To Sort, or Not to Sort?  Pellet Head Sizing And Accuracy

In this two-part investigation, HAM Contributor Matt Coulter examines the link between pellet head sizing and accuracy downrange. “To sort or not to sort?” that is the question he asks and answers.

In this first part, Matt explains his pellet sorting methodology. This is combined with some great practical tips he learned along the way.

Take it away Matt…

Introduction

Given the amount of time that sorting pellets by head-size and testing their results takes, this is a relevant question we should ask ourselves when trying squeeze the last bit of accuracy from our airguns.

So, does taking the time to individually size (and test!) minor variations in pellet head sizes help shrink the group size when target shooting?

Spoiler Alert!  Yes, it does. Pellet head sizing and accuracy really do go hand-in-hand!

This airgunner saw the average group size shrink in nine out of the ten head-size variations tested. In this test, three types of .177 pellets were sorted for head size using a device know as the PelletGage.

The pellets selected for this test include Crosman Premier Hollow Point, H&N Field Target Trophy and Air Arms Diabolo Field.

For background information on the PelletGage please refer to this 2015 HAM article and the subsequent 2017 PelletGage article.

The PelletGage used in this testing is a .177 caliber model. Its main component is a layer of stainless steel sheet metal with 10 laser-cut holes in 10 micron steps with diameters ranging from 4.45 mm to 4.54 mm.

This metal layer is sandwiched in between layers of acrylic to create a frame. Small metal bolts pass through each corner and are fixed securely with metal nuts which also serve as feet for the device.

Assembly

The PelletGage, being a simple product, is relatively easy to assemble. Determining the best way to align the acrylic guide plate (with its oversized openings) over the slightly smaller apertures in the metal plate was a bit of a challenge though.

In the initial attempts to sort pellets, I chose not to use the plastic guide over the metal layer since it seemed impossible to properly align the guide plate. However, in a second attempt at making the guide plate work, I found that by inserting pellets into as many holes as I could (when the guide plate was on loosely) helped keep these layers aligned when tightening each of the PelletGage’s four corner screws.

Using The “Go / No-Go” Gage

With the gage assembled and ready to use, it’s worth referencing the Pelletgage.com website which offers these simple instructions on using the tool:

“To use it, roll or drop the head of the pellet into the smallest expected aperture. If the pellet head is larger, 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, always caught by the skirt. This establishes the size range of the pellet head as being between the smallest aperture it will clear, and the largest that it won’t (commonly called a go/no-go).”

The web page also states: “PelletGage is NOT intended to re-size pellets.” Therefore a light and careful touch is needed when manipulating the pellet to see if its head will drop into one of the PelletGage’s 10 different aperture sizes.

In practice, this tool and a supply of pellets are all that you need. But being prepared for organizing and storing the sorted pellets is equally important. In this exercise of sorting three different types of .177 caliber pellets, I found that needed compartments for each of these sizes pellets:

Crosman Premier 7.9 Grain Hollow Point:
4.47 mm *
4.48 mm *
4.49 mm *
4.50 mm
4.51 mm
4.52 mm
4.53 mm
4.54 mm
(* there were not enough sorted pellets to accommodate testing)

Air Arms 8.4 Grain Diabolo Field (4.52 mm)
4.46 mm
4.47 mm
4.48 mm

H&N 8.64 Grain Field Target Trophy (4.50 mm)
4.50 mm
4.51 mm

This adds up to 13 “bins” that were needed for the sorted pellets. This test also included shooting unsorted pellets as a baseline for each pellet. I chose to keep those unsorted pellets in their original tins.

Not knowing how many head sizes to expect made organizing the sized pellets a bit challenging and messy. However, I believe that setting aside four bins for each type/brand of pellet you are sorting should be adequate.

While I ended up with eight size variations (!) from Crosman Premier pellets, the counts of the four smallest sized pellets were low enough to hardly justify separating them into individual bins.

Note: I did not include the smallest headed Crosman pellets in this accuracy testing because their counts were too low to accommodate the needs of this test.

Sorting H&N Pellets

Having purchased and shot all of the available H&N Field Target Trophy pellet head sizes already (they are sold in 500 count tins in 4.50, 4.51, 4.52 and 4.53 mm head sizes), I chose to conduct this test with pellets from a labeled 4.50 mm tin.

Of those four sizes, this 4.50 mm tin proved to be the most accurate out of the four factory sizes in my air rifle. Of the three brands of pellets used in this test, the H&N had the fewest size variations and were the closest to their advertised size.

Roughly 60% of the pellets were 4.51 mm and 40% were 4.50 mm. H&N Field Target Trophy pellets in .177 caliber are a HAM Gold Award winner.

Sorting Air Arms (JSB) Pellets

The Air Arms 8.4 Grain pellets (like the other JSB variants) are sold in 4.51 mm and 4.52 mm head sizes. I tested the 4.52 mm version and found that they were undersized. The JSB-branded pellets – of which these are a version – are a HAM Gold Award winner.

They were sorted into three “bins” with head sizes of 4.46 mm, 4.47 mm and 4.48 mm.

Roughly 10% of the pellets were 4.46 mm, 70% were 4.47 mm and 20% were 4.48 mm.

Sorting Crosman Pellets

Unlike the other two brands, Crosman does not package and sell their pellets with different head sizes within a specific caliber. Sorting these 7.9 grain hollow point pellets used eight of the ten available sizes in the PelletGage!

With this many sub-sizes (4.47 mm to 4.54 mm), I had to do much more sorting to get enough pellets for testing. Ultimately, I decided to test these five different Crosman head sizes; 4.50 mm, 4.51 mm, 4.52 mm, 4.53 mm and 4,54 mm.

Here’s what the results look like in a chart.

The above chart shows the head size distribution Matt found for the Crosman Premier Hollow Point pellets. Note that his completely independent test very closely matched the size distribution found in the comprehensive HAM test review. This is shown below.

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PelletGage

In the second part of this pellet head sizing and accuracy investigation, Matt shares what really matters. The results downrange!