According to Wm. C. Davis, Jr. in "Some Simplified Interior Ballistics for Handloaders"

Case capacities in grains of water are as follows.

.22-250 45grs
.22 Swift 48grs
.243 Winchester 54grs
.257 Roberts 55grs
.25-06 Remington 66grs

My questions and observations are as follows:

The 223 WSSM (with its� supposed super efficient design) is not advertised as being faster than the .220 swift which holds only 48grs of water. The last article I read (I believe by Craig Boddington) placed the velocity some ware between the 22-250 and the .220 Swift.

However, the 243 WSSM is using the exact same case and is billed as being the equal or even slightly faster than the .243 Winchester which holds 54grs of water.

Now Winchester is releasing the 25 WSSM and is billing it as being the equal of the 25-06 Remington which holds 66grs of water! (Again using the same case)

Am I missing something here ? !!

Observation #1:
.220 Swift can have good barrel life as long as you don�t try to get maximum velocity out of it. However, many people feel the .220 Swift is about the upper limit on .224 caliber.

This is evidenced by the relative unpopularity of larger .224 cal. Wildcats such as the 22-243. (Cheeta, Clark, etc) Also, many of the .224 wildcats that are built on larger cases are not intended to shoot light weight bullets (like those offered for the 223 WSSM). Instead they are designed to shoot 70-90 gr bullets.

Qs :
So is the 223 WSSM case way over bore for the .224 dia ?

If not, then how is it big enough to keep up with the 243 and 25-06 ?

When was the last time someone told you a 22-243 or 22-06 had good barrel life ?

Why doesn�t the 223 WSSM produce more velocity than the .220 Swift ?

How does a case that is suppose to duplicate the 243 Winchester also have the capacity to duplicate the 25-06 ?

it is marketing dribble designed to attract someone who wants a new gun. numbers game. they have to do it to sell new guns. we just keep fixing there old ones!
woofer

I guess I'm gettin' jaded. I don't have much use for these newfangled Winchester stunted mags. I mean, my .223 Rem is a great 300 yard prairie dog popper. The .243 Win takes me way out past where I can hit 'em. Both have been doing for years and very, very well.

But they don't have the magic "magnum" moniker.

Tim