260 Ackley, H4831, 123 Amax

Merdit

Active member
So I've had a used (advertised under 300 round count) Criterion 260 AI 26" Savage barrel sitting in my safe for a few years. Decided to screw it into my switch-barrel action and start tinkering with it.

I fired a box of factory Remington 100 grain corelokt through it to have some brass to measure and compare against any other brass I neck down, and to start load development with.

I called Criterion and was told they have two Chambers for the 260 AI, match and standard. Mine is the standard, therefore shorter throat. It will be suited better for 129's and down. So, I traded my brother for some 123 Amax that he had stashed, and built some loads at 2.800". Got a nice group at 49.5 grains compressed a little, no pressure showing up.

Hodgdon has data with a standard 260 120 grain Speer bullet up to 50 grain compressed max, 125 grain Noslers up to 48 compressed max. I've made it up to 50.5 grains with pretty good crunch compression. Fired three rounds. Two primers look really good, one is slightly flattened. How much can a guy compress this H4831? I'd like to see if there is another accuracy node if the pressure allows it and can safely load a few more tenths in the case. How much crunch is too crunchy?
 
Good question! Time to get a drop tube.

I've got a 30" 260AI Criterion barrel but I've only shot 140s out of it with H4831sc, 140 Amax was warm but doing fine at 47.7gr, 140 Berger VLD fine at 48.2. Both of those with 7mm-08 winchester brass, I cant quite compress the powder before I get flat primers.

I just got some Nosler 260 brass, COW formed the brass and the first bullet after that was 140 Amax 46.5gr H4831sc and I got surprisingly flat primers with just a three shot test.
 
Yep, a drop tube is in order!

Thanks for the primer tip. I'll see if it will yield similar results for me. Any significant change in accuracy?
 
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Built a 10.5" drop tube of copper tubing. That definitely lowered the powder column in the case. Considerably less crunch. Will get a few more tenths in, I believe.
 
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