What Is The Most Accurate Airgun BB? The Big HAM BB Test Part 1

So what is the most accurate airgun BB?

That’s a common question among BB gun shooters, so – to answer it – HAM has put together this Big HAM BB Test…

BB Gun Accuracy Test Results

HAM has been testing BB guns since 2015. In that time, we have tested 27 different BB guns, both pistols and long guns. As HAM testing uses a strictly standardized test methodology, it’s possible for us to compare the results of all these tests over the years and make comparisons.

Each of these 27 BB gun test reviews includes test targets made with five different types of BBs. These are:
– ASG Blaster BBs
– Avanti Precision Ground Shot
– Crosman Copperhead BBs
– Hornady Black Diamond BBs
– Umarex Steel BBs

By analyzing the test targets – 135 of them! – from these reviews, we can identify the BBs that were the most accurate in each test. The results are shown in the following chart…

What Is The Most Accurate Airgun BB?

So, what’s the answer to that question what is the most accurate airgun BB? HAM test results say that ASG Blaster BBs have clearly scored the best in our testing.

The Hornady Black Diamond and Umarex Steel BBs tie for second place by being the most accurate in six reviews each. Avanti Ground Shot and Crosman Copperhead BBs were the most accurate in three reviews each.

And it may not be a coincidence that most accurate BB gun ever tested by HAM – the Barra 400e – delivered the best accuracy using ASG Blaster BBs.

Yes, it’s true that there are other types of BBs in the market today. These include Air Venturi Dust Devils among others. However, these were not available in 2015 when HAM BB gun test reviews started so, for consistency, we’ve kept with the original five types.

What Is The Most Accurate Airgun BB Diameter?

Unlike pellet-firing airguns, BB guns have un-rifled, smoothbore barrels. Steel airgun BBs do not deform to conform with the bore when fired, as lead pellets do.

Of course – as with every manufactured product – individual BBs will vary from each other by a small amount. This is well demonstrated in the many HAM airgun pellet test reviews.

But there’s another variable at work here too. Each individual BB gun’s barrel will have a slightly different diameter. The industry standard for a minimum BB gun barrel bore is 4.46 mm (0.1755 Inches). That means that most will be slightly larger…

So you might think that – up to a point – the closer the BB diameter approaches to just under 4.46 mm, the more accurate it will be. It stands to reason that smaller diameter BBs will bounce along the barrel when fired, leaving the muzzle in marginally different directions. Hence inaccuracy.

However, it turns-out that this is not what is demonstrated by HAM’s accuracy tests!

You see, HAM Tester Doug Wall has been measuring the diameters and weights of the standard HAM test BBs. By testing 50 BBs of each type, we can relate the average  diameters of each type of BB against their demonstrated accuracy.

Now our chart looks like this…

What Is The Most Accurate Airgun BB?

In fact, the ASG Blasters – the most accurate BBs in HAM testing – have an average diameter of 4.40 mm (0.1732 Inches).

The Hornady BBs also share this average diameter, while the Umarex Steel BBs have an average size just slightly smaller at 4.39 mm (0.1728 Inches).

So no less than 21 out of the 27 BB guns tested by HAM – that’s 78% – were most accurate when firing BBs with an average diameter of 4.39 to 4.40 mm (0.1728 to 1732 Inches).

Interestingly, the BBs having the largest average diameter of 4.42 mm (0.1740 Inches)  – Avanti Steel Shot – were no more accurate than the Crosman Copperhead BBs with the smallest average diameter of 4.37 mm (0.1720 Inches).

Well, the data is very clear. Maybe Bob Sterne will be able to explain why in a future article!

Tomorrow we’ll look at the manufacturing consistency of the five standard HAM test BBs and see how they compare from that perspective.

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

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