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Posted: 2/5/2006 8:46:10 AM EDT
Will a Rock River Upper (Varmint A4 Upper Half) fit a Bushmaster lower?

Link Posted: 2/5/2006 8:57:37 AM EDT
why not?


Link Posted: 2/5/2006 9:15:12 AM EDT
Was just asking. I am new to this whole AR thing. Just wanted to make sure I was not buying something that don't work.
Link Posted: 2/5/2006 10:31:52 AM EDT
If it says AR15 on the side then all (well almost all) parts are interchangeable between different manufacturers.
Link Posted: 2/5/2006 10:38:11 AM EDT

Originally Posted By Sader762:
If it says AR15 on the side then all (well almost all) parts are interchangeable between different manufacturers.



Very few guns say AR15 on the side anymore. They say M-15, LAR-15, XM15-E2S, Sporter, M4, etc.

Almost everything is compatible except Colt SP1 uppers and lowers which used large hole front pivot pins. For those you need an adaptor.
Link Posted: 2/5/2006 12:03:04 PM EDT
Thanks to all. I am off to build my new toy.
Link Posted: 2/6/2006 4:43:14 AM EDT
I have seen Bushmaster uppers that were tight on RR lowers, but don't know about the other way around.

Howard
Link Posted: 2/6/2006 4:50:46 AM EDT

Originally Posted By uhsammy:
I have seen Bushmaster uppers that were tight on RR lowers, but don't know about the other way around.

Howard



You are correct. Because RRA/Stag/CMT does not machine the relief area at the back of the lower receiver, some Bushmaster and Colt uppers will not fit on a RRA lower. Some will fit, but they take a lot of pounding. All can be filed and fitted.

However, the reverse in this situation.... RRA uppers will fit fine on a Bushmaster lower.
Link Posted: 2/6/2006 5:46:15 AM EDT
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