OK, gang, here's the deal. I shoot a SW 625 in .45 ACP in competition--mostly USPSA and ourlocal unaffiliated stuff, but ICORE as well. I've gotten the trigger just about right, but it's been inconsistent, sometimes seeming heavier than others.
Got my hands on another 625 last week, and the problem was obvious. On my gun, the cylinder binds during one phase of rotation, his spins freely. Having messed with his, it's now obvious that mine's never been right. how did I misss this? Beats me, but I've never been one to spin the cylinder with the gun closed.
It only binds with the cylinder closed, never open, regardless of side forces appied to the cylinder--it it's open, it'll spin forever.
the gun is coming up on 8500 rounds through it, most heavy USPSA (old) major loads, about PF 185-90.
OK, so why? Being a competition gun, which gets slammed around pretty good (my reload, when I'm working at it and tuned up, runs right at 1.5 seconds, shot to shot--and happens a LOT at USPSA matches...), the obvious conclusion is that something's bent. So..
I should interject here that we first checked all of the obvious stuff. Headspace is perfect. B/C gap is perfect and consistent chamber to chamber. The bolt is timed right. The sight screw isn't contacting the cylinder.
Wee look at ejector rod runout first, 'cause it's easy. yep, it's out, but not a lot--but maybe that bend is enough to be binding on the ejector rod catch and tieing things up.
So, we change out the part. Now it's REALLY tight. I don't want to tell how many times this came apart and went back together before we discovered that the NEW ejector rod was out of spec by .002 (too large). Put old parts in, we're at least back where we began.
Now, the IRC's coming up in three weeks, so we're really kinda reluctant to make anything worse. After much thought, we decide that it can't be the crane (which certanly is at risk in this use) being sprung, becuase then it'd be out one direction, consistently, and would either bind during the entire rotation or not, and this is not the case.
So we swap cylinders between guns. Now, his cylinder spins freely in my gun, and my cylinder is lightly binding, again during only one aprt of the rotation, in his. It's not as bad in his as in mine, however. Hmmm.
At this point I invariably end up with the conclusion that I'm on the wrong end of a bunch of in-spec tolerances, adding up. if it's somethign in my cylinder assembly, why is it not just as bad in his gun, and if it's someghint in my crane or gun, why does his cylinder work just fine there?
More hair pulling.
having slept (poorly) on the issue, we decide to do some judicious polishing. A light polish in the crane tunnel, which on inspection looks like cast dog crap inside, a very light polish inside the cylinder (not the keyway), and we put it back together. Ona whim, we pull the ejector catch and stone a big burr off the back side of that bearing surface--this, too, looks like total crap, and is completely unfinished.
Reassemble, and things are MUCH better. it still binds on one chamber's worth of rotation, and we rechecked and rechecked that it's not external to that chamber, and it's not.
So, do we polish some more? I'm really inclined to go back and put a high polish on the extractor rod where it spins in the crane, but don't want to go too far.
Looking for suggestions, here.
Steve
Got my hands on another 625 last week, and the problem was obvious. On my gun, the cylinder binds during one phase of rotation, his spins freely. Having messed with his, it's now obvious that mine's never been right. how did I misss this? Beats me, but I've never been one to spin the cylinder with the gun closed.
It only binds with the cylinder closed, never open, regardless of side forces appied to the cylinder--it it's open, it'll spin forever.
the gun is coming up on 8500 rounds through it, most heavy USPSA (old) major loads, about PF 185-90.
OK, so why? Being a competition gun, which gets slammed around pretty good (my reload, when I'm working at it and tuned up, runs right at 1.5 seconds, shot to shot--and happens a LOT at USPSA matches...), the obvious conclusion is that something's bent. So..
I should interject here that we first checked all of the obvious stuff. Headspace is perfect. B/C gap is perfect and consistent chamber to chamber. The bolt is timed right. The sight screw isn't contacting the cylinder.
Wee look at ejector rod runout first, 'cause it's easy. yep, it's out, but not a lot--but maybe that bend is enough to be binding on the ejector rod catch and tieing things up.
So, we change out the part. Now it's REALLY tight. I don't want to tell how many times this came apart and went back together before we discovered that the NEW ejector rod was out of spec by .002 (too large). Put old parts in, we're at least back where we began.
Now, the IRC's coming up in three weeks, so we're really kinda reluctant to make anything worse. After much thought, we decide that it can't be the crane (which certanly is at risk in this use) being sprung, becuase then it'd be out one direction, consistently, and would either bind during the entire rotation or not, and this is not the case.
So we swap cylinders between guns. Now, his cylinder spins freely in my gun, and my cylinder is lightly binding, again during only one aprt of the rotation, in his. It's not as bad in his as in mine, however. Hmmm.
At this point I invariably end up with the conclusion that I'm on the wrong end of a bunch of in-spec tolerances, adding up. if it's somethign in my cylinder assembly, why is it not just as bad in his gun, and if it's someghint in my crane or gun, why does his cylinder work just fine there?
More hair pulling.
having slept (poorly) on the issue, we decide to do some judicious polishing. A light polish in the crane tunnel, which on inspection looks like cast dog crap inside, a very light polish inside the cylinder (not the keyway), and we put it back together. Ona whim, we pull the ejector catch and stone a big burr off the back side of that bearing surface--this, too, looks like total crap, and is completely unfinished.
Reassemble, and things are MUCH better. it still binds on one chamber's worth of rotation, and we rechecked and rechecked that it's not external to that chamber, and it's not.
So, do we polish some more? I'm really inclined to go back and put a high polish on the extractor rod where it spins in the crane, but don't want to go too far.
Looking for suggestions, here.
Steve