Hi everyone!
I am a newbie so please forgive if this is a stupid question.
i own a Bushmaster XM15 as well as an Olympic Arms Plinker Plus
Both rifles are fun to shoot and easy to maintain.
So i figured I would build my own and after reading all the other posts decided to go with Rock River Arms.
I just put an RRA lower together with a new lower kit, collapsible stock and a 2 stage match trigger.  I tried both of the uppers from the Bushmaster and the Oly Arms and neitiher will fit without a little help from my rubber mallet.
Besides RRA are there other brands of uppers that will easily fit onto a Rock River Upper.
Any advice is welcome!
Joe Aguirre

hmm thats odd.

i have never heard of this before.

something doesn't sound quite right


i will do some other checking for you and see if anyone else has had this problem

I've read several stories on here about RRA lowers having slightly tighter tolerances. My upper is RRA as well as my lower so they fit fine.

Over time it should loosen up a little. And heck, at least there won't be any play in it.

RRA lowers are tighter and fit best with an RRA upper, but the mallet will get them assembled until they shoot in. I have been told after tapping them together a few times they will wear in and fit snug , or you can file a bit of the upper to fit it quicker.

My Bushy and White Oak uppers both fit tighter than a virgin before prom night on my RRA lowers.
They tend to wear in after some mallet influence and some shooting.
My White Oak upper is tight enough that I might actually file just a tad off the rear lug.
This is a common issue with the RRA lowers.

neitiher will fit without a little help from my rubber mallet.

That means they are normal RRA.

Quoted: neitiher will fit without a little help from my rubber mallet. That means they are normal RRA.

+1


the rear shelf is a bit higher than others

After a few hundred rounds, they loosen up some to fit perfect.

Thanks to everyone for the great advice!
I have decided to go with an RRA upper., so I am trolling an auction site for some decent new uppers.
Joe.

Quoted: Thanks to everyone for the great advice! I have decided to go with an RRA upper., so I am trolling an auction site for some decent new uppers. Joe.

You will have the same problem situation with a RRA upper.