While noodling with a virtually new & little-fired 1911 WWII version that hard 3 point jammed on anything you tried to feed it, discovered the receiver feed ramp angle was 34.6 degrees instead of the 31.5 +/- 0.5 specified.
Having previously ruled out magazines as the cause, I was about to start whittling away at the ramp when I decided to measure the angle of the magazine well. This was also out of spec at 16.8 instead of 17.5 +/- 0.5 degrees.
Putting these two out-of-tolerances together meant the bullet about to be stripped from the magazine "sees" a feed ramp that's at an angle 3.8 degrees too shallow from mid-spec. Based on Honorable Master's teachings, Grasshopper concluded "No wonder this gun won't feed anything!"
BUT, you're probably thinking, WHAT'S THE POINT? Point is we all seem to assume the magazine well angle is within spec or (perhaps) that it has no affect on feeding. Me may be wrong, but me thinks it does. Never saw any discussion about it. Shall we?
Quote:
Having previously ruled out magazines as the cause, I was about to start
whittling away at the ramp
Might wanna leave the feed ramp alone and think about the barrel ramp instead...
Couldn't help myself
Niemi,
Can't help but ask what type of frame you are working with? Is the basic
grip angle itself correct? That is, do you have a mag well that is not cut co-
axially with the grip? Or perhaps the whole frame can distort like this during
a casting screw-up. Good idea on checking the mag well angle...that had not
occurred to me before.
Hi 1911 Tuner: Thanks for the hint - with so much out of whack with this gun I hadn't thought about the barrel ramp/cut. Looks like it's almost 1/32 in front of the frame's bed/ramp transition, but looks can be deceiving. That'll be next on my agenda.
Hi Lazarus: It's a [Auto]-Ordnance WWII model and it's the magazine well angle that's a bit too steep (16.8 instead of the mid-spec value of 17.5 degrees from the vertical). This is the same as the forestrap (front part of the grip) angle, so I guess the terms "grip angle" and "mag well angle" might refer to the same thing, unless g.a. refers to the rear of the grip. Anyway, I measured it to the rear, flat surface of the mag well - which is parallel to the curved front surface of the mag well. Don't know if the mag well is cut parallel to the forestrap, but it looks to be.
[Edited: P.S. Please note correction of manufacturer's name from Para- Ordnance to AUTO-Ordnance.]
AUTO Ordnance?? Unless it's of recent production, I think that explains it. Should be okay for a 22 conversion dedicated receiver though.
While noodling with a virtually new & little-fired 1911 WWII version that hard 3 point jammed on anything you tried to feed it, discovered the receiver feed ramp angle was 34.6 degrees instead of the 31.5 +/- 0.5 specified.
Was just wondering what kind of special tools are you using to take these meausrement
Robot1911: Bill of sale shows gun purchased in 1995. I take it this wasn't a vintage year for Auto-Ordnance? Never seen one of the things before, and if I never see one again - it'll be too soon!
Jn316: Nothing too special, I guess.
For the feed ramp angle it's just a short (2"), straight knife edge clamped to a machinist's rule. The rule is held to the top of the receiver and the knife edge adjusted until it's against the feed ramp. With the clamp securely tightened, the angle they form is carefully transferred to a 5x8 card with a fine pointed (0.3mm) pencil. The angle is then read (to within 0.2 degrees) with a draftsman's protractor. The only commercially available protractor I know of than can directly measure the feed ramp angle is a Starrett C493, and I don't have one. Hence the indirect method.
The mag well angle is measured directly with a number of different commonly available protractors (Starrett combination square set's protractor head & blade or a smaller protractor similar to a Starrett C19 or C183)
Very ingenius and smart too!
I think I'll give it a try on my 1911 and see what I come up with.
Thompson Auto Ordnance had a rep for producing some of the worst 1911 clones that ever came down the pike. Don't know if they're any better under Kahr, since I haven't examined one up close and personal... but they surely couldn't be any worse.
I think you have chosen to work on a lemon. A friend gave me an AO to work on... he was having a number of problems. This is the only 1911 I have examined that I felt was not worth the effort. The minimum work required is to replace all the small parts. But installing good quality parts didn't help because many of them defied proper fitting on this platform. Do you have a hydraulic press, by any chance?
JMB'd probably roll over in his grave if he saw this one!
The barrel's bent and has a serious internal manufacturing flaw (see "Barrel Flaw" thread). One foot had a lump that caused it to bind in the receiver slot. As 1911 Tuner hinted (thanx Tuner), the barrel ramp/cut does extend back over the receiver ramp/barrel bed transition. The extractor clocks about 30 degrees.
One nice feature of the receiver is its feed ramp: it can be whittled into spec with a pocket knife instead of my little-bit-too-big hardened bearing scraper. But, maybe this is why Robot 1911 said it should (not would) be OK for a .22LR conversion kit!
The grip screws are pretty nice, however. Wish me luck.