The custom gelatin molds were constructed from .032-inch aluminum. Pam is used as a release agent.

Over the past year, I've looked at a variety of ammunition in these pages and I thought readers might be interested in the procedure and tools that I use to do this work. When I'm off to evaluate a load, I first try to lay my hands on a cross section of firearms that will extract the normal level of its performance. I strive to come up with ballistics that will mirror what you will see on the street or in the field while hunting. In this light, it would be foolish to run a particular handgun load through a rifle, or a handgun with an abnormal barrel length.

I like to assemble at least two firearms for most tests and often rely on three. Handguns equipped with 2 1/2-, 4- and 7 1/2-inch barrels will typically generate ballistics that you can expect to see in the real world. If I'm working with a round designed for a semi-auto, you'll see me make every attempt to run the load through several firearms. Sometimes, it is only possible to use one arm, however. If this is the case, that rig should exhibit middle-of-the-road ballistics. Most of the time a semi-auto featuring a 3 1/2- to five-inch barrel works well.

Typically, we fire at least five 5-shot groups from each arm to obtain the ballistic mix. I run everything at 25 yards 95 percent of the time, but if sightless belly guns are used, I reserve the right to move things up to 10 yards to keep everything within the confines of the bullet trap. Once in a while I might look at a round aimed more at long range. When that's the case, I move to my 100-yard range in the back yard.

Because a ballistic outing typically shoots up most of an afternoon, I constructed a homemade, radio-controlled target rolling system that will roll paper from one roller to another upon command from the shooting station. I used the guts of an old RollaBull Target system and a Cabela's target stand I bought on sale. It would be just as easy to construct this system from scratch. The system relies on a transmitter (one channel, at least), a receiver (must be on the same frequency as the transmitter) and a servo. Any Radio Control shop can supply these goodies.

The target roller and bullet trap. Birchwood Casey Shoot-N-C targets are stuck to the butcher paper unless the Ransom Rest is used. When the rest is used, group size only is important.

Our downrange servo swings a homemade aluminum arm that contacts a pressure switch that closes to allow current from a 12-volt battery to drive a small, salvaged IBM printer motor, which in turn powers the bottom or take-up roll. The top or supply roller is loaded with a large roll of freezer paper. I run the paper downward over the framework and onto the take-up roll. Sticking the required number of three-inch Birchwood Casey Shoot-N-C targets on the freezer paper and then re-rolling things onto the supply roller gets things set downrange. If I'm working with a rig in the Ransom Master machine rest, I don't mess with targets on the paper. Since the machine is directing things, I only need groups to measure. The Ransom Rest is mounted on a heavy, semifixed steel bench that can be moved into position when the system is going into service. I shoot from a farm shop into the 25-yard target paper and bullet trap through an open 14x16-foot door when the weather is palatable, and when it's not we shoot through an eight-inch hole cut in the door. When I'm eyeballing things, I slide a BR Pivot bench loaded with sandbags into position. If optics aren't being used, I slip on a good pair of competition shooting glasses to clear up the front sight.

Although I do live in the boondocks and have a clear look at miles and miles of wild blue yonder, I keep everything except the noise in my yard. Twenty years ago I hit the local foundry and laid out some hard-earned cash for a 3x3-foot sheet of half-inch T-1 armor plate. The local welder made a portable bullet trap by arranging the T-1 at a 45-degree angle with a sand trap at the bottom to catch spent slugs. The sides are constructed of quarter-inch mild steel, and the rig sits on top of some large steel wheels. This bullet trap will hold anything I've run into it, including some high-velocity rifles.

In use, the bullet trap is placed directly behind the paper roller for use at 10, 25 and 50 yards. I've got a separate bullet trap set up at 100 yards. The long-range trap consists of three huge old combine tires that are filled with gravel. This trap stands about 5x5 feet in diameter and will hold everything including the .50 BMG cartridge. As you've noted, I rely on a pair of Oehler 35P chronographs to catch the flying objects. I always arrange chronograph number one to catch the velocity of the bullets about 15 feet from the muzzle. The skyscreens for this vital machine are set up on four-foot spacing, and the skyscreens are equipped with Oehler's light kit for shooting in sun or shade. If I'm working with some interesting loads-- lightweight frangible .45 ACP loads, for instance--I often set up a second Oehler 35P chronograph at the target.

A gelatin block in position for a shot. Temperature is critical. The block must be as close to 39.2 degrees F as possible. The author calibrates the block using a Daisy air rifle that has proven to be consistent.

Because the groups open up downrange, I set up the second set of skyscreens two feet apart and don't put 'em in place until the first group has been fired. Even then, it's not uncommon to blast away a downrange skyscreen or two over the course of an afternoon. These poor downrange skyscreens are patched and held together with wire as we speak. Run a shot slightly low or wide and you're quickly fixing things downrange. I also run long cabinet lights over this set of skyscreens.

The Oehler 35P has the ability to memorize up to 20 shots for record, so the ballistic charts contain the average instrumental statistics for 20 of 25 shots. It's more difficult to get information downrange unless I'm working with a real tack driver (a revolver, most of the time), so I might only get 10 shots for record there. In addition to the average instrumental velocity, you'll see the ES or extreme spread--the spread in velocity from the highest to the lowest and the SD or standard deviation, which is the measure of the ammunition's uniformity. This is possibly the most important information in the chart; perhaps it should be first in the data. The SD is based on a mathematical formula that is "equal to the square root of the arithmetic average of the squares of the deviations from the mean in a frequency distribution" according to Webster's. While this may indeed be the most important figure in one of the ballistic charts, I can assure you that I'd not take the time to calculate the figure. Fortunately, the Oehler equipment calculates the SD for each string with the push of the summary button. Regardless, keep in mind that the lower the SD, the better.