Damaged skirts cannot be good for accuracy
I personally don't wash & lube JSBs & H&N Baracuda Match, because they're pretty much clean & dust free right out of the tin.
I was surprised to find that slightly obround skirt on a JSB pellet has no discernible effect on groups out to at least 50 yards.For pellets with thick skirts and/or harder alloys, I do see a velocity loss when the skirt is deformed.