.458 SOCOM to a .450 Bushmaster

[Skiparock]

I have a Rock River .458 SOCOM complete upper on a R-Guns standard lower that I built a few years back. I would like to know if I can I use the bolt from the .458 in a new .450 Bushmaster upper build?

[Hoot]

I have a Rock River .458 SOCOM complete upper on a R-Guns standard lower that I built a few years back. I would like to know if I can I use the bolt from the .458 in a new .450 Bushmaster upper build?

Welcome Aboard!

If I'm not mistaken, all you need to do is swap the barrel and possibly the gas block & tube on that 458S rig. The latter would depend upon whether the 450b barrel you're buying has the same length gas system and block ID, as your 458S.

Hoot

[Bmt85]

There was a difference between them, Tony who owns Tromix has mentioned it a couple times. It is the extractors that are different, but some companies run an extractor that works in both, I guess.

[Skiparock]

Thank you for your reply!
To clarify, I am building a new almost complete upper for the .450 BM. I mentioned I wanted to use the .458 “bolt” for the .450 but I meant I want to use the entire BCG in the .450. Let me know if that changes anything.
Thanks again!

[Bmt85]

No, that doesn’t change anything.

[TonyRumore]

You need a little more reach in hook on a 450 Bushmaster extractor, than on a .458 SOCOM extractor.
I'm not sure if the Bushmaster extractors have enough reach to work with the 450BM case or not.
When we started building 450BM's when had to change our extractor a hair (giving it a little more reach) so it would work for both cases.

Tony Rumore
Tromix