gunner

Why are barrel lengths for wheel guns measured with just the barrel but an auto includes the chamber?....Ruger states the P345 has a 4.2" barrel but mine came out to 4.05"....big difference

Ale-8(1)

Dunno, but it is apparently the "industry standard" now and for the recent past.

Rifles and shotguns include the chamber, as well.

b.thomas

Not really sure but it would be hard to call the cylinder as part of the barrel, even though it is/does act as the chamber?? Maybe simple as that?

Iowegan

gunner, It's a long story that started with muzzle loaders. Because muzzle loader bores are rifled all the way to the end plug, barrel length was measured from the muzzle to the plug. This tradition remained the same when cartridges were introduced. All rifles, shotguns, and pistols are measured from the muzzle to the breach face. Although this measurement does not accurately account for bullet travel, it has become the industry standard. As an example, let's say you had two 12 ga shotguns with 28" barrels, one chambered for 3 1/2" shells, and another chambered for 2 3/4" shells. The usable bore with the longer shell is 24 1/2" and with the 2 3/4" shell, 25 1/4". Way too confusing so they call both a 28" barrel. The same holds true with rifles and pistols. By the time you subtract the cartridge length from the measured barrel length, the actual bullet travel is quite a bit less.

When revolvers were introduced, they were an exception where barrels were measured from the muzzle to the cylinder face, which is the length of the actual rifled bore. Revolver cylinders have a throat that extends actual bullet travel ... in some cases, quite a bit. As an example: a Ruger Blackhawk revolver chambered for 45 ACP has a cylinder about 2" long and a cartridge that is just under 1" long. That means the bullet travels about an inch more than the measured barrel length .... so a BH with a 5 1/2" barrel will have about 6 1/2" of bullet travel. At a glance, it would appear that a revolver has a significant advantage over the same advertised length pistol barrel but we are not quite finished. It turns out ... if you have a revolver chambered in the same cartridge as a pistol, both with the same advertised barrel length, muzzle velocity will be about the same. Using the above 45 ACP as an example, a 1911 with a 5" barrel only has about 4" of bullet travel. A revolver with a 5" barrel would have 6" of bullet travel. The revolver's barrel-to-cylinder gap (B/C) makes a huge difference because of pressure loss, thus the revolver and pistol will chronograph about the same velocity.

So .... here's the real answer to your question ... revolver barrel lengths are measured to the cylinder face to make the playing field more level when compared to pistols, all due to the B/C gap loss. All other guns are measured from the muzzle to the breach face to maintain a standard for measurement. You can imagine how confusing it would be to gun owners, factories, and especially our friends at BATFE if a simple standard was not maintained.

liberalsmakemepuke

Iowegan,

Every time I see you've posted an answer, even if I have no stake in the thread, I pull up my chair like a little kid at story time. Thanks for that post.

gunner

that sure is a lot of words........thanx I

bigjim

It makes sense when you tell it.

Thanks
Jim

Bagheera

I do love the fancy words Iowegan uses. What's that line in the movie "Blazing Saddles" by Mel Brooks?

Oh Yeah, "You use your tongue prettier than a twenty dollar whore."