Thread: Lower than expected velocities

Originally Posted by grandpamac

Greetings,
A check through my records yielded the following data. Both rifles are Remington 700 .308W.
Rifle 1 is my 45 plus year old .308W with the barrel cut to 20". Velocity with the 150 grain Hornady soft point is 2,675 fps with 44 grains of AR2206H. The rifle has been used for a little hunting and rather more target shooting and has had a little over 1,000 rounds through it.
Rifle 2 is a a much newer rifle with 100 or so rounds down the 24" tube. 45 grains of AR2206H with the 150 grain Hornady produced 2,865 fps and factory 150 grain Corelokt 2,850 fps.
Adjustments for the extra grain of powder 50 fps and 4 inches of barrel 100 fps give us a corrected velocity of 2,825 fps for my old rifle. Powder is the same lot and the Hornady and Win cases used are near identical in weight and likely capacity.
So we should expect a velocity loss of around 100 fps for a 20" barrel, not 300 fps. Some factory ammo produces significantly less velocity than claimed even in a standard 24" barrel and there is only one fix for that.
Regards Grandpamac.

I know - that speed figure of about 300fps is working backwards off the range drops for the trajectory to get to a muzzle velocity that makes the pill (with it's BC) match the rainbow. There's a lot of doubt and I need to get back to the range to confirm a few things up - although I very much suspect that the issue here is the ammo is not even close to the claimed velocity figure that Winchester has slapped onto their box. I am halfway wondering if they've used a 26" test barrel, which could be good for a bit more than 150fps over the 20" and then allowing for difference factor between barrels which could be 100fps - that may explain what's going on for me.