That's funny you should ask that OF. I asked the same question except about the AR10s not too long ago and everyone was just taken aback that I'd even consider putting one on my rifle...lol
I have as of yet to get one but DO plan on it once I can get out of debt from my wife's "christmas spree" and I'll be checking dimensions and everything before I do it.
As painful as it's going to be, I'm afraid it's gonna be a firing for effect kind of this where we buy one and hope it fits and then adjust from there.
Best I've got for now. You might want to contact Bushmaster and see if they have any recommendations.
All content of this site is copyright 2003 - 2017 AR-10(T)™, AR-10™, are trademarks of ArmaLite, Inc.® AR10T.com is NOT endorsed or affiliated with ArmaLite, Inc.®
About AR10T.com
AR-10(T) is a community focused on rifles, optics, scopes, gear, accessories, and components used by the professional operator and skilled marksman. Enthusiasts, shooters, and gunsmiths alike contribute to our gallery, articles, and reviews Thank you for visiting!