Measurement Setup
Ready for Testing

Backstop and Pellet Trap

         Instruments Used for Measuring  Airgun Properties

Recommended Pellet or BB:  Airguns are pretty particular about the kind of ammunition they like. Performance can vary quite a bit from one brand of pellet or BB to another in the same gun. I have measured the basic parameters of a large number of pellets and BBs suitable for air pistols and tabulated the results in a document you can view by clicking here. Each airgun in this collection was tested with a variety of appropriate pellets (wadcutter) or BBs (lead or steel) and the one that gave the best performance (good grouping and least jamming) is listed as the "Recommended Pellet or BB".
 

Weight (lb)/Length (in):  The weight of each airgun is listed in the "Info" section and was measured to the nearest 0.1 ounce (converted to nearest 0.1 lb) using a digital postage scale. Length was measured from a plane perpendicular to the muzzle to the farthest point on the gun.

Barrel Length (in)/Material/Rifled:  In most cases, this information was taken from the manufacturer's literature. With many air pistols, it is impossible to accurately measure the length of the barrel without disassembling the gun. Rifling was determined by simple visual inspection.
 

Trigger Action:  In single-action mode, pulling the trigger simply releases the hammer. The hammer is cocked in a separate step, either manually or automatically by gas expelled in the previous firing operation. In double-action mode, pulling the trigger cocks the hammer, brings a pellet into firing position, and then releases the hammer. In most cases, trigger action was determined by firing the gun and observing how the action operated.
 

Trigger Pull (lbs)/Adjustable:  Trigger pull was measured to the nearest 0.1 lb using a Lyman digital trigger pull gauge. The value reported is the average of five measurements. Trigger pull was measured for both single and double action firing. For those guns that must be charged with CO2 in order for the trigger to function (e.g. Schimel GP-22), a fresh CO2 cylinder was loaded. Guns that use a removable ammo magazine had the magazine installed when testing trigger pull since part of the trigger's action is to rotate the magazine.
 

Velocity (fps): The muzzle velocities listed in the "Info" section are from the manufacturer's literature. Velocities listed in the "Performance" section were measured using a Shooting Chrony Beta Master chronograph with the indoor light kit. The far end of the chronograph was positioned at a distance of 3 feet from the muzzle. The average velocity reported was determined from a 10 shot string. The first shot in the string was fired with a fresh CO2 cylinder. Shots were fired about 15-20 seconds apart. Guns that fire both SA and DA were tested in SA mode only. Click here for information discussing the relationship between velocity and temperature. Click here to download an Excel spreadsheet for calculating  velocity statistics and muzzle energy (fpe).
 

Sound Level (dB): The sound pressure level produced by the muzzle blast was measured with an Ivie IE-33 SPL meter. The SPL was measured with "A" weighting and peak readings were recorded for the same 10 shot string used to measure velocities. The microphone was positioned three feet from the muzzle and oriented at 45^º to the line of fire. Only the highest SPL is reported. A difference of 6 dB in SPL is a perceived doubling of the sound level. For example, a muzzle blast of 101 dB will seem twice as loud as a blast of 95 dB. These measurements were made in a 20' x 20' x 18' garage with a cement floor and sheet rock walls. Ambient sound level was approximately 35 dB.
 

Pellet Holder Thickness (in): This measurement indicates the thickness (in inches) of the clips or magazines that hold pellets in repeaters. This measurement is important when trying to match pellets with air guns to avoid jams that result when a pellet is longer than the thickness of the clip.
 

Temperature and Humidity: Environmental air temperatures were recorded to the nearest 1 ºF using an Acu-Rite digital thermometer. The vapor pressure of liquid CO2 changes with temperature. Liquid CO2 vaporizes with each shot causing the temperature of the contents of the CO2 cylinder to drop. Therefore, after the first shot, the temperature of the CO2 in the cylinder will be lower than the surrounding air temperature. The first shot fired from a fresh CO2 cylinder will have the highest velocity and this number is reported as part of the performance data. It is standard practice to report the temperature of velocity tests as the air temperature. Click here for information discussing the relationship between velocity and temperature.
 

Grouping: The precision of each airgun (commonly but incorrectly referred to as "accuracy" by most shooters) was tested by firing a series of shots into a paper target from a bench rest at a distance of 15 feet. These tests were performed using the pellet or BB that was previously determined to work best with the gun under test. A Cabela's digital caliper, with the zero offset by 0.177" or 0.22" (one pellet diameter), was used to determine the maximum outside edge-to-edge distance of holes in the target. The reading on the caliper is the C-T-C (center-to-center) spread of the group. 
 

Manufactured Dates: The beginning and ending dates for the manufacture of each airgun were obtained from a variety of sources including the Blue Book of Airguns (6th Ed.), BBAirguns.com (1, 2), Crosman, Daisy, and other manufacturer's Web sites, books on the history of airguns, and industry news reports. There is no industry standard for reporting manufacturing dates with some sources using company announcements of new products and other sources using the dates a gun was released to distribution channels. The same holds true for the dates of discontinuation, with some sources using the date the manufacturer actually stopped making the gun and others using the date the gun was pulled from marketing channels. These dates can, and often do, differ by up to a year or two.
 

Condition: The condition of each airgun is reported according to the guidelines described in the Blue Book of Airguns (6th Ed.). Click here for a description of the grading system. This grading system is specific to airguns and takes into account the fact that, even when new, airguns don't often have the same level of fit and finish that most firearms have.