450 bushmaster not feeding properly

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iowayotehunter76

New member
I just picked up an ATI 16 inch 450 bushmaster upper. Put it on my RRA lower. Went together real nice. Put five rounds in the magazine. The first 2 cycled fine. 3rd one stove piped. Number 4 and 5 I had to manually eject. Put 3 more rounds in and I had to manually eject each of them. Took rifle home and pulled the BCG and cleaned and lubed it good. It wasn't very dirty at all. Then I took 4 shots, putting only 1 round in the magazine each time. The first cycled perfect and locked the bolt open like it should. Number 2 stove piped. 3 and 4 had to be ejected manually. It does have a muzzle brake. Is it letting off too much gas? Or could this be a magazine issue ? I did buy one that is made for 450/458. Any ideas greatly appreciated.
 
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some of the 450 mags have been known to be problematic - even the bushmaster factory mags.

what specific mag did you buy? also what ammo are you using?


i have a friend with a couple of the AR-stoner ones from midway that work great, i've got a couple modified ar-stoner ones i put togther with the black followers before they started making them production.

however the premium mag right now is the Bartz/Brenton USA 450 bm mags.
 
The mag is a great lakes firearms. Ammo is hornady black 250 grain ftx. Buffer I am unsure of. It is RRA standard A2 stock. I bought it as a complete rifle for my first AR. It was predator pursuit model with a 20 inch SS barrel, if that helps. I dropped the lower and put the 450 on it hoping to switch back and forth.
 
Originally Posted By: Plant.Onealso what buffer is in your lower?
X2

I bought the 450 years ago when it first came out. When to different buffer and a spring.
 
I have a Bartz 450
when new it would not feed
they said to leave the mags loaded and store them that way because when the mags are new the springs are to tight
did this and now work fine
I changed the buffer and spring also
they are 5 rd Bartz mags
 
Originally Posted By: iowayotehunter76The mag is a great lakes firearms. Ammo is hornady black 250 grain ftx. Buffer I am unsure of. It is RRA standard A2 stock. I bought it as a complete rifle for my first AR. It was predator pursuit model with a 20 inch SS barrel, if that helps. I dropped the lower and put the 450 on it hoping to switch back and forth.


so a standard a2 buffer is usually right around 5.9 oz. the standard buffer spring is fine for your application. compared to a standard carbine buffer at 3oz.. you're probably in ok territory.

id have to guess you're dealing with a mag related issue.

order up one of the ar stoner ones as a spare and you'll know for sure, unless you know someone else who has one to test with.

https://www.midwayusa.com/product/761181...ess-steel-black


if you do find out its not mag related and you're dealing with an overgassing issue, you have a couple options.

1) xh buffer from slash's - they tip the scales at a whopping 11oz, but come with a cost of about $125. I've got one in my ar-308 and they're nice, but it was spendy option. it also may or may not work well with your factory upper. should be ok... but i cant guarantee it wouldnt require swapping buffers when you switch uppers.

2) adjustable gas block - you can cure many evils with one of these. but again you're looking around $100 price point for a quality one. If you plan to suppress this rifle in the future this will be *the* way to go. just something to consider.

3) head over to the 450 bushmaster forum and order a bolt carrier slug from Hoot (search CCWS). its a lead bar that you epxoy into the rear of your BCG and adds almost 4oz to the carrier which gets you close to the XH buffer weight at about 10% of the cost ( i think i paid like $15 for mine?) Tubb's used to make something similar, but they dont seem to be available anymore.

this is from when i did mine. and yes you can still get the firing pin out to take the bcg apart for cleaning.

OzsrxDj.jpg


add some jb weld after a full degreasing of the bcg
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the rear view
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HTH
 
It could be an ammo problem, I had the same issue with those bullets in a 45-70 lever gun.
Measure the overall length of each cartridge with calipers and write it right on the brass with a sharpie. Manually cycle the rounds thru the gun and see if the longer ones are the problem children.
 
Just FYI, I took it back to the place I bought the upper and through slow motion video they determine it is an under gassing issue. You can see in the video the bolt does not come back far enough to grab the next round, but far enough to eject the spent casing. I was told they will fix the issue no questions asked when I bought it. We shall see... The gunsmith seems to believe that the gas block is not exactly lined up properly. I am hoping so, otherwise I may be waiting on a new gas block and not having the rifle before deer season.
 
Originally Posted By: iowayotehunter76Just FYI, I took it back to the place I bought the upper and through slow motion video they determine it is an under gassing issue. You can see in the video the bolt does not come back far enough to grab the next round, but far enough to eject the spent casing. I was told they will fix the issue no questions asked when I bought it. We shall see... The gunsmith seems to believe that the gas block is not exactly lined up properly. I am hoping so, otherwise I may be waiting on a new gas block and not having the rifle before deer season.

That can be disappointing and frustrating, but sadly, it is a common problem. I just built a .450 for my uncle in Ohio. I expected to have gas AND magazine issues.

So I did my research and made sure that the gas port was sized big enough and I installed an adjustable gas block so that I could fine tune it. Sadly, if you don't use an adjustable gas block you might have problems switching to different ammunition.

I also used a Brenton USA magazine. It got great reviews and is built by a guy who has done a lot of work with the .450 cartridge. The Brenton mag ran flawlessly. I also modified a 10 round Pmag which also worked well. Sadly, I bought and tested a Tromix follower that they claimed would make a Lancer magazine work well. I read some reviews of it and they were positive reviews. I did NOT have the same experience. The Tromix follower equipped Lancer mag NEVER worked. From the first round out of it, it malfunctioned. It tended to kick the round nose up and the BCG would jam it against the barrel extension. So that was a big waste of time and money. But as a gun manufacturer, we chalk it up to R&D.

I hope they get things ironed out for you. I was impressed with the ability of the cartridge and think that it has real potential.
 
glad to hear you have your problem diagnosed. hopefully it is just a GB alignment issue that can be resolved quickly.


we've taken 5 deer with the 450 so far up at my dad's place... 3 DRT, 2 that ran about 30-40 yds and piled up. all 80-100 yds... both are bushmaster factory uppers. one of them did come with a defective mag out of the plastic, shells would just pop out of the feed lips. sometimes it would try to feed 2 or 3. BM replaced the mag no questions asked.

buddy of mine ordered up one of the BCA 18" uppers about a month back, he took a big body 4 point, and put down two other wounded deer from guys he was hunting with with his. he's in love with it.

all the above were using hornady factory ammo. i have heard nightmare stories about the remington stuff... its pure crap i guess from my readings.

the cartridge is very capable, thats for [beeep] sure.
 
It's got to be better than shotgun slugs, which is all we were allowed to use until last season when they made big bore straight walled cartridges legal. They claim they haven't had a problem with any of the others they have sold, so I am assuming it is gas block/port alignment problem.
 
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