Which gas system

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Which gas system

Postby ScottyPotty » Mon Feb 12, 2018 7:38 pm

With an 18" barrel what is the consensenses on the best gas hole location for our 450 bushmasters. Do you guys prefer mid length or rifle length?
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Re: Which gas system

Postby Al in Mi » Mon Feb 12, 2018 8:10 pm

Mid
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Re: Which gas system

Postby Hoot » Mon Feb 12, 2018 8:23 pm

ScottyPotty wrote:With an 18" barrel what is the consensuses on the best gas hole location for our 450 bushmasters. Do you guys prefer mid length or rifle length?


I'm sure my opinion will depart with some but IMHO, with these fast powders that we use, you'd cover the most bases with a carbine length. If you only intend to shoot 300 grainers and up, then maybe mid-length.

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Re: Which gas system

Postby Bmt85 » Tue Feb 13, 2018 3:22 am

If I was just running manufactured ammo, then probably carbine length and tweak the rifle. Just to make sure it will run. I reload, so midlength. I have an 18” Tromix that hasn’t had issues running 135gr Lehigh. However, I needed to run higher then what QuickLoad predicted was a 40k psi load, to get it to cycle. That’s with using a Slash’s XH buffer, which probably should have been swapped out for a standard carbine buffer at that point. Even then, my case head growth was minimal, and no other pressure signs. As far as more normal weight bullets for the 450B (200-275gr), never an issue.

An 18” with a rifle length gas would be experimental. I’m sure you could get it to run, but it’s going to be extremely finicky and likely require most loads to be over book. Doubting manufactured ammo will cycle.
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Re: Which gas system

Postby ScottyPotty » Tue Feb 13, 2018 6:07 pm

Hoot wrote:
ScottyPotty wrote:With an 18" barrel what is the consensuses on the best gas hole location for our 450 bushmasters. Do you guys prefer mid length or rifle length?


I'm sure my opinion will depart with some but IMHO, with these fast powders that we use, you'd cover the most bases with a carbine length. If you only intend to shoot 300 grainers and up, then maybe mid-length.

Hoot


Can you expand on that? What do you mean by most bases? I plan on using either factory Hornady black or reload some 200-275xpb. Right now I have a Tromix barrel with a mid length gas port and it runs the 250gn factory stuff fine. I'm looking at getting a new barrel and wanted to make sure I did my homework. Thanks for all the help!
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Re: Which gas system

Postby Hoot » Tue Feb 13, 2018 9:42 pm

ScottyPotty wrote:
Hoot wrote:
ScottyPotty wrote:With an 18" barrel what is the consensuses on the best gas hole location for our 450 bushmasters. Do you guys prefer mid length or rifle length?


I'm sure my opinion will depart with some but IMHO, with these fast powders that we use, you'd cover the most bases with a carbine length. If you only intend to shoot 300 grainers and up, then maybe mid-length.

Hoot


Can you expand on that? What do you mean by most bases? I plan on using either factory Hornady black or reload some 200-275xpb. Right now I have a Tromix barrel with a mid length gas port and it runs the 250gn factory stuff fine. I'm looking at getting a new barrel and wanted to make sure I did my homework. Thanks for all the help!


There are a lot of good candidate bullets out there for the 450b, for those who choose to reload, starting at 200gr and going up in weight. Heavier, slower moving bullets profit from the longer mid-length gas system but lighter, faster moving bullets profit more from the carbine using an 18" barrel. If you were going 20", then mid-length all the way. 16", then carbine all the way. 18" kinda falls in between, hence the statement about "covering the most bases" meaning the widest bullet and desired velocity selection. That's just my opinion however. If you're just hunting deer, the lighter, faster bullets are plenty good and shoot a little flatter. The use of 250gr bullets plus or minus is not chiseled in stone. I suspect that Hornady went with the 250gr as its initial offering, mainly because they were already out there and do offer a good compromise between velocity, which is key to expansion and weight, which is key to penetration. The Barnes 275 bullet would be a good choice if your hunting includes mature hogs and you don't like spitting out bits of lead from your food. Otherwise, there are plenty of 300gr cup and core offerings for hogs as well, even a 325gr for the big 'uns.

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Re: Which gas system

Postby ScottyPotty » Thu Feb 15, 2018 7:57 pm

Thanks for the clarification Hoot.
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Re: Which gas system

Postby Buckeye45 » Sat Feb 17, 2018 12:33 pm

I run a mid length on my 14.5 dead shot barrel. Using only factory ammo so far it works nicely. I use an Odinworks adjustable gas block and a JP silent spring and it's very smooth. So far flawless.
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Re: Which gas system

Postby ScottyPotty » Sat Feb 17, 2018 6:26 pm

I was thinking of trying an Odinworks gas block.
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Re: Which gas system

Postby Buckeye45 » Sat Feb 17, 2018 9:33 pm

Get the newer one with the click adjustments. Much nicer, and get the long Allen wrench they offer. Very much worth the few bucks to be able adjust under the Handguard. I ran mine down until it just locked back on an empty mag, then backed off one more click for deer season. Worked very well.
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