Clean the barrel using a good metal fouling remover.
Using a piloted tool to sharpen the crown would not do any harm, but the crown isn't likely the problem.
Any chance that the barrel is bulged toward the muzzle? The feel when passing the cleaning rod through with a tight patch will tell the tale.
It is my understanding that a microgroove barrel will have standard groove diameter, but a larger bore diameter. Groove diameter should be close to the standard .308, bore diameter could be larger than the usual .300. Because the grooves are shallow, heavy fouling could really mess things up.
Using a piloted tool to sharpen the crown would not do any harm, but the crown isn't likely the problem.
Any chance that the barrel is bulged toward the muzzle? The feel when passing the cleaning rod through with a tight patch will tell the tale.
It is my understanding that a microgroove barrel will have standard groove diameter, but a larger bore diameter. Groove diameter should be close to the standard .308, bore diameter could be larger than the usual .300. Because the grooves are shallow, heavy fouling could really mess things up.
