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Hornady 5.56 TAP versus TAP FPD (Heavy OTM Thread)
Molon  [Team Member]
Hornady 5.56 TAP versus TAP FPD


For those interested in Hornady's 75 grain TAP loads, here are the results of a side by side chronograph test of Hornady’s 75 grain 5.56 TAP round (NATO pressure) and their SAAMI pressure 75 grain TAP FPD (For Personal Defense) round. The TAP FPD comes in a “black box” and uses “black nickel” plated cases. The TAP 5.56 comes in a “red box” and has brass cases with crimped primers and uses the new “T2” 75 grain bullet. Both bullets have a cannelure and both rounds have a crimped case neck.

The ammunition.










The cartridges.





The headstamps. Note the 5.56 round has a crimped in primer.






The 5.56 TAP uses "temperature stablized" ball powder...





...and the TAP FPD uses a short cut extruded powder.





The bullet on the left is a virgin 75 grain BTHP sold as a reloading component. The bullet in the center is pulled from a TAP FPD round and the bullet on the right is the new “T2” bullet pulled from a round of the 5.56 TAP.







The tests were conducted using an Oehler 35P chronograph with "proof screen" technology. All strings of fire for this report consisted of 10 rounds each unless otherwise noted. All of the velocities listed in this report are MUZZLE velocities and were calculated from the instrumental velocities using Oehler’s Ballistic Explorer software.
The three different barrels used in testing were:

A Colt 14.5” M4 barrel
A Colt 16” light weight profile barrel
A Colt 20” government profile barrel

All of the barrels used are chrome lined, NATO chambered and have 1:7” twists.






Here is a table showing the muzzle velocities of each load from each of the three different barrels, along with a column showing the difference in velocities between the two loads.






If you read the fine-print in the above table you'll notice that the results for the 20” barrel were obtained using 20-shot strings of fire. This was part of a test to determine the validity of using 10-shot strings of fire when chronographing. I fired a 10-shot string of each load using the 20” barrel and then a 20-shot string of each load and compared the results. For the TAP FPD the difference in the average velocity between the 10 and 20 shot strings was ONE foot per second and the standard deviations were the same! With the 5.56 TAP the difference in average velocities between the 10 and 20 shot strings was only five fps and the standard deviations only varied by one foot per second. I think this shows quite nicely the validity of using 10-shot strings for chronographing.







The Hornady 75 grain bullets are considered to have a fragmentation threshold of 2200 fps +/- 50 fps. Based on the conservative figure of 2250 fps the table below shows the range (in yards) at which fragmentation can be expected to occur for the two loads being tested. It also shows the gain (in yards) before reaching the fragmentation threshold for the 5.56 TAP load.





On my next trip to the range I will be conducting an accuracy comparison between these two loads. I’ll post those results as soon as they are available.

For additional comparison, I chronographed a few other factory loads “of interest.” Here are the results.






Lastly, for all the O.C.D. types, here are the atmospheric conditions during testing:

Temperature- 84 degrees F
Humidity - 53%
Barometric pressure – 30.02
Elevation- 960 feet above sea level
Winds – variable
Skies – partly cloudy, Jupiter aligned with Mars


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thezman  [Team Member]

Excellent work, Thanks for the data.

PocketG  [Member]
Well informative, You did a exellent job comparing.
ChuckT  [Team Member]
Thanks for the info! Excellent work, BTW!
Troy  [Site Staff]
That's a first-class comparison.

-Troy
AZ-K9  [Team Member]

Originally Posted By Troy:
That's a first-class comparison. smiley.onegreatguy.net/thumbup.gif

-Troy


+1!
SOSNBA  [Member]
All good information that correlates fairly well with my testing in 20" and 16" weapons. One correction, however, is that the fragmentation lower limit on the 75gr hornady bullet is 2200fps, not 2300fps. That's good for another 40-50yards.
Molon  [Team Member]

Originally Posted By SOSNBA:
All good information that correlates fairly well with my testing in 20" and 16" weapons. One correction, however, is that the fragmentation lower limit on the 75gr hornady bullet is 2200fps, not 2300fps. That's good for another 40-50yards.



Thanks for your reply. What is your source for the 2,200 fps fragmentation threshold?

Molon
Spooky130  [Team Member]
Thanks for the great post!
SOSNBA  [Member]
When Hornady sent me their brochure it showed effective ranges for their various loads. The effective range for the 75gr looked like it corresponded to around 2200fps.

I also found this while searching the web.

http://www.tacticalforums.com/cgi-bin/tacticalubb/ultimatebb.cgi?ubb=get_topic;f=78;t=001101#000001
wyv3rn  [Team Member]
EXCELLENT work Molon and thank you for taking the time to share it with us. First class write up all the way. And yes that is my post on tacticalforums and yes it is accurate.
AC_Doctor  [Member]
Superb analysis! Well done!!!

AC
Molon  [Team Member]

Originally Posted By wyv3rn:
EXCELLENT work Molon and thank you for taking the time to share it with us. First class write up all the way. And yes that is my post on tacticalforums and yes it is accurate.



According to your post on tacticalforums the fragmentation threshold is "2200fps +/- 50fps for manufacturing variances." Being the conservative individual that I am, I am going to go with the "+50 fps" and post a table using 2,250 fps as the fragmentation threshold. Thank-you greatly for the information.

Molon
wyv3rn  [Team Member]
Actually, I should be clear. At the time I responded to the OP, I was unaware their 5.56mm ammunition used a different bullet (the T2). I thought it was the same projectile I had always shot loaded to higher pressures. The 2200fps +/- 50fps figure I got from talking to Hornady reps was regarding their Hornady TAP Red Box 75gr .223 pressure (same projectile as used in TAP FPD). However, I reviewed the test data I have on Hornady TAP 75gr 5.56mm T2 and their claims for maximum performance range and it is the same for a given velocity.

For instance:

Hornady TAP 75gr Red Box .223 pressure from a 20" barrel:
Hornady's data: 2663fps, claimed max performance range 225 yards

Hornady TAP 75gr 5.56mm T2 from a 14.5" barrel:
Hornady's data: 2667fps, claimed max performance range 225 yards

It is possible that the BC for the T2 projectile is slightly lower (it appears less aerodynamic to me anyway but this is only an eyeballed guess and you know what those are worth) but also has a slightly lower fragmentation floor to compensate. Although, I kind of doubt it. I'm pretty sure DocGKR would've spanked me if the data was wrong.

Also, as for the BC of the "non-T2" (does it even have a name? T1?) 75gr projectile, you may want to consider my comments in this thread:

www.ar15.com/forums/topic.html?b=3&f=16&t=282084

I personally don't believe their claim of .390 BC for the current 75gr projectile used in their .223 pressure load. More like ~.340.

ETA: When I use your numbers (environmental, BC of .389/.350, velocity) in my ballistic calculator I'm consistently reaching 2300fps 8-14 yards further than where you are hitting 2300fps. Not saying my ballistic calculator is more right than yours, just wanted to add that bit of info.
Molon  [Team Member]
In another one of Rick Jamison's excellent articles in Shooting Times, he posted the results of his testing of the Black Hills 75 grain OTM load. He chronographed SIX 10-shot groups at 200 yards and determined the ballistic coefficient for each group. The overall average BC for all six groups was .352. This is incredibly close to the BC of .350 that I used for the T2 bullet.

The BC of .389 for the TAP FPD bullet does seem a little generous. Until I can do some long range chronographing of the TAP rounds (or someone else does and posts their results) I think I'll stick with these ballistic coefficients and use the more conservative fragmentation threshold of 2,250 fps. (Table to follow)
wyv3rn  [Team Member]

I think this shows quite nicely the validity of using 10-shot strings for chronographing.


It also shows how consistent Hornady's TAP ammo is. As of late, even their lot-to-lot variation is damn near, if not, nil. IMO, Hornady TAP ammunition is hands down the best factory loaded ammunition .223/5.56mm I have ever used. I don't use the FPD hardly at all though so I can't comment on it as far as consistency. I don't like the black nickel coating. I know it is probably a harmless non-issue but it appears to chip off during the firing cycle and I just don't like that when I can get the red box. Other than that what experience I did have with it was good, very accurate and shot to the same POI as the Hornady TAP 75gr Red Box .223 pressure.

I also wanted to add to my comments that this write up is missing NOTHING that I can see or think of at this time. Everything is foot noted where it should, detailed environmental conditions are given, etc. I'm a real stickler for that kind of thing. You are certainly to be commended for the quality of your work. My own notes are often messy because I have so much crammed in to one day of testing, but they are detailed and atleast I can read them just fine.
brasidas  [Member]
Nicley done. Thanks for putting all of that together.
COLE-CARBINE  [Team Member]

Originally Posted By Troy:
That's a first-class comparison. smiley.onegreatguy.net/thumbup.gif

-Troy



My first +1. Fantastic post, nice job on the layout, very easy to read and follow.
wyv3rn  [Team Member]
I believe I found that article by Rick Jamison you referenced. It is indeed a good article, thank you for the lead.

www.shootingtimes.com/ammunition/bh_080305/index.html

Notice the 80gr projectile is the only one that even comes close to a BC of .390. Personally I'd use the average BC of .353 for the Hornady 75gr "T1" for both projectiles for now. I know the barrel the projectile is fired from and the velocity at which it travels effects the BC of the projectile (all barrels mark and launch the bullet differently) but it shouldn't be too much difference and .353 is a hell of a lot closer to the real mark than .390 IMO.

ETA: He used a Krieger 1:8 match barrel for his tests of the BH 75gr load which had a muzzle velocity of 2744-2834fps. On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more. In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.
DevL  [Member]
It is my understanding that much like M193 traveling through the 2700 to 2500 fps range that the Hornady 75 grain OTM bullet fragment violently at 2300 and above and fragment less (can still break at cannelure) and with less reliability down to 2100 fps. This would be an average of 2200 fps for a performance envelope. Right?

What range was the chrono measurement taken at? Did you add that range back to the fragmentation range when you gave it or jaust base it off the chrono speed minus velocity lost at range?

Where did you get the BC for the T2 bullet? EDIT: I SEE NOW ITS JUST A GUESS... does Hornady not have the BC info for the projectile? Are you brave enough to put your chrono out at 100 yards and take some measurements?
DevL  [Member]

Originally Posted By wyv3rn:

On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more. In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.



Where did you get this data? I know in other calibers with high velocities and thin jackets people will NOT use cut rifled barrels because they will cause enough jacket damage to casue the projectile to break up. So your claim is just the opposite of what I have heard from some other long distance shooters. I am just repeating what I heard so I wondered whre the data comes from/what the real truth is.
wyv3rn  [Team Member]

Originally Posted By DevL:
It is my understanding that much like M193 traveling through the 2700 to 2500 fps range that the Hornady 75 grain OTM bullet fragment violently at 2300 and above and fragment less (can still break at cannelure) and with less reliability down to 2100 fps.



My understanding is this.. The reliable fragmentation floor is 2200fps +/- 50fps for manufacturing variances. This means all will _reliably_ fragment at 2250fps, but some lots may fragment reliably down to 2150fps. When the velocity is lower than, but relatively close to the reliable fragmentation floor, whatever it may be for that lot, fragmentation is possible, but a crap shoot (unpredictable). I suspect by manufacturing variations they mean the exact composition of the copper jacket, the lead core, jacket thickness, cannelure depth, exact gel calibration, what the individual barrel does to the bullet, etc. All of these things have tolerance ranges and vary atleast a little. If you had one lot with all the tolerances stacked in one direction and another lot with all the tolerances stacked in the other direction I could see how there could be a 100fps range of variation in reliable fragmentation floor. Match projectiles even vary in weight by a tiny fraction of a grain here and there. I am aware of some testing on the Nosler 77gr in which it fragmented as low as ~2050fps but it was not considered a reliable fragmentation floor because it was not tested across multiple lots and not more than a few times at velocity.

ETA: We must also remember that the whole 2200fps +/- 50fps figure almost definitely follows a Gaussian distribution where, for example, 80% of the lots are actually something like 2200fps +/- 25fps, but the remaining 20% stretch the figure to 2200fps +/- 50fps. In construction/manufacturing actual far-end to far-end variances are relatively (<-key word) uncommon and variable items (such as jacket thickness or the thickness something must be machined to, etc.) are somewhere in the middle 25%-75% of their tolerance range a majority of the time.


What range was the chrono measurement taken at? Did you add that range back to the fragmentation range? Where did you get the BC for the T2 bullet? EDIT: I SEE NOW ITS JUST A GUESS... does Hornady not have the BC info for the projectile? Are you brave enough to put your chrono out at 100 yards and take some measurements?


He said he did add the velocity difference back to his muzzle velocity. I don't know about the fragmentation range. Maybe that's why I am getting 8-14 yards further on the fragmentation range on my ballistic calculator using his numbers (me starting with his muzzle velocity, him starting with his chrono'd velocity)? It could just be differences in the calculators' algorithms though. Hornady does have their claimed BC info for the Hornady T2 bullet, it is listed in their LE catalogue.
wyv3rn  [Team Member]

Originally Posted By DevL:

Originally Posted By wyv3rn:

On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more. In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.



Where did you get this data? I know in other calibers with high velocities and thin jackets people will NOT use cut rifled barrels because they will cause enough jacket damage to casue the projectile to break up. So your claim is just the opposite of what I have heard from some other long distance shooters. I am just repeating what I heard so I wondered whre the data comes from/what the real truth is.



Also just repeating what I've heard quite awhile ago, but FWIW I did hear this from a knowledgable match grade barrel maker. I've talked to a handful over the years and I don't recall who it was that said that. I know there is a conflict of interest here but none that I've talked to are known to be liars. After seeing some bore scopes of true match grade barrels vs. standard grade for myself, I can definitely believe it. Up close one's interior is smooth as glass the other looks like the Colorado rockies by comparison.
DevL  [Member]
Im not talking match vs milspec I am talking cut vs button rifled. Example... Which deforms the bullet less, a single cut Krieger or a button rifled PacNor?
Yojimbo  [Team Member]
Excellent post, thanks for sharing this info!
Molon  [Team Member]
The ballistic coefficients that I used were not “guesses.” As stated in my first post, they were estimations extrapolated from Hornady’s ballistics tables. For example, Hornady gives the following information in their ballistic table for the 75 grain TAP FPD round.

Muzzle velocity: 2790 fps
Zero: 200 yards
Trajectory at muzzle: -1.5” (height of sights above the bore line)
Trajectory at 300 yards: -8.30”

Since no atmospheric conditions are given I used the “Standard Atmospheric Conditions” for ballistics.* Punching the first three data points into an exterior ballistics calculator program and adjusting the ballistic coefficient until the trajectory matches -8.30” at 300 yards yields a ballistic coefficient of .389.



*Stand Atmospheric Conditions for ballistics.

Altitude: Sea level
Barometric pressure: 29.53 inches Hg
Temperature: 59 degrees F
Relative humidity: 78 percent
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