They usually come with a 2 1/4" & 3 1/2" weight. I made a 6" just to try a heavier butt. I'm back to the two incher. Have someone thread the end of a piece of stock for you any length you pick. Start long and keep cutting it off till your happy.
Make a longer one that's hollow with a threaded plg in the end.. then add lead shot till the weight is PERFECT.. remove plug and add a wad of cotton.. to keep lead from moving around.. As you change things.. you'll be able to adjust the weight.. Also.. you can move the lead forward if you put a spacer in the back of the tube..(fine tuning).. All Good.. Mike