450 Build Complete, One question.

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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450 Build Complete, One question.

Postby buckeye3405 » Wed Feb 22, 2017 6:02 pm

My 450 Bushmaster build is complete! I took it to the range yesterday after work and it shoots amazing! 50 yards I had 4 rounds on top of each other. Shot one round at 100 yards to verify 100 yard zero and it was right in the 1" center bullseye. Now, the only question I have is the empty brass weren't flying that far when ejected. I shot a total of 17 rounds of Hornady factory ammo and there was no issue other than what I consider weak ejection. I was using the two new Bartz 5 round hunting mags I purchased. Very nice! I'm not too concerned given how the rifle performed but just wondered if I should keep an eye on the "weak" ejection?

Love this gun!!!
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Re: 450 Build Complete, One question.

Postby buckeye3405 » Wed Feb 22, 2017 6:09 pm

Final results!
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Re: 450 Build Complete, One question.

Postby buckeye3405 » Wed Feb 22, 2017 6:10 pm

For some reason they are all tilted 90 degrees to the left there but you get the idea.
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Re: 450 Build Complete, One question.

Postby plant_one » Wed Feb 22, 2017 6:25 pm

define 'weak' ejection?

where were they in relation to the gun - distance and position - for exmple: 4 o clock, 3 feet from the gun
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Re: 450 Build Complete, One question.

Postby buckeye3405 » Wed Feb 22, 2017 6:38 pm

Some of the brass ended up off the shooting bench at about the 2 to 3 o'clock position maybe 3ft away while a few other ones I picked up off the shooting bench right next to me. I was alone so idk if these hit something to cause this or what. I'm probably just paranoid. Every time I do a new build I always expect the worst, especially on a cartridge that I have no prior experience with and after reading all the interweb stories.
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Re: 450 Build Complete, One question.

Postby Hoot » Wed Feb 22, 2017 7:13 pm

buckeye3405 wrote:Some of the brass ended up off the shooting bench at about the 2 to 3 o'clock position maybe 3ft away while a few other ones I picked up off the shooting bench right next to me. I was alone so idk if these hit something to cause this or what. I'm probably just paranoid. Every time I do a new build I always expect the worst, especially on a cartridge that I have no prior experience with and after reading all the interweb stories.


Some expended rounds fling clear into space and some fling backwards and hit the shell deflector. Those usually spin to a halt close by. Read the tea leaves. Are there dents in some and not others? Hitting the deflector usually imparts a small dent. Count your blessings if that's the only issue you ran into with a NIB gun. That having been said, watch for small shards of brass on the bolt face. They're not worth worrying about but what they can sometimes do is. Some times the small slivers slip down in the ejection plunger and make it feel crunchy when depressed, or actually bind. When cleaning your BCG, its always good practice to flex the extractor and using a small pushing implement, depress that ejection plunger and see how it feels.

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Re: 450 Build Complete, One question.

Postby Pig_Popper » Wed Feb 22, 2017 9:24 pm

Was the upper assembled by anybody in particular ?

Reason i ask is if it is a custom upper maybe the ejector spring was tuned for lighter ejection.

I did this to my 450bm myself by shortening the ejector spring as I don't like hunting my spent brass.

Nice gun and targets!
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Re: 450 Build Complete, One question.

Postby Hoot » Thu Feb 23, 2017 1:13 am

Pig_Popper wrote:Was the upper assembled by anybody in particular ?

Reason i ask is if it is a custom upper maybe the ejector spring was tuned for lighter ejection.

I did this to my 450bm myself by shortening the ejector spring as I don't like hunting my spent brass.

Nice gun and targets!


Heck, I do that with all mu AR bolts. Same reason. I use a brass catcher, so no need to reach escape velocity.
Big weather change coming in and bad hip is keeping me up. Image

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Re: 450 Build Complete, One question.

Postby plant_one » Thu Feb 23, 2017 11:23 am

how much lube are you using on your BCG? since this is a new build - you should be running it almost dripping wet for the first 5+ boxes. like spraying lube around the first few times you fire it wet.


yes i know its messy, but all AR uppers have a wear in period as the surfaces mate together and smooth out.



if you want to speed up this process to eliminate the break in, remove the lube from the BCG and manually cycle the gun with no ammo/mag in it 200 or so times.

this will wear in the mating surfaces just like normal recoil would.

[edit] this is SOP for blackouts that are going to be primarily run subsonic due to the low gas volume produced by them in many instances, especailly those with a carbine gas system - its used to just eliminate the wear in being the issue any cycling diagnostics. they are way more hypersensitive to this kind of thing when new compared to the 450 due to the powder charge difference being so significant (300 blk subs use like 10 grains or so of powder) [/edit]


then take the BCG out, clean and lube like normal and head back to the range. See if that helps things.
Last edited by plant_one on Thu Feb 23, 2017 11:26 am, edited 1 time in total.
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Re: 450 Build Complete, One question.

Postby plant_one » Thu Feb 23, 2017 11:24 am

also


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hth
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