Sounds like something has left residual material somewhere to me. Nose of a bullet hung somewhere, shaved, and now it’s catching more solidly, or something to that effect.
for what it’s worth, when I had a delta, it ate berrys 180 truncated cones and was acceptably accurate. I had issues with some random bullets hanging but once I had the truncated cones I was happy enough to stop experimenting.
another thing to look at is case sizing. If you are using cases fired in the colt then they MUST be full length sized every time. The colt barrels do not support the case head and the cases bulge. That was the thing that made me sell my delta. If it wasn’t supported then I didn’t consider it safe to shoot full power loads and if it’s not capable of full power loads I didn’t see the point of having it in 10mm. That’s a whole mother can of worms though. If factory loads work but reloads don’t, look at your cases and see if they bulge. It’s well documented that it does it, and Colt doesn’t care because they are making money.