338 SHERMAN MAX

[jmden]

Took it out to 1358 yds today in temps about 15F below what I'd zeroed at and the using the 1fps to 1F in ABMobile put me spot on. Very still day so pretty confident. Anyone else playing with this?

A little more temp data on 62.7g N550, Berger 250g and the 25" barreled 338 Sherman Max. At 52F average of 2805 fps with no pressure signs. At 14F today with same load I was at 2750 fps MV. Still good ES, but dropped 55 fps. Hope this helps folks.

The odd thing is that I run N570 in a 338 Terminator with 300g Bergers and 106g runs 3050 fps at 50F and today ran 3050 at 14F. Clearly in these chamberings, there's some differences.

 

[elkaholic]

A little more temp data on 62.7g N550, Berger 250g and the 25" barreled 338 Sherman Max. At 52F average of 2805 fps with no pressure signs. At 14F today with same load I was at 2750 fps MV. Still good ES, but dropped 55 fps. Hope this helps folks.

The odd thing is that I run N570 in a 338 Terminator with 300g Bergers and 106g runs 3050 fps at 50F and today ran 3050 at 14F. Clearly in these chamberings, there's some differences.

Yes, N570 is extremely stable! Good info on the 550.

 

[jmden]

Yep

Yes, N570 is extremely stable! Good info on the 550.

Yep, I've been running N570 for close to 10 years in the big .338s and had always seen temp stability (or the barrel was contracting too...or all the other things that we think can account for temps stability) but had never shot it in temps this low.

It's weird how N550 being in the same 'line' of powders for VV is 'unstable', comparatively, to the N570.