doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com effect of barrel length on pattern

Can anyone point me to a good study or at least firm, real data on the effect of barrel length on pattern density? I'm sure that it's been done but trying search for it only yields advertisements and junk.

I think that bbl length won't effect pattern density as much as payload, shot size, distance shot at, chokes and the loads themselves. It seems that 24" is the cut off for any effect on velocity, but of course your asking for density.

I don't don't know of any study, sorry.

Good Luck!

Greg

actually I misspoke. I meant both density and velocity really.

Well, of course if you have your feet planted in the same spot a 32" bbl will get you a half foot closer to your target than a 26" bbl will. Velocity does not actually level out in a shotgun at 4", but each added inch of bbl has less & less gain as you get much beyond that. Only guns with very light powder charges such as the .22 rim fires will reach a point where the velocity gain will cease & actually begin dropping as bbl length increases. With the .22LR max occurs at about 19" of length. It will stay fairly constant for a few more inches & then begin to fall off.
In a shotgun there is of course much less difference in the velocity of a 32" versus a 30" than between a 22" versus a 20", but a difference does still exist & will for virtually any bbl length one is likely to contemplate.
It would take a large amount of well carried out pattern testing to prove a reliable statistic of pattern density between bbls of differing length but choked the same. I will note though that while not an absolute given, much of the "Lore" surrounding long versus short bbl stemmed around the fact that short bbls were traditionally more open choked than were long ones, their basic intent of use being different.

If there is a difference it will be insignificant compared to variations in shot hardness, and other variables of the load's construction.

www.shotguninsight.com the site of Dr Andrew Jones, he has done a lot of research on just the type of question you are asking. He also references older auhtorities like Ed Lowry, Brister, Burrard and Journee.

As to the question itself, length beyond a certain point when the powder has developed all its oomph, no, it does not affect pattern say the authorities.

Per Dr. Jones, the difference is none, zero zip, nada, no siree!!

Have a look at the Dr. Jones's book "Performance of Sporting Shotguns". He has done statistical analysis on some 2500 patterns to answer many kinds of questions.

DDA

Gough Thomas, writing 50 years ago in reference to the 25" Churchill barrels, gives a velocity loss of 30 fps, going from 28" to 25" barrels. But that was based on a study done in the 1920's, when Churchill was defending his short barrels against the naysayers. Thus, the shells in question likely were not of the modern, post-Super X variety with progressive burning powder. I'm guessing the difference with current ammo would be even less than that.

actually, the practical context I'm thinking of it in is the relative performance of the long barreled, late 18th century "Fowlers" versus the much shorter barreled early and mid 19th century "shotgun". It appears that over a fairly short time period barrels went from over 50" to 30" or so.

"Progressive" burning powder is essentially another word for "Slower" burning. This allows a heavier charge of powder to be used to give a higher velocity or push a heavier shot load (or both) without an increase in max breech pressure. This will be compensated for by a slight increase in pressure for the rest of the length of the bbl. Consequently I would expect the loss to be greater for the progressive powder load than for one loaded with "Quick" powder as would have been used in those tests Thomas reported on.
Thus if one is shooting max, magnum type loads they should expect a slightly higher percentage of loss in going to a shorter bbl than when using X-Mart economy loads with light shot charges & fast powders. In neither case is the loss going to be so great as to be of real consequence.