Ok, to simplicicate benchrest as we generally discuss on this site;
There is rimfire and centerfire:
In rimfire there are three major sanctions IR 50/50. ARA and PSL.
-all use the same equipment but slightly different targets and slightly different rules.
-generally the same ammo, 22 rf match quality.
-7#, 10.5# and Unlimited.
In centerfire, short range and long range;
-In short range there is group and score and ranges common are 100, 200, and 300 yards.
-Common chamberings for group is the 6PPC. for score the 6PPC and a couple of short 30 cals.
-weight classes 10.5#, 13.5# and the railgun of unlimited weight.
In long range:
-the 600 yard game and the 1,000 yard game, both scored as group and score on the same target.
=weight classes of 17# and over 17#.
-common chamberings 6BR, 6 Dasher and whatever you brung!!
IMO, none of what you already have will fit unless the Hall/McMillan in 13.5 and 17# depending on the barrel weight and length.
Go to some shoots and see what is used and think about trading the barrel blanks you have for 6MM 14 twist for short range or 8, 9, or 10 for 600 yard and 1,000 yard. Trade your 30 cal for a 30 cal 18 twist for short range score or 8 or 9 twist for VLD bullets for 600 or 1,000 yards.
Again, IMO, since you have shot a lot of competition you expect to win some or place well. Start in one of the above games with the gear that will give you a chance.
As to reloading, forget all you knew other than where the primer goes and where the bullet goes. IDPA. IPSC, CXC, all are crude compared to what it takes to win in benchrest. For example, in most benchrest games just moving the bullet in or out 0.005" can make or kill a tune!