If you are going with an after market barrel then I would go with a 26 in barrel. Not sure if it would burn all the powder in a 20 in but I would emagine it would be close. Only reason I would go with a 26in barrel is because I would think that all powder would be burnt and I like longer barrels because I'm wierd. And I cant free hand a light gun at all, not that heavy guns help me much either but some. Have a nice day and I'm sure people who are more knowledgeable will be able to fill you in more. Have a nice day.