AOA Blog

The PelletGage is a simple-to-use device that is able to to determine the head size of pellets in 0.01 mm (ten micron) increments. Actually, it’s an extremely precise “go – no go” gauge

It is currently available in five common airgun calibers. There’s .177 and .22 calibers, of course, together with.20 cal, .25 and .30 caliber

Most air rifle shooters are interested in accuracy. They know know that their guns “like” – that is, shoot most accurately with – a particular pellet or pellets. In many cases, this may be due to the head size of that particular pellet.  Pellet dimensions actually vary significantly between different designs and the head diameter is a particularly critical measurement.

That may not be too surprising, but it’s more surprising to discover that head size can vary significantly between the “same” pellets from one tin!

Testing has shown significant size variation in tins of quality pellets, and differences of mean diameter between tins of the same size and weight. This may be a key to finding that next tin of pellets that shoots so well.

Here’s an example of this variation in head diameter for JSB Redesigned Monster pellets. These are a high quality pellet, of course. But even so, you’ll see that there are two “fliers” with head diameters slightly outside the 5.56 mm aim from the 50 pellets that were measured.

If we look at a lower-quality, anonymous pellet, we can see a much wider spread of head sizes. It’s not difficult to see that these pellets are likely to be less accurate than the JSBs…

The PelletGage allows us to know the diameter of the pellet’s head, and to make that determination quickly. It allows us to check the pellets in one tin for consistency.

Each PelletGage has ten round apertures precisely cut into a thin metal sheet. These apertures allow a range of head sizes to be measured for each caliber.

To use a PelletGage, roll or drop the head of the pellet into the smallest expected aperture.

If the pellet head is larger than the selected hole, it will not drop into the opening. Move up to the next larger size(s) – diameters are etched in the metal – and the pellet will drop partially through aperture, caught by the skirt.

This establishes the size range of the pellet head as being between the largest aperture it won’t clear, and the smallest that it will. That’s why this type of gauge is commonly called a “go no-go”.

With a PelletGage, you can rapidly sort pellets by size, or simply to give you an accurate measure of the head diameter of that new tin of pellets you just received.

Once you know what diameter your gun “likes”, you can take steps to get that same diameter for better shooting results. You’ll be confident of consistent accuracy, whether you’re hunting with your air rifle, or shooting field target competition – so long as you and the gun do your part, that is.

Note that the PelletGage is a measuring tool. It’s not intended to “size” or change the diameter of any pellet.

Measuring the diameter of a round object isn’t easily done. Normal micrometers and calipers can measure one chord or section across the object only.

PelletGage is more accurate, repeatable, and faster than using calipers or micrometers. Also, it doesn’t demand the skill of using those devices. Lead pellets are very easily damaged and you could damage the very pellets you are measuring by incorrect use of calipers or a “mike”.

So why does the PelletGage measure head diameters in mm (millimeters)?

This is because many high quality .177 caliber pellets used for precision field target shooting are manufactured in Europe where they use metric units, such as mm. So, the head diameters of these pellets are designed to be 4.51/4.52/4.53 mm, etc. rather than .177/.178 inches etc.

You’ll often find this manufacturing aim diameter printed on a sticker on the bottom of H&N pellet tins. It’s 5.53mm in this example, below.

Actually, each 0.01 mm step is actually 10 microns, or 0.0004 inches. That’s four tenths of a thou – about the width of a human hair. The accuracy of the holes in a PelletGage is assured by a state of the art laser cutting technique, combined with special alloy sheet steel. The tolerance is +/- 0.0025 mm of indicated inside diameter. That’s precision!

The Pelletgage is available from your friends at Airguns of Arizona. If you’re interested in shooting accurately – and who isn’t? – you need one for each caliber of pellets you shoot.