Patterning

[Stan Hillis]

I have always been a shotgun "patterner". For decades I went the paper route, but finally built my own grease plate for it, and take pics of the patterns if I want to save them. A big purpose in patterning is to determine if a doublegun is regulated to shoot both barrels to the same point of impact, that being my point of aim. Some do not. All that don't can't be corrected to do so. Some can by the judicious switching of loads. The length of time the payload stays in the barrels is a big determining factor in regulation.

I may have related this story here before but hopefully it's worth repeating. It is a perfect example of the value of patterning with the loads you intend to use in a double. I traded for a 20 Ga. Philly Sterlingworth Ejector to make into my dedicated quail and woodcock gun. It has 28" barrels and was choked tighter than I wanted. I patterned it with 7/8 oz. loads at about 1250 fps and it crossfired terribly, to the tune of 8" laterally with each barrel. That is absolutely not satisfactory to me so I called Dean Harris. We discussed it and he agreed to open the chokes to .006"R and .016"L, lengthen the chambers to 2 3/4", and try to regulate the barrels by his method of honing the inside of the choke area to move the pattern.


He called me some time later with the news that all she wanted was to be fed 1 oz. loads at about 1150 fps. The longer time the payload was in the barrel and the slightly greater recoil with these loads, as compared to the 7/8 oz. loads at 100 fps faster velocity, gave the gun time to move more, laterally, under recoil before the payload exited the barrel. Result was a perfectly regulated gun with one pattern dead atop the other, and both 50/50 on POA.

A shot of my plate after shooting some .410 patterns. I keep a paint roller in a plastic 5 gal. bucket with a few inches of a mixture of white housepaint and motor oil in the bottom of it. After each pattern shot I just roll it, rendering a fresh coat to represent the pattern for the next shot.



Edited for clarity

[Rick Roemer]

Thanks for this info. I want to make a plate. I assume steel - how thick? What is your's made of Randy? What is in the center? Stan, you mention a mix of paint and oil - 50/50 mix? What does the oil do? Sorry for the barrage of questions. I have always just used paper, but it gets old having to change all the time. Do you shoot more than once before you roll it?

Thanks everyone for input.

[Randy Roberts]

Originally Posted by Rick Roemer

Thanks for this info. I want to make a plate. I assume steel - how thick? What is your's made of Randy? What is in the center? Stan, you mention a mix of paint and oil - 50/50 mix? What does the oil do? Sorry for the barrage of questions. I have always just used paper, but it gets old having to change all the time. Do you shoot more than once before you roll it?

Thanks everyone for input.

Rick the owner of a local fabricating shop had a piece of scrap 1/8" metal plate that he was able to cut that out of. It's thin but easy to move around and will handle any shot size that I would ever shoot it with. He welded that doughnut aiming/focus point in the middle of it. Looks like it's a 1/4" piece. I also used paper until now and I agree that it is a PITA.

[Stan Hillis]

No problem, Rick.

My plate is 3/8" steel plate. My mix is not 50/50. I use much less oil than paint, not sure of the ratio. The purpose of the oil is to prevent the paint from drying out so quickly. A pattern can be rolled out days later and it's still wet.

I almost always roll it after each pattern. I may occasionally shoot left and right barrel's patterns atop each other to verify that they are regulated, but usually shoot separate patterns and snap a pic of each. I change the number at the top on the yellow card to keep track of those I want to save for future reference.

My other main use for the plate is shooting duck guns for pattern density measurements. I have numerous tightly choked duck guns and enjoy trying to find the tightest patterning loads for them.

[Pay Dirt]

My name is Bob and I'm a patternaholic (and I hate floating birds)

[ArtS]

Stan

More people should test more loads that differ by ballistics. I think a lot of people generally have a ballistic load they like and if they try varying loads to move the patterns they choose different brands of the same general load. There is no reason to believe the dynamics of a double shotgun are different than a double rifle. When trying to regulate a double rifle, the general method is to vary velocity and bullet weight slowly to do away with crossing point of impact. A load of shot is basically a bullet until it leaves the barrel, and will impart a varying recoil effect on the right vs left barrel depending on the recoil level of the shot. There is an effect also on vertical placement, but it is the same for both barrels and it seems, at least to me, that it is not as pronounced as the horizontal effect. That is due I think to the gun having more resistance to movement vertically due to the nature of how it is held.

[James L. Martin]

Randy my 34" VH has chokes of .030 & .036 with a stock that measures 14 15/16 - 1 9/16 - 1 3/4. Which would normally be too high for me as I see a lot of rib, but like yours it shoots dead on with 50/50 patterns. Mine has no safety

[Stan Hillis]

This is a quandary for me. I would give a "purty" if I could shoot both Randy's and James' guns to see if they shoot flat for me, too. Until now no gun with less than 2 3/8" DAH has ever shot flat for me.

Maybe I need to reread my copy of The Stockfitter's Bible by Rollin Oswald to see if I can figure out what's going on here.

[Randy Roberts]

Originally Posted by Stan Hillis

This is a quandary for me. I would give a "purty" if I could shoot both Randy's and James' guns to see if they shoot flat for me, too. Until now no gun with less than 2 3/8" DAH has ever shot flat for me.

Maybe I need to reread my copy of The Stockfitter's Bible by Rollin Oswald to see if I can figure out what's going on here.

To further add to the quandary Stan I shot a round of skeet and wobble trap last evening and this gun was spot on. One could opine or argue that the critical measurement in terms of drop is the DAC right below your eye or about 2" from the nose of the stock which I have not measured on this gun and compared with others. It may be quite similar thus negating some of the high dimensions in the DAH? Possibly? Of course that does not explain why I can see more of the rib on this one vs other guns and still shoot spot on, back to the quandary I suppose.

[Mike of the Mountain]

Originally Posted by Stan Hillis

Maybe I need to reread my copy of The Stockfitter's Bible by Rollin Oswald to see if I can figure out what's going on here.

That is an excellent book. Can't begin to tell you how many times I've read it cover to cover.