Feeds and works well on mark iii 22/45 - Ruger 90646 Ruger Mark IV 10-Round, .22 Long Rifle Magazine

On the package it says "not recommended for the mark III 22/45. But, after reading up on the subject I was confident they would fit. They do! There are 2 minor problems with them. Neither of them bother me personally but worth mentioning for other mark 3 22/45 owners.
1st, on my speed loader I can't get the 10th round to load without adjusting it. While the mags made for the Mark III load all 10 every time. I'm not sure why, but it is the case. Again, not a big issue and the speed loader is adjustable. The other minor issue which prevents the Mark 3 22/45 mags from fitting in the IV. On the rear of the mag baseplate. These are shorter so there is a small gap on the grip. Cosmetic issue only, the gun fires fine. Hope it helps. It saves a few $ from purchasing 2 of the mark 3 mags.