Thread: A whim...

Originally Posted by Tahr

I think its to do with efficiency and expansion ratios. The ratio between the bullet diameter and powder capacity dictates how efficient a combination is. By efficient I mean the loss of velocity per inch of barrel and per grain of powder. e.g. the 25-06 is less efficient than a 30-06, thus requires a longer barrel to achieve optimal performance.

The WSM has a smaller bullet diameter and larger case capacity when compared to the SAUM. So in terms of efficiency, the SAUM wins.

The same with the 22.243 and the .223. When both fired out of a 20" the 22.243 uses a heap more powder to get a similar outcome.

So, if you start hacking the 270WSM barrel you are soon back to 270W performance, but using 10 grns more powder, getting more blast, more bang, and more barrel wear.

I made most of that up, but I think that's how it works.

Think you are dead right @Tahr in your theory but the difference in bore volume between the .277 and .284 bore is negligible and overall capacity (case and bore) can be managed with the speed of the powder. As long as you don't need to shoot heavier bullets than they make in 270 I'm not sure it will make much difference.