If the barrels are above .020 I would not be that shy. 025 would be better but have you looked at the what .003 looks like? My eyes can not see .003. That is if the thin area is near the choke end of the barrel. Thin barrels in that area are more a concern of dents than bursting. Use the right loads and you will be fine unless you are prone to falling down a lot or banging barrels into walls, tables or rocks. If that is the case use a gas auto so no one cries about ruining a classic gun.