I could not get consistent groupings with NATO chambers.
After a bit of load development i found the bullet to be more difficult to obtain usual velocities due to its length, and how that affects bearing surface/pressure and cartridge case capacity. The bullet also did not like long jumps to the lands in NATO chambers. I could get some good groups from time to time, but was unable to repeat anything.
H4895 shot fairly good, but had to be very, very compressed to get good velocities. Power Pro Varmint shot Ok'ish with velocities a little slower than H4895.
I went through 2 very accurate rifles with NATO chambers and gave up....
The 3rd rifle i tried has a Wylde chamber and a jump around .070 to the lands. I gave up on H4895 due to severely compressing the loads, and tried Power Pro Varmint. I gave up on that pretty quick. I was just about to scrap the whole project.
I was at a cross roads, the long bearing surface made me think i should try a slower burning powder. With the usual suspects, you just can't get enough in there to get any velocity.
Finally a vision came to me to try a faster powder. I landed on Benchmark and that was the ticket.
24.8 grains of Benchmark
CCI #41 primer
Lake City NATO 2005 brass 2X fired
16 inch Mid Length/Suppressed
Wylde Chamber 1/8 twist
.070 of jump loaded right at 2.260, or just a touch over/under due to tip variation
2875 fps. No pressure signs at all.
Many confirmation loads at 24.8, 24.7 and 24.9.
All shoot right around 2 inches at 200 yards with excellent repeatability.
This bullet has great numbers on the app.
At 2875fps, 50 yard zero, 500 foot elevation, and 60 degrees or so: 1.1 inch high at 100 yards, - 0.8 inch low at 200 yards. 200 yard velocity of 2270fps.
That will be just fine for the usual ranges i shoot at out here in the land of Douglas Fir Tree's.
My guess is that this bullet seated even closer to the lands in a bolt rifle would make it much easier to tune.
I will post here my thoughts regarding on game performance this fall when i take my first Coyote with it.
This bullet is just .005 shorter than a 69gr SMK, sleek and shoots more than satisfactory.
Just a bit finicky with seating depths in my case.. It seems impact velocity above 2500fps would be best. Not going to happen in my case.