115 gr ball should be the easiest to get running.
Mag block should have no movement. I thought Spikes block had a tension adjuster to lock them up tight. May need to play with height of block to find sweet spot. The mag may have some play in magwell, so keep hands off mag and do not rest mag on anything while shooting.
It shouldn't be a big deal running a regular buffer, but 5-5.5 oz is "recommended/ideal" for most 9mm setups.
You can test by loading up your mags and using bolt release to drop the bolt and see how it strips rounds from the mag. It can be tedious, but it can help diagnose set up issues like block height or COL issues. If you reload, you can make some dummy rounds, or you can remove the firing pin from your bolt for safety if you want to use live rounds.
What is your parts list? barrel, mags, etc...