I got this bushmaster and it's been sitting around for a couple of years. I've cleaned and oiled it regularly, but had no chance to try it out until a couple of weeks ago. I took it to an indoor range and I fired one shot (brass casings) and the expended shell got stuck in the chamber (with another round jammed behind it.) I cleared the expended shell, which was tight in (and I noticed a part of the lip was pulled off as if the extractor got hold of it, but couldn't pull it out. I tried to fire it again. This time I got off two shots before it did the same thing. The range had a gun smith and he recommended I get it cleaned by them for $40.00, which I did, but was out of time so I left without trying it. I returned yesterday and this time I got off around 40 rounds and it happened again. I didn't bring my cleaning rod to clear the shell this time, so my shooting ended. I talked to the sun smith again and he told me it would cost $75.00 to clear the shell before they would even look at the cause, but that's ridiculous, so I didn't leave them with the rifle. I got the shell out at home, but I'm wondering what's going on. I checked the internet and found some saying it could be my buffer is too light. I have a standard buffer. Does this sound right? If I get an H or H2 buffer, could it correct this problem? What else could it be? I keep it clean.

FYI, I bought it used, but it looks brand new. The woman I bought it off of said she never really shot it too much and that's why she was getting rid of it.

Any ideas?

Thanks!

Barrel length? Gas system? Buffer weight?

Have you disassembled the bolt to see the extractor spring and insert? Examined the extractor claw?

Have you examined the chamber to see if it's rough? Have you scrubbed the chamber with a brass brush and/or tried polishing it with flitz?

The BM is a gas with a 3oz buffer, standard 16 in barrel. All standard, no upgrades.

Have you scrubbed the chamber with a brass brush and/or tried polishing it with flitz?

What's flitz? I've used a chamber brass brush on it many times and when I had it cleaned, they said it was pretty clean.

Get a chamber brush and scrub the heck out of it with some brake cleaner (Gun Scrubber).  

Consider adding a BCM Extractor Kit.

Flitz is a metal polish.  Most hardware stores and Amazon sell it.  It's very mild, it's not like valve lapping compound.  Flitz, steel wool, and a chamber brush can help clean and polish things.

Just ordered the BCM Extractor kit. Less than $10 with shipping!

Hopefully that'll fix you up.

remington ilion ny Bushmaster?

I'll let you know. I'm game for anything. I was going to buy a H buffer also. What is Flitz?

Thanks for all your help.

A metal polishing compound.  Sometimes new chambers in barrels can have rough surfaces from the machining process and it can help to polish the chamber with a wire brush and polishing compound.

Thanks, I'll try that also.

What type of ammo were you using?  Didn't see it mentioned in the OP.

Monarch .223 brass casings from Academy Sports.

I went through this with my Colt Sporter Lightweight, keep jamming.   Poor thing had 3 things wrong with it

1. broken buffer tip.

Replaced with new Colt H2, test fired with H buffer from my Colt 6920.  Even tried standard buffer got from Brownells, no luck, but at least the buffer's fixed

2. weak gas rings.  It passed the standing the bolt carrier on a table and see if it collapses test, but the slightest pressure would make it collapse.  So slapped new gas rings in it

Still had failure to extract about about 8-10 rds

3. finally diagnosed a broken extractor spring.  Only by taking the spring out I could tell it was broken, the two broken pieces were still held in place in the hole in the extractor

Slapped in a new extractor spring and will range test this weekend or the next

Wow, I checked the buffer spring. The thing was brand new. I don't know what the collapse test, but I'll google that. Finally, I'm going to replace the extractor spring with a new kit ordered and on its way. It would seem the spring is strong though because it's practically pulling the lip off the casing when it gets stuck in the chamber. I thought if I slow down the process with a heavier buffer, it would give the shell time enough to contract before the extractor tries to yank it out. (If that doesn't make sense, it's because this is my first AR. I'm mostly a pistol guy.) I spent last night trying to polish the inside of the barrel with a chamber brush. I won't have a chance to shoot till next week. (I wish I had a range in my backyard, but even here in Texas they frown on shooting in the city limits. LOL.) For now, I'm waiting on my extractor spring kit to come in and looking for a place to buy Flitz.

I'm willing to try anything. I hadn't shot an AR since the military and it feels like old times.

Where's Monarch from? I guess not the good ole USA, huh? For now I'm just putting holes in paper so I figured the cheaper the round, the more I get to shoot. There I go figuring again. When will I learn you get what you pay for. LOL

Monarch is a foreign ammo company.  Much of it is Russian.  Are you sure that the ammo you fired is brass cased?  Could it have been copper washed steel?

Steel cased ammo is know for the casings getting stuck in the chamber because of the coating on the casings.

Russian ammo uses Russian powder which has different pressure characteristics than US Made powders.

You need to try the gun again after scrubbing the chamber and barrel, and lubricating, WITH US made M855 type 5.56 ammo to properly test.

Op first try some different reputable ammo like was suggested. I'm not thinking that your extractor has anything wrong with it because it pulled the rim almost off. The case is getting stuck plain

and simple. Now what is causing the getting stuck is the question. Ammo your using could be out of spec (way over pressure) over gassing the system and not having enough time to release from

the chamber. You bought the gun used who knows what problems they could have had. I have seen people have jams that have nothing to do with the gas port and they drill out the gas port and

get problems like these. So it might be worth while to check the port to make sure its not oversized. After that I would be checking to make sure the chamber is in spec and not causing good

ammo to be over pressured.

I agree with the above.  It sounds as if the case does not release from the chamber.  I might add rough or undersized chamber.

Call and have them evaluate it. If the casings are stove piping each shot you have a tight chamber and they will replace your barrel and get it back within a couple weeks like they did my buddy.

I bet its an ammo issue.

Unless I missed it did you say what type you're shooting?  That sounds like steel case type issues to me.

The extractor kit and heavy buffer will certainly help it run smoother IMO.