I am in a position of buying a new semi-auto gas operated gun. [Probably an Extrema 2]. I will use this gun for rough shooting, I would like to know what are the advantages and disadvantages of a long barrel compared to a short barrel. Another thing is, this gun is a 3.5 inch chamber, if I use a 3 inch or shorter shell, does it effect the shot pattern?
The Beretta Xtrema 2 comes only in 26″ and 28″ shotshell barrels, so that’s what your choices will be. Other autos usually come with 26″, 28″ and 30″ barrels.
A long barrel has only the very smallest ballistic effect with modern shotshells. In the old days of black powder, longer barrels allowed the powder to burn more completely and produced higher velocity. Modern powders burn much more quickly and barrel length has minimal effect on velocity. Choke has more effect on velocity than barrel length does. Did you know that a 12 gauge using Full choke will have about 50 feet per second more velocity than the same gun/shell using a Cylinder Bore choke? I was surprised when I found that through testing.
Barrel length does have some slight effect on pointing the gun. When the gun is fully raised to the face, it is impossible to discern differences in barrel length because you are looking right down the rib. But when the shooter is in the act of raising the gun to the face, he will be aware of barrel length. In that situation, longer barrels require less visual (but the same actual) lead. This is not a good or a bad thing. It is just something to get used to.
The biggest difference between long and short barrels is balance. That is what I would concentrate on. If you can try both the 26″ and the 28″ barrels and compare them, pick the one that balances best for your taste. The longer, heavier barrel will be slower swinging, but more steady. The shorter barrel will move faster and correct more quickly, but will be a little less stable. The Xtrema is quite a heavy gun as it is, so you might not need any more weight. That is really personal taste.
When considering barrel length, remember also that the receiver of the Xtrema is quite long. It is about 3-1/2″ longer than the receiver on an Over/Under. Thus an Xtrema with a 26″ barrel would have the same sighting plane length as a 29.5″ O/U.
Using a short shell in a long chamber will not affect the pattern. The Xtrema 1 that I tested shot 32 gram 2-3/4″ shells very reliably.
Shotgun Report’s Technoid