by Tom Gaylord
Writing as B.B. Pelletier

BB Gage
The new BB Gage looks like a Pelletgage, and operates in a similar way. Photo provided by Pelletgage.comwhich is why the range is not the same as in the text.

This report covers:

  • Precision required
  • Getting started
  • Avanti Precision Ground Shot
  • Measuring procedure
  • Daisy Premium Grade BBs
  • Wide variation!
  • Hornady Black Diamond BBs
  • H&N Smart Shot
  • Crosman Copperhead BBs
  • Evaluation so far

This Thursday, December 24, is Christmas Eve. On that day I’m running a special blog that allows you readers to do most of the writing. We will all tell which airgun we would like to receive for Christmas, and I will get things rolling in the text. Be thinking about the one airgun you want the most this year. It can be a new gun or a used one — your choice.

I realize that not all readers celebrate the Christmas holiday. But don’t let that deter you. Whether you celebrate or not, this exercise is open to all readers.

I said yesterday that I was running some Best of B.B. reports starting today, to give myself some time at Christmas. I have family and guests coming today, and I won’t be able to get to the computer as often as I would like. But today’s report is a new one. Let’s get started looking at the BB gage.

Precision required

The BB Gage sounds simple, but there’s more to it than you might imagine. The BB Gage actually measures the diameter of the BB, because BBs are spheres. The diameter of a sphere is also a chord like the head of a pellet, but in this case the BBs don’t fall into the holes of the gage because their skirts are too large to pass through. They fall completely through. Or not, if they are too large.

When they don’t fall through, you start wondering about that hole. Is it perfectly round? Is it the correct size marked on the steel plate? Is there a tiny burr on an edge of the hole preventing the BB from falling through? These holes are graduated in hundredths of a millimeter. A 4.37mm hole measures 0.17204724-inches across, while a 4.38mm hole measures 0.17244094-inches. The difference is a little more than 4 ten-thousandths of an inch! Until the 1990s there weren’t any BBs that were worthy of being measured with such precision, because none of them were close to being perfect spheres.

Today I’m going to sort some popular BBs for you and show you how the gage works. In the next report I will use the Daisy Avanti 499 BB gun to test the sorted BBs by size — to see if it makes any difference on target.

Getting started

The gage plate has 10 holes ranging from 4.35mm to 4.44mm. It is made similar to the Pelletgage, except there is no plastic plate on top of the metal gage plate. The BBs don’t need to be guided to the hole.

BB Gage holes
Ten holes range from 4.35mm to 4.44mm.

I started out placing a cloth under the gage, but I soon discovered that it was better to just hold the gage in one hand and manipulate the BB with the other. I have containers for each BB size. These little balls aren’t going to stay still if you don’t have a plan.

Avanti Precision Ground Shot

The first BB I tested is the one we are most interested in — Daisy’s Avanti Precision Ground Shot. The Avanti 449 BB gun uses this shot exclusively, and shooters may want to sort their shot into groups of known size.

I sorted 58 BBs and got 5 groups that ranged from 4.41mm to greater than 4.44mm. The gage holes stop at 4.44mm, so I lumped all those that were larger into one group. The breakdown is as follows.


BB Gage in use
As soon as a BB was measured it went into a container with others of the same size.

Why 58 BBs? I was trying to get as many groups of 10 BBs as possible, for a future accuracy test with the 499. Sizes 4.42mm through 4.44mm were easy to find. It was the two outlier sizes that were difficult. My plan is to test 10-shot groups with BBs of known sizes, then shoot a group of BBs taken straight from the box. I will also probably mix the largest and smallest BBs and add 2 additional BBs for a final group. That should be a pretty good first test of whether or not the BB Gage has any affect on accuracy.

Measuring procedure

I discovered that, like the pellets, there is a procedure for measuring BBs with this gage. First they are dropped into a hole, then if they don’t pass through, I touch them lightly on one side. That overcomes any small resistance to passing through. If the BB doesn’t pass through with this, it’s on to the next largest hole and the same procedure.

I had no idea where to begin so I started trying BBs in the smallest hole first. Then I moved up until the BBs dropped through. Okay, let’s measure a conventional BB.

Daisy Premium Grade BBs

I always defer to Daisy Premium Grade BBs as the industry standard premium BB in my testing. It doesn’t mean they are always the most accurate, though. There have been several tests when other premium brand BBs have done better. The Daisy BB is just a good place to begin, because I know it produces good results in most guns.

Wide variation!

I was shocked, therefore, when the gage revealed a size spread from 4.36mm to 4.42mm. That’s huge! Fifteen BBs grouped in 7 different sizes. My past testing has shown that this doesn’t matter so much in conventional BB guns, but it could make a noticeable difference in a gun like the 499. Here is how Daisy BBs broke down.


I don’t know what to make of this, other than to note that it might not make that much difference in most guns. Conventional BB guns may be very forgiving of small size differences. Maybe the gage is revealing things that really don’t matter. Only more testing will tell us what the real impact might be.

Hornady Black Diamond BBs

I tried Hornady Black Diamond BBs next. These new BBs have surprised me with their consistency in some guns, and today’s test may reveal why. They turned out to be more uniform than even the Avanti Precision Ground Shot! The range for 15 of them went from 4.39mm to 4.42mm.


While the uniformity is good, these BBs are much smaller, on average, than the Precision Ground Shot. So it may not be a matter of simple substituting them in the 499. But isn’t it interesting how uniform they are?

H&N Smart Shot

You knew I had to test the new H&N Smart Shot lead BBs. If I hadn’t I would have been besieged with requests to go back and check them.

Surprisingly Smart Shot BBs are pretty uniform, in terms of BB uniformity. Fifteen of them ranged in size from 4.39mm to 4.43mm. Here is the breakdown.


Too bad Smart Shot BBs don’t work in the 499. I tested them that way while I was testing this lead BB, and the 499 magnet cannot hold the BB in the breech for firing.

Crosman Copperhead BBs

The final BB I tested was the Crosman Copperhead BB. These measured surprisingly uniform, with just 4 groups that ranged from 4.37mm to 4.40mm. That would make Copperheads an ideal choice for guns with smaller barrels, except for one disturbing thing. Two of the 18 BBs I measured actually spanned the entire range of sizes — from 4.37mm to 4.40mm. What I’m saying is they were both stopped by and also passed through all these holes except the largest and smallest hole. These 2 BBs were not round!


As I touched their sides while measuring them with the gage I could feel rough edges digging into the sides of the gage holes. But when I removed them and turned them on their axis, they dropped through! Both were absolutely stopped by the 4.37mm hole and also passed through the 4.40mm hole, but both could be made to both pass through or to stop on the other two holes, depending on how they were oriented.

Evaluation so far

All we know at this point is the BB Gage does work. It does show the relative diameters of the BBs that are tested on it.

I can’t say whether the holes are exactly correct, but I do know they allow BBs to be sorted into groups by their size. What remains to be seen is whether sorting BBs this way will have an affect on their accuracy.