autolaoders versus revolvers -- a real difference

R

RWK

New member
I've noted what I believe is a common error in many "handgun forum" postings, and I'd like our TFL experts to comment on the accuracy of my opinion.

Threads comparing revolvers to autoloaders seem to misunderstand the difference in EFFECTIVE BARREL LENGTH between the two handgun types:
> In semiautomatics, a significant potion of the barrel's length is consumed by the unfired round, inserted in the chamber-end of the barrel when the firearm is loaded/in-battery.
> On the other hand, in revolvers the unfired cartridge remains in the cylinder; therefore the barrel's entire length is available to direct the bullet.

This difference is important because -- using a 9mm parabellum (9 x 19) and a Glock 19 to illustrate -- about 18 percent of the barrel's length is consumed by the round, which effectively means the 4.02 inch barrel is really only about 3.27 inches long -- in terms of the physics that apply.

Accordingly, for example, a .45 ACP round fired from the five-inch barrel of a Smith 625 revolver should achieve significantly more muzzle velocity and energy than the same round fired from the five-inch barrel of a full-sized 1911A1 style semiautomatic.

Have I missed something?

Thanks.


[This message has been edited by RWK (edited June 30, 2000).]
 
Yes, you did miss something...

The effect of the cylinder gap on the velocity of the round. It might not be as significant as losing an inch of barrel space, but I don't know for certain.

------------------
Beware the man with the S&W .357 Mag.
Chances are he knows how to use it.
 
When you measure an semi-automatics barrel length, dont you measure after the chamber? Where the ejection port in the slide ends. You measure revolver barrels in much the same way, from the end of the cylinder to the muzzle.
 
MrBlond,

Nope, semi-auto barrels are measured with the action closed, chamber empty, to the breech face. IOW, drop a pencil down the barrel until it hits the slide, mark it at the barrel, and measure it.

Revolver barrels are measured from the muzzle to the forcing cone. The cylinder depth doesn't come in to play.

Why this is done this way, I have NO idea.

------------------
Beware the man with the S&W .357 Mag.
Chances are he knows how to use it.
 
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