Site Content

Frequently Asked Questions

Generally speaking, you want to avoid using any goofy 5.56 upgrade parts on your 458 SOCOM upper. The Tromix uppers are designed and built to run with standard GI type parts.


Q: Which 458 SOCOM parts are different from 5.56 parts?

A: The only unique parts to the 458 SOCOM uppers are the barrel, bolt, upper receiver, and muzzle attachment.  


Q: Do I need a heavier buffer or spring in my lower?

A: No.  The gas port is sized to blow the bolt carrier completely rearward with a standard GI buffer and spring.  Adding a heavier buffer or spring may cause the bolt to short stroke.


Q: Do I need a heavier extractor spring or insert?

A: No.  Too much extractor tension will cause pieces of brass to be chipped off the rim of the case.


Q: Do I need an adjustable gas block?

A: For non-suppressed shooting, you don't need an adjustable gas block.  For shooting both suppressed and unsuppressed, an adjustable gas block is recommended.


Q: What is the velocity loss when going to a shorter barrel?

A: Velocity will drop 25 feet per second per inch down to 10.5", then will drop 50fps per inch below 10.5".


Q: Where can I get load data for the 458 SOCOM?

A: Pressure tested load data is available in Western Powders, Nosler, and Lyman load manuals.


Q: What magazines should I use with my .458 SOCOM upper?

A: All 5.56 magazines will work with the .458 SOCOM other than Magpul P-Mags.  Those have a center divider in the front that can block the bullet path.  We recommend Lancer magazines for the best feeding reliability.


Q: What is the warranty on Tromix parts?

A: If you act like a reasonable adult, there is an unlimited warranty on all parts.  However, if you act like an asshole, there is no warranty.