I'm a new member.
Just shot my brand new Bushmaster AR 20" HBAR this weekend. It is very accurate, I was hitting bowling pins at 100 yards within 20 minutes of loading her up.
Anyways, I noticed a feeding problem that I'm hoping somebody can help me with. Here it is:
When the magazine (of which I tried several and it happened with all of them -- all mil-spec Bushmaster and C-Products) only had a few rounds in it (3-5) it ran flawlessly and the magazine locked up nicely even with the bolt forward. I was shooting American Eagle and S&S 55gr. (Mostly AE).
When I loaded a magazine with 10 or more rounds in it the rounds would eject and the bolt returned forward but failed to strip a round off of the magazine. Then if I pulled back the charging handle it would strip a round and fire, but fail again until I had about 5 rounds left, then it would feed normally. I am guessing that there is some kind of a problem with the magazine.
All of the magazines will go into the rifle with the bolt already forward when they are empty, but a magazine with 10 rounds or more will not, I had to pull the bolt back. So for some reason when there's a lot of pressure from the top bullet in the mag, it won't lock into place.
The bolt never failed to lock back after the last round with any of the magazines.
Some people have suggested that the mag is too tight against the carrier when loaded fully. I saw in the instruction manual that there is a way to loosen and tighten the magazine fit. Could this be the problem? Do I need to loosen it or tighten it?
Other people have said it could be the gas, but like I said, with 5 rounds in there it functioned flawlessly and always locked back after the last round.
I am new to the AR (but experienced with the M1A)
Any help would be greatly appreciated
Now, I've got some people saying that C-Products (AR Stoner) mages are junk and so are Bushmaster (which I thought were Labelle USGI).
I will try lubricating it more.
The bolt always locks back on the last round and there are no problems when the mag only has 5 or less rounds in it.
How to I fix the rounds pushing up on the carrier?
Is it better to lube with grease or oil?
Couple of more things to think about.
The weight of the mag may be holding it low. Take the mag out, and push the mag release in until the long thing on the other side of the magwell is sticking out and rotate it in another turn or two.
Another issue could be weak springs in your mag. Get a friends mag that is known to work and try his, or have him try yours.
Also, check to see that the gas rings on the bolt are not lined up and the carrier key is on tight and staked.
Welcome to the site. Just a question, did you clean the heck out of it before you shot it the first time? There are training manuals in the information button at top right download if you don't have one already.