ar15 carbine, not unlocking

[jacUSMC]

it is a full auto type carrier. although i did not specify I have been over this thing and the recomendations, you also may have missed where I have tried exchanging all the components including different lowers just to be sure. I even swaped charging handles. the gas key is peened into place so checking torque...not realy an option.
So what makes a m16 carrier slow down in cycle in one rifle, and not fully cycle, while an ar15 carrier will in the same rifle. and then both carriers work in another rifle completely? if there was a gas issue with the rifle, or a missalinged component then no bcg should function in the rifle, now I can buy that there may be an issue with gas key in the m16 carrier i have, but there also could be another issue...

 

[Jason248]

If the other bolt carrier works in you rifle and yours does not I think you've got it figured out. Yours may work in the 300 AAC because it's got more power to throw it back. Have you checked the gas key to make sure the bolts are tight?

If it's a factory PSA it should come with the basic carbine buffer which is the lightest so I don't think that's your issue.

Is there an obstruction from where the gas key meets the carrier? Try taking a small wire or pick and see if anything falls out. Or spend $100 on a new BCG if you've got it narrowed down and be done

 

[mtrmn]

There is a slot in the upper where the gas key and the top portion of the cam pin ride back and forth. Check that slot and clearance in that area. Change out JUST THE CAM PIN and try it.
Remove the upper and slide the BCG back and forth by hand WHILE APPLYING UPWARD PRESSURE.
Just a couple suggestions.......

 

[jacUSMC]

the cam pin may be the only thing i have not tried out. I'll switch those out before I spend money on a new carrier. as for the gas key I have cleaned it out multiple time with pipe cleaners, along with the gas tube. I know the problem lies in the bcg, but what? gas key is good. gas rings on the bolt are good, "looks" like it is in specs, compared to another. The cam pin sugestion may be an option. will get back to ya after further experimentation.

 

[HJ857]

Have you checked if the buffer tube itself is not bent or deformed? That will definitely hinder the movement of the carrier.

 

[jacUSMC]

other bcg's will work in it so I fugure not the buffer tube.

 

[ChCx2744]

Even if you are not the original purchaser, try calling PSA anyways. I used to own a PSA CHF M4 Carbine with some issues and had to send it back. They have great customer service, took care of everything free of charge, except shipping.

 

[justice06rr]

Its hard for us to tell exactly what can be wrong with your AR just over the internet. I recommend getting it looked at by a gunsmith or someone who is an expert with AR15's.

It could be your BCG or something else off spec in your upper/lower.

FYI I had an ATI poly lower that was not the best lower in terms of quality. Sold that crap a while ago because I didn't trust it.

 

[jacUSMC]

thanks

Thanks for all the helpful suggestions. This has been a pain, but everyone has been helpful...til next time.

 

[wally]

finally got to the range today. took a known good AR carbine, and started a parts swap, mine was still not functioning, and we have narrowed it down to the bolt carrier itself....now..no idea why. the 2 bolt carriers we have ar not the same, mine is what I am calling a military type, the other is a "sporter" type, not sure what to call it, but deminsionaly they are identical except for the rear of the carrier where the mil spec has more metal and the other is cut back

Does your bolt/carrier work in his gun? When yo say you've narrowed it down to the carrier, did you just swap complete BCG or did you swap bolts in the carriers?

If it doesn't work in his gun I'd bet on the gas key not being right or some FOD is blocking gas from getting inside to operate the piston.

If it does work in his gun, I'd be looking for something wrong at the rear of your rifle that interferes with the M16 carrier but not the AR15 carrier.

If you can, post photos of your hammer and bolt carrier so we can see if there might be some unusual wear.

Its hard for us to tell exactly what can be wrong with your AR just over the internet. I recommend getting it looked at by a gunsmith or someone who is an expert with AR15's.

This probably would be the most efficient option, but the education gleaned from working through the issue is IMHO invaluable in the long run.

 

[jacUSMC]

Ok. So if one of you ar armorers couldhave seen the malfunction you could have told me what it was....but it WAS the gas system, not the gas key, but the gas port on the barrel itself. To small, it was restricting the return... now it was under an A2 sight, so that made me think there would not be a problem. The light ar15 bolt would work, but would not hold open, the heavy m16 bolt justwould not move enough to cycle. So a thousandth later, it work s perfect. So, nothing against PSA or whoever builds their rifles, but that was a manufacter failure not the poor fellow who bought it to begin with, who traded it to me, and lied to me, but no worries, this was a good experience. My shooting bro and I worked it out, and the upper is now on his build kit, and i have a very nice S&W M&P15...
Thanks again. The gas system was the culprit so all of you who thought so where right, thanks.