Ruger 22/45; Will mkII mags work in an mkIII?


Gato MontÚs
September 20, 2012, 08:38 PM
I don't know if anyone else has noticed, but 22/45 mkIII mags from the usual sources are non existent. I have a single mag on backorder from Brownells for over four months.

Seeing so, I looked into whether or not mkII mags will work in the mkIII, and got an inconstant slew of answers. Some say no, while others say yes with modifications, namely removing the mag disconnect, of which I have.

I'm looking to buy up a whole bunch of mags, and paying 17.90 a mag is better than nearly 30 for the available mkIII's. If anyone can give me a solid answer to this I'd appreciate it!

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September 20, 2012, 08:47 PM
See this:

Says right there they won't fit a MkIII.

Here are the MkIII mags.


September 20, 2012, 10:53 PM
The MK II and MK III ("Luger grip angle) mags are different and don't interchange, but you can use a MK III mag in a MK II pistol if you don't mind the annoyance of the mag catch protrusion snagging the bottom of the frame. The mag compatibility issue is why I don't have a MK III.

The 22/45 and 22/45 MK III (1911 grip angle) are in my experience completely interchangeable. We've one 22/45 and a pair of 22/45 MK III and a mis-mash of 22/45 mags (44 total) mostly older 22/45 mags, and to tell the truth I can't tell which are which as there have been a fair number of minor differences in the mags over the years I've been buying them, some have needed minor mods to feed reliably.

I'd buy one of the cheaper 22/45 mags and try it, and then stock up if it works in your 22/45 MK III, just in case they have changed something in the past year or so (when I got my most recent 22/45 MK III)

General Geoff
September 20, 2012, 10:56 PM
I've used MkII mags in my MkIII 22/45 without issue.

Gato MontÚs
September 21, 2012, 03:11 AM
May I ask if you guys removed either the mag disconnect or the LCI? The MKIII mags have a cutout on the left side. Don't know what it's for but that is the only difference between the two magazines.

I'll do what you said wally and buy one to try, go from there, but it seems like I should not have a problem.

September 21, 2012, 08:05 PM
I've not removed any parts from our 22/45 Mk III pistols. The two newest 22/45 mags that came with the threaded barrel 22/45 have a cut out and small protrusion on the left side, near the top. I've no idea what it does as the mags that don't have it work fine in the pistol.

Gato MontÚs
September 25, 2012, 11:56 PM
Just an update in case anyone else is/was wondering, mkII mags arrived today and seem to function fine using dummy rounds. The cutout on the mkIII mags is to accommodate an extension on the backside of the trigger. I have noticed movement of the magazine while pulling the trigger, but like I said all seems to work just fine.

HOWEVER, two days after placing that order, the mkIII mags became available again:banghead:, so back to Brownells the mkII's will go.

If anyone knows what purpose that trigger extension serves, other than trying to prevent people from using MKII mags, I'd love to hear it.

September 26, 2012, 06:33 AM
According to the the Ruger manual, the Mark III magazines have a safety link that prevents the seer from releasing without the magazine in place. I know this to be true with my 22/45 because of the process of tear down. The trigger will not release the striker without the magazine in. My manual says that markII magazines will not work in the markIII but I can't say that I've ever tried them. It is my understanding that that extended piece is part of the magazine safety or in part design to work with it. Mixing gun stuff makes the wrong thing go boom, I'd stick to what the manuals details. If you need one you can get it from rugers website.

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