.458 socom vs 5.56 upper?

[bonzaiberger]

OK, so whats the diff between the .458 socom and 5.56 uppers of the same style? Is it just barrel and bolt, or is there more to it?

 

[fireball168]

The ejection port has to be opened up on the upper receiver, generally at least .050".

The extractor is commonly a 7.62x39, although Bushmaster and Rock River use a slightly modified version on their .473" bolts.

The barrel extension has to be throated for feeding - but it'll be attached to the barrel if you are buying one.

 

[bonzaiberger]

Hmm, interesting. The reason I'm asking is I'm wondering if I could convert my Daewoo DR-200 into a .458 socom.

 

[melensdad]

The 458 buffer assembly is often a heavier weight too.