My 450 build

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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My 450 build

Postby PJames » Sat Dec 24, 2016 2:46 pm

First off want to say hi. I am a new guy here, I have been wanting a big bore AR for some time now. I built a 6.5 Grendel and it has been just great super accurate. My buddy built a 458 Socom and I was going that route but, I like being different lol. So here it is a 16" Brownells 1:20 twist on a PSA upper/lower, hyper fire comp flat trigger. "Not in this picture but in second pic" I opened up the ejection port probably a little bit to much...but, at least it clears the ejected cases.
 Image

I was worried about the 450 bushmaster with all the horror stories, I hear about feeding/failure to fire ect. My buddy said your going to regret getting the 450 that is until he saw it in action. I think you guys just say how it sucks because you don't want everyone to know just how awesome this round really is...lol
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I had zero failures of any kind. I used some modified Elander 556 mags they hold 8 just fine but I am sure if I clip a few coils off the spring it would hold and feed 9 to 10 rounds just fine. The Elander mags have thick followers so reshaping them with a dremel drum sander didn't skeletonized them. I also modified a 20 round Pmag that holds 7 rounds and feeds awesome too. Plus it is much better from a shooting bench.
 
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Re: My 450 build

Postby Pig_Popper » Sat Dec 24, 2016 9:21 pm

I thought long and hard on the Brownells barrel/bolt with the sales price they had going but couldn't do it due to the obscure threading.

I can't see what brake your running in the photos , what did you come up with on that?

Nice target, I assume that is factory ammo at 100 yards???
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Re: My 450 build

Postby PJames » Sat Dec 24, 2016 10:06 pm

No muzzle brake as of yet but, I am in the works making my own. Or I'll go with a Ross brake if mine doesn't work lol. Yes, 100 yards with factory 250gr Hornady Black ammo.
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Re: My 450 build

Postby commander faschisto » Sun Dec 25, 2016 12:56 am

If anyone has an unusual thread on a barrel, there's an outfit called Witt Machine that will make a muzzle brake to order, and prices are very reasonable:

http://wittmachine.net/index.php?main_p ... cts_id=182
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Re: My 450 build

Postby kenn1320 » Sun Dec 25, 2016 8:35 am

Wow nice build. I was looking at that stock, hows the recoil of this round? That group is awesome!
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Re: My 450 build

Postby Hoot » Sun Dec 25, 2016 8:53 am

Nice compact rig and great 100yd group to boot!

Unless I'm misunderstanding what I see, check the clamping torque on your scope rings. The recoil may be causing the scope to drift.

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Re: My 450 build

Postby kenn1320 » Sun Dec 25, 2016 12:06 pm

Hoot wrote:Nice compact rig and great 100yd group to boot!

Unless I'm misunderstanding what I see, check the clamping torque on your scope rings. The recoil may be causing the scope to drift.

Hoot


Hoot, are you implying this gun can shoot better than what is shown? I couldn't imagine shooting this good, nothing I own currently can do that. The twist is a little faster than the 1:24, is that helping or hurting with the factory ammo?
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Re: My 450 build

Postby Hoot » Sun Dec 25, 2016 1:25 pm

kenn1320 wrote:
Hoot wrote:Nice compact rig and great 100yd group to boot!

Unless I'm misunderstanding what I see, check the clamping torque on your scope rings. The recoil may be causing the scope to drift.

Hoot


Hoot, are you implying this gun can shoot better than what is shown? I couldn't imagine shooting this good, nothing I own currently can do that. The twist is a little faster than the 1:24, is that helping or hurting with the factory ammo?


I was not referring to the target.
The consummate analyst in me noticed scratch marks on the scope body making it look like it has slid forward under recoil. Ive seen that in lightweight, recoiling calibers, when the rings are not clamped tight enough around the scope body. Most rings come with recommended torque specs. A fellow I used to hunt with 30years ago got a Winchester Model 70 featherweight in 7mm Magnum for deer hunting. Not because it was a good matchup for Northern Minnesota woods hunting, but because the guy he got it from owed him money and my friend did not have a deer rifle otherwise. Had a devil of a time getting the scope to stay in one place due to really wicked recoil, with off the shelf, ma and pa sporting goods store rings. Solved it by getting a higher quality (more expensive) set of rings. The 450b, in an AR platform is a pussy cat by comparison, but still gets your attention.

That target speaks volumes about the shooter's ability. (IE don't change a thing) Better 100yd groups than that are few and far between, with the majority that we don't see pictures of, not being nearly so nice. That's about as good as factory loads get based upon other member's reports. Now if that target is indicative of every group of factory ammo ever shot from that gun, then it is a great matchup. From the get-go and for about the first 4 years, I never shot a factory cartridge through my rifle, preferring to reload to my own quality standards. I actually had the dies and reloading components purchased about a month before the rifle actually arrived from Bushmaster.

WRT twist rate and factory 250's, again the target tells the tale. Most of the reports we have are based off of either 1:24 or 1:16 barrels. Also the only two twist rates that I've ever tried in this caliber. Load to Rifle results vary a lot, especially with so many barrel manufacturers offering this caliber now. Back when it was just the Bushmaster product line, load results could be safely assumed to apply to all the 450b rifles out there. Now its more a matter of experimentation to see what your particular brand and specification of barrel prefers.

My own experience with my original Bushmaster 20" 1:24 was that it really excelled with Hornady 225gr FTX bullets. They just got along real well. Not so with the 230FMJ (go figure), nor just about anything in 300gr, but that was just indicative of what my particular rig liked or not. Just to qualify "excelled" I'm talking reliable sub-MOA 5-shot groups at 100yds like this:

Image

The times when I've loaded 250gr FTX bullets to simulate factory ammo, my results were more along the lines of what the OP got, with an occasional "easter egg" great group, but mostly nibbling around the edge of 1 MOA for 5 shots. I sincerely believe that the forgiving nature of this caliber, makes a lot of us look good on paper. I'm not a highly accomplished AR platform shooter by any stretch of the imagination. ;) Another AR platform caliber that makes the shooter really shine is the 6.5 Grendel pushing 123gr Hornady Amax bullets.

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Re: My 450 build

Postby PJames » Sun Dec 25, 2016 2:36 pm

Hoot wrote:Nice compact rig and great 100yd group to boot!

Unless I'm misunderstanding what I see, check the clamping torque on your scope rings. The recoil may be causing the scope to drift.

Hoot


Hey Hoot those scratches on the scope was from when I had this scope and base on my AR10. I'll check the clapping of the base to the rail. But I was just testing the new build out. I plan on a 2x7 Leupold LR soon for this 450BM. BTW you think the 225gr FTX's will shoot as good in my 1:20 twist? I hope so. Oh and thank you for the compliments from all about my shooting. Some days are good and some not so much...lol I am not recoil shy so that may help.
Last edited by PJames on Sun Dec 25, 2016 10:17 pm, edited 1 time in total.
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Re: My 450 build

Postby PJames » Sun Dec 25, 2016 2:40 pm

kenn1320 wrote:Wow nice build. I was looking at that stock, hows the recoil of this round? That group is awesome!


I like the stock fit is nice and tight. I don't think recoil is bad at all more than my 6.5 Grendel though. My 350 Rem mag model 7 is a beast but puts a smile on my face every time I shoot it.
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