I posted this in another forum awhile back. I am reposting it now in response to a question asked by barge51 in another thread. This weekend I had the chance to do some makeshift tests. I took my .380acp PPK, my 9mm Glock G26, my .357sig P2000SK, my .40S&W MK40, and my .357mag/.38spl S&W m60. We did not tdo anything too scientific. We simple slaughtered a bunch of old phone books (who uses phonebooks these days anyway) that were on their way to the recycling area at the dump. I am not an expert at this but we did our best to keep the conditions fair and the results unbiased. The worst part is we did not have all the ammo weights at our disposal so we had to use what we had. I forgot to charge the battery in my camera so I did not manage to get any pictures. I also did not take anything to write detailed notes. Therefore we are going to try and do it again this coming weekend and be a little better prepared this time. What little notes I did take (besides penetration) are not available to me now so I will just sum up the results. Ammo used: .380acp - 90gr Gold Dot GDHP 9mm - 115gr Gold Dot JHP .357sig - 125gr Gold Dot GDHP .40S&W - 180gr Winchester JHP .38spl - 110gr Winchester HP .357mag - 110gr Winchester JHP Results: (penetration is based on comparison info on the web on how to covert paper penetration to Gel penetration) (expension is simply rated in POOR=did not always expand and never fully, FAIR=usually expanded partially but never fully, GOOD=always expanded partially and sometimes fully, VERY GOOD=Always expanded usually fully, and EXCELLENT=always expanded fully) (recoil is stated on a 1-10 scale with 1 being very mild and 10 being abusive) .380acp Average penetration: 11.75" - Average Expansion: Fair - Recoil: 5 .38spl Average penetration: 12.00" - Average Expansion: Very Good - Recoil: 4 9mm Average penetration: 12.50" - Average Expansion: Good - Recoil: 5 .40S&W Average penetration: 14.00" - Average Expansion: Very Good - Recoil: 7 .357sig Average penetration: 14.75" - Average Expansion: Very Good - Recoil: 6 .357mag Average penetration: 15.00" - Average Expansion: Excellent - Recoil: 9 These results are by no means scientific. They are done by two goobers with too much time on their hand and a whole lot of phonebooks. The calculations were done based on the average conversion we found on the net since there was more than one formula. Next time we will take calipers and gloves to measure bullet expansion. we might even break down and buy some gel mix.