shred

More than that, but not a ton more. It's difficult to over-crimp on a jacketed bullet. If you do it'll be obvious. OTOH It's easy to under-crimp and have a variety of issues from chambering problems & setback to gauging problems. Grab some premium factory ammo and take a look at how it's crimped with some magnifiers and copy that. If you like measuring, go with bullet diameter + 2x brass wall thickness, maybe a few thou under. Also, take one of your newly loaded rounds, measure it, and push it into the side of your bench bullet-first with two thumbs pushing hard on the primer end, measure again. If it got shorter, you've got problems.

You can also get knock from the primer slide not sliding all the way and from the shellplate not completely indexing, both requiring the alignment pins to pull them the last little bit. Is it on the downstroke or upstroke?

Probably selective-laser-sintered grip, so there's a lot of plastic powder involved. I wouldn't be too surprised if some comes off at first, although if the laser settings were wrong it could be disintegrating.

Yeah, zero gap is good, a tiny gap when viewed at 10x is usually ok. Easiest is to look at some major brand factory ammo and compare.

IME, most of them are made by whatever local welder makes the regular target stands and walls and whatnot. The MGM ones I've seen are adjustable but nothing else really special about them. I've also seen the low-rent way of just jacking a regular target stand up on a cinderblock.

I use a 10x loupe and look at the space between bullet and brass. If there's more than a minute gap there, add more crimp.

It's real fun when you're shooting a 9x25 Dillon and a media chunk gets in the chamber shoulder so rounds won't quiiite chamber.

Eh, I shoot SC until it cracks. Rare to have one get larger anywhere but the rim which gets pounded a bit over time. 1.245" is my target OAL with a JHP.

IPSC thinks Texas Stars are stilly too, btw. Still hanging on in USPSA for Level 1 only, although they used to be a thing at Nationals.

The only benefit to shooting a 9 open gun is brass availability. Everything else a SC will do as well or better. You can decide if that's 'worth it' for you. These days I do a lot of practice shooting with 9s and switch to the SCs before major matches.

A new shooter should use Doubles Drill as a Grip and Vision drill first and foremost. Improving those will improve scores. It's not until further along the learning curve that that working through how far out you can do predictive shooting is a big time saver. Mix in some Accelerator drills so you aren't just blapping away at one target at the same distance.

Newer DPPs seem to be a lot more robust than the old ones.

The trick people often miss about Doubles is you need to call both shots in the pair, even though you shoot the second shot without taking the time to confirm the sights.

Yeah, N320 was one of the gold standards. Some people (BE included) played around with Clays but it was very twitchy and unless loaded long could easily blow cases.

20 years ago with 38 Supercomp I shot 9.6 of 3N38 under a 121gr HAP from a 16" barrel Mech-Tech. 1623 FPS for 196 PF. Same load did 1392 in a 5" comp gun at the same time. 7.6gr 7625 and a 124 gr MG JHP (My Open Major load at the time) went 1357 fps pistol & 1562 in the rifle. Notes say the brass did not look good after the experience so after that I desisted except for minor loads.