Went to the pattern board today. Im right handed, I had a sx3 20ga 26 in barrel with 14 in LOP an a CZ 20ga auto with a 14 1/2 LOP 28 in barrel, shot two differnt loads 1oz winchester an 7/8 Federal both in 7.5 shot both with mod. choke, and like the came out of the box.. Shooting a 5×6 peice of cardboard with a painted spot a 30 yards. Four times I aimed two times I threw up the gun and shot. Every time with both guns I had the same results. My pattern was high and too the left. I hit the spota few pellets, but all patterns were high and left. What do I need too do too center my patterns ?
A shotgun stock works like the rear sight on a rifle. If you want to lower your point of impact, you lower the stock. If you want to move the pattern from the left towards the right, you must increase the cast. Increasing cast is basically moving the stock from the left to the right. It is usually done by bending the stock to the right or by removing wood from the left side of the stock. Basically, you move the stock in the direction you want to move the pattern.
How much to move the stock? The old rule is that if you move the stock 1/16″ it will move the pattern 1″ at 16 yards. For example, if your target is placed 16 yards away, if the center of your shot pattern is three inches high and two inches to the left, you would need to lower the comb of the stock 3/16″ and move the stock to the right 2/16″.
I’d start with the auto. I am not familiar with the CZ autos, but many of today’s autos have stock shims which go between the head of the stock and the rear of the receiver which allow adjustment for height and cast. Even when an auto or pump doesn’t come with such shims, it is often possible to make shims which will do the work. I used pieces of shotgun hull to shim adjust the stocks on my early Beretta autos before they started to include shims with the guns. A local gunsmith should be able to help you with this is you don’t want to tackle it your self.
As to the stock on your SxS, since it is too high and needs more cast, technically that could be accomplished by reducing the height and width of the stock by judicious sanding and then refinishing. Or by bending if you can find a gunsmith capable of that in your area.
And remember the old carpenter’s adage: measure twice, cut once. If you are doing the wood removal yourself, sand a little and then test the point of impact. Then sand a little some more. Then test. Don’t try to do it all at once. Trust me on that one.
Shotgun Report’s Technoid