185gr Berger OCW in 20" AI AT

[tpe187]

I thought I would share my results of a recent OCW test I conducted with Beger 185gr Juggernauts.

Brass was new Lapua
Primers were CCI BR2
Powder was IMR4064 and Varget
OAL was 008" off the lands from the ogive.
Distance was 100yds.
Alt was 6000ft
Temp was 66 degrees.
Rifle was an Accuracy International AT in .308 with 20" barrel.
I used a Magnetospeed chronograph for all rounds fired.

Interesting that the accuracy nodes for IMR4064 were at a lower velocity, but a wider range than the Varget. 41.2gr to 42.1gr (2465-2538)are almost all in the same spot. Scatter node is right above that. Unfortunately, I'm trying to push these as fast as is sensible, so it looks like Varget for now. I think 44grs of Varget will get some more testing, experimenting with OAL. No pressure signs at all with either powder. I will do this again with Sierra 175gr SMK. For comparison, 175gr FGMM averages 2588fps and Black Hills 175gr averages 2568 out of this barrel.


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[jsthntn247]

I would test seating depth at 44.1

 

[tpe187]

I've got a batch of the 4064 loaded up at 41.5 and 42 with OAL at 2.89. Hope to get out today and see what the difference is now with once fired Lapua. I went with that OAL based on ABMs loaded 185 Berger target ammuntion. Any recommendation on OAL into or off the lands with Varget at 44.1?