I was able to hit the range this morning to do the challenge. I fired it cold, no warm-up or practice runs.

I used my 642 (stock except for Spegel boot grips), firing Remington UMC Leadless 125gr FNEB.

The gun:



4 rounds @ 3 yards
6 rounds @ 5 yards
6 rounds @ 7 yards
4 rounds @ 10 yards



I'm not sure if the target's dimensions match the B27, so I took a couple more photos with a tape measure for reference:





And for the defense-minded, I did three 5-shot strings, rapid-fire, 1-handed, at 3 yards, using Speer SB-GDHP. The last 5-shot string was fired after drawing from concealment.



I used my Side Guard Quick Clip holster:



Not exactly award-winning marksmanship, but I think it would suffice.

Also noticed my groups concentrating to the left. I'll have to look into that.