I'm trying to install a TD vertical grip onto the underside rail section of an ARMS #45 CV SIR system.  It seems like a no go situation.  To get the grip onto the rail I have to unscrew the rail section from the SIR, use something to hold the grip springs open, and then hammer the grip onto the rail section.  Then when I go to remount the rail with the grip to the SIR, the top of the tango down grip extends above the rail, which then blocks the rail section from screwing down flush with the SIR.  I can't imagine that anyone would ever use it this way.   I'm wondering if anyone has any experience with this specific installation.  Any help would be greatly appreciated.

P.S. I knew when I went for the hammer that I was in trouble

Depending on whom you ask, either the ARMS rail is not to spec, or the TD Grip is not to spec, and the TD fits other rails just fine... I instead got a replacement rail from TD that fits and didn't have any problem after that... unfortunately TD is no longer making them. The other option from what I understand is to grind down a little on the TD grip to make it fit. I haven't done that so I am not the person to ask how much work is involved, but it has been posted here before.

Dave

I also had an issue mounting a TD Vertical on a Samco M33.....looks like a little "flash" leftover on the TD grip, but I wouldn't discount an out of spec M33 either.

Thanks very much for the info.  I took a chisel and started shaving off the inside top edges of the TD grip at about 45 degree angles until I had the clearance that was needed.  I can now get the SIR rail fully tightened down and flush and then slide the TD grip on.  I slid the grip forward from the rear until it was fully on the rail which resulted in about 90% of the rear most rail retaining screw being covered by the grip.  It is 100% snug with no play in any direction.  Yeah!