I am working with a 450/400 and attempting to install the 275 (7x57) Rigby express rear sight. This is part D07725HM to replace D77.

I loosened the locking screw and drove the dovetailed D77 sight out. That is right to left. Then when I go to slide the D07725HM express sight and it just slides in one end and out the other. I can even see daylight around the express sight. I can drive the D77 back if I want too. Left to right, no problem.

The first question is has anyone removed the adjustable sight and installed the proper express sight on their 257 Rigby No1? if you did that how did it work out? Exactly how? Did you get instructions?

One key detail around the sight is a vertical screw and what looks like a tapered collar that locks the sight into the dovetail. I think what I need is a new collar. I dont see part numbers for the little screw or collar on the parts diagram. That collar is stuck in there good. How is that removed? I am guessing I need to remove the rib and drive it out from the back side. That scares me. I bet those 4 rib screws are very tight and maybe locktited in place.

I probably will call Ruger tomorrow. it would be a lot better to know as much as possible. Part names,etc. I refereed to the Rigby No1 when I ordered the sight.

Link to parts list:
http://ruger-docs.s3.amazonaws.com/_manuals/no1.pdf

Don't know about the collar, but in general, sights should be driven out left to right, looking down the barrel, and driven back right to left. That may not matter in your case if the sight has some kind of screw lock, but for ordinary barrel sights, it kinda does.

On the removal, there is an "R" on one side of the sight. I placed the brass punch on the "R". The sight dovetail is tapered and only starts back the reverse way it came out. Maybe I dont know left from right. I just have a habit of pushing them out from this side. This is not my problem.

I am surprised none of the Rigby owners have installed the correct sight. What is that, collecting new in box with papers and sight still in manila envelope? I suppose the D77 sight can be just flipped down, out of sight, out of mind.

I asked a gunsmith yesterday and he never swapped sights on a No1, but he did swap the rib. Those need heat to break down the loktite and serious torque with a quality driver. I dont intend to do that. he did not have a old barrel rib on hand to examine.

I just got off the phone with Ruger and they are sending me the collar. This has to be the greatest company in the world to do business with. I got the last one in the service dept. They have to order more. No charge, will ship today.

I am told I should be able to work it out from the top.

If there is any interest I can post back with my results.

Edit: A backup plan, which will not be needed, might to to cut a stainless shim for under the express sight.Not recommended, just my own last resort if the collar was not available.

I'm interested. I saw your post this am at work but finally got home and after cutting the grass was going to pull my .275 out. I'll wait for your results now!

I got the collar today and installed the express sight (the one for the 275 Rigby) on my 450/400.

The collar does not come out easy. I was fooling around for a couple hours with various punches and angled bits. I finally hit on a solution which was to use small wire cutters. I was able to cut right through the collar. I cut it again and took a section out. The relieved the pressure and it worked out easy. Old quality American cutter. I think we used to call them dykes. The new collar was a tight fit and I ended up slightly relieving the edge all around to get it lined up before tapping it home.

I slid the sight in, seated the collar down hard and then applied as much pressure on the screw as I dare.

That should be it. I dont see reusing the old collar because it is engraved pretty good when you remove the fold down sight.

The new (express) site was a little sloppy in the v groove and I ended up cutting a 10/1000 stainless shim for the space under the sight. This is before I drove the collar down. I am sure this is not needed. I just wanted to minimize and daylight and not have to drive the collar below flush. The shim should be trimmed under size so as not to show when done.

I am sure this is an easy job for some. I was sweating bullets trying to get it done and not mess up the rib. Expect a tight fit and be prepared to fuss over it some.

Thanks for writing that up. I'll play with it after deer season.