This may sound like heresy, but in these tough times, when all I can get my hands on are the random encounters with 1-lb jugs of powder at a local gun shops, I've taken to 'compounding' my newly acquired powder by mixing it in with what's left of my 8-lb jug,... I've done this three times (two different lots, three lots total) now over the last three months with what I have left of Varget and my velocity and grouping (<0.5-MOA) have remained constant without any noticeable shift in impact. I figure it's better to compound what I have, work with that as 'one lot', rather than have to start from scratch when I finally finished off my 8-lb jug,... only to start over after finishing the 1-lb,... then the other 1-lb,...etc.... just a thought.
Ry
PS - I've noticed that H4350 has a little more variation from lot to lot, but not a ton. Here's a load you can try for your 260REM,... I've used this load (43.0gr H4350) and a slight variation (43.3gr H4350) with two (2) 26" barrels: one from Rock Creek and the other from Benchmark Barrels and they both shoot lights-out! Here's a group:
5-Shots: 43.0gr H4350 w/139gr Lapua Scenars shot prone with bipod
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