Weak hand thumb is how I did it in IDPA with 38spl brass. Cutting down cases is too much work (not allowed in IDPA anyway). Use mixed brass and leave it on the ground.
I don’t like loctite so bend the spring until just right with screw backed out a little, then tighten screw tight. If more spring tension is needed later on just straighten the spring a little.
I wouldn't worry about it, the target on the right isn't that bad. Once when I was struggling with a new platform a GM told me it can take 10,000 rounds to get it right. Stay positive and enjoy every trip to the range.
Apparently my powder measure has enough clearance between powder bar and spacer (.007) to allow Sport Pistol to get in there, wear the parts and dust the press. Today I smoothed out the roughness and made a .004 shim for the spacer. If your powder measure runs clean and smooth with fine powders you don't have a problem.
The Brazos 124 is an excellent profile, looks a lot like the H&G #331. I got a bunch in over the weekend and the first 6 I ran over the chrono gave a 0 SD with Alliant Sport Pistol. I’ve never seen a 0 SD for 6 shots before and may never see another but it made me smile.
john