As I've mentioned in several posts, I've been developing loads for a pistol caliber carbine. It takes Glock mags, and has conversion kits to change calibers. It shipped with an SGM 33 round 9mm mag, which works flawlessly. I found a deal on OEM Glock 33 round mags, and bought 2. However, I was less than thrilled at the range when, using the new Glock brand mag, it stovepiped EVERY round. I was using my standard load, 124 gn RN lipstick bullets (Acme Hi Tek coated). Run flawlessly through the SGM. I have heard that the Glock mags tend to have quite strong springs, and wonder if this could be forcing the next load up before the spent round has a chance to fully eject, thus causing the stovepiping. Any thoughts out there?
Pistol caliber carbine- Stovepiping
- Thread starter Starr1der
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LiveLife
Member
Do you also get stove piping with factory ammunition? If not, it may be your reloads.
Lloyd Smale
Member
what gun is it?
LiveLife
Member
Likely Just Right carbine with caliber conversion.
LiveLife
Member
Wasn't aware of another carbine with caliber conversion kit. Good to know.
So you getting stove piping only with Glock magazines, including factory ammunition?
So you getting stove piping only with Glock magazines, including factory ammunition?
wally
Member
Leave your new Glock mags loaded between range trips, virgin Glock mags often have very strong springs which may be slowing down the bolt leading to weak ejection and stovepipes. They generally "take a set" and drop to their "normal" working force after being held compressed for a few days.
Sunray
Member
"...generally "take a set" and drop..." Springs do not change or lose temper from being compressed.
Open the mag lips a tick with needled nosed pliers. Isn't unusual for mag lips to get bent in a wee bit in storage.
Open the mag lips a tick with needled nosed pliers. Isn't unusual for mag lips to get bent in a wee bit in storage.
wally
Member
This is not correct. Take a new spring measure its length, install it, take it out and measure it again after some usage -- it'll be shorter (for comprssion springs) This is taken into account with a proper spring design, but it means they can sometimes be "too strong" initially.
IMHO messing with the feed lips is a last resort, I've fixed a few doing this, and made things worse with others -- worth trying before you trash it, but I'd exhaust all other possibilities first.
Another thing to look for is the mag rubbing on the bolt -- anything that slows down the bolt can weaken ejection and lead to stovepipe failures. Often times the parts wear down a bit and the problem goes away with some shooting, but you should be able to see wear marks on the bolt or the magazine if they are rubbing. If you see them you can speed up the process with a bit of sand paper or a small file.
Won't hurt to swap springs between a stovepiping magazine and one that works -- if the problem switches there is your answer. If it doesn't look carefully for mag and bolt contact. You may have to swap spring and follower and most non-Glock mags don't use Glock followers so the tops of the springs might not fit the other follower.
The empty should be hitting the ejector well before its possible for the next round in the mag to move up into position -- check it out with dummy rounds. If the loaded rounds are out of the magazine and not entering the chamber when it stovepipes, then odds are the feed lips need to be moved in a bit instead of opened up.
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Ok; I went to the range today, and eliminated a few possibilities. First, I tried with the SGM magazines that worked flawlessly before; still stovepipes. I was using the exact loads that worked flawlessly before; I had done some workups using Acme coated 115 RN in front of 5.0 grains of Power Pistol. Since I have to strip and clean it anyhow, I'm going to take a real close look at the ejector.
LiveLife
Member
I would inspect the extractor area also for hard crud build up.
The TNW Aero Survival Rifle has a serialized UPPER; so they can ship the receiver, bolt head and barrel to change caliber without going through an FFL. One receiver does 9mm, 357 Sig and .40 SW; the other receiver does .45 ACP and 10mm. I currently have 9mm and 45; it's the 9mm I'm having trouble with.
Ok, I ripped it apart. No build up (didn't think there would be; I'm pretty anal about that stuff), and, although it's tough to get good pictures of something that small, looks intact. I'm attaching a photo of the bolt head with the extractor, and for comparison, the second one will be of the 45 bolt head. (Plastic bag in background-it's what I keep the bolt head that I'm not using in). To me, I don't see any issues.
View attachment 228211 View attachment 228212
View attachment 228211 View attachment 228212
Attachments
LiveLife
Member
Interesting what would cause the stove piping all of a sudden then.
So the stove piping is now with the SGM magazines too?
If the extractor is working fine, I would remove the buffer/spring and check the tube before I shot it just to make sure.
So the stove piping is now with the SGM magazines too?
If the extractor is working fine, I would remove the buffer/spring and check the tube before I shot it just to make sure.
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bds, this is not an AR platform; it's about as simple a system as possible. Here is a link to the manual so you can get an idea of the platform; too large to attach: https://www.tnwfirearms.com/Articles.asp?ID
Supposed to be a 'blowback operated' system; no gas tubes or anything of that sort.
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Test of the 10mm version of the ASR.
http://dailycaller.com/2016/01/22/gun-test-tnw-firearms
http://dailycaller.com/2016/01/22/gun-test-tnw-firearms
wally
Member
First you said it only did it with your new Glock mag, now you are saying it does it with the original magazine. Problem will not be found in the magazines.
If you slip an empty under the extractor with the bolt removed, does it stay on, or fall off, when you move the bolt? If it is held tightly the extractor should be fine. Make sure the ejector isn't damaged or bent -- I had a bent ejector cause lots of stovepipes in a previously reliable Browning Buckmark, a replacement ejector cured it.
As a long shot, is the firing pin return spring intact and in place? If the firing pin continues to stick out and not return as the bolt moves backwards it can act to move the empty off the bolt face so the case doesn't make the good contact with the ejector that is needed for brisk ejection.
Checking the buffer, spring, and tube is also a very good idea as anything that reduces the bolt velocity or prevents a full stroke during recoil can cause weak ejection.
If you slip an empty under the extractor with the bolt removed, does it stay on, or fall off, when you move the bolt? If it is held tightly the extractor should be fine. Make sure the ejector isn't damaged or bent -- I had a bent ejector cause lots of stovepipes in a previously reliable Browning Buckmark, a replacement ejector cured it.
As a long shot, is the firing pin return spring intact and in place? If the firing pin continues to stick out and not return as the bolt moves backwards it can act to move the empty off the bolt face so the case doesn't make the good contact with the ejector that is needed for brisk ejection.
Checking the buffer, spring, and tube is also a very good idea as anything that reduces the bolt velocity or prevents a full stroke during recoil can cause weak ejection.
I would assume the bolt has to return via a spring and or buffer like an AR. (Manual I found didnt really show)
Perhaps that is now worn out? Call the manufacture to see what their recommended spring change intervals are.
.
LiveLife
Member
My Just Right 9/40/45 caliber carbine and several PSA AR based carbines are all blowbacks and do not use gas system.
This TNW Firearms video discusses two buffer systems (lighter steel buffer and universal) and recommends at minimum 4 turns onto the receiver (more if using lighter buffer system).
Video suggests adjustment to allow bolt handle no more than 1/4" past the bolt hold open slot.
Check your bolt handle to see how far it travels past the bolt hold open slot.
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Ok; I wanted to thank everyone for their ideas. Figured I owe what I found out; it was easy enough when I thought it through. I simply went to the range after adjusting bolt travel. It wasn't off that I could tell, but I adjusted it to be sure. I ran 10 rounds of a previously tested round, and 9 of 10 stovepiped; this was 9mm. I changed caliber to .45 and 10 rounds fired perfectly. I conclude that it must be the extractor in the 9mm bolt carrier that is defective. I'm going to see if TNW will send me an extractor.
Finally got it fixed; I replaced both the extractor and the ejector and it works like a charm. I had had a round jam in the chamber and used a wood dowel I had previously bought at Home Depot to free it; I had the barrel loosely attached so I had my hands free. I think I may have slightly bent the ejector, but I replaced both to be sure.
Many thanks for all your suggestions.
Many thanks for all your suggestions.
JeffG
Member
Thanks for the update!
LiveLife
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