Buy the absolute best you can afford. Most of the game is mental anyways. Showing up to a match with what you think is the best of the best goes a long way.
One of the best performing 9 major powders out there. It's also very dirty but that didn't bother me. Depending on the lot I was between 9.6-10gr with a 124 jhp at 1.168. This was good for 173-174pf in a fullsize gun and no holes.
You need to push AA7 a bit to help with the unburnt powder. I was at 9.6gr with a 124jhp in my open gun. It was around 173 PF. Don't get caught up with just making major and load to what works your gun the best.
Search for pivot barrels. They are used in knives. I bought a 100 pack of the grip screws on ebay for cheap a couple of years ago. I'm sure you could do the same with the other screws too.
Most of the guys use N320 data with RS Competition. It seems Ramshot's data is a bit conservative. If you do a search on these forums for RS comp load data you will see what I'm talking about.
I was at 8.7gr with a 115 in 9mm. It was 174 PF with a fullsize and no barrel holes. You can also search for Winchester WAP loads. It is reported to be the same powder as Sil.
If you aren't going to use spacers then you need to be using the 38 super follower not the 9mm follower. I will never understand why people are so against spacers in 9mm sti mags. I've put together 8-10 reliable 9mm mags with spacers and zero tuning other than putting parts together.
Sil is reverse temp sensitive. Not much of a problem here in Fl but still good to know. I used to shoot 7.7gr with a 124. It was 174pf in a full length with zero holes.