Kind of a new guy here! I will be putting together a 22-6mm Rem in the next week or so. Nothing fancy.....older Savage 110 action, ER Shaw 26" 1:12 twist barrel, slightly modified factory tupperware stock.
Bullet of choice will be the 65g Sierra and/or the 55g Nosler BT. My goal is to put some serious hurt on the local coyote population.
I do have the new Hornady manual that has some limited data but I was hoping I could get some powder suggestions from anyone who might be shooting one.
I have not used a 22/6mm but know some who do, and most of them use Re22 with the 75 Amax.
I believe that with the Sierra 65 grain GK you could start at about 44 grains and work up with either Re 22, IMR 7828sc, Viht N560, H4831sc, or any other powder of similar burning rate. With these powders you should end up with close to a 100% load density at maximum pressure.
As a further guide for starting loads with the 65 grain GK, in my 22/250AI,(49.0 grains cap.) maximum loads with this bullet were 43.0 grains IMR 4831, 44.5 grains Viht N560, and Win WXR, and 45.0 grains Re22.
With the Nosler 55 grain BT, I estimate that you could start at about 43 grains and work up with powders such as IMR 4831, Re19, or any other powder of similar burning rate. The slightly faster burning H4350 would also be a good choice, but with this powder start working up from 41 grains.
The case capacity of the 22/6mm would be very close to a 220 Swift AI (55.4 grains) that I previously used. It would also be close to that of the 257 Roberts case necked to .224 (57.0 grains) that I then fireform to the .224 Clark. Good luck with your project. Brian.
My test was done using Win cases and Rem 91/2 primer, and I have no need to neck turn the cases as the chamber is about .255. I usually set my chrono at 10 feet from the muzzle, so the differences in temperature, barrel length, and height above sea level, between your circumstances and mine would only account for about 75 - 100 fps at the most, so your barrel is definitely a quick one.
The first 22/250AI that I built in 1972 (Shilen 27 inch 14 twist barrel) would crank the Hornady 60 grain HP out at 3,782 using 46.0 grains of Norma 205.
My current rifle struggles to reach 3,600 fps using the 60 grain bullet, and as it was chambered by the same gunsmith, it highlights that each rifle can give varying results.
This cartridge recently impressed me. I shot at a 1000 yard benchrest match last month and there were a ton of guys there shooting this cartridge, I think it was the ackley improved version.
Anyways, all were shooting the 1-8" twist with 80 grain matchkings. That bullet zipped right through the wind. The overall winner of the match shot a 4 and 3/16" group and another group was 7" for five shots @ 1000 yards.
I totally underestimated this 22 cal. cartridge.