Load testing for my CZ527

[LRRPF52]

Those loads were fine for me in my 16" Grendel. I pushed past them to see where the departure would occur, which was at 33.2gr of CFE behind the 123gr A-MAX.

Hornady's 9th lists 31.7gr as max for the 129gr cup and core pills, like the 129gr SST, 129gr IB, and 129gr SP.

Your 22" velocities compared to my 16" velocities make sense, and average

Examples:

Code:

[B] 16" 6.5 Grendel AR15[/B] [B]22" CZ527[/B] difference 31.1 2489 31.2 2612 123fps 31.4 2520 31.5 2628 108 31.7 2532 31.8 2664 132 32.0 2553 32.1 2700 147

When I run the numbers through JASmith's velocity estimator, to include the change in powder weight from 32.1gr to 32.0gr, and from 22" barrel to 16" barrel, it gives me an estimated velocity of 2555fps, 2fps off from my real world mv of 2553fps.

http://shootersnotes.com/calculator/velocity-estimator/

I loaded to 2.275" for my batch when I did those ladder tests. You should be able to easily get 2800fps with the 123gr SST. I'll show you what your next loads will register:

CZ527 22" 6.5 Grendel Estimated MV
32.6gr ~2738
32.9gr ~2761
33.2gr ~2784
33.5gr ~2806

If it were mine, I would continue to do as you have, push the COL out some more to where you are just off the lands, and see where you can go. You really should not have problems reaching 2800fps with the CZ bolt gun.

For a 22" AR15, I would not mass produce a load over 32.2gr of CFE under a 123gr, given that 31.7gr is the max under a 129gr. Even there, you have speeds that are around 2700fps, which is plenty fast. CFE223 has proven to be a very forgiving powder for me, creeps up predictably, no surprises, no spikes, just a nice gradual velocity increase that behaves well with the case capacity of the Grendel.

Thanks for your detailed report. I want a CZ527 badly[SIZE="3"], [/SIZE]chambered in 6.5 Grendel.