doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pattern density between gauges

Stan
I am as dumb as it gets when it comes to this math but from exsperience a .410 is very humbling, to me it was because of the lite weight of the gun as well as the load, but you need to order the book Sporting Guns and Gun Powder by Frederick Toms. It was reccomended to me last week by someone on double gun.It is an awesome book full of all this useless info you are talking about.Numerous experiments!

I used to get all excited about patterning until it finally became obvious to me that 2 dimensional patterns have only a loose correlation to what the target experiences as the shot cloud goes by.

Zutz and Oberfell and Thompson all have serious pictures of patterns with obvious holes in them. Zutz holds a clay target over the pattern void to illustrate the concept that a target can slip right through there without so much as a nick.

Well... during the passage of the shot cloud the target moves, unless of course you only shoot at fixed paper sheets.

No moving target ever sees the same pattern as you see on a pattern sheet unless the only motion is directly along the shot flight axis.

Shotgunning is an exercise in probability not unlike gambling.

A few patterns are useful to illustrate the range limitations of the load, and yes it's directly and most importantly related to overall density and not so much to perceived distribution.

Your target is moving through 3D space, it experiences a passing swarm of shot, and the path it takes through the cloud and how many pellets it might collect on the way is at present not measureable.

Burrard also did extensive testing on this using a large steel plate mounted on the side of a "Lorry". After reading through all his detailed descriptions consisting of numerous pages & illustrations the bottom line was basically a 40/40 situation.
The 40/40 term is mine not his but it boiled down to on a bird/taget moving at 90� to the shot line if it does not exceed 40 yds range & is flying no faster than 40 MPH just shoot, DON'T WORRY about the 3-dimensional Shot String. Under these conditions the elongation of the paterns were so slight as to be essentially meaningless. He of course only tested the 12 ga, might not hold true for a .410.
A target moving at any angle other than 90� to the shot line would of course have even less sideways movement across the shot line than the 90� one. For the most part for anyone other than extreme range pass shooters, speaking of shot strings mostly just clouds the issues & causes undue concern. As Nash Buckingham so elogantly put it the main thing is to "HIT" the bird.

Agreed Miller. I've read both Brister and Burrard and their data is similar. As I recall, Brister makes more of a deal of it.

The thing that struck me is that target motion takes your neat little 30" circle and makes it an ellipse from the viewpoint of the target.

A target with a crossing velocity component of 30 MPH equates to 528 inches/second. A six foot shot string at 800 fps passes the target in .0075 second. During that time the target moves 4". Does not sound like much, but that's 13% of the diameter of the commonly used 30" patterning circle.

It sort of makes the guys holding a clay target over a pattern 'void' look silly.

It's a crap shoot how many pellets a target might collect out of the shot swarm, but as you indicate the first order of business is to give your pattern a chance in the first place.

"A few patterns are useful to illustrate the range limitations of the load, and yes it's directly and most importantly related to overall density and not so much to perceived distribution." see above


SGJ, no meaning to jump on you, but there seems to be a point you are not understanding. Densities along any given radius of a pattern gives the distribution. Knowing the distribution allows you to calculate the probability of hits. If you have distribution at a range, it is possible to project forward and backward in range. This is what Stan is looking for. Insights gives us all the capability. We only have to learn the procedure and do the work. I'm not saying it isn't a considerable amount of work, rather that a near miricle of data is possible by doing it - data that was unthinkable a few years ago. Yes, target movenent within the pattern appears to blur the results. But, since this is a game of probability, the "loss" of the target moving out of the effective diameter of the pattern is off-set by it moving deeper into the effective diameter on the other side. It is not an issue to negate the value of patterning with digital analysis and statistical output.

No offense meant in any way, no how, at any time!!

DDA

It is so hard not to make statements like this, because so often we think linearly and do not take all shot angles into consideration. That statement is probably true for crossers. But it absolutely is not true for straight incomers or going away birds! Shooting as much as I do, I see a lot of both of those, lots of incomers on a dove field, and a sporting clays course. Lots of going away quail, sporting targets and again, doves. A two dimensional hole in a pattern can very easily cause a miss on birds like these.

I once saw a Browning 2000 that came from the factory shooting the most perfect donut patterns you ever saw. I mean every time. We patterned it after the owner's hit percentage tanked after buying it. A slight honing of the choke by a gunsmith straightened it out. Don't tell me a hole in a pattern can't cause misses, "I done seen it happen".

SRH

No offense ever taken, Don. I'm not like that.

I think we're trying to say the same thing.

By distribution, I was referring to the 'patchyness' as the term was used by O&T.

This would seem to be the only reason to ever pattern a load or a choke.

The capability to do 3D pattern analysis would be most interesting. Until this is available, I've shot my last pattern plate!

Barrel experts who do pretty extensive patterning when 'competition' choking shotguns, such as Eyster, would undoubtedly disagree with you. I, for one will continue to pattern my guns in 2D until something better comes along, which is unlikely anytime soon, IMHO.

SGJ, thanks, I'm kinda "debdey" by nature and some take offense at me. Glad we can talk openly.

Distribution is a very different meaning/definition to me in this case. I'm using the statistical definition of how a statistic (in this case pellet hits per sq inch or sq inches per pellet hit) varies with pattern radius from center to edge. No pellet will hit exactly center, so, the hits/sq in at center is zero. However, as you move even a little off center, the hits/sq in will go to the maximum and then taper off. Shotgun patterns follow the Rayleigh distribution - remember the more famous Normal distribution frequently refered to as the bell curve? Well, the Rayleigh looks like the bell except that it takes a very sharp dip from max to zero at the center of the pattern circle. Remember "center thickening?" That is slang for the high values of the distribution near the center. The difference between "center thickening" and the "Rayleigh distribution" is that the distribution gives you hits /sq in which can be related to lethalness of the pattern. Matter of fact, you get a very good picture of the diameter of the effective part of your pattern as opposed to the overall diameter of the pattern. "Central thickening" simply tells you there is more shot per sq. in. toward the middle of the pattern than toward the edge. Remember I said the pattern can be predicted for greater and lesser ranges? Well, that is the beauty of this method.

Off topic for a moment, folks, but I'm sure you'll understand. Rocketman, I sent you some hard-copy mail and had my letter returned. If you still have my email address, I'd greatly like to hear from you and re-establish contact....