1. If I understand correctly, the extractor depth, ideally, should measure approximately .035... but not less than .032.
and,
2. approximately 4-5 lbs of pressure should be exerted by the spring steel extractor onto the brass case by the 'wall' (the flat vertical side inside of the extractor recess)...
and,
3. this pressure should NOT be exerted by the tip of the extractor.
O.K. .These two statements seem to be mutally exclusive. Maybe my measuring ability is flawed but...
1A. when statement #1 is followed. then the angle of extractor is pressing against the extractor groove in the brass case, not the 'wall'... Not good according to statement #2 above..
2A. When statement #2 is followed, the extractor hook, when modified and not touching the extractor groove in the brass case, is considerably less than.032. The tip of the extractor when dressed, is pointed and sharp enough on the tip that it would seem that a 'push feed' or a dirty chamber extraction would soon cause the extractor tip to shear.
I dunno, maybe I'm missing something here. The forest may be getting in the way of the trees again, or was it the other way?
Break the caliper back out Salty, mah fren. Measure the small diameter in the groove (Nominally .395)... measure the rim (Nominally .475)... subtract and divide by two. That should give you the distance from the edge of the rim to the bottom of the groove. (Should be in the neighborhood of .040 inch.)
These dimensions are nominal, and will vary from cartridge to cartridge.. lot to lot... brand to brand.
The rims on often-reloaded brass will grow a little in diamether every time they go through a fire and reload cycle. This is very often why a pistol that is ultra-reliable with new ammo will produce occasional failures to return to battery with reloads. The increasing rim diameters have the same effect as increasing extractor tension or mvoing the hook closer to the breechface centerline. Moreover, brass from different manufacturers grow at different rates. Brand X will grow .005 inch in 10 loadings, while Brand Y or Z will grow only .003 or less. I tell ya, it's enough to drive a tweaker 'round the bend sometimes.
Quote:
2. approx 4-5 lbs of pressure should be exerted by the spring steel
extractor onto the brass case by the 'wall' (the flat vertical side inside of
the extractor recess)...
I read that in the Kuhnhausen manual as well, but I don't think it applies to how extractor tension is actually measured.
You take the slide off and insert an empty brass under the hook (against the breech face) and measure the amount of force it takes to pull it straight downward from under the extractor. You can tie dental floss really tight around the rim groove of an empty brass and use a trigger pull gauge to measure this, or there are brass flat pieces cut which fit like the brass does.
Minimum should be about 15 ounces, upper limit depends on gun. Some say 24 ounces, but I have one that turns into a cranky feeder above 20 ounces.
bountyhunter, what trigger pull gauge do you have? I don't have access to any trigger pull gauge less than 2 lbs.
I got it from Brownells. It is spring loaded mechanical gauge and reads up to 8# but can read down to about 1/2# accurately. It's been so long since I bought it, I don't recall the name.
Here it is:
747-873-070
Premium Trigger Pull Gauge $35.95
"...pulls of 5 lbs. and higher can be optionally checked using a Brownell's recording trigger pull gauge or a std. ordnance/NRA weight type measuring system. Pulls of 4-1/2 lbs. and less should be checked with an ordnance or NRA type trigger pull weight system, only."
--Kuhnhausen, Jerry. The U.S. M1911/M1911A1 Pistols & Commercial M1911 type Pistols A Shop Manual, Volume II. McCall: Heritage Gun Books, 1997. Page 171, Note 5.
Now Jammer... We all know that Jerry only writes books and doesn't have a clue about actually building pistols...