Trying to figure out wich barrel

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Trying to figure out wich barrel

Postby Eric H » Fri Jan 12, 2018 6:24 pm

Hello people.
My second post. I am currently building a 450b. I have decided on a 20 inch barrel as far as lenght goes. Not sure of twist though. I love casting and shooting my own. I will admit. I have a thing for chucking large chunks of lead.
I have been reading up on cast in a ar platform and how to adjust things according.
If memory serves me right. Wich it probably doesn't. I have mainly seen barrels with 1/16 twist. Is that what you guys would recommend.
I don't figure there is a rubber stamp answer.
Thanks
Eric H
 
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Re: Trying to figure out wich barrel

Postby Hoot » Fri Jan 12, 2018 7:55 pm

Welcome Aboard Eric!

The first barrels from Bushmaster were and still are a 1:24 twist. Many members here, myself included, dedicated a lot of time to working up load recipes that offered good performance, using a 1:24 AR platform. In recent years, some other manufacturers have made them available in a host of other twists, with 1:16 being the next most common, from what I've seen. Bullet length dictates the optimum twist rate more than weight. Generally speaking, longer bullets weight more than shorter ones but not always. A jacketed hollow point with a ballistic tip while long, may not weigh nearly as much as a shorter, solid lead alloy bullet due to the air in it. A 1:16 twist is a good choice as long as the rifling is strong. You wouldn't want the lead bullet skidding across them. There's plenty of reading material available online to assist you in picking the right barrel twist for the length and weight of cast boolits you want to use. AR platforms and cast boolits are not as easy a marriage as jacketed bullets but then most cast boolit enthusiasts I run into at the range, love a challenge.

Keep us abreast of your progress as many readers harbor a desire to find a cheaper projectile that delivers accurate performance in their AR based 450s.

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
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Re: Trying to figure out wich barrel

Postby MOOSE EARS » Sat Jan 13, 2018 6:50 am

Something about shooting lead bullets in AR rifles makes me cringe, except for subs, which makes sense. Powder coated lead is marginally acceptable only because I haven't used any. If you run plain lead much above subsonic, you are going to lead the barrel. If you're going to slow things down, you might as well go 45ACP. I believe a 450BM is supposed to shake the ground when it goes off! Just my opinion...
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Re: Trying to figure out wich barrel

Postby Eric H » Sat Jan 13, 2018 1:15 pm

The more I read on cast in a ar. The more I think I will stick with jackets. I have other boulder chuckers I play with.
Needless to say I'm vary excited to finish this. After reading some post on here and your guys input. It has helped me get my mind around this cartridge a little better.
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Re: Trying to figure out wich barrel

Postby plant_one » Sat Jan 13, 2018 1:21 pm

the easy answer to shooting cast is powder coated or with something like hitek and then adding a gas check.

it keeps the gas cutting down and should give good results when used with a properly hardened alloy.

from expierence i can tell you non-gas checked coated supers with lil-gun is bad idea though...
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