Does improving the .308 Winchester case to a 40-degree shoulder make possible higher velocities?

If so, *roughly* how much velocity gain might one expect to see? (And with how much more powder?)

Somewhere here recently there was a discussion on the Ackley's and the statement was made that on cartridges introduced after 1950 or so there was very little to be gained from Ackley-ing the case. Sean

much less than doing a 30-06 or rechambering for 300wsm..

i would expect LESS than 50fps

10% case capacity increase will get you a 5% velocity increase. Do the math, it's not a large gain. - Dan

Even in the .375 H&H Ackley Improved, where powder capacity is significantly increased, velocity is only increased perhaps 100 fps. In the .308, you might not even get a measurable increase. The .308 case is just about perfect as it is.

Balisarda,

If your only desire is increased velocity and you shoot less than 200 rounds per year and do very little reloading--to chamber a rifle for a 308 Ackley Improved is, IMHO, a total waste of time, effort and money. This is coming from a dyed-in-the-wool Ackley fan. There are other benefits that present themselves when you do go the Ackley route--longer case life, less bolt thrust and very seldom, if ever, trimming the cases. For the occasional shooter it presents no benefits that I can see.

Ol' John

I bought a used 308AI several years ago and experimented with it before rebarreling it to another wildcat. I was unable to conclude of any velocity increase. I have several AI's and would estimate a velocity increase from none to maybe 50 fps for the 308AI.