What I didn't realize at the time is that these recipes for green dot don't give much room for error. For these 200gr bullets, the starting load is 5.8grain, the do not exceed is 5.9.
That usually means that someone was lazy when brewing the recipe for that particular bullet or powder. The real min/max are probably far more spread apart than that, but the author didn't test it so he's not going to publish it.
I've gone under "starting loads" many times. Most often with cheap lead cast bullets where load data is sometimes scarce.
Yes, you do theoretically have to worry about "detonation." But that tends to happen when you have so little powder in the case that it is less than 50% full, and the spark from the primer coats the entire surface area of the powder all at once rather than burning from back to front. And mostly using fast pistol powders in larger volume rifle cases, brewing up 1000fps .30-30 loads and things like that.
Your components: Green Dot, 200gr plated (not jacketed), mixed brass.
http://castboolits.gunloads.com/showthread.php?100896-Green-Dot-in-45-acp-200-gr-LSWCSpeer reloading Manual #9 lists Green dot under a 200 gr lead bullet .
CCI-300 primer
5.0 grs. for 833 f/s
4.6 grs. for 729 f/s
No pressure data however this is the data for a 200 gr Jacketed HP
6.0 grs. for 957 f/s
5.6 grs. for 896 f/s
Generally you don't drive plated bullets to the same speed as jacketed. Plated bullets are soft swaged, then dunked in a chemical bath to put a very thin layer of copper on them. It's much thinner than a jacket.
And, they're soft swaged. Not hard-cast. You can drive a big mean sumbich 230gr hardcast lead bullet as fast as pressure will let you from a .45acp. Do the same thing with a soft swaged bullet and you get bad leading, boil-off from behind the bullet, gas burning the bullet from the sides, and bad accuracy.
5.8gr does not seem like a particularly ideal load for your chosen projectile, and I'd suggest dropping it at least 0.5gr. Possibly more if you experience excessive leading.
And as for the crimp... barely touch it. The cartridge headspaces in the chamber on the edge of the case mouth, so you need to see the case mouth when viewing an assembled cartridge from above. Just remove the bell that makes it possible to seat the bullet without shaving lead during the seating stroke. That's it.