Monday, June 30, 2014

Secondary Project: the old frame

Couple of days ago finally got in the last part I needed to complete the Kimber frame.  Most of it dropped right in.  Not completely stripped, but here's (most of)the parts:
Clockwise from the top: disconnector, pin, sear; hammer, strut pin, strut, hammer pivot pin; thumb safety; grip safety; sear/disconnector/grip safety spring.  The trigger, magazine latch, thumb safety & slide lock plungers & spring are in place in the frame.  And yes, I forgot to put the mainspring housing in the picture.

If you're wondering how these all work, I point you to this marvelous illustration thanks to STI and  You can hide or show different parts so as to see just how others function.  Which brings me to the one part that actually required fitting: the disconnector.
One pin fits through the disconnector and sear, holding them in place in the frame.  That three-finger spring bears on them with different arms: one causes the sear to pivot against the hammer, one bears on the angled face at the bottom of the disconnector and forces it up.  The third pushes the grip safety out and doesn't bear on the matter at hand.

Sear holds hammer in cocked position, top of the sear fits in a recess in the bottom of the slide.  Pull trigger, it actually pushes on the front face of the disconnector which pivots the sear, releasing the hammer.  Cartridge fires, and slide cycles back, cocking the hammer and pushing the disconnector down, which means the sear cannot be moved by the trigger.  As the slide moves back into battery, the top of the sear moves back up into that recess, which puts that bottom part in place between trigger and sear, allowing the trigger to trip the process again.

If the disconnector were too short, that could allow the hammer to follow the slide down instead of being caught at full-cock; that could allow the gun to double, or could cause an out-of-battery fire; Bad.  If it's too long?  That can prevent the sear from being able to pivot far enough; it'll let the hammer fall, but the sear nose will catch in the half-cock notch and prevent the piece from firing.  Which is what was happening.

Two fixes for this.  The preferred is to use a special scraper and scrape some steel out of that recess, so the disconnector can move far enough up.  Problem is, this is going to be working with the Ciener .22 upper, and the slide is aluminum with a hard coating to prevent wear; scrape that depression and you'll get rid of the coating, not a good thing to do.  Careful measuring found the new piece was .020" long, some careful cutting was able to shorten it that much, including polishing the surfaces.  Assembled everything and worked the action, all now cycled as it should.  This morning went to the range and tried it, and all worked as should.

One more thing I want to do.  The frame rails are badly worn, I want to work them in the proper places to get a better fit to the slide, then have the frame hard anodized to cut down on future wear.


Gerry N. said...

Those little parts and their ineractions are why I don't monkey around with the internals of my sidearms. Or the geometric shapes and interactions of my long arms.

I have a Star B in 9mm Para. that has the annoying habit of smokestacking about every thirty rounds. Or so. I don't know who to talk to about it. I was thinking of polishing the ramp, it is steel and hard. I could put a felt bob on my (hack,choke,gasp) Dremel, set it at a low speed and simply shine it up with jeweler's rouge a tiny bit, not enough to remove the polishing marks that are already there.

I also have a Steyr M98 Mauser variant rebarreled to .243 Win. That one insists the proper place to feed a cartridge is directly into the face of the breech directly above the chamber. Again, I'm not about to go after the feed ramp, but I need to know a name of someone competent to adjust the feed so I can shoot my rifle. Where do I find such a person?

BTW, your pistol's lookin' good.

It wonders me, is there an available .22 LR adaptor for the Star B?

Stuck ol'

Gerry N.

Firehand said...

Smokestack jams are usually a extractor or ejector problem; if the ejector is still solid, could just be the extractor spring is getting weak, or the hook getting a bit worn.

The Steyr... that sounds like something in the feed lips more than the ramp. Removable magazine? If so, could tweak the lips to mess with it. If it's the standard Mauser 'it's part of the receiver' lips, that'll require someone with more knowledge than I to look at.

I don't know of one for the Star; lots of these various pistols, it would be nice.