Rear sight will not stay in place on mark ii

tulanebme · Post by **tulanebme** » Fri May 08, 2009 11:59 am

So, I recently began upgrading my friend's mark II as a gift: VQ sear, VQ trigger, oversized hammer pin/bushing, oversized sear pin, Hogue grips, stainless grip screws, stainless trigger shield, etc. However, the gun has problems with the front sight loosening and the rear sight's base gradually drifting to the left. Some threadlocker has taken care of the front sight, but how can I better secure the dovetail joint between the site and receiver? Thanks.

The pistol had a couple other problems that I found interesting. First, with the new sear installed, the trigger almost behaved like a two-stage with the initial pretravel followed by a resisted stage, then creep, and then the break. As it turned out, the disconnector was slipping across the surface of the sear. Squaring up the disconnector's surface with a stone and tightening up the sear fit with a larger pin fixed the problem. Second, he had managed to really gouge out the body of the magazine where the button rides along it making loading difficult. Luckily, the mag bodies are thick enough to machine down smooth again.

smokey · Post by **smokey** » Fri May 08, 2009 12:49 pm

I had the same issue with my rear sight. I tightened the set screw but the sight still slid left while shooting. I finally removed the set screw, cleaned screw and hole to remove any oil. I replaced the screw with blue loc-tite and tightened it really tight. I have not had any more issues.

Georgezilla · Post by **Georgezilla** » Fri May 08, 2009 3:22 pm

Welcome to the forum, Tulanebme! I too had the same problem with the rear sight base. I did the same thing Smokey did and have not had a problem since. When you put the sight body back on after cleaning both surfaces, be sure that it is even in the dove tail.

Unless the portion of the disconnector that engages the sear had some burrs or other imperfections on it, you could have fixed the problem by backing off on the pre-travel screw.

tulanebme · Post by **tulanebme** » Fri May 08, 2009 4:30 pm

Thanks for the advice guys. I cleaned everything up, applied some loctite, and, when I just began to thread the set screw, it fell apart! My friend is an engineer, but he's still a big fan of using brute force to solve problems. He must have really been torquing that screw down to try and keep that sight from moving. Well, I guess I'm shopping for a new set screw now. Anyone know the size?

Georgezilla wrote:Welcome to the forum, Tulanebme! I too had the same problem with the rear sight base. I did the same thing Smokey did and have not had a problem since. When you put the sight body back on after cleaning both surfaces, be sure that it is even in the dove tail.

Unless the portion of the disconnector that engages the sear had some burrs or other imperfections on it, you could have fixed the problem by backing off on the pre-travel screw.

Thanks for the welcome! I hung out on markii.org years ago, but I've been out of the hobby for a while. Actually, the problem occurred without any pretravel adjustment. I think a few things were at fault: the portion of the disconnector contacting the sear was not perpendicular to the long axis of the disconnector, the play in the sear probably allowed it to tilt somewhat when force was applied, and I accidentally left a bit of polishing compound on the disconnector which then polished the contact surfaces.

Georgezilla · Post by **Georgezilla** » Fri May 08, 2009 4:41 pm

I see. Now that I look at it one of my extra disconnectors looks like it may have the same issue the one you fixed had.

I am not sure what the size the set screw is, but I'm sure someone here does. Just to be sure the sight is a factory Ruger adjustable sight, correct?

tulanebme · Post by **tulanebme** » Fri May 08, 2009 4:42 pm

Georgezilla wrote:I see. Now that I look at it one of my extra disconnectors looks like it may have the same issue the one you fixed had.

I am not sure what the size the set screw is, but I'm sure someone here does. Just to be sure the sight is a factory Ruger adjustable sight, correct?

Yes, it's the factory adjustable sight.

Post by **Bullseye** » Fri May 08, 2009 6:35 pm

There is another way. Take off the rear sight. Use a pointed punch to tap two or three dimples into the flat part of the receiver's dovetail slot. Reinstall the rear sight and that should hold it better with locktite and moderate mounting screw torque.

R,
Bullseye