doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pattern and Shotstring question...

Perhaps you guys can help me out on this one....

What is the difference in patterning and shot string between firing 1oz of a particular size shot(let's say 7.5's) from a 12 gauge that throws a consistant 30" pattern at 40 yards, versus a 1oz payload of the same size shot from a 20 gauge that throws a consistant 30" pattern at 40 yards?

I suppose I meant to say the guns throw an even pattern, consistantly as opposed to a consistant pattern.

No gun throws an evenly distributed pattern, say, like the holes on pegboard. All shot patterns are distributed according to the Rayleigh distribution (akin to a normal distribution). The rate at which the distribution blooms and withers is controlled by choke effect. If the two patterns have the same number of pellets within the 30" circle, it is very likely they have the same distribution. If so, then you have to say they have the same pattern performance. On the other hand, shot string is third dimension of the pellet swarm and can't be seen by capturing a typical pattern. It would be only just slightly incorrect to expect exactly identical performance between two equal patterns where one has a longer string. I know of no definitive data comparing 12 bore to 20 bore for loads of identical power (shot weight and MV).

Ok I understand that no shotgun throws the same pattern twice, nor is the perfect pattern ever repeatable. What I'm saying is that there are no major holes in the pattern, nor any major clumping of pellets. AKA even pattern. For the sake of the question, let's assume that all 350 pellets in both the 12 and 20 gauge loads are inside the 30" circle.

Now, because a 1 oz payload in a 20 bore is in a longer shot column as it sits in the shell and in the chamber and as it goes down the barrel, how is the pellet swarm different as opposed to that same 1 oz payload in a 12 bore which is not as tall in the shot column while in the shell and the chamber and the bore? Because of the larger bore size, does a 12 gauge have a shorter (from first pellet to hit the patterning board to last) shot string?

Length of shot string is not totally determined by length of payload in the shell. The longer/taller payload COULD cause a longer shot string, indirectly, by causing more pellets to scrub the bore and be deformed, but length of shot string is determined more than anything else by hardness of the shot used. The harder the shot the shorter the shot string.

So, if the 20 gauge load happened to be loaded with harder shot than the same weight load in the 12 gauge it would be possible for the shot string to be shorter with the taller payload in the 20 than with the shorter payload in the 12.

It is probable that a 1 oz. load of steel in a 20 would have a shorter shot string than a 1 oz. load of lead in a 12, in spite of the taller load in the shell.

There we go. Thanks Stan. That's good info. So am I left to assume that the harder shot has less friction leaving the barrel since it's not deforming, therefore it has better velocity?

It's odd to me that a shot string that is stacked in a more column like position leaving the barrel in a more linear fashion could actually throw a shorter shot string than the 12 gauge load that because of the larger bore is clearing the choke and muzzle quicker than the smaller bore gun. Interesting.

How many angels can you fit on the head of a pin? If both patterns are equal, and you stick around for them to hit you, there is no difference. I think length of shot string is one of the more useless things to worry about. It was a marketing ploy for Gods sake. Short shot strings were thought to be harder hitting, than long shot strings. But from the birds viewpoint it is not when, but if you get hit, that is important. If a fatal pellet hits you from the first or last part of the pellet stream does it matter? No. Dead is dead.

A late pellet from the end of the shot string may still be in the center of the pattern. If it is in the center of the pattern it just thickness the pattern after the fact of a target perspective. If it is on the fringes it is statically a fluke and not something you can rely on. Either way it is a fools argument.

A pattern board only shows you the total result of a shell. Not the order of the shot hitting the board. Use it to check the point of impact. Use it a a rough guide to what should happen with a certain load. It is not set on stone.

You can worry about the effects of bore scrubbing on a long shot column all you want. Fret about wad protection and buffering of shot all you want. I rather worry about how to get shot on target as fast a possible, to impart all the residual energy as possible on the target as you can. Remember speed kills and never more so true than shot on target. The rest os just foddr to argue over a cold beer or single malt.

The hardness of the shot equates to less shot deformation. The deformed shot, whether from bore scrubbing or setback forces, are less aerodynamic and make their way to the rear of the shot string. We may be talking about a difference of 1/8" to 1/4" in payload length, but a possible range of 4 feet to 12 feet length of shot string.

While it is true that this is nothing to worry about in shooting, IMO, there is nothing wrong with discussing it on a forum like this and trying to understand it more. I do not think anyone who is posting or reading posts on here is in the middle of a shooting session, but may VERY WELL BE enjoying a beer or single malt. Shooting like there is no variation in shot string length and also trying to better understand shotgun ballistics are not mutually exclusive. I'm proof of that.

All my best, Stan

Stan:
My personal preference is for a Boodles and tonic, thank you. And I agree that discussion is the lifeblood of such forums as this. But if you or Phideaux seek answers, it has all been disclosed before in "The Mysteries of Shotgun Patterns" by Oberfell and Thompson. In 1957.

Best (Cheers),
Kensal

More important, how much wood could a woodchuck chuck, if a woodchuck could chuck wood?