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450 Bushmaster or 458 Socom






tdyoung58

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#1
So thinking of buying a new upper.
Narrowed it down to either 450 Bushmaster or 458 Socom. Who's got experience with either.
• Going with a side charging.
• 10.5", 12" or 16" or ... ???
• twist rates ... ???
•Ammo availability, seems 450 Bushmaster is less money per round
 

MAC702

LEGEN...wait for it... DARY!
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#2
Does .450 Bushmaster use special magazines? I see conflicting results.

458 SOCOM uses standard 223 magazines, or at least is designed to, if that helps. I've had one for testing, and it worked well if the COAL was long enough, but don't use these things with cheap collapsible buttstocks. I learned that one the hard way, and I get a bloody nose just thinking about it.

Looks like they use different bullet diameters, with 450 Bushmaster the same as the 45-cal pistols at .452", and 458 SOCOM the same as 45-cal rifles at .458". If true, that might affect reloading.
 
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Janizary

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#3
Been there, done both (and a few other big bore AR builds as well).

For 458 while it is supposed to work with standard AR mags, in reality it can be fussy and require manipulation of the feed lips. For each "My AR mags work just fine I don't know what people are (b****)ing about" you'll have another person that has issues getting a full 10rd mag to run properly (10rd 458 in a 30rd AR mag). Additionally, for the most part PMags are verboten (though with a bit of filing they can be made to run just peachy). Lancer mags with the Tromix 458 follower runs golden. As Mac pointed out these use rifle bullets for reloading. Related to barrel length I have run 16" and 10", both running well with everything from 250gr to 500gr rounds. 458 retail ammo is very pricey. For the best in parts and reliability, Tromix is your friend.

450 Bushy is a delight to reload (both ease and cheaper bullets on average), uses pistol bullets, but is a bit less friendly on magazines. For most part I use 20rd AR mags for 450 rounds and run just fine. It is a straight-walled round so the curve of the 30rd mag can be problematic. I've run 16" well and like it quite a bit. 450 retail ammo is (typically) 2/3 to 1/2 the price of 458, depending on where you shop and ammo type. Running big, fat 450 subs with my Hybrid46 is just stupidly fun and still have a pretty good wallop. My current 450 Bushy is a side-charger.
 
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tdyoung58

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#4
Thanks y'all .... Ordered a Bear Creek Arsenal 450 Bushmaster 16" upper. $215.99, free shipping. Even on sale. Not a side charging one, but eh, it's all good.
Will pick up a rifle stock for it. From what I read a non-collapsible one is best.
I think my 5/10 round metal magazines will work

Guess I'll need to hit up Scheels tomorrow looking for the feed.