[AZshooter]

Does anyone have both Ruger Mk I and also a Mk II or III?

I need to know if a Mk II or III mag will fit & function in a Mk I.

 

[Bill_in_VA]

I have one of each, and if I recall correctly, they will interchange, but the thumb button needs to switched over the other side (an easy fix.) (Of course, now this means I'm going to have to double-check myself once I get home, but I'm fairly confident I'm correct. If not, I reckon I'll have a double helping of crow for dinner tonight, and slice of humble pie for dessert.)

 

[masterblaster62]

I use a MKII mag in my MKI. I've got a MKIII but havn't tried that combo.

 

[AZshooter]

MK II mag it will be, then! The Mk I mag holds 9 rounds. Doesn't the MK II hold an even 10?

 

[cpw]

That is correct.

 

[Deltaboy]

As the other guy said just switch the button and the MK II will work just fine.