Velocity Loss with 26" Barrel & 7mm STW

#1 12-28-2002, 09:38 PM

I am trying to figure out how much velocity would be lost going from a 30" to a 26" tube when shooting a 156 grain bullet.

Also, does anyone know the difference in velocities between a 7mm RUM and a 7mm STW?

Brent · #2 12-29-2002, 05:24 AM

Hey John, I figure about 30 fps per inch. The Ultra has over 100 fps on the STW if I remember correctly.

#3 12-29-2002, 10:26 AM

So if a 7mm RUM is getting 3450 with a 30" tube, I should fiugre 3230 with a STW and a 26" tube?

Brent · #4 12-29-2002, 03:51 PM

John, the Barnes manual shows 3360 for their 150 from the STW and Nosler shows 3300 with their 150. Don't have any data for the Ultra. Both used 26" barrels for testing. I let a guy a the range use my Oehler and he was getting easily over 3500 from his Ultra and using 150s in a 26" BDL, he approached 3700 but pressure signs were clearly evident before that though.

[ 12-29-2002: Message edited by: Brent ]