450 Bushmaster Feeding Problems

[SpinKiller]

I just recieved my new 450 Bushy upper. I have ran 30 or so rounds through it. I have had feeding problems with almost every mag. The first round of every mag needs forward assist. I want to be able to hunt with this firearm, but I need to know I can rely on it to chamber and fire every time.
Factory Hornady 250 Grn FTX. Full length stock, buffer and spring. I was going to try the CAR lower, but settled on this combo.
I've had several stovepipes, a couple hammer drops that didn't touch the primer, one that did, but didn't go off. Most the time it has ejected....It must chamber hard because of the foward assist every first round.....shouldn't be so particular, should it? I have some other lowers, maybe they will work?
Has anybody else have this problem? Does it need a break in period? Any other experiance with this impressive upper reciever?

[Hoot]

Does it feel bound up at all when you cycle the action by hand? Do you own a 5.56 AR that you could try the magazine from, assuming you haven't already done so? Any wear spots showing up already on the bolt and carrier that seem greater than the wear indications on the rest of it?

For my experience. I thoroughly cleaned mine right out of the box, then burnished WS2 grease on both the carrier external surface and receiver internal surface, carefully removing any excess, but I did not cycle it a lot to break it in before going to the range. It ran flawlessly. I did find that once in a while. After putting in the last round and tapping the mag gently backward to seat all the cartridges to the rear, that the top round seems to tip upward slightly more than it should. I then push the stack down a little bit to re-indexing the top one. Gosh, I'm at a loss for words to describe that simply.

I've been amateur smithing for over 20 years. If you're local to me, I would be happy to render a second opinion FWIW. Even share a little of my concocted WS2 grease.

Hoot

[Old Blue]

I had similar problems with mine. The XM-15 is VERY senistive to lubrication. It will malfuction if not properly lubricated. Having said that, it is possible that the bolt has an issue. If disassembly and lubrication of the bolt does not work, contact bushmaster customer service.

[tacster]

I had similar problems with mine. The XM-15 is VERY senistive to lubrication. It will malfuction if not properly lubricated. Having said that, it is possible that the bolt has an issue. If disassembly and lubrication of the bolt does not work, contact bushmaster customer service.

good luck. there customer service is horrible.

[maxbid]

I just recieved my new 450 Bushy upper. I have ran 30 or so rounds through it. I have had feeding problems with almost every mag. The first round of every mag needs forward assist.

You say "Almost every mag" ..... Does the stock Bushmaster mag work ok? Use this factory supplied mag to rule out any other mag problems. It's the one supplied by Bushmaster with your upper. If you have to phone Bushmaster they will be asking if it works "ok" with their supplied mag.

If it's not chambering the first Hornady 250FTX round (without using the FA) then you may have either (or both): a chamber that is too tight and/or a very weak buffer spring.

Here's what it should do = With the bolt locked back, insert stock Bushmaster mag full of 5 rounds of Hornady 450gr FTX, release bolt with bolt catch release... it should robustly slam the top round out of the mag into the chamber and lock up the bolt. No FA required. <--- If it's not doing that then tell us what it did do = Did the bolt slowly move forward without enough force to strip a round from the mag and chamber it and lock the bolt?

A little more info and we can help you diagnose what's going on. Make sure the bolt carrier is lubed up good too.

[SpinKiller]

I have cleaned and lubed it before I ever shot it. I Have manualy dropped the bolt on a round and it has not chambered without help. I also thought the chamber acted tight. Let me strip the bolt and give it a good lubing, and manualy chamber a round to see how it fits. I'll get back to you in a few days.
Thanks,

[wildcatter]

I have cleaned and lubed it before I ever shot it. I Have manualy dropped the bolt on a round and it has not chambered without help. I also thought the chamber acted tight. Let me strip the bolt and give it a good lubing, and manualy chamber a round to see how it fits. I'll get back to you in a few days.
Thanks,

Try the Thunk test, wherein, with a factory round, just drop it in a clean chamber, with the barrel pointed down, you'd better hear a decided thunk as the sound reverberates up and down the barrel. If you do hear a Thunk, the chamber is not tight..t

[Billsmith63]

I've not had any problems with my new .450 but I do notice that when operating the charging handle, it's not as smooth as my XM15. I've thoroughly cleaned it and coated the bolt carrier with lubriplate (used it for years and never a problem). Every round has chambered properly and I'm assuming that sending a bunch of lead downrange may smooth things out a bit.

[SpinKiller]

OK, disassembled, cleaned, and lubed the bolt. Did the "drop the round into the chamber, no problem.

Here is the issue, the factory round chambered from the factory 450 mag, but when I tried to eject, it jammed at about 1/2" the way out....it looks like the bolt lugs are catching on the chanmber lugs! I can't get the shell out, or pull the bolt past this point using the charge handle..... will have to get it out of course....It came out after several hard pulls..
So what do you think caused that?

[deskjockey]

sounds like the lower needs some looking at.

was this a factory lower or did you build the lower?