I just started loading for my new 260 Rem. The best load I found in my 20" 1:9 twist using 120 grain sierra mk hpbt with 44.5 grains of H4350 getting .50 at 100 yards.

My chrony says im getting 2935 average but my load data Lee reloading manual says max is 46.5 compression load and 2915 fps with this load. So why am I getting 2935 out of less powder and shorter barrel?

I thought chrony was wrong so i zero at 100 then took it out to 300 and found my drop 12" at 300 is consistent with my fps. Has anyone found such a discrepancy in the load data?

My primers aren't flat and no case deforming or extractor marks showing high head pressure and this is not a compression load seating the 120's at sammi 2.80.

I just found it odd but this is the best group I get with the powder bullet combo.