Sort of dissapointed in this caliber

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Sort of dissapointed in this caliber

Postby wrangler » Fri Sep 14, 2018 6:23 pm

Okay....I am old but I have been building AR's since 1994. First off building rifles for DCM/CMP match rifles and I did very well with them. I have also built NM M1's and M1A rifles. I made Distinguished and the Presidents 100 all with the "black rifle". I have built or rather "assembled" every configuration imaginable in 223/5.56 for myself and numerous friends. That said, being bored, I strayed away from the norm with the 300 Blackout and I'll say...it is what it is for it's intended purpose. Then moved on to the 6.5 Grendel. Accuracy ....so, so after two barrels. Almost total frustration with this caliber / platform. The first barrel was a 2 m.o.a. at BEST and also anemic velocity over my chronograph with a 20" barrel" barrel for ringing gongs beyond 600 yards. Again it is what it is!
Moving on....I went into debt with the 450 Bushmaster caliber. Dies, brass, bullets, barrel, BCG etc. The barrel and BCG, are from Midway USA....whoever makes them which they label "AR Stoner". This barrel, under the naked eye has "chatter" marks on the lands through out it's 16" length. Worked up numerous loads with Hodgdon Lil Gun powder, CCI 41, Rem. 7 1/2 and WW small pistol primers in new Star Line brass. Bullets were 240 gr. Hornady XTP Mag, Hornady 250 gr. FTX and Hornady 300 gr. XTP Mag. bullets. Charges were to max. out of the Hornady loading manual. This was a day at the range and I have no problem with that because any day at the range is better than a day at work!

So.....my results are and I must say....very disappointing with the 450 Bushmaster caliber! Short stroking leaving a spent round in the chamber or mostly with the bolt half way open with a spent case ready to chamber without a HINT of ejecting it! Accuracy at 50 yards.....1/2 MOA. At 100 yards.....from 1 1/2 moa to 3 1/2 moa depending on the bullets I named.

Now I am wondering where did I miss any info on the internet telling me that on the standard AR15 upper receiver that it's ejection port (Anderson upper) will be too small for ejection of spent rounds. Hey.....I can rack the bolt back sharply with the charging handle and a empty case just turns around on top of the mag. at best but does not EJECT, It gets caught / hung up inside the upper receiver!

Well, I hope that I have missed something along the way and I am open for suggestion. I certainly hope there is a simple solution because I am at a loss both in finances and the logic of this "routine" build.

Wrangler
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Re: Sort of dissapointed in this caliber

Postby Al in Mi » Sun Sep 16, 2018 6:40 am

your ejection port should be opened up http://www.450bushmaster.net/viewtopic.php?f=2&t=12877 or buy one already done, Tromix has them.

That' the first report I've heard on the Stoner barrels, dunno if a quick lap would help smooth things out or not.
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Re: Sort of dissapointed in this caliber

Postby Seedyn » Sun Sep 16, 2018 8:08 pm

Not sure what you are looking for here.. Do you want some advice or just looking to vent, or, hate on, something you obviously know nothing about.

Yes you have to open up the ejection port but this is well documented on this forum, and several others, so frankly you have no excuse not to know that.

I got into this caliber about a year ago. Spent tons of time reading and researching the great information and advice from some great folks found on this forum. Built my AR and started hand loading based on the tons of excellent research done by those who have gone before. If you are looking for a tack driver get yourself a 222 rem bolt and build your handloads, but, do not expect this from this round. This round is clearly designed as a "minute of deer" round out to 200-300 yards and it does it very well!

End result is a well running AR that is capable of producing cloverleafs at 100yds If I do my part) with the standard factory 250 gr ammo. My results are very similar to what you will see reported by others if you actually spend the time to read a bit more about this cartridge. Still trying to duplicate this factory accuracy with my hand loads and am getting closer every trip out.

Love everything about this round and am looking forward to hunting this fall with it. Get your research done and rebuild your rifle the right way, try out the factory loads and then handloads based on research you can find on the forum and you just may find yourself a fan too.
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Re: Sort of dissapointed in this caliber

Postby Bmt85 » Mon Sep 17, 2018 5:30 am

Some standard uppers have an ejection port just big enough to allow the 450B case to slide through, but most of the time it needs to be opened up.

As far as AR Stoner barrels, they are not known for making great barrels. From other calibers they offer, I have heard of a lot of issues, most being the tooling/chatter marks. It's not to say you can't get them to shoot, look at BCA's. They are the same quality, yet the few I have seen mentioned on this forum, actually show some promise. Honestly, you can't expect great results from cheaper barrels, if you can get them to shoot, you did good, but don't expect it. I have a couple cheap barrels in other calibers, one shoots great, especially for a beater. The other, so far, I can't get to shoot worth a crap, but it's another beater, so I'm not really concerned.

As to the cartridge, it really isn't set up for great accuracy. It's a straight wall, big bore cartridge, with some pretty good recoil. A lot things playing against it, when concerned with accuracy. There have been numerous people getting sub moa accuracy, but it isn't quite the norm. Some bullets will give you a better chance, but it's almost more luck. With that said, it is a very forgiving cartridge most of the time. I find that it's not too hard to find a "window" that a bullet prefers to get good accuracy (around 1.5 moa +/-). The 450B was meant to be a great hunting cartridge for the AR platform at short distances, which it excels at. There are a few bullets that "should" (on paper, not all proven) still perform well past 200yds, but the problem is ballistics. You have a big heavy bullet, with poor b.c. and ok muzzle velocity. Drop and wind drift are going to make things a bit difficult. Not to say it's impossible, but I doubt most can handle it, I know I wouldn't be able to without a lot of practice, as I have never been at a place where I could shoot that far. So, if you have a load that shoots 1.5 moa and you take it 200yds, that's a 3" group, which is more than enough for hunting, especially when consider the diameter of the bullet. I have a few loads that will shoot 1moa or a touch better, yet most of my hunting is done at 50yds or in. I actually have one load I took out hunting that was slightly more than 2moa, I knew I wasn't even going to have a chance to shoot past 50yds if I wanted to. Another load I have gave me tight cloverleafs during work up, but decided to take it up to a higher velocity. I still had about 1.5moa with it. It's a hunting cartridge first, and foremost, so personally, accuracy isn't my number one concern.

To help you out a bit, some bullet's that have shown to work in most rifles are the 225FTX, 250ftx, 200gr XPB, 275 XPB, and 275 TSX. Most FMJ's don't do too well for most, but usually you can find a window of decent enough accuracy for cheap plinking.

That's my opinion, for what it's worth.
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Re: Sort of dissapointed in this caliber

Postby Zad Fnark » Mon Sep 17, 2018 7:24 am

Funny with the ejection issue...

The first time I took mine out, I would have a case clogged in the chamber. Funny, as it was always the last round in the magazine that would do this. The rest would cycle fine. I was thinking I had a magazine issue.

The second time I took it out, I fired 30-40 rounds and only had one round stick in the chamber. At this point I think she just needs to "loosen up" a bit.

Ed
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Re: Sort of dissapointed in this caliber

Postby wrangler » Mon Sep 17, 2018 4:58 pm

Okay thanks to all for the advice. Today I opened up the ejection port to .532". Prior to my build, I read up on the 450 but didn't know about this site / forum until I encountered problems and did a help search.

I removed all material at the bottom of the ejection port for it's entire length. I did this with a fine cut knife file and a fine cut round file. Took me over an hour but it looks like a machinist did the work. Went back to the range for some more testing. I fired 5 rounds. That is all I had loaded. Will load more rounds in the morning. Two ejected and the bolt failed to stay locked back. The other three jammed or rather short cycled as they did on my first time out. I have tried a standard 3 oz. buffer then a 4.9 oz. buffer. Then the 4.9 oz. again with a carrier weight installed. All cycling seemed to be the same.

After coming back to my shop, I removed the gas block and measured the gas port. It measures .070" or a #50 drill. Re-installed the gas block this time with Loc-Tite.

These five rounds were 240 gr. Hornady XTP Mag, 36.2 gr. Lil Gun, WW small rifle primers in new Star Line brass. First two rounds I corrected off of and the three remaining rounds went into a a 1 1/2" group at 100 yards with two of them touching. As for the tooling marks on the lands....yes they are visually there and I'll live with them if accuracy stays under 2 m.o.a. I understand it is a 100 - 200 yard hunting caliber and not a tack driving varmint rifle. I have a couple other AR Stoner barrels, one a 5R and the other standard button rifled and they are perfect to the naked eye looking at good light and each shoot sub m.o.a.

So far I have tried two mags. Both will feed but not all the time. Some rounds get hung up on the feed ramp. These mags are 20 round GI Nam type issue mags with alloy followers. I bought blue follows from a fella on ebay that roll into place over the issued follower with the use of a allen wrench or your firing pin. My guess is the 240 gr. Hornady hollow point XTP mag isn't the best bullet to use for feeding. I'll be working with the 250 gr. flex tip next trip to the range.

I will also be try a rifle A2 lower next time out if the carbine buffer system still gives me issues.

I will get this upper to shoot as I am not one to give up but I must admit, it has been nothing short of frustration up until this point. I wish I had found this group before I ordered my parts. I would have been better prepared before heading out to the range with this caliber / upper combo. Not really much info anywhere else but here.

My thanks to all!
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Re: Sort of dissapointed in this caliber

Postby wrangler » Mon Sep 17, 2018 4:59 pm

Okay thanks to all for the advice. Today I opened up the ejection port to .532". Prior to my build, I read up on the 450 but didn't know about this site / forum until I encountered problems and did a help search.

I removed all material at the bottom of the ejection port for it's entire length. I did this with a fine cut knife file and a fine cut round file. Took me over an hour but it looks like a machinist did the work. Went back to the range for some more testing. I fired 5 rounds. That is all I had loaded. Will load more rounds in the morning. Two ejected and the bolt failed to stay locked back. The other three jammed or rather short cycled as they did on my first time out. I have tried a standard 3 oz. buffer then a 4.9 oz. buffer. Then the 4.9 oz. again with a carrier weight installed. All cycling seemed to be the same.

After coming back to my shop, I removed the gas block and measured the gas port. It measures .070" or a #50 drill. Re-installed the gas block this time with Loc-Tite.

These five rounds were 240 gr. Hornady XTP Mag, 36.2 gr. Lil Gun, WW small rifle primers in new Star Line brass. First two rounds I corrected off of and the three remaining rounds went into a a 1 1/2" group at 100 yards with two of them touching. As for the tooling marks on the lands....yes they are visually there and I'll live with them if accuracy stays under 2 m.o.a. I understand it is a 100 - 200 yard hunting caliber and not a tack driving varmint rifle. I have a couple other AR Stoner barrels, one a 5R and the other standard button rifled and they are perfect to the naked eye looking at good light and each shoot sub m.o.a.

So far I have tried two mags. Both will feed but not all the time. Some rounds get hung up on the feed ramp. These mags are 20 round GI Nam type issue mags with alloy followers. I bought blue follows from a fella on ebay that roll into place over the issued follower with the use of a allen wrench or your firing pin. My guess is the 240 gr. Hornady hollow point XTP mag isn't the best bullet to use for feeding. I'll be working with the 250 gr. flex tip next trip to the range.

I will also be try a rifle A2 lower next time out if the carbine buffer system still gives me issues.

I will get this upper to shoot as I am not one to give up but I must admit, it has been nothing short of frustration up until this point. I wish I had found this group before I ordered my parts. I would have been better prepared before heading out to the range with this caliber / upper combo. Not really much info anywhere else but here.

My thanks to all!
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Re: Sort of dissapointed in this caliber

Postby Al in Mi » Mon Sep 17, 2018 6:23 pm

What type of feed ramp is in that extension, did they use a standard or make it for straight on feed?

On your mags, you might need to make a "U" notch on the front of those mags, sometimes on GI mags the case mouth will hit the front of the mag.
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Re: Sort of dissapointed in this caliber

Postby Bmt85 » Mon Sep 17, 2018 8:24 pm

Ok, so you got the ejection port fixed time to move on. First, I’m guessing your under gassed, mainly because you changed buffer weights, and it’s not locking open. I don’t recall gas port sizes off hand, but that seems small. What barrel length and gas length system? Either way, I would go back to the lighter buffer and when it’s running, then try going heavier if need be.

Another thing that could be affecting you is mags and barrel extension, as Al has pointed out. To add to what he said, I have found that with blunter bullets, it’s best to tweak the feed lips so the cartridge is pointing slightly up, with the tips of the feed lips opened up quite a bit to help release the cartridge a little sooner. I’ll post pics tomorrow, as I can’t right now. I was running Lehigh 135 XD bullets, and that bullet will really hang up if given the chance. I tweaked my mags, and have no issues. But some others have done different, so play with it. Also make sure the feed lips are smooth out so as not to cut into the brass. Most mags will do this, just takes a little time to clean them up. As to the barrel extension, as long as it’s not a normal 5.56 extension, you should be ok. Even if it’s a 5.56 but slightly hogged/smoothed out, it should work.
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Re: Sort of dissapointed in this caliber

Postby wrangler » Mon Sep 17, 2018 8:49 pm

I have a 16" AR Stoner barrel with a carbine length gas system. Yes I agree my rifle is under gassed. I would have thought buying a complete bca and barrel from the same supplier that all would work. Well I guess that is better than getting a over gassed system! Will deal with that later if need be.

I'll try the standard weight buffer next time out and go from there. I will also more closely look at a round that fails to feed. Today, I just cleared the round and moved on. If need be, I'll grind a U notch in the mags.

Again....thanks for all of the advice and tips.

If need be, I'll open up the gas port to .073" or a number 51 drill.
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