RUGER MAGAZINE QUESTION 22/45

I have a Ruger factory magazine for a 22/45 22 auto pistol. The package is marked AP-10. At one time i had a MKII 22/45 and a MKIII 22/45. I can't remember which auto pistol it fits. Ruger no longer uses AP-10 as a model number. The back of the package is dated 10 of 87 and has no listing for a 22/45 model. The magazine does have a little bump on the side.

EvilDr235

If I recall correctly, it will work in either gun.