Shot Talk

For the serious shotgunner, it seems to me imperative that a certain modicum of precise measuring instruments must be acquired. These tools allow the shooter to know—rather than guess—the internal dimensions of the various zones of a shotgun barrel. They allow him to know—rather than guess—the actual weight of powder and shot charges in shotshell ammunition, whether reloaded or factory. If you’re a serious shooter, they allow you to know—rather than guess—the actual trigger pull of one gun versus another.

It never ceases to amaze me that many shotgunners have no tools beyond a simple ruler or yardstick with which to measure their pet smoothbores or shotshell ammunition. They have no way to measure the dimensions of their chambers or integral chokes or screw-in choke tubes, including those that may have come with their guns, or aftermarket tubes for which they’re ready to lay out several hundred dollars. They really don’t know the dimensions of their stocks. In addition most shotgunners, whether reloaders or not, don’t even own powder scales. The reality is that most shooters go through life guessing and hoping about what their equipment really is or does and what’s really in those shotshells they’re assembling or buying. They never really know; they just operate on faith.

Read on if you’d like to replace hope with confidence. Read on if you’d like to save yourself the expenses of needless barrelwork or products that, after being measured, turn out to be far from what’s represented.

Bore Master

Serious shotgunners need to be able to measure the guts of their barrels. It is time-consuming and unreliable to have gunsmiths, machinists or choke-tube vendors measure your chambers, bores and chokes for you. Why? Because they all use different tools to do their measuring, and there is the “human factor” in operating all of the gauges that yield measurements. A “heavy thumb” gets a slightly higher reading than a “light thumb.” If you do the measuring, the variability remains constant with every gauge, thus you end up with much more accurate relative measures. This said, you need some kind of accurate bore gauge.

The Robert Louis Co., in Newtown, Connecticut, markets a handy item called the Bore Master. This compact device is capable of accurately measuring bore and choke dimensions, chamber lengths, chamber and forcing cone dimensions plus barrel-wall thicknesses. What’s more, the Bore Master can do this for .410 bore through 4 gauge in both metric and English units.

Consisting of two calibrated legs, the Bore Master can be inserted six inches into the muzzle or chamber end of any shotgun barrel. Thus the dimensions of any choke can be fully and completely measured as can the chamber and forcing- cone area and the bore a few inches beyond both. Because shotgunners seem to be an aging population where close-vision focus is becoming more problematic, the Bore Master provides an LED digital readout. And the unit comes with clear and easy-to-understand print directions plus an instructional DVD, all for $290.

It’s true that the Bore Master cannot measure the entire length of the bore. For that you’ll need a full-length bore gauge set up on the three-expanding-balls system. (This system uses three spring-loaded balls set 120° apart around the circumference of one end of the measuring rod. The balls compress against the inside of whatever tubular structure is being measured; the degree to which they compress is the internal diameter, which is displayed on the dial indicator at the other end of the rod.) These devices are available for .410 bore through 10 gauge, and I have a full set. But being some 21/2 feet long, they are delicate and easy to accidentally bend—and once bent they no longer work. They are also a bear to store. Full-length gauges can run $200 for each gauge, with a savings of about $100 for a full set. And you’ll be required to squint at a tiny calibrated dial to get a reading.

To my way of thinking, the Bore Master is by far the more economical and practical alternative to measuring internal shotgun-barrel dimensions. Although it won’t measure 100 percent of a barrel’s interior, it will measure 100 percent of both ends of a barrel—the areas of interest to the vast majority of shotgunners. In other words, with the Bore Master you easily can answer all of your choke-dimension and chamber/ forcing-cone-dimension questions. I highly recommend it.

Dial Calipers

You’ve just bought or shot a couple of boxes of a foreign-manufactured lead load said to contain size No. 8 shot. Given the notoriously wide tolerances that shotshell manufacturers allow themselves, and given the fact that foreign shot sizes are designated by a different system than that used in the US, what size are those pellets really? You aren’t going to know unless you have an instrument that can measure the tiny diameters of these pellets.

For this you’ll need a dial caliper, also known as a vernier caliper. Yes, a micrometer also will work, but it is much more restrictive in its range of applications. With a dial caliper you can measure not only pellet diameters but also thicknesses, lengths and depths of wads. You also can measure the overall length of shotshell loads both in fired and unfired condition. With careful usage, you can use a dial caliper to measure the internal diameters of chokes at the muzzle.

In the old days dial calipers came only with tiny, fairly difficult-to-read English or metric calibrations inside the dials. Today dial calipers commonly are available with easy-to-read LED digital displays, making them in fact electronic digital calipers. These calipers also measure in both metric and English units.

There’s no sense naming one company as a standout in the vernier-caliper field, as most produce calipers that are equally accurate and user-friendly. Every sensible shotgunner should own one. A very good caliper can be purchased for less than $50. And one word of advice: Always zero your caliper before each use; it takes about one second.

Trigger-Pull Gauges

Do you have a pet shotgun that you shoot well? Are you in the market for a new shotgun that you want to shoot just as well? There’s a lot more to shooting a different shotgun well than just obtaining one with the same stock dimensions, barrel length and approximate overall weight as your pet gun. It’s crucial that you match the trigger-pull weight(s) as well.

Trust me, every serious competitive shooter sooner or later comes to appreciate that he or she performs best with a certain trigger-pull weight. But, hey, if you don’t own a trigger-pull gauge, you don’t have any way of knowing what your preferred trigger pull is. And there’s absolutely no way to tell by finger pressure. So every serious shotgunner needs one of these devices.

For less than $25 you can buy perfectly satisfactory trigger-pull gauges that are nothing more than glorified fish-weighing scales with long hook devices that connect to the trigger. Although these devices are simple and absolutely foolproof in operation, those who have trouble reading small numbers may have problems using them.

Fear not. As with calipers, today’s trigger-pull gauges are also available with easy-to-read LED digital displays. The gauge I like is made by Lyman and retails for $65.

Reloading Scales

To my way of thinking, another absolutely indispensable precision measuring instrument is the so-called reloading scale. Calibrated to measure in grains, reloading scales allow you to measure the weight of wads and shot charges in both factory loads and reloads. They are essential for checking powder charges thrown when reloading—either that or you remain a slave to guessing and hoping that the bushing you are using really does throw the powder charge listed in the bushing manufacturer’s charge-weight table. And everyone knows charge-weight tables are rough approximations.

Numerous companies manufacture reloading scales. Absolutely foolproof ones are of the balance-beam design and usually sell for less than $75. Hornady, RCBS and Lyman all manufacture balance-beam scales. But again, reading the fine calibrations can be problematic for some shooters.

The solution is to purchase an electronic scale that displays readings in lighted LED format. Pact, Hornady, Lyman and RCBS all make excellent and highly accurate digital scales. Generally measuring up to at least 1,000 grains, these scales retail between $125 and $150. However, MTM Case Gard manufactures a 1,200-grain Mini Digital Reloading Scale that’s available for the wonderful price of $29.99.

Every serious shotgunner should check out the above devices and purchase some if not all. With them you can accurately determine critical information and stop having to rely on others to take measurements for you. Knowing your shotgun and ammunition measurements will allow you to go afield with a world of confidence. Trust me: These devices will not only save you money in the long run but also significantly help your shooting.

To correspond with Tom Roster or to order his third-edition reloading manual on buffered lead and bismuth shotshells, his new HEVI-Shot reloading manual, his 75-page manual on shotgun-barrel modifications or his instructional shooting videos, contact Tom Roster, 1190 Lynnewood Blvd., Klamath Falls, OR 97601; 541-884-2974; tomroster@charter.net.