I would like to build a .458 but I have some questions. Does anyone make stainless bbls for this caliber? Can I get a company like Adco to retrofit the ejection port on a standard 5.56 upper? I tried signing up on the soccom forum but could not get it to work. I know going this route will be more expensive but thats ok,thanks for any help.

I would contact Marty ter Weeme, the designer of the 458 SOCOM, and talk to him; his website is teppojutsu.com.  you really can't go wrong with one of his barrels, or full uppers.

If you are having troubles getting onto the 458 site, IM or email COLD; he is a Moderator/member here, and he runs that site.

Hope this helps.

thanks VT

You're welcome.  Good luck in your pursuits, they are a blast to shoot, and the 458 site is a wealth of knowledge.