Still working on my first rebuild of a Colt M1991A1 Commander, and have become stuck on the fitting of the disconnector. I'm using a Briley disconnector, which measures 1.135" (Long?). The tip is being forced down by the forward beveled portion of the slide disconnector cutaway when the slide is in correct position, which disconnects the sear. I realize that shortening the disconnector is generally a BAD idea, and have also read of warnings to not extend the slide cutaway. Assuming that nothing else is interfering (Assembled the firing mechanism, spring and MSH many times to observe for correct functioning of sear/ disconnector/ trigger/ spring- All seem to be working well). I used marker to observe for areas of slide/ disconnector drag- nothing big found, but I can feel it drag when hand cycling the slide. Can I safely shorten the disconnector tip by maybe 0.005 and/ or deepen the forward beveled portion of the slide disconnector cutaway a bit at a time until it allows the disconnector to stand up all the way when the slide is in position? Or am I way off track here?
Kuhnhausen #1 page 78 figure 118 states that in Mr Kuhnhausen's documented experience Colt factory disconnectors run from 1.287 to 1.290 overall length and he has seen aftermarket disconnectors that exceed 1.310. Extending the slide cut away or disconnector notch is bad as the gun will be be ready to fire before the slide is all of the way home. Brownells makes a disconnector notch scraping tool on page 78 of their catalog for 11.18 it is used to deepen the notch. Also after reading this I would not get terribly worried about pruning .005 off of it although I would do it incrementally until I got desired functionality.
Just a suggestion here. I have found it is best to modify the least expensive part first. This way the learning curve doesn't cost as much.
In my haste to type this AM, I meant to state that the Briley disconnector was 1.315" long- slightly longer than the common lengths listed in Kuhnhousen's Vol I. Good point about the cheapest part getting modified first. Disconnectors are much cheaper than slides. I still wonder if my Colt's slide disconnector cutaway is off (to the rear) a bit. When the slide is worked back and forth I can feel the disconnector as it hits the fore and aft ends of the cutaway. When the slide is in correct/ locked position, the disconnector tip is just beginning to bump up on the foreward end of the cutaway, and I can see/ feel it disconnect from the sear.
On both my builds I have had to shorten the disconnector to under 1.30". I take material off the top (and recut the angles) until it works properly. I would leave the slide alone on principle.
Late last night, I had a lull in the action at work and shortened the disconnector a bit at a time until it's just touching the foreword beveled surface of the slide cutaway, when the slide is in position (In other words, it's as long as absolutely possible. Any longer an it would begin to disconnect). Came out to 0.005" (1.310" OAL). I'll re check today with a magnifying glass to confirm it allows the disconnector to fully engage the sear, then polish the tip. Hopefully on to the next part of the project- adjusting the trigger pull. I built a NRA type pull scale, using steel discs as weights in 1lb, 8 oz, 4 oz and 1 oz weights. Working toward 4 to 4-1/lb pull weights. Short of a course, I think this is the best way to "learn" 1911's.
Sounds like your on your way to knowing the 1911. For the record I had to shorten my disconector also to get it to work properly. I don't have the exact dimension, but I did have to do some filing.