Thread: Muzzle Velocity Loss Across Different Ammo

Hi guys

I might be barking up an unclimbable tree here but I've got a wee query that you guys might be able to help with.

Up until now I have been using Sako Gamehead Pro 165g with great results through my .308, unfortunately, these now appear to be discontinued and I'm all out! I've picked up a box of Hornady Precision Hunter 178g & Nosler 165g BT to see how they shoot and rezero with the best candidate .

My question is around drop charts, I chrony'd the Sako through my 18 inch barrel and had a drop chart that was working really well, I currently don't have a chrony and was wondering how to figure out a rough drop chart based on the specs on box (I know these aren't the most accurate but its all I have right now and I'm off for a roar hunt in a couple of days).

Does anyone have any idea if there is ANY consistency across different ammo when looking at velocity drop in a shorter barrel? Ie if the sako was 2600f/s out of a 24-inch barrel per the box and this dropped to 2500f/s out of an 18 inch could I expect:

a) a consistent reduction in fps? (ie 2800 fps becomes 2700fps)
b) a consistent % reduction in fps (ie 2600 to 2500fps = 4% velocity loss than 2800fps becomes 2688fps)
c) nothing consistent and I best just 200yard zero it and hope my hold overs are close
d) someone has some chrony data for the Precision Hunter or Nosler BT's out of an 18inch barrel that I can use
e) I'm an idiot and there's an easy answer Im not thinking of. (note I only have access to a 100 yard range so can't really walk out the drop myself)

Any help would be appreciated, I would hate to end up missing out, or worse wounding and losing, a good animal because I've got this wrong.

Cheers!