I use "00" Buckshot, which is pure lead and .330" diameter to slug .300, .303 and 8mm Barrels. I use a similar method to Pblatzz, but do not put the dowelling in in sections, once I have started the slug in the bore. I have 3 - P14 rifles, and they measure: .3126, .3128, and .3125. I bought some of Steve Redgwell's Mk 9 - 200 grain bullets, sized to .313, and it shoots very well in all these. Surprisingly, the next best shooting bullet in them is Sierra's 180 grain spitzer, which is usually right around .311" Another great shooting bullet in the P14's I own is Hornadys 150 grain spitzer, a .312 bullet. Go figure! Proves that barrels are fairly forgiving as to diameter of the bullet. I have a supply of Norma RN 180's that one rifle likes, but the other two hate, apparently. Note the 180 Power Point from Winchester. It does not shoot in any of them. The Speer 180RN and the Hornady 174RN are OK bullets, but not outstanding in any of these rifles. You just have to try em out to find out what works. Regards, Eagleye.