In trying to install my new rail system, I am running into a problem and wondering if it is just me or if any of you have had this issue.

I have removed the M4 handguards, bottom half of the SIR 50, as well as the ring.  WHen I place the rail on top, against the front sight as directed, the slots over top the flat top do not line up with the slots in the flat top itself.  Hence, I cannot insert the three square pins that are supposed to slide in.

Any suggestions?

First thing I'd suggest you do is contact ARMS about it.

I take it that your AR is as the title of your thread says, a complete Bushmaster?

When the SIR first came out, board member [b]SF[/b], if I recall correctly, had a Bushmaster upper in which the forward-most portion of the railing was out-of-spec.

I believe he filed the upper to make the SIR fit.


Chris

Yep, it is a complete Bushmaster M4-style 16" rifle with the mini-ycomp brake.  Came in a box with the hard plastic case.

The two opposing slots appear to be about 1/8 to 1/16 of an inch off.

I was curious if the front sight was off or exactly what the deal was as I thought ARMS products were supposed to be guaranteed to fit Bushmaster products.