Glory land in my 8T, .020 freebore Dasher is with the 60g sierra and old 60g Berger, 60-62g Watsons with AA2230 and H335 at 4000-4100 fps depending on the barrel, have two. I like the 6 BRX(.020 freebore) better, less finicky. Rem 7 1/2's on all.
I have an old lot of Scott's H322 from the mid 80's that shoots fantastic, but slower. This lot# of H322 gets a pretty good powder ring in the bore around 125 rounds, but the H335 and AA2230 is a solid 300 round shot string in-between cleanings. Both the H335 and the 2230 burn real clean on the top end loads. The issue of course with the ball powders is that you can not load them on the very top end, back off 1.0g-1.5g from the top end load for hot weather....dumb butt simple.
I used to carry 2000 rounds of 6 BRX on a single p. dog trip, shot them all, zero freebore chamber shooting 60g sierra and BR bullets at 3800 due to the Rem brass I was shooting. 6 BRX was not a cartridge back then, we called it a 6BR Long with the 6 BR reamer ran in .100 deeper, idea of Jim Williams in Ga. After about 5 firings, I left all 2000 pieces of brass in a p. dog hole up in S.D., and never went back to the cartridge till Lapua brass came out. I had 13 burnt holes in my bolt face from primer leakage on the rem cases.
If you have not tried the 6 BRX with short freebore, you are in for a real treat. 55g Noslers at 4100 on a 27" finished blank is the real deal. The 55g Nosler 6mm bullet has a slightly better BC than the 22 caliber Nosler BT. So, the 6 BRX shooting the 55's is on par with a 22/250 AI shooting 55g Nosler, but the 6 BRX is a LOT easier on barrels.
If you start off with a 30" unturned blank on a 6 BRX, you will get at least one set back on the barrel, if not two. Start the new throat at the same dia as the muzzle dia, you will be good to go. You will scrap the barrel after one chamber with N133,N135, R#15, H4895, and varget as 10" of the barrel will look like it has been "ate up".
I have a theory, after shooting fast twists in 22 PPC, 6 PPC, 6's of various types, and that is that as outside Temperature effects your load, the faster twist increases the pressure spike vs using the same powder in a slow twist. This pressure spike was very, very apparent in the 22 PPC when I was shooting the 52g Speers with approximately the same load, both barrels of the same maker, 8 and 14Twists, chambered with the same reamer.
Make no mistake about the fact that the faster twist makes the bullets open up faster, this is no joke. I saw this in a custom 700, 223 shooting 40g Noslers in a 9T vs 14 Twist. Also, I saw my 22/250 custom shooting the 55g Sierra BTHP just knock over p. dogs at 3650 fps, then saw the HBAR in 223, 7T, blow the p. dogs sky high, 3000 fps, with the 55g bthp doing 600 fps slower!
Rotational Torque on the base of the bullet as the bullet obturates in the barrel is a serious issue, and I suspect that the Nosler Ballistic tips with their thick base are going to shoot very well vs thin cup bullets.
Alex Wheeler lives in p. dog and Squirrel land, I am sure he could write a book on all of this if he had the time.
