I read mixed reviews on the quality of Radical Firearms. Anyone have any personal experience good or bad? Was looking at this upper as the price is attractive for a .458 build. 

https://www.opticsplanet.com/radical-firearms-16-in-458-socom-upper-assembly.html?_iv_code=2CS-URC-16458SO-CFU16-458SOC-15FHR

I’m not a fan of things from radical firearms and when purchasing .458 it’s particularly tricky. I did my .458 with Tromix is considered the expert. Prices are not expensive and no one knows more about .458 than Tony.  A close second, other opinions may say first place, is Teppo Jutsu.  

will have cycling and ejection issues.  Feed ramp blending is critical to smooth function.  If you’re serious about .458 or .375. SOCOM check these two guys out. 

http://www.tromix.com/

http://www.teppojutsu.com/458.htm

 

Teppo Jutsu was the driving force behind the 458Socom's creation.  Have a RRA Beast upper that is a real hammer of Thor.  Reloading has proved a little tricky to get all the quirks worked out,like the feed ramp, magazine, load data, etc.  But, when it's on it makes a great hog hunting tool.

Thanks for the info, looks like I have two more places to start looking.