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.308 Winchester Improved 40-degree

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14 July 2003, 15:21
Balisarda
.308 Winchester Improved 40-degree
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?)
15 July 2003, 02:12
LoneEagle
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
15 July 2003, 02:33
jeffeosso
much less than doing a 30-06 or rechambering for 300wsm..

i would expect LESS than 50fps
15 July 2003, 03:26
dan belisle
10% case capacity increase will get you a 5% velocity increase. Do the math, it's not a large gain. - Dan
16 July 2003, 09:27
KLN
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.
16 July 2003, 01:55
<eldeguello>
quote:
Does improving the .308 Winchester case to a 40-degree shoulder make possible higher velocities?
No.
16 July 2003, 03:17
HondoJohn6508
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
20 July 2003, 13:05
<LReynolds>
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.