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Since converting my GLOCK 21 to 10mm, I’ve tested a few different types of ammo from it, but the requests just keep coming — everyone wants to see DoubleTap ammo tested in 10mm.┬áThe reason is simple — most major manufacturers are selling “watered-down” versions of 10mm ammo. A simple example is Federal’s Hydra Shok. The 10mm version is barely, scarcely any more powerful than the .40 S&W version. According to Federal’s own ratings, the .40 S&W Hydra Shok is rated at 1,000 fps. Their 10mm version is just 1,030 fps. That’s barely over 420 ft/lbs of energy — paltry for what the 10mm is capable of. “Full-power” 10mm loads should be delivering more on the order of about 650 ft/lbs or more . . .

Unfortunately, the major manufacturers like Speer, Federal, Hornady, Remington and Winchester just don’t offer full-power loads in 10mm. Or if they do, it’s with ancient bullet technology (yes, I’m talking about the Winchester SilverTip here). Wouldn’t it be nice if we could get a good, modern, full-power load with something like, oh, say, a Speer Gold Dot bullet?

That’s pretty much exactly what I’m reviewing in this video — the DoubleTap 165-grain Bonded JHP. It’s a basically full-power load (in my test it delivered about 640 ft/lbs of energy) and it uses a Speer Gold Dot as its bullet. I think. I mean, nowhere on the box, or on DoubleTap’s site, does it mention that the bullet is a Gold Dot, but — after testing hundreds of Gold Dots, I know how gold dots perform and what they look like, and I am 99.8% certain that the bullets that DoubleTap is using are Gold Dots (which are, of course, Bonded JHPs).

How did they work? About as you’d expect — phenomenally. The two bullets through the denim penetrated right to the sweet spot of 15″, expanded gigantically, and in all ways exhibited ideal performance for self-defense/personal protection use. In the bare gel, I fired two shots but only recovered one bullet (the other escaped out of the top of the block after penetrating about 14″). The bullet I was able to recover penetrated to 14.25″, and did expand.

It looked like it exhibited classic “overexpanding”, where the petals bend over so far that they actually look like they might be close to shearing off, and the bullet ends up looking like a jellyfish. I prefer how the denim bullets looked, but the bare bullet was still a large expanded hollowpoint that penetrated well, so I have no complaint — especially since people who pull bullets out of bodies for a living have said that generally, bullets from a body look like the bullets from denim-covered gel tests.

If that holds true in this case, I think these DoubleTap 165gr Gold Dot bullets would be a superb choice for defense against human attackers. I might not choose them for a woods gun where the firearm might reasonably be expected to be employed against a big cat or bear; for that situation you may prefer a hardcast bullet or perhaps a hunting bullet like the XTP. But for personal defense, this ammo is outstanding.

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  1. 165 is a good carry load and is about as close to the orig Norma Spec load which was a 170 grain at first 1400 fps and reduced to 1300 fps. Norma didn’t expand though, hence over penetration. Underwood Ammo is the best full power maker of 10mm. Cost wise as well.

    • The original load for the 10mm, produced by Hornady, was a 170 grain bullet at 1350 fps with 631 foot pounds of energy at the muzzle in a 5 inch barrel. My Delta Elite began to show damage in the slide after only 300 rounds. That is a hot load. That was .357 Magnum performance in a semi-auto handgun. This was a great round but was a bit hard on the guns. A little maintenance with a file takes care of the hammering of the slide.

  2. Well, well well.

    Someone is actually producing a true 10mm defensive load for *people* as opposed to bears. Might have to swap out the nightstand load.

    (Personally I’d have been happy with 600 ft lbs, not to push the edges of a safe load too hard, but 430 is just ridiculously anemic. Now if only someone made a practice load at about 600 instead of a 40 S&W long, life would be good.)

  3. Thanks for testing this! Love my 10mm. I have the 180gr because I was slightly concerned that the 165gr would be over-driven from my 5″ barrel. I think that the G21 is a 4.6″ (?) barrel. Not sure how much of a difference that .4″ makes, but that one bullet did seem right on the edge. I find DT labeling confusing. I am not entirely sure I understand why DT makes a 155 *and* a 165 grain, and it’s hard to tell what bullets they use. The 200gr is labeled as “controlled expansion.” Well, duh. No kidding. I feel like if I ask too many questions, I am buying it from Vinnie in NJ. Well do you want it, or not?

  4. Cool test!

    I believe the rounds actually fly out faster from the 416R stainless LWD / Stormlake / Bar Sto barrels than they do from the polygonal riflling in stock Glock barrels. The Underwood 165 grain .40 “+P” shoots these rounds almost as fast as the 10mm. When you put about 636 FPE / shot into a gel block, the result is definitely a larger sound track.

    I’m thinking a stainless steel 5.3″ Glock 35 .40 cal barrel would yield very similar velocity results. If I get one, I’ll confirm the results with my chrono.

  5. The two 10mm Doubletap loads I tested in my G20 printed a good 5″ off every other load I tested. Sorry, I’m not willing to use a load that I have to compensate for at short distances. On another note, I sent Doubletap a heads up email regarding a box of their ammo that I received with the cartridges covered in metal shavings. Gave them the lot number and didn’t even ask for a replacement. Crickets. And I had such high hopes too…

    • At what distance, and in which direction? If the Double Tap load is higher, I’d guess the load just shoots flatter.

      (If something I said makes me sound clueless, it’s because I don’t know enough abuot your situation.)

      • Distance was both 17 and 25 feet and groups were off to the right so it was definitely not a trajectory issue IMHO since height was more or less to POA. I don’t know enough about ballistics to get techy but those were the only 2 loads out of 6 brands that were so far off. (Prvi, PMC, Doubletap, Federal, Armscor, PNW).

    • Personally, since I’m not worried about distances over 21 ft. as long as the ammo performs as indicated its fine. If I had it to do over, all 10mm ammo would be underwood 135 or 165 jhps with some extreme penetrations for pesky idiots who think refrigerators are cover. I won’t put anything hotter than Winchester or Federal HST in a 40 S&W without a supported barrel and updated springs

  6. I believe that Speer won’t allow any other ammunition company to use the ‘Gold Dot’ brand, although they’re happy to sell them the bullets. Gold Dots are usually labeled as just ‘bonded hollowpoint’. Nosler and Hornady don’t mind other companies using their names when they’re using their bullets.

  7. I’m glad to see you guys are testing and seeing how good Mike McNett’s DT ammo is. I’ve been using his stuff for 5 plus years after reading a review somewhere, ChuckHawks maybe, where his ammo was discussed at length with supporting data. He started out with the 10mm Sig I believe and has always received high marks for his no nonsense full power loads.

    High quality stuff!

  8. I firmly believe 165 gr is the sweet spot for 40 s&w, and that 180 gr is the lightest you should go with 10 mm.

  9. I’d be curios to see your results from testing Buffalo Bore 200 and 220 grain 10mm loads. It’s what I carry in my Glock. And yes, I live in Grizzly country.

    • That would be a waste of time for him. 10mm hardcast and FMJs are going zip right through those blocks. Those bullets are all about penetration, he’d likely need 4 or 5 blocks, end to end, to get them to not end up in the woods. Besides, those ballistics tests were designed to be a repeatable medium for effects on people, not 500lb+ CXP3 class game.

    • Don’t know about the Glock but I have shot Buffalo Bore JHPs through my 1911 and they are way too hot. Was flinching after the first round. I would imagine the fecoil would be worse through the lighter pistol.

  10. I carry a 10mm for anti-bear defense. I seldom carry it for personal defense against two legged threats. What I really want to see tested is the performance of 45ACP JHP out of Commander sized pistol. All this test shows is that 10mm is a badass round. I think we already knew that.

    • Smith built the 1006 and variants for it as well. There is no excuse for some many ammo makers to keep making FBI Lite rounds for this pistol. Buffalo Bore, Double Tap and Underwood tells people which of theirs’ to shoot in an Elite and which to not.

    • Yes and no. Glock scaled a standard Glock brand Glock for 10mm. It is really no different than any other Glock. That is the thing about Glock pistols they are identical. The Glock may be beefed up for the stress but it is a light weight pistol. I have friend who has a Glock 29 that he gave up on because of the recoil. He is 6’5″ and 270. He switched to a 1911 frame because of he recoil. As I said above I have never shot a round like a Buffalo Bore from a Glock but I imagine if I flinching with a heavy steal framed pistol a polymer would be unshootable for me.

      • Really, the Glock 20 is a different beast than the G29. The G20 and G21 really are different beasts than the rest of the Glocks. They are the same design, but the size and the rounds they shoot make them behave a little differently. I like my G20 but don’t care for the 29.

  11. I just upgraded the standard recoil spring on my G29 gen 4 to a tungsten guide rod with a 19-pound spring. Will the 19-pound rig handle the force of the barrel base against the block or should I use a stiffer spring? I have read that others have used the stock spring (17 pounds) within high pressure ammo, such as Buffalo Bore, but I had some malfunctions with it; when I called the store that sells the spring, they said 19 pounds would be enough. Anyone have experience with recoil springs and Buffalo Bore?

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