I have an old model. I fire lapped the barrel with 10 shots of std velocity cci with 600 grit al oxide, then 10 shots of 800grit. You get two flat pieces of steel, put some of the compound on the steel, roll the bullets between the two plates with the rim outside the plate.
The 552 shot about an inch at 100 yards with cci std velocity after that. Clean thoroughly when you are done fire lapping.
