I just finished building this rifle. I ordered the parts in the summer of 2021, did the metal work last December, worked on the stock from January to June. Stolle Atlas RBLP receiver, full floating Brux 29" 1:20" twist barrel with Heavy Palma profile, Arrowhead brake & ignition, Timney 533 trigger, bedded & triple pillared Richard's stock. This rifle uses 80 grains of H322 under a 45 cal 300 grain Arrowhead NSR (No Sizing Required) bullet that is shooting Bullet To Bore (no sabot).
I have a similar rifle, based on the same ignition system, that's a T/C Encore Pro Hunter barrel, and it uses 60 grains of 4198 under 45 cal 275 grain Arrowhead NSR bullets, also B-B. Both are wonderfully accurate. This bolt gun is the heavy hitter, though.
I have another one that's a custom build on a Savage ML-II receiver, with a 26” 1:22 twist 45 cal PAC-Nor stainless barrel. I believe it was built by the late Rick Bibby of Arkansas. That one could probably shoot Bullet To Bore, but I've only used saboted 40 cal 180 grain Hornady XTP and 200 grain SST bullets so far with it. With sabots, I used 45 grains of 4198. Now that I've learned more B-B techniques, I'll bet I could go back to it and maybe get it shooting as well as the two based on the Arrowhead ignition system.
I also have a stock Savage ML-II 50 cal and I use 45 grains of 5744 behind 300 grain 45 cal SST Hornady bullets in that. The two Savages shoot OK, but the two rifles shooting B-B and based on the Arrowhead ignition are in another class, both power and accuracy.
Here's a picture of the loading block I made for this rifle. The little brass modules have a 308 head and use a Large Magnum Rifle primer. My Encore barrel uses modules with a 45-70 head. In the other picture, I am holding a 300 gr Arrowhead bullet and a Parker 300 gr, with one of the Arrowhead ignition modules laying between them. I haven't tried the Parkers, yet, though. It would be hard for them to top what I've gotten from the Arrowhead bullets so far.
and I love it!
