Optimal velocity x caliber x barrel length

[dttheliman]

Potentially a dumbass question , however I am new to 6.5x47L and wondering considering barrel life /brass life etc - if there are optimum speeds one should push a round to for example ,
with a 140gr Berger Hybrid Match / Lapua brass, H4350 (and CCI450) all chrono'ed , I went up from 38.1gr @ 2619 through 40.8gr @2796 , no pressure signs at all , however I got two distinct nodes:
All at 100 yards of a bench 24" barrel .

1. from 38.7, 39 and 39.3gr three groups all shot basically 1 hole groups (POI differed slightly) @ 2649, 2678, 2719
2. and 40.2, 40.5 and 40.8 similarly 1 hole groups @2772, 2790, 2796

My thoughts are if my max range will never be more than 1200 yards (all I have access to) AB calculates that from lowest to highest, at 1200 yards my velocity is 1187 through 1284fps , and therefore as the numbers state I have not gone subsonic (<1125fps) over the range I would be fine in terms of shoot'ability selecting the middle of the lower node .

What say you and why - or am I over thinking it? (as usual) bearing in mind that the Lapua factory ammo 139gr runs at 2697fps .

Thanks
Tim

 

[spife7980]

It depends on environmental factors but the transonic zone begins about 1340 fps and ends at the 1170 or so. Its this range that causes the issues with some bullets, others arent effected to the same degree. Above and below can be consistent and accounted for but its that area in between of the the super and subsonic worlds that things get tricky. So run your number and see how far you can get before you hit 1350 and see if that satisfies your needs. If the slow doesnt but the fast does then you have your answer. If both do you can load hot and save a few tenths in mils or you can load slow and save on brass life.

Theres no magic equation for optimal. If you get the bullet going fast enough to get to your target thats all that matters.

 

[Milo 2.5]

Another twist on spife's analogy, if you are shooting against guys at said range shooting the same bullet at 2850fps, and you are at 2700fps, now you are at more than a slight disadvantage.
But, it will make you a much better shot.