Welcome to the joys of "shootin' dirty."
You don't have to clean between every shot with most rifles, just when the ball starts to get tight. I've had rifles where this happened about every 3rd shot and others where I could go close to 10 before they got tight. I use a bronze brush with a squirt of WonderLube 100 followed with a dry patch.
The 1:48 is a compromise in twist, but some rifles are more finicky than others. Try with round balls and see what happens. Sometimes, even varying the thickness of the patch will change the pattern. It just depends on whether your rifle is male (shoot anything just to get a bang) or female (finicky as all getout and changes day-2-day.)
(That sould get me some flames.
)
Pops