I’ve got several different responses 11/16 x 24, 5/8 x 24 etc. Mine was 11/16, but there are others. I went with the largest I could find to make the threading easier for me. It's gonna depend on the particular MD. [ARCHIVED THREAD] - What’s the standard barrel thread on the 450 Bushmaster? Win a FREE Membership! More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.