During disassembly of my 22/45 I was not able to get the upper off of the frame.  I followed a simplified youtube video, which may have been my downfall.  I bought the gun alone, no box/manual/tools.

After watching Ruger's video, the only step I missed was the disengaging the internal safety.  I do not have the tool for this.  Is this why the upper wouldn't come off?  I used plenty of force, that wasn't the problem.

Please give me any advice you can, it needs a good cleaning after many suppressed rounds through it.

I had to whack the back of my upper with a plastic faced hammer to remove it.  It's pretty tight.  Good Vid: http://www.youtube.com/watch?v=wOGVChhMCjg
I'm gonna do a couple of these mods on my pistol, too.

ETA:  I thought there was a mallet used in that vid.  Here's a better one: http://www.youtube.com/watch?v=4fIYIWK0boo

Plus 1 on the plastic or rubber mallet, it's on really tight.

I used a plastic hammer too.  Then a heavier rubber mallet.  Then grabbed the grip backwards and hit the rear of the upper on an ammo can (with a rag on it to keep it from scratching the gun).  I wasn't particularly soft with the hits either, I went as hard as I could without being to the point of breaking the gun.  Now I have a dented ammo can and a gun that is still together  

Yup, mine is tight too. I used a rubber mallet

So disengaging the internal safety isn't necessary to get the upper off?

As seen at :50 in this video:

ETA: Nevermind, I see that piece comes out of the gun with the bolt stop pin assembly.

So what's left?  Soak it in PB Blaster and beat the shit out of it?

don't think it matters, but mark 2 or 3?

my mark 2 22/45 pulls apart pretty easy. that hook on the front is the only thing holding it on after you pull the thing that holds the bolt in.

the pic in this thread shows the hook pretty good.
http://www.ar15.com/forums/t_5_50/119183_Ruger_MKIII_22_45_Bolt_Stop_peening_after_about_20k_rnds___normal_wear_.html

not sure what could be holding it on. nothing sticks up to stop it from sliding forward.

I am not sure what it is either.  I figured I whacked it hard enough to break it loose, or just break it.  Neither happened.

I ended up just blasting it all out with gun scrubber, lubing it, and putting it back together.  Fired a couple magazines in my backyard and it worked fine.

Maybe if I let a vice do the pushing for me it would work?  It would more likely break something though.  I may just have to smash this gun apart next time it needs cleaning to satisfy my curiosity of what's going on in there, haha.