weak, it will blow out. Been there and done that and its really not pretty.

A blow-back firearm seems overly simple at first glance but the truth is while the parts are simple, the physics of what happen are a bit more complex. The mass of bolt, stiffness of the recoil spring, weight of the bullet and speed of the pressure rise in the chamber all come into play. Call it "timing" if you will. They all have to work together perfectly.
Link Posted: 12/23/2014 5:01:38 PM EDT
[#8]
Factory built RRA Carbine with stock buffer etc. Loading was 115 gr rn bullet over 4.2 gr of Univ. Clay. Seating depth was just about exactly as book listed with an medium taper crimp. I did fire the three rounds quickly (call it a triple tap) into a silly wet target, do you think I may have tripped the trigger and the hammer followed the bolt down?
Also do I need to install the quarters/spacer under the buffer spring?

Steve..........
Link Posted: 12/23/2014 6:51:00 PM EDT
[#9]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Factory built RRA Carbine with stock buffer etc. Loading was 115 gr rn bullet over 4.2 gr of Univ. Clay. Seating depth was just about exactly as book listed with an medium taper crimp. I did fire the three rounds quickly (call it a triple tap) into a silly wet target, do you think I may have tripped the trigger and the hammer followed the hammer down?
Also do I need to install the quarters/spacer under the buffer spring?

Steve..........
View Quote


If you look at the manufacturer's loading data for Clays with a 115gr. bullet they list 3.7 to 3.9 gr. as the acceptable range.   4.2 seems to be a 10% over-load based on the manufacture's own recommendation. I don't know about others but after 40 years of reloading maybe I have gotten conservative but I go BELOW the max range and work up find what works best.

Maybe you have a different listing on this, I just went with what the powder manufacturer recommended.

Still, there could be other issues. Just because the rifle is new does not mean that everything is OK. I would make sure that when a round is chambered that the bolt has no problem going completely into battery, that is, touching the back of the barrel.
Link Posted: 12/23/2014 9:43:24 PM EDT
[#10]
After 40 or so years of reloading myself I usually check several Manuals and the info I was using was for a Hornady bullet and 4.2 gr's is listed in the middle of their data and Sierra listed 4.2 gr's as a starting load. No pressure signs on any of the brass except the bulge on that one and it fired before it was fully chambered. I suspect that was one that slipped by my inspection of the loaded rounds and there was a burr or something that kept it from being fully chambered. It hasn't done it again and I have put about 300 rounds of the same batch through it. This was my first time for this to happen and hopefully the last.

Steve............

Link Posted: 12/24/2014 1:39:31 PM EDT
[#11]
Were you bump firing?

I only ask because I had a few out of battery KBs while bumping. I just get a little leery about bumping blow back guns as they can fire OOB.

Link Posted: 12/24/2014 2:59:13 PM EDT
[#12]
Not bump firing, I learned my lesson about bump firing a blowback rifle several years ago myself. I was firing pretty fast (call it a triple tap into a 'silly wet') from the shoulder, as I mentioned above I think I may have tripped the trigger/sear a little quick and the hammer followed the bolt down. After all the inspections and checking we believe it was that or a problem with one of my reloads which were mid range according to Hornady (their bullet, their book)

Steve........
Link Posted: 12/24/2014 3:07:13 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Not bump firing, I learned my lesson about bump firing a blowback rifle several years ago myself. I was firing pretty fast (call it a triple tap into a 'silly wet') from the shoulder, as I mentioned above I think I may have tripped the trigger/sear a little quick and the hammer followed the bolt down. After all the inspections and checking we believe it was that or a problem with one of my reloads which were mid range according to Hornady (their bullet, their book)

Steve........
View Quote


Gotcha......I learned my lesson too That doesn't mean I have learned my lesson on my 5.56.....but only when I feel like I have an excess of ammo

Link Posted: 12/24/2014 3:11:18 PM EDT
[#14]
I was playing with a friends Marlin Camp Carbine in 45 acp and had one that just leaked a little gas (crack near the base as in starting to separate)  but didn't blow completely all the way.

Steve........
Link Posted: 12/24/2014 11:49:16 PM EDT
[#15]
I have had two case blow-outs on 9mm. These were the full-blown rip a hole in the side of the case variety.
I put that firearm away and never wanted to see it again. Took a month for my right hand to recover from the blast.
Its not pretty to blow out a case on a centerfire.

I have had several .22 blow outs on blow back .22 AR's. They are bad enough...
Page AR-15 » Rimfire and Pistol Calibers
AR Sponsor: bravocompany
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