Will the bolt lock all the way back on a empty mag when you manual cycle the action?
Have you checked alignment at the gas block and barrel?
Have you checked alignment at the gas block and barrel?
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Feeding and lockback issue with new rifle w/pics... The diagnosis?
So I just finished my first 6.8 rifle and took it to the range to sight in the scope and immediately noticed a problem. On the last round, the Bolt wouldn't lock fully to the back(and once or twice it didn't lock back at all), requiring me to use the charging handle on each subsequent mag change. It would eject every round fired, but every once in a while I would get a FTF.
It was well lubed and the action is very smooth. I did try 2 different ASC 10rd mags and 2 different weights of bullets(Older SSA 90gr and SSA 110gr)
Is it under gassed? Overgassed or cycling too quickly(14.7 welded, with mid-length gas and CAR buffer)?
Is it clear to anyone what the problem is?
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It was well lubed and the action is very smooth. I did try 2 different ASC 10rd mags and 2 different weights of bullets(Older SSA 90gr and SSA 110gr)
Is it under gassed? Overgassed or cycling too quickly(14.7 welded, with mid-length gas and CAR buffer)?
Is it clear to anyone what the problem is?
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The bolt locks back manually just fine.Will the bolt lock all the way back on a empty mag when you manual cycle the action?
Have you checked alignment at the gas block and barrel?
This is THE most frequent malfunction discussed on this site. usually something simple,, but the experts will need more information. what buffer is being used? carbine type? is it marked H for heavy? What BCG is being used? M16 or lighter versions? is this the only ammo you've shot through it? is the gun a new build? what bolt is being used? all these things by themselves may not be a problem but when coupled together could cause issues. gas block alignment is usually the first thing that should be checked.The bolt locks back manually just fine.
As the others have alluded to, you are most likely slightly under-gassed which can be due to multiple causes. The whole system is setup to balance the generation/capture of the gas (ammunition, barrel, gas block & tube) with the management of the forces created by the gas (BCG, buffer, buffer spring).
On the FTF, I suspect the feed angle of the magazine is too shallow, but that's only a hunch.
On the FTF, I suspect the feed angle of the magazine is too shallow, but that's only a hunch.
Same here
So I just finished my first 6.8 rifle and took it to the range to sight in the scope and immediately noticed......
I am in the same boat. I have run about 100 rounds through mine and am having the same issues. Will not lock back after last round except for every once in a while. It fails to feed from time to time. Some times it will feed the next round into the chamber but it never resets the hammer, therefore I have to manually eject the loaded round and grab another. I have ARP 16" with match set Anderson receivers and AIM Surplus BCG and bolt and mid length gas tube and carbine buffer and spring. ASC Magazines; 4 different ones. I'm thinking it is just stiff and needs using but I can't be sure.
Thank you for the reply. New rifle, only SSA 90 and 110gr was shot though it, Carbine buffer, mid-length gas, Bolt and FA carrier from PSA(came with the 6.8 upper).This is THE most frequent malfunction discussed on this site. usually something simple,, but the experts will need more information. what buffer is being used? carbine type? is it marked H for heavy? What BCG is being used? M16 or lighter versions? is this the only ammo you've shot through it? is the gun a new build? what bolt is being used? all these things by themselves may not be a problem but when coupled together could cause issues. gas block alignment is usually the first thing that should be checked.
Did you assemble the upper?
Check your gas system by making sure the gas block is perfectly aligned with the gas port in the barrel. Also make sure the gas tube port is aligned and clear with the port in the gas block.
It sounds like your slightly under gassed which may be a mis-alignment or blockage within your gas system.
Check your gas system by making sure the gas block is perfectly aligned with the gas port in the barrel. Also make sure the gas tube port is aligned and clear with the port in the gas block.
It sounds like your slightly under gassed which may be a mis-alignment or blockage within your gas system.
constructor has a great short stroking write up in the ar15 performance forum . I had some problems with 110 ssa not cycling my rifle. they had some low powered ammo for a while, there's a thread on it here somewhere.
Nope. I bought a complete upper and lower in two purchases and simply slapped them together.Did you assemble the upper?
Check your gas system by making sure the gas block is perfectly aligned with the gas port in the barrel. Also make sure the gas tube port is aligned and clear with the port in the gas block.
It sounds like your slightly under gassed which may be a mis-alignment or blockage within your gas system.
AH! This would explain what was happening. This is older SSA ammo.constructor has a great short stroking write up in the ar15 performance forum . I had some problems with 110 ssa not cycling my rifle. they had some low powered ammo for a while, there's a thread on it here somewhere.
In that case try some Hornady and see if it runs.AH! This would explain what was happening. This is older SSA ammo.
http://68forums.com/forums/showthread.php?55097-SHORT-STROKING-PROBLEMS-build-tips
Skip down to TESTING and Short Stroking
Skip down to TESTING and Short Stroking
There is one step most people overlook. The gas tubes port is usually off. When you install the gas tube in the gas block remove the rear set screw, look down through the hole and make sure the gas tube is not covering any part of the port in the gas block. If it is that will disrupt the flow and cause issues.
One other thing we don't talk about much because most get butt hurt when someone suggest it. Hold the rifle firm to your shoulder. I saw a video of a guy shooting last week. The rifle had been checked more than a few times and works with one shooter but not the owner. When the owner was shooting he was trying to hold the stock off his shoulder with his left hand. Every time he fired the scope would move to the rear 1.5" easy. That will cause problems and give you "scope" eyebrow.
One other thing we don't talk about much because most get butt hurt when someone suggest it. Hold the rifle firm to your shoulder. I saw a video of a guy shooting last week. The rifle had been checked more than a few times and works with one shooter but not the owner. When the owner was shooting he was trying to hold the stock off his shoulder with his left hand. Every time he fired the scope would move to the rear 1.5" easy. That will cause problems and give you "scope" eyebrow.
Thanks for the advice. I'll definitely look into the gas tube port. There's no worry the rifle wasn't secure against my shoulder.
I think his (Constructor's) point was that the rifle should ABSOLUTELY be held firm against your shoulder.There's no worry the rifle wasn't secure against my shoulder.
And that's what I said. lol
gas tube blow by at the gas block
Check your gas tube coming out of the gas block. I was having the same issues. I was getting to much gas leaking around the tube at the gas block. I pulled the gas block off and covered the port inside the gas black and blew on the end of the gas tube with my mouth and there was very little resistance. too much blow by. I degreased it and sealed around it with red loctite. Runs like a champ now. Something to look at anyway. Hope that helps.
Check your gas tube coming out of the gas block. I was having the same issues. I was getting to much gas leaking around the tube at the gas block. I pulled the gas block off and covered the port inside the gas black and blew on the end of the gas tube with my mouth and there was very little resistance. too much blow by. I degreased it and sealed around it with red loctite. Runs like a champ now. Something to look at anyway. Hope that helps.
I've only been shooting ARs fo a year, built two.
My second one the gas tub was a easy slip fit in the gasblock.
Thanks to all the good troubleshooting guides on this forum I knew to proactively seal this junction.
I hope to shoot it next weekend, and I'm happy to know that if I have undergassing this is one area I won't have to worry about.
The guys on this forum really are great and do an awesome job of walking folks through issues!
My second one the gas tub was a easy slip fit in the gasblock.
Thanks to all the good troubleshooting guides on this forum I knew to proactively seal this junction.
I hope to shoot it next weekend, and I'm happy to know that if I have undergassing this is one area I won't have to worry about.
The guys on this forum really are great and do an awesome job of walking folks through issues!
Try some different ammo and see if it still does it. S&B or Hornady.Nope. I bought a complete upper and lower in two purchases and simply slapped them together.
Edit: I see semi_cop has already covered that.
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