Daly Burps
Not taken as a hijack...It's on topic, after all.
Okay...Case "rolls" back and stays in the port. Extractor hook depth may be
pinching the rim between it and the extended ejector. Depth should be about .032-.036 inch. Shorter often causes the hook to slip the rim...longer sometimes binds the rim with the ejector as it twists and tries to release.
Best educated guess is short-cycle though...Too much recoil spring.
On the failure to feed/stopping on the ramp...If the gun has the standard
barrel/frame design, (Not an integral ramped barrel) Lay the barrel in the frame and push if down and back firmly. The lower edge of the barrel throat.(ramp) should sit slightly forward of the top corner of the frame ramp/bed area. About a 32nd inch (.0325) is good. It can be more, but not less.
Though many guns do okay with the barrel throat flush with the top of the ramp, it can and does cause problems in most.
Check for a sharp corner on the bottom of the extractor hook, and for signs of
contact in the extractor groove. If the corner digs in as the round strips, it puts things in a bind. Relieve the bind by breaking the corner on a stone with a swiping motion to form a radius. Check for a sharp corner on the bottom wall of the extractor, where the rim first engages it. Lightly bevel that area with a square needle file with light cutting pressure to keep it smooth. Polish with fine paper on a flat, hard tool. Easy does it. Too much bevel, and you lose contact area with the rim and wall.
If the barrel throat/ramp has too steep of an angle, it can cause a hangup there. This is the place where you get into altering the barrel throat. Careful
as you go here. Best done with a scrape if you have to work freehand. Avoid a Dremel and a grinding wheel. You can go too far too quickly to correct the mistake. Decreasing the angle sets the top of the ramp deeper into the chamber...which causes reduced case head support. No way around that, but you can get away with a little as long as headspace is good.
Check for a sharp corner at the top of the barrel throat and break it LIGHTLY
with a scrape...Smooth it up with fine paper. BUT...before you start cutting and scraping, try good mag springs. Weak springs don't give the feeding round a good boost under the extractor, and the slide has to overcome the
angle in order to break the round over to horizontal during the final approach into the chamber. When the round reaches the release point in the magazine...where the feed lips flare out...the rim should be well under the extractor hook.