Posted: 6/10/2007 4:24:09 AM EDT
| Their listed velocities tend to be much greater than any of the commercial manufacturers and they apparently do it with less pressure. Is it snake oil or do they really know something that no one else does? |
That's one problem only relying on the manufacturer for data. You're right - something sounds fishy. The thing is, nobody ever checks that stuff I bet. The only way they could get lower pressure with higher velocity is if they managed to discover a completely new kind of powder. |
| For what its worth, over my Chrony, Double Tap shoots with in 50fps of their listed velocity and frequenty matches it. It is considerably faster than any other factory ammo I have chronographed to date. Don't know how they do it, but I'm a happy camper. Yesterday, I was shooting theire 230s Gold Dots against another manuctures loading of the same round. We were shooting a steel cylinder. I could knock it over with the Double tap ammo, and merely move it with the other ammo! |
Huh. That's good news. I just wonder why they can do things that no other ammunition manufacturer can. Maybe their ammo has a lot more flash? I've heard that Federal's +p+ is higher pressure due to the flash-retardant in there. |
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Double tap, and others like corbon, use blended powders that are not offered to the reloading public. There are some powders out that can get you pretty close to those higher velocities. HS-6 is one that the ipsc crowd is playing with in 9mm major, and 38TJ. 357 sig 115gr gold dot at 1700 fps can be done, but case life is about 2 loadings. The other thing is that most major ammo companies have had a downward trend on velocity over the last 20 years, their thinking seems to be all the older guns out there... And bullet tech has come a long way in recent years, used to be you needed to push a jhp well over 1000fps to get it to expand. Some of today's designer hp's will open at 650-700fps. |
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The energy the bullet exits with depends on the area under the pressure curve. The peak pressure generated typically limits the area that can be generated. By adjusting powder burn rates the peak pressure can be held down while the area under the curve is made larger. More pressure for a longer time produces a faster bullet. |
I remember reading some posts over on 10mmtalk.com a while back, where a fellow weighed a bunch of DT brass against the ususal commercial suspects and it consistently came out more than a few grains lighter. Now...he didn't do a full mic-up on the pieces, but his conclusion was was that there was less brass there and hence maybe another kernel or three could be crammed in there, to get that higher velocity. Me personally? I'd be watching for pressure signs if I didn't reload myself, were I to shoot it. Later and don't blow your faces off. Chris |
Correct. The 9mm is WAY downloaded (some guns in 9mm out there are approaching 100 years old). But with new brass and modern powder? Properly loaded 9mm in a modern gun makes .357 sig seem pointless (i.e. 9mm throwing 124 grns bullets at 1350 to 1400 FPS and 115 grns from 1440 to 1500 FPS). |
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Before DT started doing it commercially, he always talked alot about it on glocktalk. According to him, he was always able to get faster bullets out of his glock 20 with normal pressure curves. It's been a few years now, and I still have not heard anyone shooting his ammo having a problem at all. If I get a G-20, I will be buying a shitload of DT ammo. TXL |
Does a .308 also make a 30-06 pointless? |
YES oops 
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We've found Double Tap's loadings to be consistently closer to their published numbers (for a given barrel length) than other companies' ammo that we've chronographed. I don't have certain detailed technical information on how Double Tap reaches their velocities, but putting together all the available information leads me to the following opinion: 1. Double Tap loads closer to the SAAMI spec for a given cartridge than many companies. The liability lawyers seem hold sway at many of the bigger ammo companies leading to the downloading of ammunition due to fear of firearm deficiencies being blamed on the ammunition company. 2. Double Tap uses powders and combnations of powders that maintain the pressure level closer to the peak pressure for longer so that the average pressure is higher. Michael Courtney |
Michael Courtney, your input is greatly appreciated and respected here!  I wonder if When the .454 Casull first came on scene the cases often held duplex and triplex loads that used two and three different powers --- at the expense of excessive pressures. I believe using computer programs and formulas it would be possible to achieve the same results gained by DT in their cartridges, except at standard and +P pressures accepted by SAAMI . When Vihtavuori smokeless powder by Lapua was introduced in America, reloaders were amazed at the results with some of their 'in-between' powders for magnum-level loads. N110 for .357 and .44mag immediately comes to mind. Either fixed |
+1! I've heard it discussed that certain powders are available to ammunition companies that are not sold commercially. |
Doh! I just realized i was calling Double Tap DP  You guys know what i meant  |
I'm no expert on handloading pistol ammo although I've loaded many thousands of rounds of rifle ammo including full velocity Weatherby rounds. After pulling apart factory rounds and weighing powder charges, i long ago realized that many of the manufactures used propellants not available to us mere consumers. In addition, most mainstream ammo manufacturers signficantly underload their ammo, particularly when it is a round of older origin--ie 7mm mauser/30-06 or was originally marketed in an autoloader 280 remington (aka 7mm express). I suspect that doubletap is simply loading to SAAMI pressures (with or without blended/new powders). I happily count Doubletap as having joined Weatherby in loading full pressure loads. Interestingly, years ago, Norma (who makes Weatherby Ammo) published its loading data for the factory loads. The last time I looked for it, it was unavailable. It would be nice if the manufactures shared their recipies--although I can understand why they do not (classic trade secret), particularly if they are getting exceptional performance. One last thought, this directed to our esteemed moderator. Many of us use handguns for more than personal defense, and greatly appreciate wild expansion and/or penetration that would be undesirable in a self defense setting. I for one enjoy introducing DT 10mm 135 jhps to jackrabbits and rockchucks. It is colorful, and a satisfying use of one of my favorite handguns. I've killed a bunch with standard velocity 45 ACP loads, but it is not as entertaining! Does that make the gun/ammo combo objectively silly absurd or a waste? I guess it depends on whose using it!
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Testing Results of all Double Tap Ammo Thought that Glock Talk members might like this info which I recieved from Mike McNett- All of these tests were done using 10% ballistic gelatin provided by Vyse gelatin using all FBI protocols and 4 layers of denim and two layers of light cotton T-shirt in front of the gelatin. DoubleTap 9mm+P 115gr. Gold Dot JHP @ 1415fps - 12.25" / .72" 124gr. Gold Dot JHP @ 1310fps - 13.25" / .72" 147gr. Gold Dot JHP @ 1125fps - 14.25" / .68" DoubleTap .40 S&W Penetration / expansion 135gr Nosler JHP @ 1375fps – 11.5” / .68” 155gr Gold Dot JHP @ 1275fps – 13.0” / .78” 165gr Gold Dot JHP @ 1200fps - 14.0" / .70" 180gr Gold Dot JHP @ 1100fps - 14.75" / .68" 180gr. XTP @ 1100fps – 16.0” / .64” 200gr XTP @ 1050fps - 17.0” / .61” DoubleTap .357 Sig 115gr Gold Dot JHP @ 1550fps - 12.25" / .71" 125gr Gold Dot JHP @ 1450fps - 14.5" / .70" 147gr Gold Dot JHP @ 1250fps - 14.75" / .73" DoubleTap .357 Magnum 125gr. Gold Dot JHP @ 1600fps - 12.75" / .72" 158gr. Gold Dot JHP @ 1400fps - 19.0" .56" DoubleTap 10mm 135gr JHP @ 1600fps - 11.0" / .70" frag nasty 155gr Gold Dot JHP @ 1475fps - 13.5" / .88" 165gr Gold Dot JHP @ 1400fps - 14.25" / 1.02" 165gr Golden Saber JHP @ 1425fps - 14.75" / .82" 180gr XTP @ 1350fps – 17.25” / .77” 180gr Gold Dot JHP @ 1300fps - 15.25" / .96" 200gr XTP @ 1250fps - 19.5" / .72" 230gr Equalizer @ 1040fps - 11.0" and 17.0" / .62" and .40" DoubleTap 45 GAP 165gr. JHP @ 1275fps – 12.0” / .90” 185gr Gold Dot JHP @ 1150fps – 13.0" / .82" 200gr Gold Dot JHP @ 1050fps – 14.5" / .80" 230gr Gold Dot JHP @ 935fps – 15.75" / .76" DoubleTap .45ACP 165gr. JHP @ 1325fps – 12.25” / .98” 185gr Gold Dot JHP @ 1225fps - 12.75" / .90" 200gr Gold Dot JHP @ 1125fps - 14.25" / .88" 230gr Gold Dot JHP @ 1010fps - 15.25" / .95" DoubleTap 9X25 115gr Gold Dot JHP @ 1800fps - 10.0" / .64" frag nasty 125gr Gold Dot JHP @ 1725fps - 15.0" / .74" 147gr Gold Dot JHP @ 1550fps - 17.5" / .58" |