Can anyone give an approximate difference in velocity from the same load in a 26 inch barrel compared to a 23 inch barrel. I have a Barnes reloading manual and their FPS calculations for the .458 Lott are from a 26 inch barrel. Wondering what the difference in velocity would be using their stated powder charges in the shorter barrel. Also noticed that many members on the forum use RL 15 and IMR 4320 in loading their Lott's. Barnes recommends IMR 4064 and AA3520. Curious about the difference.

I would opt for the IMR4064 too. The MV should drop between 15 and 25 fps per inch of barrel.

ASS_CLOWN

You`ll gain or lose 25-50 fps depending on the cartridge per inch of barrel. I`d figure yours on the ~25-30fps side.

I strongly recommend that when using Barnes bullets you use Barnes data.

Sorry about the search thing being down....there's been a ton of data regarding barrel length and velocity.

Basically I'd guess about 75 '/sec loss for the 3" you mentioned.

ASS_CLOWN is pretty close.