bushmaster upper on a rra lower

[cali02026]

Will a complete bushmaster upper fit on a rock river arms lower? Will I need to modify anything?

 

[PatMcD]

It will go right on. No problem.

 

[doobie]

RockRiverArms usually has a very very tight tolerance. You may find that you have to work in the pivot/take down pins. Use a little oil and do them about 30 times and it'll loosen up.