That extra pellet adds to the recoil with out add to much to the velocity if its not burning fast enough. Try two pellets as that's what usually is most accurate other than that loose is always better cheaper and more efficient and 110 gr would normally be accurate. Part of the problem is that's a side lock designed to use a #11 cap or a musket cap Pellets work best with a 209 ignition. Irregardless of the advertising that gun will always function better with loose powder because that's what the ignition is suited to, you may have ignition problems in cold weather and with #11 caps I doubt you are even close to burning 3 pellets with any efficiency, with Musket caps and a Musket nipple it would do some better but still short of what a 209 would do.