I usually have to clean mine after each use. I use triple seven and it's fairly dirty powder but cleans up easy with boiling water. I do have some blackhorn 209 I'm wanting to try. I hear it doesn't foul near as bad as t7 but would still need to be cleaned after shooting just not between shots.
I guess I meant, how many shots to you go through before the ML should be cleaned.
I usually take to range, shoot 5 to 10 shots and clean at the range, just out of habit.
However in the field, if you shoot 2, 3 times (not as good as many on here) then I would assume at the end of the day it should be cleaned...but perhaps not in the field after that few a shots. Just wondered how many shots in the field before it is less than accurate and should be cleaned.
With t7 powder I run a wet patch then a dry patch between each shot. I have shot a dozen rounds or so at a time before cleaning with solvent. my barrel shoots better with some fouling anyway. With BH209 I have heard of people shooting many rounds without swabbing, then just clean later.
I shoot BH209 and have shot over 30 rounds at targets without any change in P.O.I. However, after a sesion on the range, I always clean the rifle.
When hunting, I ALWAYS foul the barrel with two shots and hunt the complete season/s, regardless of the number of deer harvested or, times shot. The only exception would be, if I fell in a creek or got caught in a down pour. But please understand, this is with BH209 and not Pyrodex or T7. Prior to BH209 becoming available, it was very different except for the fouling shots.