Yesterday afternoon I chrony'd nine different 10mm loads including offerings from Double Tap, Hornady, Prvi Partisan, and some of my own handloads. If found the results pretty interesting. Conditions: Elevation 4600', afternoon high-desert, temperature approx 53*F, wind light and variable. Shooting was performed kneeling using a bar stool as a rest (placing floorplate of magazine on top of the barstool to stabilize). No sandbag available, so accuracy was only as good as my own skills. Chronograph used: "Beta" Master Chrony, set up approximately 5 yards away (the 18' remote cable to the chrony was extened most of the way out). Target was an 8" bullseye at the 15 yard line. All loads had the same impact center on the target (which happened to be about 2" left and 4" higher than point of aim... I guess I need to adjust my sights). Firearm used: Glock 20sf, factory 4.6" barrel. All stock except for ISMI 22lb recoil spring and stainless guiderod. First load tested - PRVI Partisan Factory loads (10mm Lite) Group size: 3" Average Velocity: 891.9 fps Avg Energy: 318 ft/lbs Std Deviation: 18.89 Extreme Spread: 66.56 Case expansion (first number=unfired diameter at widest, second number=same dimension after firing) 0.423" 0.430" As expected, these were *****cats. Mild recoil, no signs of overpressure. Sooty external casewalls (perhaps from not expanding enough to fully seal chamber). Decent target load for the price, delivering good accuracy for range work. Second load tested - Handloads (180gr Hornady XTP, PPU brass, CCI Mag primers, 6.0 gr. Unique) Group Size: 2" Average Velocity: 984.1 fps Average Energy: 387 ft/lbs Std Deviation: 38.85 Extreme Spread: 143.3 Case Expansion: 0.423 0.430 Advertised Velocity: 1000 Dev. from Advertised Velocity: -15.9 Mild starting load for Unique powder. Little muzzle flash/blast, and low recoil. Very tame, tied for most accurate. Third load tested - Handload (180gr FMJ-FP pulldowns, Double Tap once fired brass, Win LP primers, 8.5gr Blue Dot) Group Size: 2" Average Velocity: 1062 fps Average Energy: 451 ft/lbs Std Deviation: 25.49 Extreme Spread: 74.62 fps Case Expansion: 0.423 0.434" Advertised Velocity: 1000-1050 fps Dev. from Advertised Velocity: +12 to +62 fps Moderate to large muzzle blast with medium muzzle flash and moderate loudness. Tied for most accurate. Fourth load tested - Handloads (180gr FMJ-FP, PPU 1x fired case, Win LP primer, 7.4gr Power Pistol) Group Size: 3.5" Average Velocity: 1090 fps Average Energy: 475 ft/lbs Std Deviation: 11.53 Extreme Spread: 39.37 fps Case Expansion: 0.423 0.433" Advertised Velocity: 1125-1130 fps Dev. from Advertised Velocity: -35 fps Slightly slower than book prediction based on 5" barrel, so deviation is understandable. OK accuracy. Mild pressure signs in case, primers not flattened. Big, bright muzzle flash, loud muzzle blast. Easily comparable to a .357 Magnum. Fifth load tested - Hornady Factory loads (180gr XTP) Group Size: 3.25" Average Velocity: 1185 fps Average Energy: 561 ft/lbs Std Deviation: 13.92 Extreme Spread: 43.44 fps Case Expansion: 0.422 0.433" Advertised Velocity: 1180 fps Dev. from Advertised Velocity: +5 fps Excellent, consistent (although pricey) ammo. Only factory load tested that came in at or above advertised velocity. Only mild pressure signs, no flattened primers. Sixth load tested - Double Tap 180gr Controlled Expansion (Montana Gold bullet) Group Size: 5" Average Velocity: 1217 fps Average Energy: 592 ft/lbs Std Deviation: 19.92 Extreme Spread: 50.15 fps Case Expansion: 0.423 0.436" Advertised Velocity: 1350 fps Dev. from Advertised Velocity: -133 fps While certainly hot, it fell well short of advertised velocities. Accuracy was bad, which I'm chalking up to the bullet. Recoil and muzzle flash/blast were hot but manageable. IMHO, this is full-power plinking ammo. 7 out of 10 have overpressure signs (flattened primers, glock smileys). Would not buy this load again. Seventh load tested - Double Tap 200gr Nosler JHP Group Size: 2.75" Average Velocity: 1096 fps Average Energy: 533 ft/lbs Std Deviation: 10.0 Extreme Spread: 31.95 fps Case Expansion: 0.420 0.437" Advertised Velocity: 1250 fps (5" barrel) Dev. from Advertised Velocity: -154 fps This was the most accurate DT load of the bunch. It came in WAY under advertised velocity, but is still powerful enough for a defensive cartridge. It is within 100fps of the original Norma loading, and was actually the mildest shooting of all the DT loadings so it's my choice for carry. Nice medium recoil/flash/blast, although 60% of fired cases have "glock smileys" and other overpressure signs. Eighth Load - Double Tap 200gr FMJ-FP Group Size: 3" Average Velocity: 1098 fps Average Energy: 535 ft/lbs Std Deviation: 7.34 Extreme Spread: 22.2 fps Case Expansion: 0.420 0.433 Advertised Velocity: 1275 fps Dev. from Advertised Velocity: -177 fps This load performed almost identically to the 200gr Nosler JHP except for two areas: This load had NO glock smileys, and only exhibited moderate pressure signs, and it's advertised velocity was VERY wishful thinking. This load was the most overrated (in terms of velocity) of all the DT loads. 177 fps slower than advertised is simply not acceptable, and cannot be attributed to environmental or firearm factors. It is pure and simple deceptive advertising. Don't get me wrong, I like this load, it is certainly hotter than the "10mm lite" factory loadings available from other companies, and it is a good value IMHO, but the velocity advertisements need to be re-vamped. DT has had enough notice on this topic that continuing to put out their "pie in the sky" velocity claims is nothing less than fraudulent. Ninth load - Double Tap 135gr Nosler JHP Group Size: 5"+ Average Velocity: 1541 fps Average Energy: 712 ft/lbs Std Deviation: 25.25 Extreme Spread: 67.38 fps Case Expansion: 0.420 0.435" Advertised Velocity: 1608 fps Dev. from Advertised Velocity: -67 fps This was one of the better DT loads IMHO. It came closest to its advertised velocity, and delivers hard-hitting energy levels. In my "milk jug" ballistics tests, it obliterates one milk jug before going frag-nasty and lodging its fragments in the second jug. An excellent SD round if overpenetration is a concern. This round also is extremely flat-shooting. I was hitting "minute of man" at 100 yards, with only about 6" of bullet drop. I don't know of any other semi-auto handgun round that will allow you to aim center-mass at 100yds and still hit the badguy. OTOH, the penalty you pay for this performance is extreme recoil, muzzle flip, muzzle flash, and muzzle blast. I tested all my loads while wearing Peltor shooting earmuffs (good ones), and had no problems. When I let one of these bad boys off the chain, it made my ears ring EVEN THOUGH I was wearing the earmuffs. I stopped, and doubled up my hearing protection using both foam earplugs (inners) and the peltor earmuffs (outers). Even then, it seemed as loud as the other loads with outers alone. This load also had a nice fireball coming out the end of the muzzle that was about the size of a cantaloupe. Awesome for night shooting, and since I finished shooting this load as the sun was going down, it made for a nice light show. Muzzle flip was intense, and I actually experienced a bit of "trigger guard slap" on my trigger finger when the muzzle would flip back fast enough for the trigger guard to come up and slap my index finger. After about 10 rounds, it made my trigger finger pretty sore (and I'm no slouch!). It was definitely fun shooting since I'm a recoil junky, but it would be VERY difficult to control in rapid-fire. My right forearm is pretty sore today (the next morning) from this little load which is a first for me. Lastly, this round exhibited a bunch of overpressure signs with 6 of 13 having glock smileys, and all having flattened primers. So there's my data an analysis. My overall conclusions in cliffs notes version are below: Handloads are the most accurate. PPU is loaded to 40 s&w specs or less. Hornady is a nice moderate load, and is probably the best factory load tested. Double Tap ammo is nice and hot, and is a decent price, but their velocity claims are WAY WAY WAY overinflated. DT is certainly hot, but not nuclear hot, and Buffalo Bore or Underwood Ammo would probably be better choices for full-house loads if you were going to stake your life on them.