Chokes and Pellet Counts
What is often lost in comparing chokes and gauges is that the definition of pattern efficiency does not change just because you change shells, payload, or gauge. A “Full” choke should put about 65-75% of your payload into a 30 inch circle at 40 yards. It doesn't matter if you are using a 28 gauge or a 10 gauge; it doesn't matter if you are using a 3/4 ounce payload or a 1-7/8 ounce payload. It doesn't matter if you are using #9 shot or BB's; regardless, a 65-75% pattern percentage is roughly Full choke performance.
This is why making any all-encompassing recommendation for choke isn't possible. The question quickly changes into “65% of what?” Percentages, of course, don't drop doves or smash targets, pellets do. Suggesting that someone should use a modified choke doesn't make any sense, unless you also consider the shooting range, target size, payload, pellet size and so forth.
Recently, I have been dove hunting. The most appropriate choke, under our conditions, is Full. This may not be the case for others and probably isn't. The kill zone of a dove is very small, as is the bird itself. More often than not, I'm using one ounce of #7-1/2 shot out of a 20 gauge gun. Yesterday, it was Winchester AA one ounce shells, 1165 fps catalog muzzle velocity, a Browning B-80 20 gauge gun and a Full Trulock Precision Hunter choke.
Pellets in the vitals bags birds, not percentages, so consider what a Full choke actually means. American #7-1/2 shot is nominally .095 in. in diameter, with about 338 pellets to the ounce. (Most everything in shotguns is “approximately” or “about.”)
Full choke (65%) pellet counts in a 30 inch circle at 40 yards with #7-1/2 shot
· 3/4 oz. (219.7 pellets): about 143 pellets
· 7/8 oz. (295.75 pellets): about 192 pellets
· 1 oz. (338 pellets): about 220 pellets
· 1-1/8 oz. (380.25 pellets): about 247 pellets
· 1-1/4 oz. (422.5 pellets): about 275 pellets
Modified choke performance with a 1-1/8 ounce payload is 55-60%, or about 228 pellets at 60%. The notion of suggesting a choke, to be helpful, must include pellet count. An Improved Cylinder pattern with a 1-1/8 ounce payload (190 pellets) puts about as many pellets into a 30 inch circle at 40 yards as a Full choke 7/8 ounce payload.
That means that, with the same size pellets, a 3/4 ounce 28 gauge shooter using a Full choke and a 1-1/8 ounce 12 gauge shooter using an Improved Cylinder choke are doing very close to the same thing, in terms of pellet count in a 30 inch circle at 40 yards. A one ounce load out of a 16 or 20 gauge that produces Full choke performance is no different than a one ounce load out of a 12 gauge that produces Full choke performance.
With one ounce, #7-1/2, 20 gauge loads I'm throwing 65-70% patterns at 40 yards. This puts 143-154 pellets into a 30 inch circle. It is virtually indistinguishable from any other 65-70%, one ounce load. Sure, a heavier 1-1/8 ounce load that throws 65-70% means more pellets, 160-172, in that 30 inch circle. An extra 14-18 pellets in a 30 inch circle (surface area 706.85 square inches) doesn't mean much compared to the tiny kill zone of a dove. It is well centered patterns that bag birds.
Copyright 2012 by Randy Wakeman. All rights reserved.