I've recently had my HW95 (.22) professionally tuned. When the rifle was returned I was told that the power was set to 11.66 ft/lb with Ely wasp , however when I preformed my own test using H&N FTT pellets the power was much higher - between 13.5 - 14ft/lb.

Is it possible that such a power difference could occur between two different makes of pellets?

Or, could it be more likely that my chrono is playing up and giving an incorrect reading?

I'm not sure whether I should send my rifle back to be re-tuned or buy another chrono and retest.

Has anyone had a similar experience?

I'm obviously extremely worried that I may have an illegal rifle.