When mine has the the problem, it isnt because the ramp is too short, its because its there. The ramp catches the nose of the round and instead of guiding it up into the chamber, it goes down, and causes the stoppage.
I use the same mags in both my Colt and Tisas, and with the Colt, the rounds dont nose dive at all, and hit the lower edge of the barrel and straight into the chamber, with very little deflection.
I should get an idea here this morning if tweaking the extractor has changed anything. Seems like it did with some proving rounds, but that's not shooting the gun.
The other thing that kind of bugs me is, OAL. OAL shouldnt matter, and the gun should feed anything with a proper bullet, within the rounds acceptable OAL. I shouldnt have to fiddle with and tweak that. I expect all my ammo to work in all my guns chambered for it. If that is the issue, then the gun is gone just for that reason.
This is my story too, only substitute Colt with Dan Wesson. My rounds nose dive almost perpendicular into the feed ramp. The rims do not come in contact with the extractor.
Mine is the commander with rail. I did not expect Dan Wesson performance, but I did expect a functional firearm. My purpose for this was a beater woods/camping/play gun so I'm not beating the hell out of my Dan Wesson Specialist Commander.