Sorry to slam the door on you JohnK... the Ruger Mark III 22/45 is complete crap. It's billed as a "1911 Trainer"... but it's gritty and grotty and a pain to strip - and no 22LR will "train" you for a 1911, they just took the worst part of the layout of it (the near 90 degree "rake"). They're showing up at the range at an alarming pace these days... I've had the chance to fire a few and yeeeeech... I'd rather just hold the .22 with a pair of pliers and hit it with a ballpeen.
I have a Mark III target (
this one) with a 5.5" bull barrel. A lot of people online complain about how hard it is to strip as well, but after the first few times, I can completely empty and replace everything in the frame in about 60 minutes (including cleaning time). The stock trigger, sear, hammer and bolt release really stink... but Rimfire Sports has an accurizing kit for it (which I'm finding has to be done to just about any new firearm these days). Honestly, the internals are a bit Rube Goldberg, but that's the lawyers creating that problem.
I like the Mark III target... I hate the 22/45 Mark III (feels like shooting a hockey stick)... and for the price, hard to beat... unless you can find a good Model 17 or High Standard used.
If you do get one of the Mark IIIs, PM me on how to remove the magazine disconnect... it's a colossal pain in the rectum.
My .02 - YMMV.
Bren R.
