Ok, just for S&G (and anyone who cares) I'm going to document the reloading for a new 243 I'm setting up.
After much debate, I picked up a Savage 12LRP in 243. It is a target action, heavy barrel, magazine fed gun that I intend to use for a variety of shooting from longer range Coyotes, to local bench competitions, and possibly deer. I topped it with a Vortex Viper HS-T 6-24. After an initial barrel break of shoot-clean-shoot-clean ... with a box of factory, it is time to start reloading. I'll try to post a little review of the gun and the scope in the appropriate forums later.
I'm starting with 100 round of new Lapua brass
95gr Berger Classic Hunters
CCI 200 primers
Berger's reloading advice is summarized as follows: Start by finding the bullet jam or jump that works at minimum book charge and then find the charge node using that jump. Some don't like this method for one reason or another but I decided it would be the route I would take.
I full length resized all of the brass. They didn't need to be trimmed as all cases were very uniform and near trim length anyway. I slightly chamferred and deburred the case mouths and called it good.
I found where these bullets touched the lands by disassembling the bolt, removing the firing pin, extractor and ejector and the making a dummy round. With no powder or primer, I seated a bullet WAY long. Of course the bolt wouldn't close on this round. I kept turning my seating die in little by little and kept checking for resistance when closing the the bolt. It took a bit, but I finally found point where the last 0.005 seating depth change made the bolt close without resistance. I took the last COL prior to this and considered it the "at the lands" measurement. Technically it is somewhere between at 0.005 jam and just touching, but close enough for my purpose. With this gun, I have plenty of magazine length to seat the bullets long if need be.
Next, 25 cases were primed and charged with 40 gr of powder. NOTE: ALWAYS REFERENCE RELIABLE RELOADING MANUAL AND WORK UP FROM THE MINIMUM LOAD. NEVER USE SOMEONE ELSE'S LOAD DATA.
5 sets of 5 were loaded at different COL's. I used my at the lands length, 0.020 off, 0.050 off, 0.080 off and 0.110 off the the lands.
Today was a great morning for shooting so I shot each of the batches, starting with the longest jump.
As Berger stated would happen, there was a noticeable difference.
The best 5 shot, 100 yard group was with an 0.080 jump to the lands, That group had the first 3 shots in the same hole with shots 4 and 5 making the overall group 0.507"
The 0.110 and 0.050 jump groups also shot well, coming in at around 0.0570. Hopefully this means that in this jump area, it isn't too jump sensitive.
The shorter jumps, 0.020 and touching opened up a lot. Not what I was expecting, but they were around 0.870 and 1.500 respectively.
Half inch isn't a bad start. The next step will be to work up the powder charge using the 0.080 jump COL to see if I can tighten them up a little more.
I'll try to post a few photos in a bit.