I boneheaded this up pretty good. I took a video to better explain the problem. Any help would be appreciated.
Insert mag, pull trigger with the muzzle down so the hammer moves forward. The problem is the magazine disconnect. Get a mk2 hammer bushing. Profit. Also, get the volquartsen accurizing kit.
Inserted the mag, cocked it and pulled trigger. No dice. Doesn't even dry fire at this point.
Hmm. The mk3 is tricky. If I could get my hands on it, I could probably unstick it. Don't feel bad, you are not the first to have problems.
Good luck. When you do get it unstuck drop a mk2 bushing in it. Some have had to send them back to ruger in this condition.
Muzzle pointed down on a towel or something semi-soft and with a rubber mallet give the back of the frame (lower) a good firm whack to ensure that the frame and receiver (upper) are fully seated together. Then try to disassemble. The first time I tried reassembly I thought it was fully seated but couldn't get the mainspring back in until hitting it with a mallet. May or may not be your problem.
If that doesn't help, try tapping the pin that sticks up thru the top of the receiver and is connected to the mainspring housing with a rubber mallet while pulling down and out on the mainspring lever.
If you haven't already, watch this video on reassembly, it's the most helpful one I've found
pull and hold trigger, point it down and slam it into a cloth covered 2x4 or hardwood floor covered in carpet with the same amount of force you would use if you were using a fly swatter. let go of trigger and the mainspring sould come out.
ETA, I had a ruger vid on here, but it sucks compared to the one captain posted.