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Posted: 8/14/2006 10:10:07 PM EDT
[Last Edit: brasidas]
[#1]
It appears to be crimped (?). A fresh round is on the left; the blown case is on the right. 
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Posted: 8/16/2006 3:41:45 PM EDT
[Last Edit: Molon]
[#2]
Sounds like you may have had a squib load just before the overpressure round. Do all Bushmasters have NATO chambers? |
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Posted: 8/16/2006 5:40:22 PM EDT
[#3]
Yikes. I was thinking the excessive pressure locked up the bolt for too long. I am just not sure if the weakly ejected round was the blown shot or the one before. 
They claim all of the chrome lined ones do, and this one is chrome lined. |
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Posted: 8/18/2006 2:26:29 AM EDT
[#4]
Nice pic, thanks for posting it. Molon |
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Posted: 8/18/2006 4:24:17 AM EDT
[#5]
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NE, USA
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Posted: 8/18/2006 6:24:41 PM EDT
[#6]
How old are they? I'm pretty sure on older ammo the first 2 digits of the lot number represents the year. Have you shot any? |
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Posted: 8/19/2006 11:04:07 PM EDT
[Last Edit: Molon]
[#7]
On the rare occasion when I crimp the bullet in place during reloading I prefer to use the Redding taper crimp die also. I have yet to find a crimp die that does a better job. Using a K&M arbor press fitted with a compression gauge (see the pic below) I am able to measure, in pounds per square inch, the force necessary to cause a bullet to set-back in the case. Hornady’s 5.56 TAP round requires about 30 psi to cause the bullet to start to set-back into the case. With the application of 30 psi the bullet will travel about 0.020” into the case and at that point the case mouth snags on the upper shoulder of the cannelure. It requires another 60+ psi , for a total of 90+ psi, to push the top shoulder of the cannelure down into the case neck and force the bullet to set-back all the way into the case. Using Redding’s taper crimp die, I have been able to duplicate a crimp having approximately the same specifications as noted above when loading my 75 grain TAP clones. It really only takes a very light crimp to accomplish this. Here is a picture of one of my 75 grain hand-loads with a taper crimp next to a round of Hornady’s 5.56 TAP.  compression gauge used to measure bullet set-back 
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Posted: 8/20/2006 11:44:31 PM EDT
[#8]
CLASSIC squib. Check the barrel for a "ring" before shooting it any more... either outside the barrel or a dark ring in the bore. |
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Posted: 8/21/2006 8:44:27 PM EDT
[Last Edit: Molon]
[#9]
TAP porn.
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Posted: 8/22/2006 11:34:33 AM EDT
[#10]
Reading Bushmaster's reveiw here it sounds to me like their 40 gr. bullets would be the best thing for inside your house. I wonder if anyone knows how it would perform out of a 1:7 twist barrel.
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USA
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Posted: 8/22/2006 2:56:28 PM EDT
[#11]
"Intended primarily for situations where its' limited penetration, extreme fragmentation and reduced ricochet potential are desired." Limited penetration from a 40-gr. varmint bullet can get you killed. You're much better off with the 75-gr. that doesn't overpenetrate like most folks think it does.
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IN, USA
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Posted: 8/22/2006 3:13:48 PM EDT
[Last Edit: INTrooper4255]
[#12]
I've got a mag full of 60 grain TAP for my AR inside the house, and I wouldn't want to go any lighter than that. My duty rifle's mags are loaded with the 62 grain TAP barrier round, which is a jacketed SP.
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Posted: 8/22/2006 10:28:01 PM EDT
[Last Edit: Molon]
[#13]
The 40 grain TAP would probably show no discernible difference in terminal performance out of a 1:7" twist barrel, but you may want to read Dr. Gary Roberts' recommendations for defensive ammunition....click here |
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Posted: 8/23/2006 10:47:34 AM EDT
[Last Edit: Molon]
[#14]
More TAP porn.
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Posted: 8/25/2006 6:56:05 PM EDT
[Last Edit: Molon]
[#15]
Here are some results of ballistic gelatin testing of Hornady’s 40 grain TAP ammunition. These results were published in the December 1998 issue of Tactical Shooter magazine (out of print) in an article by M.L. McPherson. Fired from a 16” Bushmaster with a 1:9” twist and a muzzle velocity of 3370 fps, the 40 grain TAP round had a total penetration depth of 5.70” and a maximum temporary cavity diameter of 4.70”. When fired from a 14.5” SIG 551 with a 1:7” twist and a muzzle velocity of 3295 fps, the 40 grain TAP round had a TPD of 5.85” and a MTCD of 5.55”. Although this is not exactly an apples to apples comparison due to the 75 fps difference in muzzle velocities, note the lack of penetration depth in both instances. |
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Posted: 8/25/2006 10:52:36 PM EDT
[#16]
Molon,
Have you been able to find out any more differences between the T1 amd T2 projectiles (other than what you described earlier)? Thank you. Justin |
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Posted: 8/26/2006 3:58:46 AM EDT
[#17]
Tack-Fu is weak
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Posted: 8/27/2006 12:26:43 AM EDT
[Last Edit: Molon]
[#18]
I recently pulled several of the T2 bullets from the cases to measure the length of the individual bullets and was amazed to find they only varied by a few thousandths of an inch. Sierra 77 grain MatchKings for example, can easily vary by over 10 thousandths of an inch in length. I'd swear Hornady must be using a meplat uniformer on the T2 bullets. Here is another close-up of the T2 meplats.  |
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Posted: 8/28/2006 6:18:38 PM EDT
[Last Edit: Molon]
[#19]
Here are some "gel shots" of 40 grain, 55 grain and 75 grain TAP.
   These images are from the article "Terminal Ballistics; A Critical Consideration" by M.L. McPherson published in the December 1998 issue of Tactical Shooter (out of print). |
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NE, USA
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Posted: 8/30/2006 7:20:07 PM EDT
[Last Edit: Thunderbolt882]
[#20]
I'm guessing that's just the 2279 match or 2279 w/ cannelure, I'd like to see how the 5.56 T2 compares in ballistics gel.
It also makes you question the use of 75 grain TAP for home defense, considering the 75 grain bullets required 2 blocks of gel. 
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USA
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Posted: 8/30/2006 9:32:12 PM EDT
[Last Edit: 147_Grain]
[#21]
Hornady T1 and T2 bullets perform the same in gelatin (with or without cannelure), providing the velocities are the same. T2 projectiles are supposed to help with slightly improved feeding. The Hornady 75-gr. BTHP usually only penetrate 13 1/2" in gel and doesn't penetrate as much as most folks think - due to the thin Match-grade jacket that easily fragments / yaws sooner than other projectiles.
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NE, USA
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Posted: 8/30/2006 10:11:02 PM EDT
[Last Edit: Thunderbolt882]
[#22]
What we're seeing in the picture is gonna be the match bullet (With cannelure? Otherwise the exact same bullet.) loaded to SAAMI specs, since it would be a couple years before the T2 appears.
I'd like to imagine the 8126N with it's own bullet and extra boost of 5.56 behind it would increase penetration a bit. 
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Posted: 8/31/2006 11:26:32 AM EDT
[#23]
The Hornady TAP 75gr depicted in Molon's most recent picture would be Hornady's pre-2003 75gr projectile without a cannelure. The terminal performance of the "T1" and T2 projectiles are not identical, but they are very similar. Also, when speaking of match bullets, the "extra boost of 5.56 behind it" is often more likely to increase fragmentation and reduce penetration. My problem with calling the most recent Hornady 75gr projectile that is shipped publicly the "T1" is that it was actually changed in 2003. It really should be "T1 Rev. A" and "T1 Rev. B" or something similar. Again, all 3 iterations of the Hornady 75gr projectile have similar terminal ballistics. With the 75/77gr match projectiles, cannelure does not come into play to any significant level when speaking of terminal ballistics. Also, a proper cannelure, in and of itself, does not destroy accuracy as I've seen a few say on this forum lately. It will change the BC, but should have very little, if any effect on accuracy. Blame bad crimps, inconsistent powder measure, bad load developement (unsuitable/nonoptimal powder/primer selection), overpressure, etc. I've shot Hornady TAP 75gr cannelured & non-cannelured loads and cannelured & non-cannelured versions of both Black Hills Blue and Red Box 75gr side by side. No significant change in accuracy was ever observed or recorded. A cannelure+crimp has one purpose, to help prevent setback in self-loading firearms. It does it very well. Using a non-cannelured projectile in 5.56 pressure ammunition in a self-loading rifle is just asking for trouble to bite you one day when you least expect it. You know why there is a Mk262 Mod1? Because the Mod0 didn't have a cannelure and problems DID arise. Mk262 was designed for a precision version of the AR15/M16-pattern rifle. They did not want to add a cannelure if they didn't have to. The cannelure is not a fix for an imaginary problem. |
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TX, USA
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Posted: 8/31/2006 2:42:43 PM EDT
[#24]
Yes thats correct the old 75 grain bullet was actually longer than the 77 grain SMK. It had slipped my mind. Odd noone mentioned that before now.
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Posted: 8/31/2006 4:52:27 PM EDT
[Last Edit: Molon]
[#25]
Excellent points. The current T1 bullets have a nominal length of about 0.980" - 0.990". The T2 bullets that I have pulled from the lots I have are running around 0.974". The pre-2003 bullet that you and DevL refer to had a nominal length right around 1.000". Let's take your "rev A, rev B" concept a little further. Why not refer to the pre-2003 projectile as "T0". (T-zero) We could then refer to the current T1 bullets as T1 rev A (no cannelure) and T1 rev B (with a cannelure). Naturally the 5.56 projectile would still be called the T2. |
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Posted: 8/31/2006 5:20:56 PM EDT
[#26]
I talked to Hornady today. They still carry the 223 75 grain TAP # 80265. It runs the same price as the NATO 5.56 TAP.
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Posted: 8/31/2006 5:51:47 PM EDT
[Last Edit: wyv3rn]
[#27]
DevL, I did mention that it was changed in 2003 earlier in the thread when we were trying to figure out the real BC of the projectiles.
 Molon, I like your T0 (pre-'03), T1 (current), T2 (5.56) designations better than my T1 Rev. A/B. However, I do not like calling the T1 Rev. A/B simply because one has a cannelure. They are the same projectile. To call them Revision A/B implies a difference other than the addition of a cannelure in my book. The T1 was never revised and is still available both w/ and w/o a cannelure. I can just see it now.. 10 threads asking what the difference is between a Rev. A and B Hornady T1 projectile. Then people getting mixed up as to which is A and which is B and giving incorrect data in their reports, chorono results, etc. I'd just call it T1 w/o cann or T1 w/ cann to keep communication less murky. My $.02. You are correct on the length of the Hornady 75gr T0 @ .995"-1.000". They are also easy to spot vs. the new Hornady T1 because the boattail is visibly longer and the meplat diameter smaller. I cannot confirm the T0 was longer than the 77gr SMK but I can confirm the T0 was longer than the Nosler 77gr and the Hornady 75gr T1 is almost exactly the same length, maybe even .005" longer than the Nosler 77gr. |
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Posted: 8/31/2006 6:12:06 PM EDT
[Last Edit: Molon]
[#28]
I started thinking the same thing after I posted that. I guess just T1 and T1 with cannelure would be more self explanatory and therefore less confusing. |
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NE, USA
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Posted: 8/31/2006 6:24:56 PM EDT
[#29]
The current BTHP match bullet is the 2279. The proper designation for the 75 grain BTHP w/ canneulure is 2279C, the "T" refers to the bullet's profile which is exactly the same as the 2279 match, and it's not "1." There was no "change" in 2003, it is still availible (though not publicly as a reloading component, industry partners only). The T2 (I don't know it's part number) is a completely different bullet, it never replaced anything. |
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Posted: 8/31/2006 6:40:18 PM EDT
[Last Edit: wyv3rn]
[#30]
This is the one used in Hornady's .223 pressure match & TAP loads.
Actually the projectile used in Hornady TAP 5.56mm 75gr is designated the "T2". To my knowledge, Hornady does not refer to the projectile used in their .223 TAP by any "T" designation. This forum started that by calling it what seemed logical - "T1".
What is still available? The pre-2003 Hornady 75gr 2279/2279C projectile is still available through Hornady? Are you sure about that? I was told it was gone for good.
True and I never claimed it did. For simplicity sake and the fact that T1/T2 is already commonly accepted language/designations on ar15.com, I do not see a problem continuing to refer to them as T0/T1/T2 for the sake of communication. Most will know clearly what you are speaking about, but many do not know what Part #2279 is. The 2279C did give me an idea though.. Molon, how about T1 and T1c? 
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NE, USA
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Posted: 8/31/2006 6:44:07 PM EDT
[#31]
To be honest it's actually T4.
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Posted: 8/31/2006 6:48:01 PM EDT
[Last Edit: wyv3rn]
[#32]
You are confusing me by referring to everything in non-specific terms such as "it". We have 3 different Hornady 75gr projectiles we are talking about. I know it seems redundant but I try to refer to them by name each time I reference them for this very reason.
"T2" - Current Hornady 75gr projectile used exclusively in Hornady TAP 5.56mm 75gr. "T2" designation given by Hornady. "T1/T1c" (2279/2279C) - Current Hornady 75gr projectile sold to manufacturers and used in Hornady .223 pressure TAP. AR15.com members required a way to reference this projectile specifically. "T1" seems a logical designation as it is a play off Hornady's own "T2" designation. "T0" (old 2279/2279C)- Pre-2003 Hornady 75gr projectile sold to manufacturers and used in Hornady .223 pressure TAP. AR15.com members required a way to reference this projectile specifically. "T0" seems a logical designation as it is a play off Hornady's own "T2" desgination. |
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NE, USA
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Posted: 8/31/2006 7:03:25 PM EDT
[Last Edit: Thunderbolt882]
[#33]
Here we go:
There's no "T0". It's actually the 2279C, see below. Your T1/T1C, are the 2279 and 2279C, as follows: T2, part number unknown. |
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Posted: 8/31/2006 7:16:29 PM EDT
[Last Edit: wyv3rn]
[#34]
Ok, now we are getting somewhere. 1. You are correct in that there is no projectile truly named "T0" but there IS a previous version of what is now the 2279/2279C projectile. It had the same part # of 2279/2279C. That is nice and all from a supply/dealing/booking standpoint, but when we are trying to discuss the two, we need a way to distinguish between the pre-2003 #2279/2279C and the current #2279/2279C projectile. 2. Ok, part #2279/2279C, commonly referred to on ar15.com as "T1/T1c" is actually "T4" profile. Good to know. 3. Agreed. |
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Posted: 8/31/2006 8:49:29 PM EDT
[#35]
It's short and to the point. That works for me. I wish I had saved some of the longer pre-2003 projectiles so I could include them in the picture.  |
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Posted: 8/31/2006 11:42:35 PM EDT
[#36]
Are the Moly Coated 75g Match pre-2003?
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NE, USA
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Posted: 9/1/2006 6:08:26 AM EDT
[Last Edit: Thunderbolt882]
[#37]
Mine are 1998. I'll see if I can pull one.
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TX, USA
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Posted: 9/1/2006 7:48:26 AM EDT
[#38]
Refresh my memory! What was thr eason for the T2? The ogive? Better performance in the 1/9" barrels?
hinking.gif Mick |
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TX, USA
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Posted: 9/1/2006 8:51:02 AM EDT
[#39]
Reliable loading.
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Posted: 9/1/2006 9:34:34 AM EDT
[#40]
 man. Why is it that Civilians can't purchase 5.56TAP (T2) stuff again?Arfcommers have M885 stuff onhand, so what's the deal? |
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Posted: 9/3/2006 8:29:20 PM EDT
[Last Edit: Molon]
[#41]
I came across a few more "gel shots" for comparison.
SAAMI pressure Hornady 75 grain OTM from a 16" barrel  NATO pressure Sierra 77 grain OTM from a 16" barrel.  NATO pressure Nosler 77 grain OTM from a 20" barrel.  (No author was credited for these images in the pdf file I obtained them from, but they sure look like the work of Dr. GK Roberts.) |
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Posted: 9/3/2006 10:56:33 PM EDT
[#42]
Nail, head, hit. |
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Posted: 9/4/2006 10:24:47 AM EDT
[#43]
I like the TC start of the 77 gr Nosler.
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Posted: 9/4/2006 10:26:56 AM EDT
[#44]
Worth a shot, all they can say is no. Hornady LE rep Kathy McHale (800) 338-3220 x200
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TX, USA
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Posted: 9/4/2006 9:53:14 PM EDT
[#45]
I have never seen the neck of the Sierra 77 be that low. Wish we had some photos of the 5.56 TAP.
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TX, USA
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Posted: 9/4/2006 9:56:28 PM EDT
[Last Edit: DevL]
[#46]
Arfcommers have all the 5.56 TAP they want. There is litteraly noone that participates in the ammo forums who has ever expressed an interest in having the ammo and was actually willing to buy it that does not have it. Dont get me started on this subject. |
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NE, USA
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Posted: 9/4/2006 9:56:39 PM EDT
[#47]
If a team member can go back and find my thread which had scans of the Police Marksman article on 5.56 TAP it had a picture of a gel test.
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Posted: 9/5/2006 12:52:50 AM EDT
[#48]
Thunderbolt882, Are you referring to the article entitled "Hornady Law Enforcement Rifle Ammunition: New Products in 5.56mm and 6.8 SPC"? If so, that article unfortunately only has a picture of a gel shot from the 6.8 SPC. Molon |
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Posted: 9/5/2006 1:41:45 AM EDT
[#49]
tag- got a case of this on the rack
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Posted: 9/6/2006 11:24:00 AM EDT
[#50]
Here are some amazing gel-shots filmed using high speed photography showing the temporary cavity in full expansion.
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