Arc problems AGAIN!!!

[KenC]

New brass 1st firing....book load, 29.4,29.7 lever, Berger 105 BT Target, .020 off . Tried to post pictures, but won't let me. Anyway, have shot Hornady Black and new load 6.5 cases necked down.On the new cases necked down had 4 cases crack, from body shoulder junction down the body between 1/4" to almost 3/4" long. None of the Hornady  cases had cracks, or were scratched. The new cases other than the 4 I have discovered so far look ok. I did have some that after sizing, had the "belt".  I discarded the belted ones...but I am really skeptical about reloading any of the new/ resized cases....I was expecting the Hornady brass to be the throw away brass, but even though the primers were flat, the brass held up better than the new cases. Would really appreciate an education on the idiosyncrasies of loads, brass, tricks to make the ARC run smoothly. I do have 100  6.5 Grendle Lapua brass I could size, but till I know it's not going to be one and done, I won't risk it. Thanks for any help....rsbhunter

I have found 29.4, 29.7 to be way to much for a 105. In my 24", 28.9 of LVR got me 2813 at .010" off the lands for velocity testing(slightly hot). These were Hornady Black rounds which I pulled and replaced the powder. I found the factory Black, on one box I pulled, had a range of 30.4 to 31.4gr of powder. First cold bore shot got me over 2913. Way to hot. Let Hornady know and told them what I got. They told me on a 24" test they were getting 2705-2750. They said they would reload them for me, but I declined since I bought them for the brass anyway. I seem to have found a velocity node around 28.1 and 28.9(I think this is too hot). With a Barnes 105 Match burner, around 28.6 is a node(2775) and 107 SMK is 27.9(2650+-) and 28.4(2750, but getting OP signs with re-sized Grendel brass and going to test this with Hornady brass later). This is what I measured in my barrel. I go a little light on first fire after re-sizing, annealing the brass after the initial re-size. I found some 100gr cheap pulls for this function. Be careful on your test. More to come, but for now, I have work which has to be done.