Mk III / Mk III 22/45 Receivers Interchangeable?

[slowrider]

I need some education. I've searched the rimfire section but have not found a definitive answer. I'd like to put a 22/45 target upper on a Mk III std. I've tried to install but it doesn't want to go on even after rapping it harder with the mallet than I'd like. If they are not interchangeable I'll stop of course, but if they are I may try to take a little material off the roof of the 22/45 receiver's recess that accepts the frame's square lug. Anyone with words of wisdom?

 

[Geezer]

The 22/45's receiver is peened where it fits onto the lug on the frame. You can remove a little metal where it is peened and it will fit. Be careful and go slowly, don't remove too much metal. I have put a MK III 22/45 upper on a Standard frame. You can do it. You must use a MK III bolt with a MK III upper or you will have to remove the LCI completely. Here is a photo of my hybrid.

 

[slowrider]

Geezer, thanks for the encouragement. I used a dremel with diamond cutting head to open up the the recess and got the 22/45 receiver to fit snuggly. Just need to shoot it now and see if all operates correctly.

I still don't know if the lug and recess are purposely different on the two models to discourage barrel swapping between the Mk and 22/45 guns but I suspect from the tool marks seen in the recess on both receivers that most or many of these receivers have to be hand fitted to the frame at the factory.

It would be interesting if someone who had both model frames would
compare the lugs and let us know if they are shaped differently.

 

[deuce03]

Geezer, thanks for your help finally got it together

 

[ab4ka]

Geezer, thanks for your help finally got it together

that's sharp looking!

 

[Geezer]

Yep, looks nice. Have you tried it out yet?

 

[deuce03]

Ran a couple of mags thru it, no problems

 

[one eye joe]

That is a HANDSOME weapon ! What advantage is gained by such a hybridization ?