Barrel Length vs *Usable* Barrel Length

[mgood]

Does anyone ever consider that a 24-inch barrel on a 308 Winchester has has over a half inch more rifling than a 24-inch barrel on a 30-06 Springfield? Since barrel length is measured down to the bolt, and the longer cartridge occupies more of that length, you have more "usable" barrel in the shorter cartridge with the same barrel length.

Maybe this is so obvious to everyone that it never gets mentioned?

Since a 7mm WSM is .74" shorter than a 7mm STW, the longer cartridge needs a three-quarter-inch longer barrel to have the same amount of tube out in front of the bullet. Or stated another way, when someone says the 300 WSM compares favorably to the 300 WinMag with the same length barrel, just what is "the same length barrel"?

I'm using SAAMI lengths here. I know not everyone sticks to those, but just using them as a point of reference.

Start talking about shorter actions for shorter cartridges and you can easily have an inch more usable barrel on the same length gun (or a shorter overall length rifle with the same amount of barrel).

I'm not trying to bad-mouth the longer cartridges, whether you love the 7STW or the 416 Rigby or whatever. I'm just thinking out loud.
[Next we'll compare 40 S&W to 408 CheyTac ]

 

[Varminator 911]

Good point. And it's always seemed to me that real barrel length should be measured from case mouth to muzzle. Not bolt face to muzzle.

 

[pondskipper]

That or either to the front of the recoil lug but the front of the case would be even better. Never understood why it wouldn't be measured from the front of the recoil lug myself because for the most part, that's where the actual barrel begins on the exterior of the rifle, and yet on the flip side, you could and probably should measure where the actual rifling begins because that's where the actual difference is made.

 

[pondskipper]

If you look at something like old sharps rifles 45/100 110 120 and even the 140 or even something like a 50bmg saying you have a 30 or 32 or 34 inch barrel isn't saying much for the actual surface area the bullet it's self has to get running and ready to leave the barrel