Not content to rest on our laurels, Hard Air Magazine has now introduced a new version of the HAM pellet BC database.
This version includes yet more data. Yet, at the same time, we’ve introduced improvements that make our pellet BC database easier to use!
Firstly, I’d like to thank Bob Sterne for his input. Bob is a familiar name to many as a long-time contributor to multiple Airgun Forums. His technical airgun knowledge is legendary and his willingness to share it with others outstanding.
Bob will be joining the HAM Team as a contributor. So you’ll be seeing more his material in Hard Air Magazine in future. Welcome Bob!
At Bob’s suggestion, we have added Sectional Density and Form Factor data to every pellet in our pellet BC database. This data will be useful to those wanting the ability to compare pellet ballistics beyond their Ballistic Coefficient values.
Pellet Sectional Density
Sectional Density (SD) is the “weight per unit area” of the pellet. It allows comparison between different pellets and calibers. Obviously, heavier pellets within a given caliber have a higher Sectional Density.
The Sectional Density of a pellet is one of the two primary factors in determining its Ballistic Coefficient. The second is the Form Factor (FF).
Pellet Form Factor
The Form Factor compares the pellet’s drag with that of the GA drag model which is used in calculating the values for the HAM pellet BC database.
If the Form Factor is 1.00, the pellet’s shape has the same drag as the GA Ballistic Coefficient model. If the FF is 2.00, it has twice the drag of the GA drag model at that velocity.
Ballistic Coefficient, Sectional Density and Form Factor are related by this formula:
BC = SD / FF
Pellet Penetration
This information will be of great use to the many airgun hunters among HAM readers!
For a given shape, with no expansion, penetration is proportional to the product of the SD and the impact velocity. So, for a given velocity and SD, a lower FF will generally have a greater penetration as well.
Just as pellets with a high FF slows down quickly in the air, they tend to do the same thing in the target.
If two pellets have the same SD and FF, they will have similar penetration at the same velocity, regardless of caliber.
HAM Pellet BC Database Usability Improvements
In order to make the HAM pellet BC database easier to use – particularly when viewed on a smartphone or tablet – we’ve also made a number of “backroom” technical improvements.
Firstly, we’ve reduced column widths so that more data fits on the screen at once. Also, we fixed a bug whereby some of the pellet BC database calibers would not scroll across a limited-width screen. Now they do, for easier viewing. This will be particularly useful when viewing the HAM pellet BC database on a cellphone.
Also, there’s now a search capability for each caliber in the HAM pellet BC database. You can use this instead of scrolling down the list of data, if you wish. This makes it easier to find a specific pellet, or desired BC, SD or FF for comparison. If you want to find, for example, all of the .177 caliber pellets with a specific BC, just type that number into the search box.
It’s also a “predictive” search system. This means that – for example – if you want to find the BCs for Crosman pellets, you just need to type “cro” into the Search box and the system displays just Crosman pellet data for that caliber.
I hope that you will enjoy and value these improvements to the HAM pellet BC database. Please tell all your airgunning friends about it!
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