Do Ruger MKIV and MKIV 22/45 mags fit the MKIIIs?

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Thanks. Now for the 64-dollar question: are the MKIV and MKIII standard and 22/45 mag bodies the same? Is it just the baseplates that are different? In other words, can I put mkiii 22/45 baseplates in MKIV mag bodies and have them work?
 
I can only partially answer the question, but hope this helps some. (or maybe confuses the issue altogether) I have, currently, only MkIV 22/45s, but I had a number of MKIII magazines.

MkIII magazines have a protruding heel on their floor plate. MkIV magazines are flush.

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And then in one of Ruger's "gotcha" moments, then decided not to provide a cutout on the MkIV.


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So. MKIII mags well definitely NOT fit into MKIV magwells. Remember I'm dealing only with 22/45s so standard models may vary.

This doesn't fully answer your question, but it does suggest that MkIV mags should fit in MkIII magwells. However other factors may
come to play such as feed lip shape and dimensions, and other design factors.


Follow up: So what I had two choices: Grind down the heel on all my MKIII mags. Or cut a slot in the MKIV mag well. I did the later. Mainly because if
down the road I borrowed or acquire MKIII mags they would fit. My MKIII mags work in my MKIV 22/45 without any problems. YMMV

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Agreed. I can’t see myself getting a MKIV unless there are no II/IIIs left.

it’s really not that hard. I honestly don’t see what all the fuss is about.

Absolutely, once you've done it a few times, it's pretty easy. No only that, you can give your friends a hard time that complain about doing it.

I do highly recommend getting the Tandemkross bushing to remove the magazine disconnect.
 
I can comment on the magazines for the regular Mark III and Mark IV (not the 22/45 versions).

They are functionally completely interchangeable. In fact, they are identical, with two exceptions:
1. The follower button on the Mark IV has annular grooves, while the Mark III follower button is smooth and domed.
2. The Ruger emblem on the floorplate is simplified on the Mark IV -- it's all black instead of being silver on a red background. The monogram on the chest of the eagle is just "R" instead of an intertwined "SR." And the eagle's head is oriented toward the rear of the magazine instead of toward the front.

By way of comparison, the original magazine for the Mark II does not have the projection on the body that engages the 1911-style magazine catch on the Mark III and Mark IV. And the emblem on the floorplate has a black background (with a silver eagle) instead of a red one. Nevertheless, later magazines (with the projection) still work in the Mark II.

These comments apply to the original magazines that came with the guns. There are plenty of hybrid magazines, made up of parts of various vintages, that are out there.
 
Absolutely, once you've done it a few times, it's pretty easy. No only that, you can give your friends a hard time that complain about doing it.

I do highly recommend getting the Tandemkross bushing to remove the magazine disconnect.
Yeah, mine wears a Clark bushing, VQ sear and hammer, and some other goodies.
 
I can comment on the magazines for the regular Mark III and Mark IV (not the 22/45 versions).

They are functionally completely interchangeable. In fact, they are identical, with two exceptions:
1. The follower button on the Mark IV has annular grooves, while the Mark III follower button is smooth and domed.
2. The Ruger emblem on the floorplate is simplified on the Mark IV -- it's all black instead of being silver on a red background. The monogram on the chest of the eagle is just "R" instead of an intertwined "SR." And the eagle's head is oriented toward the rear of the magazine instead of toward the front.

By way of comparison, the original magazine for the Mark II does not have the projection on the body that engages the 1911-style magazine catch on the Mark III and Mark IV. And the emblem on the floorplate has a black background (with a silver eagle) instead of a red one. Nevertheless, later magazines (with the projection) still work in the Mark II.

These comments apply to the original magazines that came with the guns. There are plenty of hybrid magazines, made up of parts of various vintages, that are out there.
Highly useful info, thanks!:cool:
 
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