Question, does each shot feel and sound different with either load?
I may can shed a little light on this. I had a some eractic ejection issues with my 35 for awhile. I am shooting TG with a plated 180.
I had multiple things going against me.
1. I was getting erratic powder dumps from my 550.
2. I was getting bullet setback. This was found to be SPEER brass that was so thin at the neck that case neck tension and crimping wouldn't hold bullet in place. It took me awhile to figure this one out. I would have a misfeed in a match, rack the slide and move on. When I finally recovered a couple of rounds, I noticed that they were both SPEER brass. I took loaded rounds and could push the bullets back in the SPEER cases by hand but not the Rem, Win, Starline, ........ I started messuring the brass thickness at the case mouth of different brass and found the Speer to be much thinner for some reason???????? The SPEER brass came from a police range. Guessing it is SPEER Lawman ammo?
3. The plated bullets I was shooting are very slick. A lead bullet seated in the SPEER brass would not set back but the plated one would. I wasn't going to change bullets so out with all the SPEER brass(it also had a dang primer crimp!!!! ).
My 550 was do a break down and cleaning. I checked the powder measure and was getting 4.3 - 3.8 on each dump. That was part of the problem. It everything needed to be adjusted back to spec. The bullet set back was another. I now wipe them down with a cloth to get some of the oily residue off them before loading. This can be very dangerous with a high pressure round like the 40. Once I got all of this ironed out, my 35 ran great. Brass piles up just behind me and to the right. Don't know if any of this applies to you, but thought I would share my trial and tribulations.
PS- I do use small rifle primers in all of my 40 reloads.