Slide mount on a Range Officer

I am mounting a RRA 1911 slide mount and UltraDot on my Range Officer and it appears that the rear mounting hole will be right on the edge of the cut for the adjustable sight on the back of the slide.  I'm assuming the RRA mount is the same hole pattern as a Bomar rib, but I don't have one to compare.

I have done the same with the RRA combo mount. I was told that since the combo mount is steel, its strong enough to be held on with three out of the four screws. The fourth screw on mine goes into the flat part where the rear sight was in front of the dovetail. You should be able to get a couple tuns of that fourth screw into the slide to lock it in.  I was also told  that the the optic mount is aluminum and will need to have that 4th screw used because the rail could flex. I hunted around for options to fill that void left by the rear sight, however there were none that I could find. The pattern is the same as the Bo-mar ribs, at least the ones that do not have a tuner. The RRA mount also matches the Clark slide mounts, as I interchange this mount with my LB that came with a clark mount.

My aluminum rail on my Springfield always holds tight with just 3 screws.  1" Ultradot optic.

Getting a wadgun to function reliably with a load that is accurate and also minimizes recoil is always a somewhat tender balance between the load, recoil spring weight, and the mass of the slide.  The steel RRA rib/mount you have chosen weighs 5-6 oz, which is more than many complete slide mounted dot sites in total.  When you add the 3 or 4 oz of an ultradot or similar, be aware that you make that tender balance a little more tender.  The recoil spring weight that it will take to reliably cycle and feed with that much slide mass is going to take a hotter load to cycle it than you would otherwise need.  On the positive side, the additional slide mass will dampen recoil a bit more.  You might not like the feel of the load it takes to be reliable; then again you may like it fine.  Every gun is a little different.  But if you have trouble finding the recoil/reliability zone you really like, consider going back to a 1 or 2 oz aluminum slide mount for the dot sight.

The Rock River Arms mount I have is the aluminum one with the rack ears on the rear.  I am considering milling the front of the ejection port cut out just enough to get the rearmost hole off the edge of the sight relief cut.  Would only be 1/2 to 3/4 of the width of a mounting screw.  This would allow for a shim to be added to equal top of slide height.  Am I over thinking this?  I would hate to try to run with only three screws and have issues keeping it solid.

You are definitely over thinking this.  If you want more holes, have your smith drill and countersink your rail to accommodate more holes.

It will hold fine with three screws.  I just can't stand the way it looks with the gap under the rear.  If your set up will allow it, cut the rib off at the begining of the sight cut and you're done.  Just another option.

I have the same Rock River Arms mount on my Range Officer.  The back screw does go down into where the sight cut is.  I don't think the screw does much since it isn't clamping up a tight joint, but that is how my gunsmith installed it.  I like the rear ears to rack the slide.  Here is a picture...

That is exactly what I am doing.  Is the back screw actually in the sight cut?  Or is it only partially in the cut?

kc.crawford.7 wrote:It will hold fine with three screws. 

Right on the money KC!  My first wad gun has over 53,000 rounds with only 3 screws on the clark base.
Al

iawolfeman,

Here is a picture of it where you can see the screw in the sight cut.

Doug

Is the RRA mount as good as the Clark mount? They changed the finish on the Clark mount. It now has a rough finish that appears to be a spray on of some sort. Looks awful on my new build.

IMHO the RRA mount is "better" than the Clark because of more / different mounting options.  There are many more cross slots in the RRA mount that the Clark that allow many more positions to put your rings.