Hey guys. I apologize for not posting and update sooner. I must say that I probably bit off far more than I can chew by starting up this little project with Christmas so close on the horizon. My business has kept me very busy and I ain't complaining about that.
First, thanks again to Dave S. and to Bill Z. for his kind offer. When the barrel arrived I had about thirty minutes to sit down with my Kuhnhausen shop manual and read-and-tinker.
I love this manual! The illustrations are great and it's a very helpful to have it handy when going over some of the posts on THR. However, like I said, I've been very pressed for time. However, here are some things that I noticed immediately:
1. The norinco barrel still binds on the slide stop pin when I do the test than Tuner has described in numerous posts here on THR - the same test that Wil Schuemann describes on his site: when I remove the slide and assemble only the barrel and slide stop pin in the frame, leaving the slide stop pin dangling and put the barrel in the bed, the slide stop doesn't move freely but is in fact quite restricted.
BTW, the slide stop pin in question measures .2" in diameter.
2. When the barrel is in the bed, lower lug touching the bridge, the norinco barrel's frame ramp almost overhangs the frame ramp.
3. I still don't get the .02" clearance when the barrel and slide (no pin) are assembled and the slide is moved .25" to the rear from battery.
So, in a minor fit of angst, I decided to pay the new (to me) local 1911 pistolsmith a visit. Actually I really just wanted to get out of the house and have a face-to-face conversation with a grown adult that was not a business partner or a family member. His analysis was that even after the modifications the gun is still out of time and that that the lug grooves in the slide are slightly off, the norinco barrel's bottom lugs were just slightly too far forward and the frame's bridge was slightly rearward. He took the gun home to meditate upon it further and here is what he came up with twenty four hours later: he can fit a used barrel from his parts bin and recut the slide's lug grooves.
I picked it up from him this afternoon. The donor barrel was from a Sistema Colt and it looked basically unfired. He charged $50 for barrel and $50 to fit it. Another $100 in the money pit. The gun appeared to lock up much tighter and the play in the slide to frame fit was slightly reduced. I took the gun and 150rds of FMJ to range and gave it a little trial run. No malfunctions and the gun was every bit as accurate as I was. Ok, so I went home and took the gun appart and here's what I noticed after comparing the new sistema barrel with the "old" norinco barrel:
1. the sistema barrel passed the test in item #1 above with flying colors.
2. out of battery .25", the sistema barrel does have more clearance, but I am not sure if it has .02". Still looking for typing paper and/or feeler gauges.
3. the sistem barrel's ramp doesn't overhang the frame ramp and appears to be about perfect, per Kuhnhausen pp 65.
However, there seems to be some scraping on the hood and the middle lug of the barrel seems suspiciously shiny on the it's forward (muzzle end) edge. The other lug edges seem fine.
Note that the smith did NOT relieve the frame bridge. He said that he didn't think that it was necessary with the sistema barrel. What do you think? Put another 100rds or so through it and if there is more wear send it back to him?
Some other things that I have noticed about the Sistema barrel: It's link will not travel completely to the rear. It gets stuck between the feet. It will go back far enough for the pin to mount under the lugs obviously but not much farther. I don't know that this matters as the link obviously won't be traveling there if the pin is in place, but I just thought I'd mention it.
I've gone and done it.
I've polluted the thread. Dave and Bill Z. didn't want to give up but it looks like I did. Sorry guys. I made the decision to jump on another barrel when I compared the fit of norinco barrel in my slide with the fit of the slide and barrels of some other guns in the shop, some of which had been heavily used.