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Expert Advice - Chokes
By: George Trulock and Jerrod Trulock For
more information about Mr. Trulock and his choke designs, What
Is A Shotgun Choke? They can be grouped in 3 general types: 1- Fixed chokes- They are made as an integral part of the barrel and cannot be readily changed except by a gunsmith and any alteration is considered permanent. 2- Interchangeable chokes- These can be of the ‘screw on” style which is externally attached or the “screw in” which is recessed into the barrel. To change the degree of constriction you simply remove and replace with a choke of a different diameter. 3-
Adjustable chokes- This style of choke is adjustable
throughout the entire range by turning a sleeve, which collapses or allows a
collet to expand thus changing the exit diameter. A popular choke of this type
is the Polychoke. The internal design of chokes can also be broken down into three main groups: 1- Conical Parallel- They have a cone that blends into a parallel section which helps to stabilize the shot charge as it leaves the choke. 2- Straight Conical- This has a cone only. Where the cone stops is the point where the shot exits the choke. 3-
Wad Retarding-They do not have the constriction in
the same manner as either of the above designs but instead use bumps or
projections to alter the shot pattern. The most common design in use is the conical parallel. All Trulock Chokes are of this design. Shotgun PatternsPatterns are normally expressed as a percentage such as 50%, 60%, 70% ect. This is the commonly accepted method comparing pattern density. In a 50% pattern ½ of all the pellets contained in the shell will strike inside of a circle of 30 inches in diameter. To find the percentage of any given load divide the number of hits inside the circle by the total number of pellets contained in the shell. You can obtain the approximate number of pellets any given load will have from a shotgun shell reloading book or you can open a couple of shells and actually count the pellets. All pattern testing is done at a distance of 40 yards with the exception of cylinder and skeet 1 chokes in all gauges and all chokes for the .410 bore which are normally measured at 25 yards. The purpose for this is to allow you to select a choke that will throw a pattern that is as large as possible without having the pellets so far apart that the target can escape multiple hits. For shooting both game and clay targets you want a pattern that is perfectly even in pellet distribution over the 30-inch circle. Having said that, and after looking at thousands of patterns over a span of 25 years I could count on my fingers the number that I would call perfect and if these were measured close enough they would not have qualified. In this instance “very close” is good enough. Two exceptions to the preceding would be buckshot and turkey patterns. With both of these you are looking for a tight center cluster of pellets. One thing to remember –The only thing that is consistent about shotguns is that very few things are consistent. Identical guns with the same degree of choke and using the same shell may not pattern the same. The same load between various brands of shells can pattern differently. Patterns will change when changing from hard to soft shot. Patterns can change when anything in the shell changes such as different wads, powders or primers. What I am trying to get across is that when you change anything such as brands, shot size, or components you will need to check the pattern as it could have changed, sometimes by an extreme amount. Once you find a choke/shell combination that gives you the pattern you want it should remain reasonably consistent as long as nothing is changed. I am satisfied as long as the percentage stays within a 5% plus or minus deviation. The
chart shows the relationship between the degree of choke, the percentage and
constriction based on lead shot. Keep in mind that the percentages are a guide
only. What you actually want is a pattern that is dense enough to insure
multiple hits on your target at the distance you normally shoot.
Keep
in mind that this chart should be used as a starting point only. Select the
choke and pattern it. Change chokes or loads as needed to get the pattern you
want. If you do not pattern your gun please
feel free to accept this chart as being infallible. How
To Pattern
I like to use paper that measures 4 feet square. Paper this size may be hard to find locally. If it is not available try taping several sheets of butcher paper together. The reason for the large paper is that if your gun does not shoot to the point of aim part of your pattern could be off of the target with a small paper and you could confuse this with a bad pattern. If it helps you, mark the target center for use as an aiming point. I prefer to use a rest when shooting. If you do make sure the gun is not touching any hard object. The reason for using a rest is that it helps remove some of the variables. From the correct distance shoot at the center of the target. I would do this a minimum of 5 times on different targets with each shell or choke that is being tested. You will need to draw a 30-inch circle around the most dense portion of the pattern on each target. Count the pellets inside of the circle. Divide this number by the total number of shot contained in the shell and you will have your percentage. Average your percentage by the total number of shots fired with the particular shell or choke to obtain your overall average. Sounds like a royal pain doesn’t it? It is, but there are no short cuts if you really want to know what your shotgun is doing. After you have finished look carefully at each pattern for holes that are big enough to let your intended target slip through. You want a dense enough pattern to ensure multiple hits. Steel Shot/Waterfowl Chokes Much has changed over the years with steel loadings. The quality and consistency of the shells has been greatly improved. However, the fact that steel shot exerts much more stress on choke tubes has not changed. The problem is that steel shot is much harder than lead. It will transmit much more energy to the choke when it strikes the conical portion and if the tube is not of sufficient strength it will cause it to deform. This is known as “choke creep” Over a period of time choke creep can lock a choke in the barrel so that it is next to impossible to remove. All Trulock Chokes are rated for use with steel shot from cylinder bore through improved modified with the exception of the Tru-Choke S.D. which are not recommended for any shot other than lead. In addition our Super Waterfowl Choke was designed especially for steel and all other environmentally friendly shot. It is strongly suggested that you use our Extended Precision Hunter style choke for steel shot as they normally give a superior pattern over the flush style chokes. Close Range –approximately out to 30 yards - Skt 1= pattern percentage of about 55% Medium range- approximately out to 35 yards-Skt 2 [light mod] =pattern percentage of 65% Long Range-35yards and further- Improved Modified =pattern percentage of 75% Extreme Range= Super Waterfowl series These suggestions should be used as a starting point and should not be taken as a substitute for patterning your shotgun. Alternative Alloy Shot- These are recommendations for Trulock Chokes only Tungsten
Iron- Treat this shot the same as steel Turkey Chokes We make a wide assortment of chokes that fall under this heading. No one choke works well in all guns with all loads but one thing has to be consistent, the shot shell. You will have to shoot premium factory loads or assemble your hand loads with the best components available in order to get good dense patterns at long range. While this basically holds true for all shotgunning it is especially so when hunting turkeys. You have a very small kill zone even when the bird is up close and it is imperative that you know exactly what your shotgun and shell is capable of doing. In testing different shells we have found that as a rule, two combinations work very well, factory loaded Hevi-Shot and factory loaded shells with buffered high antimony plated shot. These two loads normally work better than anything else, but patterning is needed to see which load your gun likes the best. To get a dense pattern with a tight center you will need the Precision Hunter style choke. Our three most popular chokes have exit diameters of .670, .665 and .660. Although some shotguns like a .680 generally one of the above ends up working better. We also make a.650 and .640 but these are better suited to card shooting and not live bird hunting as they like smaller shot #8 better. The smallest exit diameter does not always give the most dense pattern. We find that the smaller the exit diameter the more erratic the patterns. Normally one particular load will pattern considerably better than the rest. Let me repeat that you will be wasting your time to shoot a cheaply made or promotional type shell. We have patterned Hevi-Shot and have really good results with their #6 shot in the .670 turkey. In fact we had several patterns going 60% at 70 yards with #2 shot. Suggested
turkey chokes and shot size .670
#4 lead and #6 Hevi-Shot Choke
Cleaning
Ideally chokes should be cleaned each time the gun is used. Plastic fouling and powder residue will build up in screw in chokes much faster than in fixed choke guns. Powder fouling will also work between the choke and the choke counter bore in the barrel. Remove the choke and clean with a toothbrush using some sort of solvent. We use and suggest Choke Shine as a cleaner. Simply, drop the choke into the solution for a short time and it will come out with the fouling dissolved. Clean the inside of the barrel with a cleaner/lubricant such as Clenzoil (1-800-OIL-IT-UP) making sure the threads do not have any residue, lightly wipe the choke with oil and reassemble. Remember that rust can occur in the barrel and freeze a choke in place even if the choke is made from stainless steel. Waterfowl hunters should pay particular attention to keeping the choke and barrel clean. Choke
Tightness
Although this seems like a no brainer we believe that there is a proper way to install a choke tube. When changing a choke in the field or at the range, wipe the choke with a clean rag to keep grit, dirt, ect. from being ground into the threaded area of the choke/barrel. Finger tighten and then use a wrench that properly fits the tube to finish tightening using a moderate amount of pressure. This will help keep the choke from loosening up when in use. The wad can hang on the rear edge of a choke that is loose and cause damage to both choke and barrel. Most chokes will loosen up if they are left finger tight. A perfectly clean, dry choke installed in a clean, dry barrel and moderately tightened with a wrench should not work loose. Most shooters are better off to make sure that there is a light coating of oil on the choke before installing as this will help prevent rust in the barrel. All choke should be checked occasionally for tightness. We have tried to give you a very basic course on chokes and their use. If we can be of any service to you please call us. We will be glad to help with any questions or problems you may have. 1-800-293-9402 George
Trulock |
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