Hey guys. I was putting some rounds though my new SBR the other day and was getting what I think is a FTE every so often. I already have an H3 buffer and a Wolff extra power buffer spring. I was shooting yellow box PMC .223 55gr out of Magpul Pmags. This was my second time shooting it. First time out it did the same thing. I took it home and cleaned and lubed it up(what I thought was enough). I have some white box Winchester 5.56 ammo I hope to shoot tomorrow and see what happens. Any thoughts?
Sbr fte?
- Thread starter mercracing
- Start date
There are a number of issues that could be contributing to the FTE's you are experiencing. Where did your barrel and bolt group come from?
Looks like a not enough gas issue. Bolt carrier never made it back far enough to get behind the next round in the mag. Several things can cause this. Loose gas key, mis-aligned gas block, weak ammo, burr in gas port of barrel, etc. Chambered round did not eject due to tip of bullet still in the barrel extension so ejector could not flip it away from the extractor.
I have also gotten the suggestion that the bolt isn't making it all the way back. That the H3 buffer and Wolff spring are making too much resistance. Could that be happening?
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I looked at the brass(White box Winchester 55gr 5.56 today) after it had been fired and there are minimal marks on the head from extraction. It's got a 7.5" barrel. In theory, is the bullet leaving the barrel so soon that it is not making enough pressure to force the bolt back all the way?
You guys are jumping the gun. First things first...
The cycle of operation was interrupted at extraction. You need to head back to the range with some quality ammunition and test the operation of the carbine by loading a single round into the magazine and see if it will complete the recoil phase of the cycle of operation. Repeat 10 times and report your results. The most glaring problem here is that the OP bought an unknown quality upper from a retailer who uses surplus in their name.
I can do that. I am NOT getting the issue every time. It is more often with the 5.56 then it was with the .223
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Ok. I loaded and shot ten rounds. One round in the mag at a time. Shooting American eagle 50gr AR 223. I split the rounds between a GI mag and a Pmag. Here's what happened. Number 4 GI mag didn't hold the bolt open
Number 6 GI mag bolt held open, round didn't fly out. Loose above mag.
Number 8 same as 6.
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Number 6 GI mag bolt held open, round didn't fly out. Loose above mag.
Number 8 same as 6.
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Did it first start doing this when you put the new buffer and spring in? The H3 is a really heavy buffer usually used on fully automatic
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To be honest, I don't know. With it having a 7" barrel, I would assume pistol length? I need to do more learning on gas systems in general.
I would try a lighter buffer and spring, also make sure your disconnect spring is not fouled up or missing
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If your buffer has a roll pin on the end cap you can punch it out and remove 1 of the weights
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I would put 1 round in your magazine fire the shot and see if your bolt locks back like it should. If your bolt doesn't go far enough back for the bolt catch you either have to heavy buffer and spring or something is going on with your gas system
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Add @harris1990 to your ignore list. Anyone who recommends removing a weight from your buffer assembly should be avoided at all costs.
There is nothing quality about AE223. It's the American equivalent of PMC Bronze. Nothing short of junk. You have to use high quality ammunition to diagnose malfunctions or you'll spend your time and money chasing ghosts. Pistol length gas systems are problematic. If you're going to throw any parts at this problem, I'd start with a quality extractor spring and o-ring set. If that doesn't solve your problem. the fix is going to be expensive. If this is in fact an SBR and not just a AR pistol, a quality carbine length gas upper should be your next purchase. Good luck with this mess...
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Why can't you take a weights out of the buffer I play with the weights on my buffer all the time, just curious
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I'm willing to bet with with the fact you are running a 7" barrel your problems will disappear with a standard H buffer and standard spring problem. Pistol length gas systems can be finicky especially as different barrel manufacturers will drill the pistol ports different sizes. To be using a stiffer spring and heavier buffer without knowing what components are on that upper is not wise as there are ways different manufacturers will attempt to "solve" the issues of a shorter barrel length and some of the associated cycling problems.
Short story is that your bolt is likely cycling at too slow of a speed or not quite fully back on a consistent basis due to a number possible issues. Post some links to the products you purchased and we might be able to give you a better idea.
Also, are you running this suppressed sometimes or is it strictly being run without a can?
Short story is that your bolt is likely cycling at too slow of a speed or not quite fully back on a consistent basis due to a number possible issues. Post some links to the products you purchased and we might be able to give you a better idea.
Also, are you running this suppressed sometimes or is it strictly being run without a can?
I am running it without a can always. I was able to find a friend with an extra buffer and spring he lent to me. I tried all combinations of buffers and springs. When I was shooting the Winchester 5.56 55gr it seemed to do better, but still jam some. When I tried some of the PMC .223 it did it right away. I think I am going to hit up a friend when I get home and try his bolt and lower just to eliminate things. I got mad when I was done shooting and started taking the gun apart. I have some soot/carbon on both ends of the gas tube. Should there be any leakage on either end?
From the googling I have done it looks like Bravo Company makes an extractor kit that is the best for around 5$ so that also sounds like a good upgrade for little money.
From the googling I have done it looks like Bravo Company makes an extractor kit that is the best for around 5$ so that also sounds like a good upgrade for little money.
You can try a different carrier if you think the extractor is shit you can swap that, but I would be curious as to what diameter the gas port has been drilled to since you've experimented with the different buffers.
I can check that tomorrow evening once I get home and grab a caliper
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I got the Bravo Company extractor installed and a DA series adjustable gas block from SLR installed with a new gas tube. Spoke to Todd the owner at SLR for a bit, nice guy. I also measured the size of the gas hole in the barrel. It's .0935" I dont know if that's big or small for a 7" barrel, but thats what it is. Hope to hit the range Saturday. Bought some American Eagle 62gr ammo to try out.
Loaded one round at a time and adjusted the gas block till the bolt locked back. Everything works great now! Thanks for all the input!
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