I'll have a separate thread regarding the barrels developed by DPG. In short summary it's the newest technology available utilizing electronic chemical etch machining. Similar to a sinker EDM.
DPG's family business helped developed some of these machine tooling along with a contract programs needing stainless rods and bushings made for fiber optic data transmission for Elons space-x rockets. The idea was finding the best way to bore a hole straight as even a thou deflection of fiber lines reduces transmission rate through refraction. DPG took this technology and applied it into boring a barrel and now rifling. The metal is forged in California with a proprietary blend in reducing harmonics, softer than traditional 416r, with peak pressure at only 60k PSI, so suitable only for Rimfire.
A lot of research and testing was done finding how to make a repeatable accurate 22lr barrel. This being a 170+ year old cartridge, it's one of the best documented and theory tested cartridges While many chased after faster twist rates, DPG chased BC. Finding out which barrels produced the highest G1 and RA4 BC over a Oehler 89 BC chronograph. BHN testing and eddy current test of our current match 22lr ammo shown these lead projectiles are not pure lead, having voids and imbalance material. The 22lr projectile is designed to be optimized at 16 twist. Faster twist rates tend to bring defects in these projectiles outward causing an imbalance, hence flyers.
Shilen select barrels with the ratchet rifling produced the highest BC value at an average .205-.210 over a 50 shot string. However slowest velocity due to the taper lapping, followed by a tie between Mullerworks and DPG at .190-.200 G1 BC and cut rifled barrels at a .160-.180 G1 BC. However, testing mass batches of our well known barrel manufacturers shown a wide performance band. Lead times started reaching over a year. DPG sought after a superior process in producing the straightest most uniform barrel so performance between each rifle developed is identical. ECM allows any geometry rifling without the induced stress in the bore from button rifling.
EMAG finally released some videos on this ECM process here
Pictures shown from recovered projectiles left to right (Shilen, Mullerworks, DPG, Krieger)