I bet its very narrow sharp lands with taper rifling in the bore. You get the bullet moving first without rifling and then slowly start to progressively engrave the rifling in to the projectile. It's the only way it's going to work. Full contact just at the muzzle. Marko
Patents about shooting copper jacketed ammo from an airgun barrel:https://patentimages.storage.googleapis.com/e7/17/2d/ae2248281634e7/US11262156.pdfhttps://patentimages.storage.googleapis.com/f9/b3/bc/fafc8b46d5af1f/US20220187041A1.pdf
The first patent has as title: AIR GUN FOR CONVENTIONAL METAL - JACKET BULLETSThe second patent is by the same inventors, but appears intended for PBs.I found the patents after watching the video earlier in the thread (or one related to that). The statement that the rifling was patented was a clear clue to do a search for it. So, these patents may or may not be related to Chad's contacts. The air rifle being tested using the tech may be protected by NDA, but if there is a patent for the rifling, the tech is already public - as is the air rifle shown in the video because it was shown to the public. Patent means to make obvious; as in public. No longer hidden to protect the IP, but protected from infringement by the USPTO. What may be protected under NDA is the name of the manufacturer of the air rifle using the tech, and their planned release date on the market. Not the rifling - if the above patent is assigned to the airgun manufacturer. It may use yet other rifling, but if it is patented, there is no need to be cagey about it.The small sharp land rifling makes sense to reduce engravement force and friction when shooting a copper projectile. I wonder how its wear life compares to conventional rifling. Perhaps not an issue, providing the projectiles are kept clean.
Tried .223 nosler out of one airgun and it came out like throwing a stone. Not much velocity at all. Didn't try a second one. Just too much pressure needed for engraving the rifling on a real jacketed bullet.Marko
Maybe it's not as bad with big bores?
Quote from: Spacebus on January 26, 2023, 08:32:37 AMMaybe it's not as bad with big bores?And with the the special rifling that is the subject of this thread. So, not as hopeless as you guys experienced with conventional rifling.
I found the patentThe bottom design looks like the three land barrel tested by Troyhammer some number of months ago.
Actually Not the case what so ever outside 3 lands. Troys barrel is nearly ALL groove and very narrow lands.
Quote from: Motorhead on January 26, 2023, 12:43:10 PMActually Not the case what so ever outside 3 lands. Troys barrel is nearly ALL groove and very narrow lands.Everything reminds someone of something. The Troyhammer lands are conventional style for a barrel that had more than 3 lands. The patent in question ALSO has a configuration with three sharp triangular lands that appear shallow for the caliber. So, similar enough to make one think about it; but completely different