The Big HAM BB Test Part Two – Airgun BB Consistency

In this second part of the Big HAM BB Test, we’re looking at airgun BB consistency. That’s consistency of BB size and weight.

To investigate this, HAM Tester Doug Wall measured the diameters of 50 samples of each of the five standard HAM BB types. This was done using a “BBGage”, the version of the PelletGage that’s designed specifically for use with BBs.

The weights were measured using HAM’s standard, high precision, milligram balance. Doug meticulously weighed and measured a total of 250 BBs to create this data. Thanks Doug!

Airgun BB Consistency – Weight Summary

This first table summarizes the results of Doug’s weighing exercise. As you can see, the average actual weights were very close to the claimed weights for each type.

The variability in weight between lightest and heaviest was also quite well controlled and comparable to results we find for pellet manufacturing.

BB TypeClaimed WeightActual Average WeightVariability, Lightest to Heaviest
ASG Blaster5.32 Grains5.35 Grains4.2%
Avanti Precision Ground Shot5.44 Grains5.43 Grains1.1%
Crosman Copperhead5.13 Grains5.12 Grains4.8%
Hornady Black Diamond5.36 Grains5.35 Grains3.2%
Umarex Steel5.29 Grains5.30 Grains2.1%

Airgun BB Consistency – Diameter Summary

As no type of BBs is provided with a diameter specification, we’ve sanity-checked Doug’s actual measured diameters against the measured weights. As expected, lighter BBs also tend to have smaller diameters.

Again, the manufacturing variability was well controlled. In fact, it was much better controlled than we might expect for a product that sells for around $0.005 each!

BB TypeActual WeightActual Average DiameterDiameter Variability, Smallest to Largest
ASG Blaster5.35 Grains4.40 mm0.9%
Avanti Precision Ground Shot5.43 Grains4.42 mm0.4%
Crosman Copperhead5.12 Grains4.37 mm1.1%
Hornady Black Diamond5.35 Grains4.40 mm0.9%
Umarex Steel5.30 Grains4.39 mm0.7%

Now let’s move on to look at the data for individual BB types.

ASG Blaster BBs

These BBs produced best accuracy in the Legends M712 Full-Auto BB Pistol, among others.

The average weight of these BBs was 5.35 Grains, even though – as can be seen in the chart – no individual BB actually showed-up at that weight!

Airgun BB Consistency

From the next chart, we see that the average diameter was 4.40 mm (0.1732 Inches) and that the variability was well controlled.

Airgun BB ConsistencyBUY FROM AMAZON
ASG Blaster BBs

Avanti Precision Ground Shot

These BBs produced the best accuracy in the S&W M&P 40, among others.

Airgun BB Consistency

If you’re looking for airgun BB consistency in manufacturing, there’s no doubt that these Avanti BBs deliver the tightest results.

Airgun BB Consistency

The control over diameters was particularly good, as we can see from the chart below. This level of consistency is right up there with the best pellet test results recorded by HAM!

Airgun BB Consistency

Daisy Match Grade Avanti Precision Ground Shot .177 Cal, 5.1 Grains, Steel BBs, 1050ct 0.177

Crosman Copperhead BBs

Crosman BBs produced best accuracy in the SIG 1911 We The People BB Gun test review.

Airgun BB Consistency

By comparison with the Avantis, the manufacturing consistency of these BBs is a little more ragged. However, they are cheaper!

There’s no doubt that the manufacturing target diameter is 4.37 mm (0.1720 Inches) and that this is well-met in production.

Copperhead .177 Cal, 5.1 Grains, BBs, 1500ct 0.177

Hornady Black Diamond BBs

These BBs were the preferred diet of the Legends P08 Blowback pistol in HAM testing.

Again, control of weights and diameters was well-managed. Just a couple of outliers spoiled the picture of manufacturing consistency here.

Airgun BB Consistency

Airgun BB Consistency

Hornady Black Diamond Steel BBs, .177 Cal, 5.1 Grains, Anodized Finish, 1500ct 0.177

Umarex Steel BBs

These BBs were the most accurate in six guns, including the SIG P365 BB Gun.

The average weight was 5.30 Grains. Although – again – no individual BB actually achieved that weight.

Airgun BB Consistency

While 4.39 mm (0.1728 Inches) was clearly the manufacturing aim for the diameter of these BBs!

Airgun BB Consistency

Umarex Precision Steel BBs 5.1 grains, Speedloader, 1,500ct, 0.177 0.177


As we can see from the data presented here, airgun BB consistency in manufacturing is really quite high across the range of products tested. However, it’s clear that all steel BBs are NOT the same and that it’s worth experimenting with different types if you want to achieve the accuracy of which your BB gun is capable.