Adding Slugs To Airgun Safety Standards Moves Another Step Forward
By adding slugs to airgun safety standards, airgun slug shooters have an official industry standard for the first time. It’s an example of the kind of international standards work the Airgun Sporting Association engages in to help grow the sport. HAM first mentioned this back in February, now this is major progress!
It’s deeply-procedural, grinding, behind-the-scenes work that’s also often technical. As ASA President and CEO Ed Schultz explains, there’s always a TON of discussion involved in bringing standards like this into the market.
Adding Slugs To Airgun Safety Standards – Why It Matters
A caliber name alone doesn’t tell you the actual diameter – .50 cal, for example, could mean the barrel rifling of a .50 BMG or the round ball of a .50 cal muzzleloader. A standardized table gives shooters and manufacturers a shared reference point for what each size actually means. That’s important for safety!
The Airgun Sporting Association (ASA) worked with its members as well as ammunition manufacturers to help reach agreement on this revision It’s part of the ASA’s broader work engaging with the standards process to support the growth and legitimacy of the airgun industry.
Slugs have become one of the fastest-growing segments of the sport, especially in big-bore and PCP shooting, and until now there was no consistent industry definition of what a slug is or how it should be sized.
This revision to ASTM F590 – the Consumer Safety Specification for Non-Powder Gun Projectiles and Propellants – has cleared both rounds of ASTM balloting and is expected to be published within the next couple of months. For the first time, F590 will formally define airgun slugs and set dimensional, material, and marking requirements for them across two dozen calibers.
Adding Slugs To Airgun Safety Standards – What’s New
The revision adds definitions for airgun slug, hard cast slugs, Match Grade Sizing, and standardized test sizing dies.
It also sets material and hardness rules. Lead slugs must use pure lead (with recycled-content alloy capped at 2%) and a maximum hardness of 10 BHN (Brinell Hardness Number, a standard measure of how resistant a material is to permanent indentation). Unless they are marketed as hard cast, that is.
In the standard, Match Grade Sizing is defined as “a precision airgun slug refinement of a projectile’s outer diameter to within a restricted tolerance of +/- 0.001 Inch (0.0254mm)”. If the slug is claiming Match Grade Sizing (MGS), the target size is to be called out on packaging. Interesting!
All slugs, regardless of material, must meet a maximum push force of 45 Ft/Lbs through that standardized test sizing die, measured against the new standard’s minimum allowable diameters. (This is similar to the way pellets are tested). The sizing die is a precision-machined tool used to compress a lead projectile to a specific, uniform diameter to ensure it matches a rifle’s bore.
The purpose, of course, is to ensure that when you buy an airgun and slugs, they actually work together. You don’t want to have a mis-match that leads to a slug becoming stock in the barrel. Like this…
Adding Slugs To Airgun Safety Standards – Min And Max Diameter Table
The centerpiece is a new caliber table setting minimum and maximum diameters, in both inches and millimeters, for 21 sizes – from .177 cal (4.5mm) up through .72 cal (18.5mm), spanning both traditional airgun calibers and larger big-bore sizes.
Here it is. You’re seeing it for the first time in Hard Air Magazine…
| Caliber | Min Dia (in) | Min Dia (mm) | Max Dia (in) | Max Dia (mm) |
|---|---|---|---|---|
| .177 cal (4.5mm) | 0.177 | 4.50 | 0.179 | 4.55 |
| 5 mm (.20 cal) | 0.198 | 5.03 | 0.200 | 5.08 |
| .22 cal (5.5mm) | 0.216 | 5.49 | 0.219 | 5.56 |
| .223 cal (5.6mm) | 0.222 | 5.63 | 0.225 | 5.70 |
| 6mm (.243 cal) | 0.241 | 6.12 | 0.244 | 6.20 |
| .25 cal (6.3mm) | 0.249 | 6.32 | 0.252 | 6.40 |
| .257 cal (6.5mm) | 0.255 | 6.48 | 0.258 | 6.55 |
| 7mm (.284 cal) | 0.282 | 7.16 | 0.285 | 7.24 |
| .30 cal (7.6mm) | 0.300 | 7.62 | 0.303 | 7.70 |
| .308 cal (7.8mm) | 0.305 | 7.75 | 0.308 | 7.82 |
| 9mm (.35 cal) | 0.353 | 8.95 | 0.356 | 9.03 |
| .357 cal (9.1mm) | 0.355 | 9.02 | 0.358 | 9.09 |
| .375 cal (9.5mm) | 0.373 | 9.47 | 0.376 | 9.55 |
| .40 cal (10.1mm) | 0.398 | 10.11 | 0.401 | 10.19 |
| .408 cal (10.3mm) | 0.405 | 10.29 | 0.408 | 10.36 |
| .45 cal (11.4mm) | 0.449 | 11.40 | 0.452 | 11.48 |
| .457 cal (11.6mm) | 0.455 | 11.56 | 0.458 | 11.63 |
| .50 cal DAQ (12.6mm) | 0.495 | 12.57 | 0.498 | 12.65 |
| .50 cal (12.9mm) | 0.508 | 12.90 | 0.511 | 12.98 |
| .58 cal (14.7mm) | 0.577 | 14.66 | 0.580 | 14.73 |
| .62 cal (15.8mm) | 0.622 | 15.80 | 0.625 | 15.88 |
| .72 cal (18.5mm) | 0.727 | 18.47 | 0.730 | 18.54 |
Keep in mind that ASTM standards are voluntary, so it will take time for the new specs to show up across the market as companies work through existing inventory.
Readers of Hard Air Magazine pellet and slug tests will be familiar with diameter variations in airgun ammo production. Here they are being standardized for slugs through an international safety standard. That’s a great step forward, thanks to efforts from the Airgun Sporting Association.
