So I just bought an upper and a lower to build an ar10. Both are PSA for the PA10 model.
While I was setting it up today, I noticed I can’t pull the BCG all the way back. It only goes about 2/3rds of the way, hence it won’t strip a round from the mag. I haven’t even shot it yet. Just lubed it up to make sure that wasn’t the issue, checked for debris, checked to make sure I have the correct buffer spring, etc. The BCG seats into battery properly, and the mag well accepts mags just fine.
I did some googling and some people said it was a faulty forward assist issue. I still can’t figure it out. Any ideas?
Ok. Got some more info. I took out the forward assist. Nothing LOOKED wrong with it. I can cycle the weapon better though. Here’s what I also noticed:
When I lock the bolt back, is it supposed to be that far forward? What I’m still having issues with, is the bolt isn’t even stripping a round from the magazine. Keep in mind, I’m hand cycling the weapon so this is definitely not a gassing issue.
I’m using PMAG 20 round SR/LR mags I bought at Cabelas.
Let me see your buffer. Does it have the short carbine buffer in it or a standard C buffer? It should have the short. You can compare it to a regular ar15 buffer if you have one.
let me see a pic of the assembled lower. If you have an adjustable stock and a standard carbine buffer tube your buffer should be much shorter. The spring is fine.
If the buffer tube is tge issue, could I request PSA just send me a new tube? I’d rather not have to mail the lower receiver back. Especially since there is nothing wrong with it
all that looks right. You can use a carbine tube on an ar10. I just know PSA has both. Your buffer and the spring look correct also. I dont have my ar10 in front of me. Does the bcg clear the mag to allow loading a new round?
edit: can you push the bcg back further through the ejection port using your finger? Next thing to check would be the charging handle if that is as far back as you can pull it, make sure something isn’t binding with it.
The BCG doesn’t even touch the mag. It won’t strip a new round AT ALL. The bolt catch works fine. I cannot push the bolt back but maybe that might be because of the buffer being so strong. This thing feels super tight compared to my 15, but that gun has been broken in with at least 2.5k rounds through it by now.
This is how far it goes if I yank on the charging handle.
I also just took the buffer and spring out and pulled the bcg all the way back. Cleared the mag easily and gravity alone let it slide back into place. So there obviously isn’t a machining problem. I really am wondering if the buffer spring is too long?
Just did some googling and found the carbine tubes need something like a 28 coil spring and this one is a 39
That sounds like someone put a rifle spring in. Coil Bind is a Thing.
With the upper and lower apart (from one-another, not in pieces ), spring and buffer in the tube - can you (carefully!) push the BCG into the tube far enough that the (extended) bolt clears the back of the magwell?
If you have a soft-vise (or helper), that helps hold the lower.
Ar15 spring on bottom. Ar10 on top. Aren’t they supposed to be the same length?
I haven’t been able to push the bcg to clear the mag well. I can move it a little further back, but still not enough. I don’t think it can go any further since it physically doesn’t have the space
