Factory ammo often uses non-canister powders, which you can not buy. It results in velocities that will exceed what a handloader can achieve without very high pressure levels.
I think the .50 was 800, the .338 was on the side of the mountain at 1400, if memory serves me fairly correctly. Both were bonus targets shot off the clock.
A First Focal Plane, the reticle increased and decreases in size as the power changes. The BDC is the same regardless of power. Second Focal Plane, the reticle is constant in size and the BDC is only calibrated at maximum power.
If you're not left handed, why put one on? As Isaac mentioned, it can hit the joint on your right hand, and put it on when you least want it to be functioning.
Pioneer is busy with both IDPA and USPSA, and 3 gun starting this year. Closer to Portsmouth is Piscataqua which runs USPSA and Steel Challenge matches. Chester was USPSA and Steel Challenge, maybe IDPA too. Check the club web site on them.
I've not used the 50 grain Ballistic Tip, but use the 55's as one of my accuracy bullets. I would try H335 and a charge of 26.0 that should shoot pretty well.
The original had a lead acid battery. The newer ones didn't, hence the "Lighter" description. Also, when you turned on the originals, the display came up with Made For and the owners name.