Bushmaster feed issues?

[Highpoint]

A co-worker brought a older model bushmaster nm a2 to me the other day and said he was having feed issues and wanted me to look it over.
So I get it home and take all it apart, clean it good ( including gas tube), put it all back together , oil it down, and take it to the range at my dads place. I brought the 20 rd and 30 rd older style mag he has and a few new p mags that I own.
The ammo he supplied me was crap pmc, but he is bringing me some remington stuff tonight. But after the good scrubbing I gave it , jamming stil occurs. manual cycling of the action shows the loaded ammmo in mags start to tilt back in the mags( bullet side up, even with my new p mags that I never have issues with), and the bolt slides right over the top of the ammo , jamming the gun , or failing to pick up ammo all together. This was the case with all 4 mags. I took apart his 20 rd mag and bent and streached the spring a bit , to get the rear of the ammo up a bit to get it to feed. This seems like it did the trick but I wouldnt feel comfortable using it in a " must fire situation".
I thought about trying the rra bolt from my rifle, to see if that might help( just a thought).I know its probably not the gas system, or anything in the lower( tried out mine). But other than that , Im stumped, my p mags even jammed, and they fire flawless through my rra.

Any ideas, thanks

 

[BOL556]

Re: Bushmaster feed issues?

There are 2 things it could be. There is a burr in the feed ramp causing this to happen or the bolt is out of spec. For the burr run your finger along the feed ramp you should be able to feel something out of place if its smooth your good. Just learned this to test the play in the bolt. Take off the upper and remove the charging handle then place the bolt group back in place. With the bolt carrier in all the way stick your finger in the opening in the back of the bolt and see how much play is in it going side to side and up and down. Recently did it with my RRA and found there was to much play in the bolt carrier group. Hope this works for you.

 

[dtask]

Re: Bushmaster feed issues?

PMC ammo is the only ammo that I have ever experienced a hiccup with in my old Bushmaster. Ditched the ammo and the problem went away with it. Hope your issue is as easily fixed as mine was.

 

[s4b1106]

Re: Bushmaster feed issues?

Definately check the feed ramps. Several years ago we had an M4 Bushy that wouldn't feed. Feed problem was exactly as you describe. Inspection revealed that the feed ramps had grooves from the cutting tool in them and they had never been polished out. Little time with a polishing stone and felt wheel, it has been fine since. Odd thing was, it shot ok when it was new. Started having problems after it was a year old.

 

[RockSteady]

Re: Bushmaster feed issues?

I know we're not on the topic of ammo, but I've run about 2k of pmc .223 in a colt ar-15 and some in a RRA recently and it has run fine. No problems.

Just adding my 2 cents to help, perhaps, negate it as a ammo issue.

BTW, a student at a CSAT class had an issue with his Bushmaster and feeding like you described. I am unsure how they fixed the issue.

Goodluck.