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View Full Version : Test: Double Tap 155 gr Gold Dot vs. Speer 165 gr Gold Dot



DocGKR
02-09-09, 01:17
We recently had the opportunity to test the .40 S&W Gold Dot 155 gr JHP loaded by Double Tap Ammunition, along with the .40 S&W Speer Gold Dot 165 gr JHP, as requested by an individual LE officer. These new results are contrasted with the standard .40 S&W Speer 155 gr Gold Dot we previously tested for an LE agency:

.40 S&W Speer 155 gr Gold Dot JHP; ave vel=1166 fps (S&W 4006); gel cal= 9.5cm@ 585fps
BG: pen=13.2", RD=0.64", RL=0.32", RW=155.5 gr
4LD: pen=16.0", RD=0.60", RL=0.44", RW=155.3gr

.40 S&W Double Tap 155 gr Gold Dot JHP; ave vel=1208 fps (S&W 4006); gel cal=10cm@578fps
BG: pen=15.0", RD=0.66", RL=0.39", RW=155.6gr
4LD: pen=17.1", RD=0.55", RL=0.42", RW=155.2gr

.40 S&W Speer 165 gr Gold Dot JHP; ave vel=1092 fps (S&W 4006); gel cal=10cm@578fps
BG: pen=15.0" RD=0.63", RL=0.37", RW=165.2gr
4LD: pen=16.5", RD=0.55", RL=0.51", RW=165.4gr

http://i459.photobucket.com/albums/qq319/DocGKR/40155DT_GD165GD.jpg?t=1234162840
Double Tap 155gr Gold Dot & Speer 165 gr Gold Dot

Both newly tested loads performed adequately, however, there was a noticeable increase in flash, blast, and recoil with the Double Tap ammunition. Neither the Speer 165 gr Gold Dot nor the Double Tap Ammunition 155 gr loading was able to outperform the standard .40 S&W 155 gr Speer Gold Dot loading.

Marcus L.
02-09-09, 06:35
Thank you for this testing, Doc. I knew from my own understanding of bullet construction that increased velocity for a given bullet weight does not improve penetration and expansion. Each JHP has an expansion threshold and a .40S&W simply will not expand beyond .6x" with any reliability. The most influencial factors seem to be bullet mass and sectional density.....not velocity.

I think we can pretty much stick a fork in this one.......Double Taps loads do not "dramatically" increase performance as they claim, and their testing data is grossly inaccurate if not just outright made up. There might be "slight" improvement, but when it comes to shooting substances increasing bullet mass is superior to increasing velocity.

Double Tap data:
155gr Gold Dot JHP @ 1275fps - 13.00" / .76"

sjc3081
02-09-09, 06:49
.40 S&W Speer 155 gr Gold Dot JHP; ave vel=1166 fps (S&W 4006); gel cal= 9.5cm@ 585fps
BG: pen=13.2", RD=0.64", RL=0.32", RW=155.5 gr
4 layers denim: pen=16.0", RD=0.60", RL=0.44", RW=155.3gr

.40 S&W Double Tap 155 gr Gold Dot JHP; ave vel=1208 fps (S&W 4006); gel cal=10cm@578fps
BG: pen=15.0", RD=0.66", RL=0.39", RW=155.6gr
4 layer denim: pen=17.1", RD=0.55", RL=0.42", RW=155.2gr

.40 S&W Speer 165 gr Gold Dot JHP; ave vel=1092 fps (S&W 4006); gel cal=10cm@578fps
BG: pen=15.0" RD=0.63", RL=0.37", RW=165.2gr
4 layer denim: pen=16.5", RD=0.55", RL=0.51", RW=165.4gr


I see two more inchs of bare jell penetration and one inch more penetration in denim with the DT 155.

Marcus L.
02-09-09, 07:00
Perhaps you are missing the point. If these numbers are indeed representative of the rest of Double Taps ammunition, then the testing data that DT has been putting out is most likely false. Doesn't that give you pause on anything they are trying to sell you? I think a pressure test of their ammunition might also be in order.

Anything DT can do, Federal, Winchester, and Speer can do better and safer given that they actually employ real engineers.

As I said earlier, increase the bullet weight(and sectional density), and the heavier loads are superior to the lighter ones.....even when they are cranked up in velocity:

.40S&W 180gr(996fps) Speer Gold Dot:
Bare Gel: 14.8”/.67”
Through Denim: 18.2”/.61”

Better recoil management, lower blast, lower flash, and it does better overall than Double Tap's supercharged 155gr load.

If additional penetration is what you want given that the average human torso is only 8" from front to back, then I guess Double Tap might be for you. However, considering that most loads that penetration 12" in ballistic gel usually exit the body in shootings, that increased penetration might be a moot point.

sjc3081
02-09-09, 07:23
I get your point and generally concur. But Doc should have at least used a Glock 23 to make a proper comparison if his intent was to compare to DT data. I suspect he was just tested the load and you tried to extrapolate the data. By comparing testing using a Glock 23 and SW4006.

Marcus L.
02-09-09, 08:52
Glock 23 barrel length: 4.02"
S&W 4006 barrel length: 4.05"
Sig P229 barrel length: 3.94"

CCI Speer Gold Dots averages from 10-shot samples:

155gr:
-Sig P229 1180fps
-Glock 23 1192fps

165gr:
-Sig P229 1139fps
-Glock 23 1148fps

180gr:
-Sig P229 993fps
-Glock 23 998fps

sjc3081
02-09-09, 11:45
If I remember correctly the Sig and the Glock have polygonal rifling that adds about 50fps in velocity.

The Smith does not have polygonal rifling.

Why did you use a Sig compared to the Glock when the actual firearm that would be a 4006.

If you did this intentionally, than you are being intentionally dishonest and attemping to mislead.

Marcus L.
02-09-09, 12:16
Why did you use a Sig compared to the Glock when the actual firearm that would be a 4006.

.....because Sig Sauer uses standard rifling and the comparison would be very similar to that of the S&W 4006 which also uses standard rifling. I should know, I'm a Sig armorer and have used the 4006 for duty carry in the past. Couldn't find any Glock 23 and S&W 4006 velocity comparisons because the 4006 isn't very common. Sig P229s are.

Polygonal rifling doesn't add as much velocity to a bullet as is claimed.

ToddG
02-09-09, 12:24
sjc -- I don't think a tiny change in barrel length or rifling is going to explain the difference between Doctor Roberts's independent controlled test results and the stuff Double Tap is claiming. My opinion, you are off base calling it misleading and dishonest.

DocGKR
02-09-09, 12:36
The 4006 is very common in CA, as it is the standard issue CHP pistol. On the other hand, Glocks in calibers other than 9mm are not something I am fond of. FWIW, there is minimal difference in velocity between conventional and polygonal rifled pistol barrels--something around 10fps or so. Bottom line, in this test, the DT ammunition offered NO advantages over standard factory ammunition and had the disadvantage of increased flash, blast, and recoil. Pressure testing might be prudent as well.

Marcus L.
02-09-09, 12:41
sjc,

If you are wanting additional penetration from your .40s, then Double Tap might be the brand for you. I can see it serving a function in large game protection such as black bears. In that case though, you would still be better served using heavier bullets which do better against bone once the bullet has penetrated through thick hide and muscle.

Each caliber/bullet diameter has an expansion threshold which time, and time again has been demonstrated to not expand beyond a certain point. Double Tap advertized their .40S&W loads as expanding to unheard of .75"-plus which just doesn't happen. It looks like their penetration is good, but I also knew a guy who pulled the petals away from the trunk of a load he was testing to make it look good. DT's expansion data by all unbias accounts is false, or done incorrectly. The only reliable, and proven way to improve on your existing caliber of choice is to switch to a larger caliber which has a larger entry hole, and a larger expansion threshold.

sjc3081
02-09-09, 13:37
sjc -- I don't think a tiny change in barrel length or rifling is going to explain the difference between Doctor Roberts's independent controlled test results and the stuff Double Tap is claiming. My opinion, you are off base calling it misleading and dishonest.


The 4006 is very common in CA, as it is the standard issue CHP pistol. On the other hand, Glocks in calibers other than 9mm are not something I am fond of. FWIW, there is minimal difference in velocity between conventional and polygonal rifled pistol barrels--something around 10fps or so. Bottom line, in this test, the DT ammunition offered NO advantages over standard factory ammunition and had the disadvantage of increased flash, blast, and recoil. Pressure testing might be prudent as well.


sjc,

If you are wanting additional penetration from your .40s, then Double Tap might be the brand for you. I can see it serving a function in large game protection such as black bears. In that case though, you would still be better served using heavier bullets which do better against bone once the bullet has penetrated through thick hide and muscle.

Each caliber/bullet diameter has an expansion threshold which time, and time again has been demonstrated to not expand beyond a certain point. Double Tap advertized their .40S&W loads as expanding to unheard of .75"-plus which just doesn't happen. It looks like their penetration is good, but I also knew a guy who pulled the petals away from the trunk of a load he was testing to make it look good. DT's expansion data by all unbias accounts is false, or done incorrectly. The only reliable, and proven way to improve on your existing caliber of choice is to switch to a larger caliber which has a larger entry hole, and a larger expansion threshold.

Ok points well explained. Marcus I thought you were intentionally misleading but I was wrong.

DocGKR
02-09-09, 14:29
Conducting and interpreting gel testing is not hard; there is no reason why manufacturers should not know exactly how what they are selling will perform--I have included a sticky with info here: https://www.m4carbine.net/showthread.php?t=26028

Marcus L.
02-09-09, 15:54
That's a good read, Doc. It makes me wonder if a lot of testers are measuring their expanded bullets incorrectly resulting in exaggerated expansion numbers. It is certainly possible that McNett at Double Tap is just measuring his bullets at their peak expansion point which isn't necessarily being dishonest, but it isn't adhering to the standard. I'll have to go over my old copy of Bullet Penetration and review MacPherson's notes. :p

sjc3081
02-09-09, 16:05
Why was the definition of diameter changed and why is it acceptable. I'm floored. This seems to add a advantage to heavily constructed slow moving bullets that don't frag.

DRT
02-09-09, 17:57
DocGKR, Thanks for testing these loads! I'm issued 165gr GD that I carry in my P226-40 while on duty. This data just solidifies my belief that, in .40 s&w, you can't do much better than a premium, well-designed 180gr bullet, which is what I carry when it's my choice.

Since everyone is asking about velocities, I had previously chrono'd (prochrono) these loads out of my G27, G22, and G35. I'm going from memory but the velocities I measured were approximately (within 10fps) as follows.

155gr DT = 1180, 1240, 1290 fps, (G27, G22, G35)
165gr GD = 1080, 1170 (G27, G35)

Given the choice, I'd take my G35 with 16 rounds of 180gr HSTs at ~1030fps (~950fps out of my G27). 180gr Ranger T-series would be just as good. 180gr Gold Dot wouldn't be bad as a 3rd option.

DocGKR
02-09-09, 19:06
sjc3081,


"Why was the definition of diameter changed and why is it acceptable. I'm floored."

I am unclear what you mean--the standard accepted calculation for projectile recovered diameter (RD) has been constant since the early 1980's...nothing has changed.


"This seems to add a advantage to heavily constructed slow moving bullets that don't frag."

It is definitely an advantage for handgun bullets that crush more tissue. With handgun bullets, fragmentation is a BAD thing, as bullet mass and surface area is reduced, causing a smaller permanent crush cavity. In addition, most handgun bullet fragments are usually found within 1 cm of the permanent cavity track and do not produce the synergistic effect found with rifle bullet fragmentation and temporary cavity stretch.

DRT
02-09-09, 19:10
A couple more points.

1) The 165gr GD load tested above was the higher-velocity version rated at 1150fps by ATK

2) My P226-40 with a 4.4" conventionally-rifled barrel generally chrono's about 10fps slower than my G22 with a 4.49" polygonally-rifled barrel. Once again, DocGKR is spot on with his assessment.

sjc3081
02-09-09, 22:12
I don't understand why the government would invent a way to measure the actual diameter of a recovered round by not actually measuring the diameter of the round. Than create a testing method by not measuring the actual widest diameter and call the results , a recovered diameter. The more I find out about this jello shooting the more I question the results. It seems like the test method is designed to prove and confirm the testers predetermined expectations. I confused with logic of these testing methods.

Jim from Houston
02-10-09, 00:03
No one "invented" anything...the issue is the following: the EMPTY space between the expanded petals of a round like the HST or DPX rounds does not crush tissue. With such a round, you're trying to find the "diameter" of an object that is not a perfect circle, so you need to do some math...

The projectiles with "petals" may form a differently SHAPED crush cavity, but the VOLUME of said cavity would, in most instances, be nearly the same as similar rounds with a cylindrical profile...

The fact that ATK chooses to willfully ignore these facts in their SALES presentations is a reflection on them, not on the field of terminal ballistics, or researchers within that field...

This is not a matter that is some sort of "debate" between different philosophies...the volume of a crush cavity is something that can be measured, and if certain ammo companies decide to willfully ignore that, well, that's an issue with them...

ToddG
02-10-09, 00:04
sjc -- Coincidentally, DocGKR and I were discussing this just the other day. There are certainly better approaches, but the one listed above is, as DocGKR pointed out, the standard that's been used for years. Changing it now, if nothing else, would invalidate a ton of historical data.

Measuring only the widest diameter wouldn't make any sense, because if the bullet doesn't expand perfectly evenly then you'd be giving it credit for being, say, 0.6" wide when in many places it's not that wide. One unusual petal sticking out would grossly misrepresent the actual (or average) expansion.

DocGKR
02-10-09, 00:43
sjc3081,


"It seems like the test method is designed to prove and confirm the testers predetermined expectations."

What were those "predetermined expectations"? In the early to mid-1980's, when the RD measurement method was developed, the prevailing theory was that lightweight high velocity projectiles were the best choice for duty use--common LE duty loads included the 9 mm 115gr +P+ and .357 Mag 125 gr JHP.


"I don't understand why the government would invent a way to measure the actual diameter of a recovered round by not actually measuring the diameter of the round."

As noted in the excellent posts above, many recovered projectiles are not of a uniform round shape. The RD methodology attempts to take into consideration the fact that many recovered projectiles are not of a uniform round shape; averaging the largest and smallest dimension is a reasonable attempt to compensate for this factor.


"The more I find out about this jello shooting the more I question the results. "

I am sorry you are so confused. A variety of equally important methodologies are used for terminal performance testing, including actual shooting incident reconstruction, forensic evidence analysis, and post-mortem data and/or surgical findings; properly conducted ethical animal test results; and laboratory testing—this includes the use of tissue simulants proven to have correlation with living tissue. Some individuals seem to be under the mistaken impression that one of these areas is more important than others--this is not the case, as each category provides important information to researchers.

The IWBA published some of Gene Wolberg’s material from his study of San Diego PD officer involved shootings that compared bullet performance in calibrated 10% ordnance gelatin with the autopsy results using the same ammunition. When I last spoke with Mr. Wolberg in May of 2000, he had collected data on nearly 150 OIS incidents which showed the majority of the 9mm 147 gr bullets fired by officers had penetrated 13 to 15 inches and expanded between 0.60 to 0.62 inches in both human tissue and 10% ordnance gelatin. Several other agencies with strong, scientifically based ammunition terminal performance testing programs have conducted similar reviews of their shooting incidents with much the same results--there is an extremely strong correlation between properly conducted and interpreted 10% ordnance gelatin laboratory studies and the physiological effects of projectiles in actual shooting incidents.

The last several years of OCONUS GWOT operations have provided a tremendous amount of combat derived terminal performance information. The U.S. government gathered numerous experts from a variety of disciplines, including military and law enforcement end-users, trauma surgeons, aero ballisticians, weapon and munitions engineers, and other scientific specialists to form the Joint Service Wound Ballistic Integrated Product Team to conduct a 4 year, 6 million dollar study to determine what terminal performance assessment best reflected the actual findings noted in combat the past few years. The test protocol that was found to be correct, valid, and became the agreed upon JSWB-IPT “standard” evolved from the one first developed by Dr. Fackler at LAIR in the 1980’s, promoted by the IWBA in the 1990’s, and used by most reputable wound ballistic researchers.

The JSWB-IPT, FBI BRF, AFTE, and other organizations get to assess an extensive amount of post-shooting forensic data. The whole raison d'être of these independent, non-profit organizations is to interpret and disseminate information that will help LE and military personnel more safely and effectively perform their duties and missions. Physiological damage potential is the only metric that has been shown to have any correlation with field results in actual shooting incidents, based on law enforcement autopsy findings, as well as historical and ongoing combat trauma results. Again, I am sorry if these ongoing efforts in the support of U.S. military and LE personnel are confusing to you, however, they have been proven to work in the real world...

DrJSW
02-16-09, 04:23
Well summarized and succinctly put, DocGKR.

Jack-O
02-16-09, 12:38
It look like about a 10% increase in performance.

The question we have to ask then is, Is it worth the extra flash and recoil to get 10%?

DocGKR
02-16-09, 14:07
While all three loads were acceptable, I'd say the standard Speer loaded 155 gr GD performed the best...

Marcus L.
02-16-09, 16:03
While all three loads were acceptable, I'd say the standard Speer loaded 155 gr GD performed the best...

Yep. It beat out the Double Tap load in the demin test by creating a larger overall wound volume within the first 12".

"Given desirable and reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound by increasing the size of hole made by the bullet." -Handgun Wounding Factors and Effectiveness

The FBI protocol tests were designed to maximize ammunition engineering around the human target and when it comes to this model the Double Tap loads offer no measurable advantages. You might say they only offer disadvantages with decreased handling.

zydeco76
08-25-09, 10:41
I want to thank Doc and the devils advocate here. I learned a few things I would not have otherwise. Doc you are an asset to us all.

DRT
08-28-09, 17:55
I've tried to lobby for upgrading our issued duty load to a premium 180gr round like Ranger T-series or HST. Despite supplying all the references and terminal ballistics data that I could find, we're unfortunately still being issued the 165gr Gold Dot. Very disappointing.

DocGKR
08-28-09, 19:37
DRT--FWIW, I personally would not feel bad about carrying the GD 165 gr Gold Dot as a duty load, as it offers acceptable penetration, robust expansion, and reasonable intermediate barrier capability; you could do a lot worse...

crenca
08-29-09, 00:49
On a tangent, my limited testing over a chrony revealed to me Double Tap's 6.8 loads are very consistent, and about 25 fps under SSA's commercial loading. No extra flash or recoil with these loads in my experience.

I have not chronographed their .40 loads but I have noticed more percussion and the brass does travel farther than anything else I have used.

I keep a supply of their 200 grain XTP & FMJ loadings on hand for when I hike in mountain lion country here in NM. Since my G22 is the heaviest pistol I own right now, it will have to do and I like the fact that they load the 200's. Doubt I will ever have to rely on it - at least I hope.

I bet their expansion claims are based on wet phone book testing...;)

DRT
08-29-09, 16:10
DRT--FWIW, I personally would not feel bad about carrying the GD 165 gr Gold Dot as a duty load, as it offers acceptable penetration, robust expansion, and reasonable intermediate barrier capability; you could do a lot worse...

Doctor Roberts, Yes, it could be worse. I was glad to see that the 165gr load expanded more reliably than it did the last time that you tested it. At this point, I figure that it would be a better use of my time to concentrate on training (both mindset and skills) vs beating my head against the wall regarding ammo. Everyone, including myself, looks to you for guidance regarding ammo selection yet we forget your advice that training and developing a combat mindset are more import. Time for me to refocus my attention on these important items. Thanks.