Thumbscrew scope mounts...

[mpress]

Whats the consensus on scope mounts that attach via thumbscrews. I picked up a Trijicon TA51 mount for my compact ACOG scope. Is this a decent mount or will I have to worry about the thumbscrews shooting loose and the scope losing zero? Would I be able to take it off and remount without having to re-zero? Would I have been better off with a LaRue mount cantlever or std mount?

TIA.

[JSantoro]

The TA51 is issue to the PVQ-31A/B Rifle Combat Optic, which is the Marine Corps version of the ACOG. There's nothing inherently wrong with it, you just need to remember a few things when mounting it, some of which you may already know, so I'll apologize in advance if anything reads as condescending. It's not, I just see Marines make simple mounting errors that impact big-time later, all the time.

Before you snug the screws down, ensure that you apply forward pressure to the optic so that there's no gap in between the recoil lug on the mount and the rail forward of it. Maintain as you tighten it snug.

Tighten until the screws are hand tight, then get what we call a BFS (Big F-ing Screwdriver) and give it an extra 90 to 180 degrees. A wide-tip, flathead screwdriver. A quarter works in a pinch, but you probably won't get too much tourque out of it. The tip of the file on my Gerber multi-tool is a perfect fit, which is good, since I don't tend to cart a BFS everywhere.

Put at least 5 rounds through the rifle, just to shake it up, warm it up. Re-tighten.

Zero. Give the sight a solid thump with the heel of your hand to set the prism after each adjustment and before each shot. Put witness marks in place, both on the screws/mount and on the mount/rail once you're happy with your zero, if witness marks are something you do.

If you remove the optic, all you have to do is make sure you put it back in the same rail slot and tighten properly. Your zero is maintained. If you plan to swap optics a lot, it makes sense to get a throw-lever mount of some type.

I have my own RCO w/TA51, and it's all I use, so as tacticool it would be to get another mount, I don't have a need. But, the beauty of a free-market economy is you can buy whatever you want. I've BZO'ed mine to 7 different weapons, and shot in excess of 25,000 rounds with it over it's lifespan with no loss of zero except in one case, in which I brain-farted and forgot to thump the RCO after an adjustment, which had nothing to do with the mount.

Somebody please hit on any bad experiences they've had with the TA51. We're investigating a throw-lever mount for the RCO, and I'd love to have a failure of some sort to attempt to replicate.

[RB1968]

The TA51 mount is a quality mount and is used by our Military, and I have never read or heard of it failing in any way or form.

I have one on my ACOG and it has been removed and reinstalled many times on my 1913 rail without losing it's zero setting.:)

[mpress]

Thanks for advice guys.

[JSantoro]

One option you can exercise: flip the optic around on the mount so that the screws are on the right side of the weapon, instead of the left, when mounted.

It's unusual, but we've seen people yank on the screws on the left side, thinking that they are the charging handle during IA drills and whatnot. So, we flip them just to eliminate the possibility , and our RCOs are now coming from Trijicon with the rail clamp screws on the right side already. Just one of those things, the majority have never had an issue getting to the charging handle, but it's a simple configuration fix anybody can do if they want to.

Just undo the two flathead screws on the underside of the TA51, flip the ACOG 180 degrees, reinstall the two screws after you apply some BLUE Loctite (NOT I SAY AGAIN NOT RED!). Re-mount, re-BZO, and go.

[fabulous45s]

Not sure how much difference it will make, but I think the TA60 is meant for the compact ACOG's.
It looks like the major difference is the one centered mounting hole vice the two on the TA51. I'm sure you can just slide forward or aft and use either hole, but that means less mating surface.
I doubt that'll be an issue unless there's a MAJOR impact involved.