Had a treat last Wednesday night of shooting a real "race gun" belonging to one of our "open" class shooters. It was an STI frame/ Caspian slide/ master machinist beauty. Full-size 1911 in .38 Super with one of those exotic red-dot "monacle" sights. I believe this guy was trying to "infect" me with this marvel of surgical pin-killing! All I can say is WOW!! (The infection has not thus far spread to me, however). Anyway I was checking it out after the session and noticed that it had a very small clearance between the cocked hammer and the slide rail that strips the rounds from the magazine. The owner explained that the hammer had been filed down some such that while the hammer still cocked, there was less drag on the slide and less upward pressure on the slide as well. The slide was AWFULLY smooth as far as I could tell and he told me this was a big reason why. I have never seen this on any stock gun I've handled and would like your thoughts on wether this would be worth doing on my essentially-stock Commander. Seems quite the fine line between not functioning and a proper clearance with full function. I'm thinking that, with that bit of clearance, the gun relies on a little extra "bounce" to fully cock it?
I used to see that hammer mod years ago. It was done to reduce the distance that the hammer falls after the slide moves off of it on the return to battery in order to reduce the hammer hook to sear impact. It helps a little, but from the sound of it, the one you describe was cut a little too much, and is actually rougher on the sear than one correctly done. It does reduce drag on the slide... but at a cost. No such thing as a free lunch.
When the slide cocks the hammer on a 1911, the hammer doesn't ride the slide smoothly. It's knocked back violently and bounces off the grip safety tang. By the time it tries to engage the sear, the slide catches it and the hammer hooks don't actually engage the sear until the slide moves forward and releases the hammer. The release is a little more gradual than a sudden drop unless the mainspring is so weak that the hammer "floats" in air for a nanosecond after the slide moves off of it.
If the hammer is clearanced to let the hooks reach the sear after it rebounds instead of being stopped by the slide, the sear catches the full momentum of the hammer driven by the mainspring... and that ain't good for it, as JeffC discovered after pulling his hammer past full-cock and releasing it to check for hammer follow.
Cutting an angle on the face of the hammer to let it hit the slide just enough to keep it from dropping all the way to the sear has some benefit... but it has to be carefully done. Too much metal removed... the hooks and sear take a real beating.
Yep, if there's a way to break it, I can usually find out the hard way.
I'm troubled also by that whole cocking on inertia concept, cost me a hammer and sear on a Kimber I had a long time ago, in a galaxy far far away.
This used to be a common modification on bullseye match guns that had less then 4 pound trigger pulls. As Tuner said, done right it worked, done wrong you had a mess - especially when the hammer hooks had been substantially cut down. In time the hammer would start following down, and the condition would be attributed to all the wrong reasons.