Thread: 7mm mag 26" velocity

I also have 7mmRM Sendero with a 26" barrel and a 7mmRM T3 with a 24 3/8" Barrel. With 162SST's, 168 VLD's, and 180 VLD's there is about a 2% increase in velocity for the same powder charge and projectile (bugger all). The difference with 150 Nosler BT's was more pronounced. Around 5% increase in the longer barrel. It is not a very scientific experiment as the Sendero has a much shorter throat than the T3. I guess the only sure way to figure out the actual velocity gain per inch is to start out with 26" and chop off an inch at a time and chronograph it (velocity loss really). I'm not recommending that!

For the record I have choreographed Hornady 308 Superformance 150SST's at 2965 fps Average, and 7mmRM Superformance 154 SST's at 3092 fps Average. Both out of T3's. The 308 only has a 22.5" barrel. I think most ammo makers now days are well aware of the availability of the internet and chronographs to shooter, and no longer put bullshit velocity figures on the boxes.