Interesting - except a 4" barrel is not a snub nose - not by about an inch and a half (or more). That extra barrel length can make a relatively significant difference in how much difference in speed and penetration power there is between rounds. I know that a .38 +P will go through a combination of dense carpet, thick pad and subflooring when shot from a 2 1/2" snub nose. Do you need more penetrating power than that? Just something to think about.