Stan, what's your method for checking regulation at your pattern plate? Thanks
Nothing elaborate or complicated. I just shoot the right barrel on a S x S, or the bottom on an O/U, while aiming at the center spot I built onto the plate, at 15 to 20 yds.. See if it is centered. Take a pic if you need to, and number it. Then shoot the other barrel and do the same. If both are centered, or if both shoot to the same point above or below the spot, it's regulated. I'm not overly concerned with where they are hitting in relation to the spot, at this point, as long as they both hit in the same place. I can move the POI after establishing that the gun is regulated.
Are shotgunjones and I the only two shooters on earth that understand that "there is no converging of a shotgun pattern"? There is no convergence simply because the distance from bore center to rib center is less than a half inch. Someone may claim to know what the difference is in two patterns with centers a half inch apart, but I sure can't see that difference.
Nope, there's at least one more.
Barrels converge on a S x S gun to compensate for the "off axis" recoil effect, if they are set up properly, but not patterns. If they are
not set up with exactly the right amount of convergence you get cross firing, or the opposite.
As an amplification -
Suppose a well-heeled man places an order with (insert favorite custom shotgun maker here).
They ask him which load he wants the gun to be regulated with.
Seriously, they do. If they forget to ask, the customer should tell them. He should fully expect that for his (insert vast sum here) and several year wait that the gun should shoot as specified.
Now, suppose the load chosen was the classic 1 1/16 oz. 1250 fps Eley Grand Prix.
Should our sport now choose to warm up for the season with the ever popular 7/8 oz. hand load that the books all run at 1300 fps he should not be shocked when the gun cross fires a good bit.
When stuffed with a 1 1/4 oz. load running at a lower velocity, say 1125 fps, to 'tame recoil' that gun will spread fire, ie the right barrel will shoot to the right. Guaranteed.
Bore time trumps mass of ejecta. A heavier bullet will cause a pistol to shoot higher.
So, field guns that crossfire with target loads are not necessarily built wrong. Neither are trap guns that throw duck loads off to the side.
While this is entirely true, it does not always work out that way in practice. I have in my possession right now a .410 gun that crossfires. It crossfires the exact same amount with 1/2 oz. loads as with 11/16 oz. magnum loads. Frustrating. Why is this important to know? I did not know it wasn't regulated when I bought it, obviously, and shot doves with it a couple years before building my pattern plate to test the guns. I couldn't understand why I missed more, and crippled more, with it than my other S x S .410. Now I know why, and something will be done about it.
Another thing. Do not assume that O/U guns are more likely to be regulated than S x Ss. They're not. Beretta says if their O/U guns put the individual barrel's pattern within 8" of being on top of each other it is within their tolerances. IMO, 8" is pretty bad, and I will not tolerate it on a gun of mine. Both the Perazzis I've owned were regulated. I've never patterned an A H Fox that wasn't regulated. I'm sure there are exceptions, but I'm forming opinions of certain brands of guns based on my findings.
SRH
