ORIGINAL: cayugad
If all you have been using is bore butter, try something. Take a bore brush, dunk it in solvent. Now run that brush 15 strokes in the barrel. Then run a couple solvent patches and see what you got. The condition of the patches might change your mind about using only bore butter to protect your rifle.
Just to clarify, this is exactly why the total cleaning / lubing regimen has to be used...just using bore butter is not the point...it's the less than 100% absoulte cleaning & drying steps that lead to problems.
I absolutely guarantee you that anyone who has gotten rust in their bores while using Natural Lube 1000 has failed in one of the three steps:
Not 100% clean
Not 100% dry
Didn't 100% coat the bore with Natural Lube
There are no other magic steps involved with a bore...get it clean, get it dry, get it completely covered with lube...if that's done, it cannot rust...period.
I have numerous TC Hawkens in this family dating bact to the late 80's, they get shot often in the course of a year, and they remain in showroom condition with a simple 20 minute regimen in the garage every time I shoot them...it's really quite simple, and 100% reliable.