
Introduction SHOTGUN CHOKES is the first subject
we would like to introduce, a topic few people understand , and we
trust this explanation will deal with this problem. Shotgun patterns
dictate the CHOKING of any particular shotgun, REGARDLESS OF WHAT
IS STAMPED ON THE BARREL OR CHOKE. Choking is the constriction
in any barrel, which on average, dictates the pattern percentage,
although this will also change when using a variety of ammunition
(lead shot, nickel plated shot etc). Pattern percentages should be
taken at a distance of 40 yards, at a piece of paper with a 30"
circle. The amount of strikes within the 30" circle, compared to the
number of pellets contained in an identical unfired shotshell, will
result in a percentage. For example, if one were to use a
12GA 28gram No 7 ½ shotshell, which contains 400 pellets, fired at
the 30" circle resulting in 200 strikes within the 30"
circle, the result is 50% , and therefore the choking of the
barrel would be Improved Cylinder (British Standard). If one
were to use the same load 28 grams, but using Nickel Plated
shot , will usually result in a tighter pattern , as nickel is
harder, and less likely to deform on the way down the barrel. The
result would probably be 55% , and therefore the choking would be ¼
choke (British Standard) The best patterns, are the ones without
any excessive holes through which your target could escape, and
therefore even patterns, are the most efficient for breaking
targets, or killing birds in flight.
|
| British Standard | Constriction | Pattern % @ 40 yards | |
| Cylinder Improved Cylinder ¼ Choke ½ Choke ¾ Choke Full Choke |
.000 inch .005 inch .010 inch .020 inch .030 inch .040 inch |
40% 50% 55% 60% 65% 70% | |
| American Standard | |||
| Cylinder Skeet Improved Cylinder Modified Improved Modified Full Choke |
.000 inch .005 inch .010 inch .020 inch .030 inch .040 inch |
40% 53% 57% 67% 73% 75% | |
| Italian Standard ( Beretta ) | |||
| Cylinder Skeet Improved Cylinder Modified Improved Modified Full Choke |
.000 inch .002 inch .005 to .010 inch .020 inch .030 inch .036-.039 inch |
40% - 50-57% 60% 65% 70-80% | |
| European / Continental Standard ( Browning ) | |||
| CL ( Cylinder
) **** Improved Cylinder *** ½ Choke ** ¾ Choke * Full Choke |
.00 mm .25 mm .50 mm .75 mm 1.0 mm |
40% 50% 60% 65% 70% | |
| Briley Choke Tube Specifications | |||
| Cylinder Skeet Improved Cylinder Light Modified Modified Improved Modified Light Full Choke Full Choke Extra Full Choke |
.000 inch .005 inch .010 inch .015 inch .020 inch .025 inch .030 inch .035 inch .040 inch |
||
| Winchester | |||
| Cylinder Skeet # 1 Improved Cylinder Skeet # 2 Modified Improved Modified Full Choke |
.000 inch - .005 inch .007 inch .012 inch .022 inch .036 inch |
25-35% 33% 45% 50% 45-55% 55-65% 65-75% | |
| Shot Size Details | ||||
| Designation | Dia/mm | Dia/inch | Shot Count per ounce (28grams) | |
| LG SG Special SSG AAA BB NO 1 NO 3 NO 4 NO 5 NO 6 NO 7 NO 7 ½ NO 8 NO 9 |
9.1 8.4 7.6 6.8 5.2 4.1 3.6 3.3 3.1 2.8 2.6 2.4 2.3 2.2 2.0 |
.36 .33 .30 .27 .20 .16 .14 .13 .12 .11 .10 .095 .09 .085 .08 |
6 8 11 15 35 70 100 140 170 220 270 340 400 450 580 | |
| Shot Size Equivalents | |||||||
| English | Metric | American | French | Belgian | Italian | Spanish | |
|
LG |
9.1mm 8.4mm 7.6mm 6.8mm 5.2mm 4.1mm 3.6mm 3.3mm 3.1mm 2.8mm 2.6mm 2.4mm 2.3mm 2.2mm 2.0mm |
- 00 Buck 1 Buck 3 Buck 4 Buck Air Rifle 2 4 5 6 - 7 8 - 9 |
- - C2 C3 5/0 1 3 4 5 6 - 7 7 8 9 |
- 9G 12G - - 00 - - - 5 6 7 7 ½ 8 9 |
- 11/0 9/0 - - 00 1 or 2 3 4 5 6 7 ½ 8 - 9 ½ |
- - - - - 1 3 4 5 6 - 7 7 ½ 8 9 | |
| Number of Pellets per Shot Load | ||||||||
| Weight grams | Weight Oz | #3 | #4 | #5 | #6 | #7 | #8 | |
| 46 42.5 36 34 32 30 28.5 26.5 25 23 17.5 16 12.5 9 |
1 5/8 1 ½ 1 ¼ 1 3/16 1 1/8 1 1/16 1 15/16 7/8 13/16 5/8 9/16 7/16 5/16 |
228 210 175 166 157 149 140 131 122 113 87 78 61 44 |
276 255 213 202 191 181 170 159 149 138 106 96 75 53 |
358 330 275 261 248 234 220 206 193 179 138 124 97 69 |
439 405 338 321 304 287 270 253 236 219 169 152 118 84 |
552 510 425 404 383 361 340 319 298 276 212 191 149 106 |
732 675 562 534 506 478 450 422 394 366 282 254 187 141 | |
| Percentage of Total Pellets in 75cm Circle | |||||||||
| Boring of Gun Or Choke |
Range in Metres | ||||||||
| 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | ||
| True Cylinder Improved Cylinder ¼ Choke ½ Choke ¾ Choke Full Choke |
75 85 90 97 100 100 |
63 74 80 86 93 100 |
53 64 70 76 83 90 |
43 53 58 64 70 74 |
35 43 48 54 58 62 |
28 34 39 43 47 51 |
22 27 31 34 38 41 |
18 22 25 27 30 32 | |
| Choice of Shot Size for South African Gamebirds and Clay Targets | ||||
| Quarry /Target | Shot Size | Quarry/Target | Shot Size | |
| Guinea Fowl Quail Egyptian Geese Teal Yellow Bill Duck Bush Doves Skeet ISSF Skeet English Olympic Trap |
4 or 5 8 or 9 1 or 3 5 or 6 5 or 6 8 or 9 8 or 9 8 or 9 7 ½ |
Francolin Partridge Spurwing Geese White Face Duck Rabbit / Hare Rock Pigeons Skeet USA Trap DTL Sporting FITASC |
5 or 6 5 or 6 BB or 1 5 or 6 3 or 4 7 or 7 ½ 8 or 9 7 or 7 ½ 7 , 7 ½ , 8 and 9's | |