T7 attracts moisture after it has burned so if you fire the gun it should be cleaned.
My personal method which has never failed me is to clean well with boiling water and completely dry the gun before I load it then run a very lightly oiled patch over the bore down to the bullet and put a finger cot or a balloon over the end of the barrel to keep out moisture, and when I take the primer out I use a spent primer to plug the hole and keep the action closed. This has worked well for me for many years and the seasons here are separated by 3 weeks and if I do not fire the gun in the first season then it stays loaded until the second season. Lee