Got my new Impact MKII .22 cal. recently but am still waiting for my slug liner. I watched all the videos on the difference between the FX pellet liners and slug liner with one thing being the less aggressive rifling in the slug liners due to the slugs being solid and less able to conform to the bore like the softer pellets. I had some leftover .22 cal. Nielsens .217 dia. in 19 and 21 grain from when I tried them in my Leshiy. I thought maybe with these slugs having such a minimal bearing surface they might shoot through the pellet liner. The first thing I did was to shoot them into a 5 gal. bucket of water to see the depth of the rifling. From there I did so more test groups and the results weren't too bad. Bill
https://www.youtube.com/watch?v=cesCdK0K_Xk&t=258s&ab_channel=GunPowder%26AirPower
Today I did some groups at 80 yards and the 19's did a little better than the 21's. I will post that video later. I will note I did go look at the difference in twist rates and I think I have the letter B pellet liner which is 1:16 verse the A liner which is slower at 1:19. The 600 mm slug liner A is 1:15.5 I know there is a lot more differences in liners but it was an interesting test to do.
https://www.youtube.com/watch?v=cesCdK0K_Xk&t=258s&ab_channel=GunPowder%26AirPower
Today I did some groups at 80 yards and the 19's did a little better than the 21's. I will post that video later. I will note I did go look at the difference in twist rates and I think I have the letter B pellet liner which is 1:16 verse the A liner which is slower at 1:19. The 600 mm slug liner A is 1:15.5 I know there is a lot more differences in liners but it was an interesting test to do.