450Bushmaster.net

What changes have to made to a AR upper to install a 450 Bushmaster barrel build?

MK111 wrote:What changes have to made to a AR upper to install a 450 Bushmaster barrel build?

Welcome aboard MKIII.

The only thing you have to do to a functioning AR is make sure the ejection port opening is wide enough to pass the fatter 450b case through during ejection. Some come that way already and some do not. There are multiple references to this including dimensions to measure beforehand, in this sub-forum. For the best luck finding them go to Google and enter the search term site:450bushmaster.net "ejection port" just as its written. The first search hit should be just what you need.

Hoot

I have been thinking about the same build. Does anyone make an upper receiver that has the enlarged port?

Yes there are quite a few, I know Tromix and Sota arms both do. I'm sure there are others.

Any upper that works for the other big bores will work. Also most, if not all side charger uppers will work. I know Tromix offers forged uppers for big bores. Wilson combat does, but I believe they are marked 458 socom. Franklin Armory also sells big bore uppers, but don't know anything about them. Satern offers big bore uppers, but I've heard a lot of bad reviews on them.