measurement of 12 gauge {12 bore gun }

[Royal Gun House]

Measuring Up: Gauge vs. Caliber
Shotgun sizes have always been measured in a somewhat roundabout way. You would think that the "12" in a 12-gauge shotgun corresponds to some linear measurement -- maybe inches or centimeters. But that's not the case. "12-gauge" means you can make 12 lead balls, each of equal diameter to the gun barrel, out of 1 pound of lead. This originated in the days when you would buy lead by the pound to make your own ammo. The gauge told you how many rounds you could make for the gun from 1 pound of lead.

The smaller the gauge number, the wider the barrel. The largest shotgun is a 4-gauge. The .410 shotgun, the smallest, is an exception to the rule: It's actually a .410-caliber -- it has a .41-inch barrel diameter.

In general, the smaller the barrel diameter, the less "kick" or recoil the shooter feels from the gun. Many experts say that a 20-gauge shotgun is a good beginner's gun because it has relatively little recoil but fires more shot per shell than the smaller-diameter .410-caliber.

[Sakobav]

Nice RGH do provide the link or the source where you found this info

best

[brihacharan]

Hi Guys,
> Good info on 12 gauge guns ... some more!
> The barrel lengths range from 22" / 24" / 26" / 28" / 30" & 32" thus giving a wide choice to suit the shooter & the purpose for which the gun is used.
> One barrel is choke & the other a cylinder.
> The choke invariably is the right one & cycinder being the left one.
> Chokes are used for mainly shooting tight groups using cartridge nos. 8 / 6 / 4 - normally nos. 8 & 6 are used for wing shots in bird hunting, while no. 4 can be effectively used for small game animals.
> The cylinder barrel is used for shooting a ball (either totally round or with flutes) The fluted ones have better ballistics and are used for hunting wild boar / nilgai / sambhar & big cats.
> The mechanism comes with ejectors & non ejectors and some with hammers.
> A well made 12 gauge gun that's well balanced is a sight to behold, especially the British, Italian & Spanish makes.
Cheers
Brihacharan

[grewal]

I think this is the partial source http://en.wikipedia.org/wiki/.410_bore

[TwoRivers]

One barrel is normally choked "Full", with the other one having less constriction; being half or quarter choke. You do not find barrels without choke, i.e. cylinder, in a production SxS or O/U. Unless the gun is specifically made to fire slugs. Usually where civilians are not allowed to own rifles for hunting.

The barrel you would fire first, front trigger, right barrel, will have the more open choke. Likewise the bottom barrel of an O/U. With a non-selective single trigger, you'd fire in the same sequence, right/left. Lower/upper with an O/U.
With the now common screw-in chokes, you can, of course, have any combination of chokes you want.

[Royal Gun House]

Dear N_Grewal ji

Link for above information

http://science.howstuffworks.com/shotgun.htm

RGH