A .22 air rifle firing a 14.4 gr pellet should not exceed 612ftps so basicaly mate that rifle shooting a .22 pellet weighing 14.3 gr at 860ftps is illegal you will need a FAC.......there can be variation in chrono test but it should not be that high for .22
860fps with 14.3gr pellet is 23.5ftlbs
790fps with 14.3gr pellet is 19.8ftlbs
both over the limit my .22 tx does 611fps with 14.3 gr pellet thats 11.9ftlbs but over 10 shots i average about 11.5ftlbs