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Discussion Starter #1
Just when you think you've got it all figured out something happens that proves you're not as smart as you thought you were.

The back story

As a retirement gift to myself I bought two JEM frames to put together a 5" and a 6" 1911. I've done others over the years and learned lots in the process. Over those years I settled on the parts that I liked and had plenty of experience fitting them. I really liked a specific extractor and fit many of them without any problems.

The issue

After a year working on those two retirement gifts, I finally got them to the point of range testing. During the past couple of months I've put 500 rounds of factory 230gr FMJ rounds through each one 50 rounds at a time at the range followed by tweaking indicated by those range trips. Shoot a little, tweak a little. Wipe on, wipe off.

Excellent, proven, newly manufactured magazines. New Wolff recoil and hammer springs in various weights. Complete detailed cleaning of the pistols after each 50 rounds. I was solidly on the path to success.

Until . . . they were having intermittent feeding problems in the form of the cartridge being chambered but with the rim ahead of the extractor and thus being out of battery. No problem says I. Obviously, this was a symptom of inertia feed.

But I was confused. I had fit oversized, flat bottom firing pin stops to both and was running 16lb recoil springs teamed up with 23lb mainsprings. Didn't make any sense but I pushed ahead by swapping out the recoil springs for 16lb then 18.5 lb recoil springs as well as putting in 26lb mainsprings. I also thoroughly cleaned the magazines, made sure they were bone dry, and put in the strongest springs known to man.

None of it made any difference. The intermittent rims ahead of the extractor problem continued.

After racking my brain endlessly for weeks and on the verge of giving up I decided to go through every piece measuring and inspecting for flaws.

Eureka!

Yesterday I discovered the cause. When prepping the extractors I followed my well trod path and got perfect geometry, deflection, and tension. But I didn't bother to measure the hook-to-breechface distance before filing the firing pin stop slot. I didn't have to, don't you know, because I'd fit many of these extractors to these kind of slides so I knew from experience that I had to take material off the front wall of the firing pin stop slot to achieve a perfect .075" hook-to-breechface gap.

I was WRONG. In this case I should have removed material from the rear wall of the firing pin stop slot. The result was the hook-to-breechface gap ended up being way less than .075". There wasn't enough gap to allow the case rim to rotate up into the extractor 100% of the time.

I can't explain the physics of how a cartridge that wouldn't go behind the hook managed to get in front of the hook but that's what happened.

Lesson learned

Don't assume anything!

Humble pie doesn't taste good.

Happy ending

After fitting new extractors so there is the needed .075" gap I now have tested both pistols with several hundred rounds using recoil springs from 11 to 18.5lbs and 23lb mainsprings, They run liked raped apes. 100% with zero malfunctions. I feel like a great weight has been lifted off me.
 
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