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Discussion Starter · #1 ·
Hi guys. New to the Mark II and I noticed when mounting a red dot on my pistol that there is a little play between my barrel and the lower receiver and wondered if that is normal. It's not fore/aft but rather the barrel can be twisted slightly on the lower receiver. In other words, the barrel can be rotated slightly clockwise or counterclockwise.

Just wondering what the tolerances are for others? Thanks.
 

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My Dad's older Mark II is the same way. When I installed a Red Dot on it the other day, we noticed that it would rotate a little and rattle around. It has not had a chance to be fired since the installation but I wonder if accuracy will be affected. Anyone know of some way to shim it so it fits snug?
 

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MKII Barreled Receiver to Grip Frame Fit

rimfire newbie,
....., a little play between my barrel and the lower receiver....
This condition is usually reported by shooters who have had their MKII's apart many times. You did not indicated 'how much'...? ? It is a correctable condition. However, with our SEARCH function disabled, I do not know how far back my Post on the subject is in the RFC archives...? ? :eek:
 

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Discussion Starter · #5 ·
I wonder too. I've only fired 100 rounds during break-in through this pistol with iron sights and I didn't notice the fit until I grabbed the red dot while installing the scope. I sure wouldn't want that much play with a reticle scope. I think I'll ask ruger about this issue on Monday.
 

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Hi rimfire newbie,

This is an annoying condition (not very common but does occur), but usually does not greatly affect accuracy. The sight system is mounted to the rcvr, not the frame. Shim stock can be used to snug the fit, or attitude adjust (hammer) the frame hook down (don't hit it too hard, might break - shims work OK).

HTH
 

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Loose receiver/frame fit will have a negative effect on accuracy.

I have experienced this phenomenon more than a few times when mounting dot sights for bullseye shooters on Rugers. The extra leverage of the mounted sight makes it easier to rotate the barrel/receiver and to perceive the looseness of the fit. The inside surface of the notch on the front of the receiver and the bottom of the latch boss are flat and, if held together with enough force, will not allow barrel rotaion.

You can tighten the receiver/frame fit on the MK I and MK II Rugers to get rid of the rotational movement. Here is how I do it.

1. Remove the barrel/receiver from the frame. You do not have to remove any of the components in the frame (trigger, disconnector , hammer etc.)
2. Pad the jaws of a good vise with brass or lead so you don’t mark the frame.
3. Place the frame in the vise, pointing down as if you were shooting the floor, with the jaw surfaces parallel to the flat frame surfaces.
4. Position the jaws so they will squeeze the flanges in the area between the trigger pin and the front of the trigger guard. The trigger pin should be visible above the jaws of the vise. What we are trying to do is reduce the diameter of the curved area that the receiver sits in. This will cause the receiver to sit higher in relation to the latch boss in the frame which causes the two surfaces to mate more perfectly.
5. Snug up the vise and with a magic marker make an index mark on the vise and vise handle so that you know where you started.
6. Turn the handle on the vise about 10 degrees. Make a new index mark, remove the frame from the vise and put the barrel back on. You should have to lightly drive the receiver/barrel onto the frame with a wooden or leather mallet when the proper fit is achieved.
7. If the receiver /frame fit is still loose (doesn’t require force to put it on and off the frame) put the frame back in the vise, tighten another 10 degrees from the last index mark, make a new index mark, and try the fit again. Repeat step 7 until you achieve the desired fit.

WARNING - WARNING – WARNING!
1.Go slowly – if you over tighten you won’t be able to get the receiver on the frame. Go only as tight as you need to get rid of the rocking. If you over-tighten it can be cured in various ways but that’s a whole ‘nother post.
2. DO NOT squeeze any area other than that which is described. !!!! The front of the trigger guard and the latch boss maintain the frame dimensions allowing only the lips that the receiver sits on to distort. If you squeeze anywhere else the whole sheet metal frame will compress and cause all sorts of dimensional clearance problems for your internal working parts!!!!
 

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Discussion Starter · #13 ·
Mine's at Ruger right now. I bought it new this year and am unsure of my gunsmithing abilities, so I sent it back to Ruger for service. Were you happy with the repair on yours and is it tightly fit now, Corpsie?
 
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