A Visit with Scott Carlson: "Mr. Choke Tube"
Nestled in the "Pride of the Prairie" is Carlson's Choke Tubes. Scott Carlson, fearless proprietor of choketube.com, has graciously consented to talk a bit with us about shotgun chokes, and the story behind Carlson's Choke Tubes. Carlson's not only has an ever-expanding line of top-notch choke tubes, but also a 2-day turn around on fixed-choke to screw-choke barrel conversion machining. This is currently offered for Invector (WinChoke), Tru-Choke, and RemChoke tubes that I've used over the years, invariably with excellent results. Carlson's does custom choke work as well.
RW: First of all, Scott, thank you for taking time out to discuss what most of us seem to take for granted today: easily removable, interchangeable shotgun screw chokes that gives any shotgun more versatility than "back in the day." It may be just a matter of trivia to some, but a factory screw-choked shotgun first appeared on the Olin-Kodensha produced "Winchester 101" and by now is expected, standard equipment on most popular shotguns. Scott, how did you first enter the business, and when?
SC: We started installing choke tubes into shotgun barrels in the early 80's and manufacturing the choke tubes in 1988. Our main purpose for manufacturing the choke tubes was to get better patterns from flush and extended chokes over what the factories were offering in their choke tube lines. We have accomplished this through our patterning tests.
RW: I guess all of us would like to believe that all firearms are clones of each other, and that if a shotgun is a specific make and model; they "all perform exactly the same." It is easier than accepting that all shotguns, just like rifles, are unique individuals unto themselves and none of them throw identical patterns. Even though we have a published "standard" of .725" for European 12 gauge bores, and .729" for "American" 12 gauge bores, measuring the bore of some shotguns shows that this is not the case at all. I've owned .718" inside diameter 12 gauge guns, for example. Have you seen the same thing?
SC: We see pretty much the same thing. Seldom do two shotguns pattern the same. I cannot stress the importance of patterning your shotgun with the choke and shotshell load you are going to use at the range or in the field. If you plan a deer hunt most generally you mount your scope on your rifle and go sight it in. Well, you ought to be doing the same thing with your shotgun!
RW: Though what we call "choke" is performance based, not constriction based, there is some relationship between constriction and pattern density. If our bore measures .718, and we have a so-called improved cylinder choke tube that has a minimum inside diameter of .715", it looks like we can quickly be off on the wrong track, as there is only a .003" actual constriction present. We might think we are vaguely in the area for early season pheasants over dogs, but the more likely scenario is that we are better equipped for the skeet field. Scott, have you seen this?
SC: Yes, we have seen the same thing. Again, pattern your shotgun before going to the field. You can speed the patterning process up by having your bore measured then you can figure out the constriction each of your choke tubes has and you will know if you have a true skeet (.005 constriction) or Improved Cylinder (.010 constriction), etc.
RW: Though a knowledge of our own shotguns' measured bores, and an understanding of what constrictions we are working with helps as a starting point, I think we really have to pattern of we want to know what density of pattern we have at a certain range with a specific shotshell in our specific guns. Let me make a few general observations, and let me know if your experiences are similar. As a vague generalization, high-antimony ("magnum") shot gives higher pattern percentages than soft chilled shot, nickel plated magnum shot patterns better still, and larger shot sizes (#4 vs. #8) seem to pattern more tightly with the same constriction. Scott, how are we doing so far?
SC: Generally, this is what we see when we pattern shotguns. Also for hunting situation Hevi-Shot, Nickel, and Copper shot penetrate game much better than lead and they don't carry feathers into your bird and slow shot performance.
RW: Also, as a trend of sorts, I've noticed that the ability to handle larger shot sizes changes with gauge, as noted by Bob Brister (Shotgunning The Art and the Science) and other sources. Most 20 gauges seem to handle up to #5 lead shot well, but do not well with #4. Some 20 gauges don't care for #5's either, but that is a bit rare. 16 gauge guns handle up to # 5's without fail, and most also do well with #4 shot. Virtually all 12 gauge guns I've tried pattern well with #4, #2, and even larger shot. Is this a fair trend, in your view?
SC: Yes, we have seen the same trend. But again, each gun is different and because of the great variety of chokes offered you can generally get an acceptable pattern with a given shot if you pattern your gun.
RW: There is a velocity relationship as well. What my patterning tells me is that, again as a general trend, lower velocity loads tend to give denser, more even patterns. If I had to pick a number, somewhere around 1300 fps or so appears to be about it for un-buffered lead shot, with 1500 fps rocket loads likely to be far more erratic. What have you seen in this area?
SC: Somewhat more erratic, but we have but we also have had some great patterns with the faster loads. Again, spend the time patterning with a variety of chokes.
RW: The "more is more" approach does not seem to always work with lead shotshells. 20 gauge generally does well to 1 oz., 16 gauge to 1-1/8 oz, and 12 gauge to 1-1/4 oz. almost without fail. Beyond that, though, it appears to me to be far from a "given," and the more we go overbore capacity departing from the "squared" shot column, the greater the likelihood of problematic patterns. Certainly, we can go a lot father with nickel-plated shot, nickel-plated buffered loads, and a quality choke tube on the end. Does that correlate with your testing?
SC: Yes, generally with heavier loads you're going to get more flyers, but you also have a lot more shot to get the job done, and you are going to end up with much better patterns than with the lighter loads.
RW: I was taught that for a given constriction of choke, there is an optimum minimum parallel section of a choke required to stabilize the shot mass. A Belgium A-5 fixed full choke barrel (*) has a comparatively long parallel section, to cite one example I'm familiar with. The problem with factory flush mount chokes is that we are designed into a box. Whether skeet chokes or extra full, we only have a finite space to work with that cannot be ideal for all degrees of choke. What do you think?
SC: Each choke from Cylinder through Extra Full has a different choke or parallel section in it. Generally longer parallel sections throw tighter, denser patterns, and this is why the extended choke tubes can be so beneficial in patterns, especially with shorter choke tubes such as Win-chokes.
RW: I see potential advantages in extended choke tubes in three areas. We can either accommodate heavier payloads, tighter constrictions, larger shot sizes, or perhaps a combination of all three; yet still produce very consistent, effective patterns. Have I missed something?
SC: No, you haven't missed a thing. We started making choke tubes to get the better patterns you are talking about and most of these come from extended chokes, depending on the shotgun or choke type. In most cases factory chokes will not give you the performance that after market choke tubes will. Factories tend to use cheaper steel (watch shooting steel or Hevi-Shot in these) and they don't pay close attention to tolerances since they have their choke tubes made elsewhere.
RW: In closing, the best advice I can give to most of the questions we have covered is pattern your shotgun with the choke and shotshell load you are planning on using.
With that, I'd like to thank Scott Carlson and the team at Carlson's for the visit, and you can look forward to reading some "before and after" patterning results with a few of their latest tubes. With all the new loads and shot types coming out, I have a feeling that the folk's at Carlson's won't have a rough time finding things to do for a long, long time.
Copyright 2006 by Randy Wakeman. All rights reserved.