Going to run some ladder tests tomorrow with 140 Amax's. Thinking of starting at 42.3 grain of H4350. Distance to the lands is 2.26". So going to start at 2.24 and increase length in .003" and work to box length. Going to decrease by .003 from 2.24 to 2.234. I am only doing 3 rounds each length. Closing on 200 rounds down the pipe and really would like to find something that works and enjoy the rifle. I did a thorough cleaning today with Sweet 7.62 and when I felt it was clean, ran more through and got more copper out. So I am heading out around 10 tomorrow morning barring weather. Supposed to be a light breeze of 5mph. Fingers crossed I shoot straight and find a node quick. At that point I'm packing up and saving the rest and resize to the node I found.
Well the load that produced the last 3 shot group was to long for the box. How I managed to do that I'm not sure. So I took the box length and stepped them down in .003" and hit another node at 2.207" with comparator. Going to tweak it a little more and confident I can reproduce it. This was the 140 Amax behind 41.9 grain of H4350.
Right on! I have a 26" Shilen chrome moly in the same contour. I'm still fireforming brass, only about 75 left, then final load development.
My fireforming loads are pretty accurate, especially when my buddies 16 year old can line up behind the trigger and connect on a cold bore shot @ 790 yds first time he ever shot the rifle!!
I've only so far managed to load 123 gr Sierra MK's with an estimated vel of 2900 fps (guessed on that the first time shooting long range and it worked within a couple of inches in my ballistic app) won't be running em over the chrony till I'm working up that final load.
I know you will enjoy this rifle and your next build sounds like a death ray, happy shooting & hunting!!