firebirdude said:
Ok. It looks like the barrel is twisted a 1/64". After removing the barrel again and reinstalling, I noticed the barrel seems to have some play in it before you push it back into place (right when you place the two square together).
If your barrel is loose on the frame this procedure will fix it. It is reversible with a dental pick should you desire.
This procedure will fix a loose receiver to barrel fitting on Mark pistols by using putty epoxy to take up all the space worn by wear and tear between the square receiver lug hole and the frame lug it attaches to.
Step 1. Break the gun down to receiver/barrel and frame.
Step 2. With alcohol or acetone on a Qtip clean out the square hole on the barrel that the lug on the frame fits into, no oil based solvents please.
Step 3. Again with a Qtip place a film of oil on the lug in the frame…
so nothing will stick to it.
Step 4. Mix a small amount putty epoxy, the kind you can form and shape.
Step 5. Place a small amount of the mixed putty epoxy in lug hole on the barrel.
Step 6. Reassemble the barrel to the frame and make sure you install the bolt stop completely in the assembled barrel receiver. You may have to bang the front of the barrel to get it far enough down to install the bolt stop. If you can't reassemble the bolt stop you've probably put too much epoxy in the lug hole and the receiver is not going far enough down on the frame… remove the excess epoxy and retry.
Step7. After you've obtained a tight fit with the gun completely reassembled with the epoxy, disassemble it again and remove any excess epoxy that oozed from the barrel and frame. You just want the epoxy to be in the lug hole on the barrel.
Step 8. Then leave the gun disassembled overnight before the final reassembling to give the epoxy time to cure.
I've done this to my MarkIII and have cycled the barrel on and off many times with no adverse reaction and the barrel is still tight on the frame... the epoxy has stood up quite well. We're dealing with thousands of an inch here so there's not going to be much epoxy in the lug hole. This procedure is repeatable if you take down the gun enough to wear the epoxy down and if you don't like it at all just take a dental pick and scrape the epoxy out. It's easier than the soda can spacer and safer than squeezing the frame in a vice.
P.S. I was using heavy gear grease to take up on the lug and it worked. It just got to be a pain in the a$$ cleaning up so I experimented with the epoxy and it seems to work.