Why not just call Ruger?Contact Greg Cote LLC. He should be able to give you a definitive answer.
Well, according to Ruger customer service, they are not cross compatible.
Do you have a regular MKIII or a 22/45 MKIII? The OP is asking about the 22/45. I used to own a 22/45 MKIII. Magazines from the "regular" MK pistols didn't work, and magazines from the earlier 22/45 models didn't work.Zukiphile said:I don't have any MKIVs, but I do use MKIV magazines in MKIII pstols without issue. My MKII magazines are great in my MKIIIs, and the MKIII and IV magazines aren't great in the MKII.
Aguila Blanca said:Do you have a regular MKIII or a 22/45 MKIII? The OP is asking about the 22/45. I used to own a 22/45 MKIII.
Aguila Blanca said:Magazines from the "regular" MK pistols didn't work, and magazines from the earlier 22/45 models didn't work.