1911Tuner
Moderator Emeritus
Since this one is being watched closely, I decided to start a new thread so that it will be uncluttered. Fairly long, but a good read for students of the
1911's design and function. Pay attention Dave...Ya might just learn somethin.'
Dominic! The clearance at the frame bridge being a little less than .020 isn't critical. .010 is good as long as the barrel and slide don't crash.
The gun may be a trifle more sensitive to being kept clean...but you're probably fine on the clearance.
The Scheumann Timing Test has one flaw. It only determines the timing at the END of the sequence, and ignores the beginning. The clearance has to be there at the quarter-inch mark...but it's also important that the
barrel BEGINS linkdown at the right time.
It's often been said that the link's sole function is to unlock the barrel, and that's true enough in a purely technical sense...but it also has another equally important function that it shares with the lower lug's geometry.
It also TIMES the linkdown sequence...and the linkdown must begin and end at the right time. Too short advances it. Too long delays it. Lower lug geometry also figures in, but I'll defer the explanation until a later point in this thread. As little as .003 inch in length can make a very real difference.
The scraped/polished areas that you described suggests...just as a best guess, because I don't have the gun...that the link is still a little too long...
and the lower lug is just a bit out of spec on the forward radius...to allow the sequence to START at the right time. This condition will not correct itself,
and the barrel won't catch up. If it starts late, it ends late. The good news is that since you have enough clearance between the hood and slide bridge...that it probably won't hurt anything.
Slightly delayed linkdown timing isn't an altogether bad thing, as long as the lugs don't crash. The bad thing is...that the window of opportunity is
much narrower. If the gun gets badly fouled, that fouling could
delay the barrel just a tiny bit too long. That's an extreme circumstance though, and you'd likely have to neglect the gun sorely to cause a problem.
Slightly delayed unlock timing allows the use of higher-pressure ammunition without danger of case head blowout because it gives the chamber pressure a tick longer to drop before the sequence starts. I'll provide a link to another thread that illustrates this point. It involved a certain "Officer's Model from Hell" that belonged to forum member "Saltydog" a few weeks ago.
Shoot the pistol as is, and keep a very close watch on the locking lugs...particularly the front one...#3. If you notice even light flanging
on the top of that lug...PM me.
Luck!
Tuner
1911's design and function. Pay attention Dave...Ya might just learn somethin.'
Dominic! The clearance at the frame bridge being a little less than .020 isn't critical. .010 is good as long as the barrel and slide don't crash.
The gun may be a trifle more sensitive to being kept clean...but you're probably fine on the clearance.
The Scheumann Timing Test has one flaw. It only determines the timing at the END of the sequence, and ignores the beginning. The clearance has to be there at the quarter-inch mark...but it's also important that the
barrel BEGINS linkdown at the right time.
It's often been said that the link's sole function is to unlock the barrel, and that's true enough in a purely technical sense...but it also has another equally important function that it shares with the lower lug's geometry.
It also TIMES the linkdown sequence...and the linkdown must begin and end at the right time. Too short advances it. Too long delays it. Lower lug geometry also figures in, but I'll defer the explanation until a later point in this thread. As little as .003 inch in length can make a very real difference.
The scraped/polished areas that you described suggests...just as a best guess, because I don't have the gun...that the link is still a little too long...
and the lower lug is just a bit out of spec on the forward radius...to allow the sequence to START at the right time. This condition will not correct itself,
and the barrel won't catch up. If it starts late, it ends late. The good news is that since you have enough clearance between the hood and slide bridge...that it probably won't hurt anything.
Slightly delayed linkdown timing isn't an altogether bad thing, as long as the lugs don't crash. The bad thing is...that the window of opportunity is
much narrower. If the gun gets badly fouled, that fouling could
delay the barrel just a tiny bit too long. That's an extreme circumstance though, and you'd likely have to neglect the gun sorely to cause a problem.
Slightly delayed unlock timing allows the use of higher-pressure ammunition without danger of case head blowout because it gives the chamber pressure a tick longer to drop before the sequence starts. I'll provide a link to another thread that illustrates this point. It involved a certain "Officer's Model from Hell" that belonged to forum member "Saltydog" a few weeks ago.
Shoot the pistol as is, and keep a very close watch on the locking lugs...particularly the front one...#3. If you notice even light flanging
on the top of that lug...PM me.
Luck!
Tuner
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NEVER give UP! 'Bout 12 years ago I waltzed with a dagnab blankety-blank 
Officer's Model :banghead: four times before I hit the sweet spot...I was ready to take a sledge hammer to it when all of a sudden birds started singin' and the clouds parted. I reckon the gun gave up and decided to behave its bad self. 