Air Rifle Research - Slugs vs Pellets

[DocBeech]

We are delving into the world of Air Rifles, have been for over a year now. We are developing systems and integrations into the AB Ecosystem that will include Air Rifles tools in the future. What I can share is limited but we are attaining some very good research material to be published later. With that being said, I can only share what you see here.

Air rifle slugs vs. pellets

Initial radar testing shows an interesting stability trend for slugs vs. pellets: drag is minimized for pellets in slower twist barrels, while drag of slugs is minimized for a faster twist.

Also, consistency of drag/BC is best when drag is minimized (BC maximized).

Attached are data for .300 caliber 44.5 grain Slug and .300 caliber 44.8 grain Pellet, both around 800 fps.

Experienced air rifle shooters told us to expect this so it's nice to see the measurements supporting this trend!

So why is fast twist good for slugs / bad for pellets and vice versa?

Air rifle pellets with a skirt are mostly drag-stabilized, not spin-stabilized. So, they don't need much if any spin at all to fly point forward; the skirt catches the air like the fins of a rocket. As such, spinning the pellets faster only becomes a problem of dynamic stability. If I had any suggestion after looking at this data, it would be to try an even slower twist for pellets, perhaps a 1:60" (one turn in 5 feet) or even 1:120".

Slugs are spin-stabilized so it reasons that more spin suppresses yaw and maximizes BC, to a point. Based on these results, it appears the slug is reaching max stability/BC with the 1:22" and the 1:18" provides no further benefit.

Again, these are just initial findings, we're eager to explore further in the coming weeks! To view our recent testing visit: https://thescienceofaccuracy.com/video/v023-getting-started-with-air-rifles-part-1/

If you would like to see further research or have any ideas please email us at support@ab.us.com. Again I cannot share more than you see here.

 

[jmohme]

Welcome to the increadibly addictive world of PCP air guns!
Looks like an FX. What model is it?

You are pretty much spot on, but pellets do benefit from some spin. The problem really arises from the same drag that stabilizes a pellet. As this drag scrubs off speed, too much spin can start a precession that destablilize or sometimes start a spiraling. Either way, accuracy goes in the toilet. And that is why most pellets are good to 75 yards and in some cases 100. Past that is where slugs come into play.

I have two barrels for my RTI Prophet Performance. One is a .22 slow twist (1:32) choked and was designed for one specific 25.39 grain pellet. It is pretty much dead on out to 100 yards at 950 to 1000 fps

The second is a .25 has a 1:17 twist. It still shoots 25 cal pellets well but I need to keep the velocity down in the 850 fps range. It also has a lighter choke so does well with slugs too.

I am still experimenting with diiferent slugs and have not pushed it out to longer distances, but expect decent performance out to 150.

 

[jmohme]

Also I see you were using FX hybrid slugs. I had mixed results with them in both .22 and .25.
Getting much better results with Nielsens. With them you not only have choices on slug weights, but also diameters.

 

[DocBeech]

Also I see you were using FX hybrid slugs. I had mixed results with them in both .22 and .25.
Getting much better results with Nielsens. With them you not only have choices on slug weights, but also diameters.

These are just what we have published. We are just getting started on releasing information.