First time test loads
I'm looking for expert advice as a first timer. I have just loaded, and tested my first test rounds in a 7mm-08 TC Pro Hunter, Bergara barrel. I will be loading for 300 RUM soon, as I am having a build I'm expecting by the end of this month.
The break action I know is not a long range action, but possibly a good starting tool? This gun will not shoot any factory loaded ammo well, with a 2" 100 yd. average, and POI changes with factory loads.
My first loads ever were loaded with a moderate charge, 44 gr H414, 210 primers, new Rem cases, 139 gr. SST's. I determined that the factory loads are .135 off the lands in this gun. I loaded 6 rounds each at 4 different seating depths. .013, .045 .070, .106 off lands. I was surprised with a dramatic increase in accuracy, and POI consistency from group to group. The best being the shortest OAL, set back .106 off lands. I got a 3 shot .553, and a 3 shot .997 group. Exactly the opposite of what I expected, and was the last load I tested. I had expected the loads set closer to the lands to do better. I'm using an RCBS FL 2 die set, and think concentricity could be factoring in, as well.
I would appreciate any advice as to technique, strategy, and direction from here forward, as I know now that after my first experience I'll not be shooting factory loads anymore. I was pleasantly surprised with the first loadings, and see that things are going in a much better direction.
My thought has been to select my components, find the correct seating depth, and then work the load out from there. Opinions I see here, and I've been lurking on this site lately vary greatly. I'd like to hear them all directly. All advice will be greatly appreciated, and all things will be seriously considered.