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10/30/2020 2:42:12 PM
Posted: 12/22/2003 1:16:57 AM EDT
Does anyone know the average velocity out of a 16" barrel for Black Hills 68 grain OTM?  What is the lowest speed the round can reach and still reliably fragment?  At around what distance does this occur?  
Link Posted: 12/22/2003 6:37:09 AM EDT
I'm not sure of the velocity, but I've heard from reliable sources that this round will fragment out to about 200 yds
Link Posted: 12/22/2003 6:57:00 AM EDT
I can't find my results on a 16", but on an 18" it was 2816fps @10'.  IIRC velocity was in the hgh 2700s.  

IIRC it is mentioned in Dr Roberts paper: [i]"Law Enforcement General Purpose Shoulder Fired Weapons, The Wounding Effects of 5.56mm/.223 Carbines Compared With 12 ga. Shotguns and Pistol Caliber Weapons Using 10% Ordnance Gelatin as a Tissue Simulant", Gary K. Roberts, The Police Marksman, pp. 38-45, July/August 1998.[/i]

My copy is at home - but perhaps one of the other site members has their copy handy.

Link Posted: 12/22/2003 9:03:48 AM EDT
The 68gr Hornady bullet still fragments down to 2350fps.  However, I do not know how severely.  If anyone finds out/knows, please share.
Link Posted: 12/22/2003 12:37:49 PM EDT
[Last Edit: 12/22/2003 12:38:34 PM EDT by DevL]
Originally Posted By Artifex:
I'm not sure of the velocity, but I've heard from reliable sources that this round will fragment out to about 200 yds
View Quote


Not from a 16" barrel.  It will barely be over 100.  It MIGHT make 150 but no further.
Link Posted: 12/22/2003 1:24:31 PM EDT
Originally Posted By DevL:
Originally Posted By Artifex:
I'm not sure of the velocity, but I've heard from reliable sources that this round will fragment out to about 200 yds
View Quote


Not from a 16" barrel.  It will barely be over 100.  It MIGHT make 150 but no further.
View Quote


55gr M193 fragments out to 100y from a 16" barrel, no problem.  150y if you count breaking in half as fragmenting.  68gr should be a bit further than that if loaded to the same pressure spec.
Link Posted: 12/22/2003 1:54:47 PM EDT
Originally Posted By wyv3rn:
Originally Posted By DevL:
Originally Posted By Artifex:
I'm not sure of the velocity, but I've heard from reliable sources that this round will fragment out to about 200 yds
View Quote


Not from a 16" barrel.  It will barely be over 100.  It MIGHT make 150 but no further.
View Quote


55gr M193 fragments out to 100y from a 16" barrel, no problem.  150y if you count breaking in half as fragmenting.  68gr should be a bit further than that if loaded to the same pressure spec.
View Quote


The problem is the factory loading is not to milspec pressures.  I would assume the range is probably the same as M193 then.  However, would the round fragment more violently than M193 at the same distances with the factory loading?
Link Posted: 12/22/2003 2:25:33 PM EDT
Originally Posted By knightone:
Originally Posted By wyv3rn:
Originally Posted By DevL:
Originally Posted By Artifex:
I'm not sure of the velocity, but I've heard from reliable sources that this round will fragment out to about 200 yds
View Quote


Not from a 16" barrel.  It will barely be over 100.  It MIGHT make 150 but no further.
View Quote


55gr M193 fragments out to 100y from a 16" barrel, no problem.  150y if you count breaking in half as fragmenting.  68gr should be a bit further than that if loaded to the same pressure spec.
View Quote


The problem is the factory loading is not to milspec pressures.  I would assume the range is probably the same as M193 then.  However, would the round fragment more violently than M193 at the same distances with the factory loading?
View Quote


Hard to say.  Despite the lower pressure loading of the 68gr, giving it the same (approximately) fragmentation distance as 55gr mil-spec, there are still benefits:

1.  It's still match ammunition, and will be more accurate than mil-spec 55gr.
2.  It begins it's yaw and fragmentation cycle much earlier @ about 1-2" instead of 3-4".
3.  There is just more material there TO fragment, so even if they both fragment 50% (largest fragment recovered is 50% of the bullet's weight) the 68gr is going to have a larger overall mass of fragments.  So I guess the question to your answer is PROBABLY yes.

The only drawbacks are:

1.  More expensive.
2.  Slightly more arched bullet path, which is so insigificant it's hardly worth mentioning, but I do for completeness.
Link Posted: 12/22/2003 6:25:44 PM EDT
The Doc posted some info on 68 grain frag % on tactical forums.  Its less than 69 grain but more than M193 if my memory serves me correctly.
Link Posted: 12/22/2003 9:47:45 PM EDT
Originally Posted By Forest:
IIRC it is mentioned in Dr Roberts paper: [i]"Law Enforcement General Purpose Shoulder Fired Weapons, The Wounding Effects of 5.56mm/.223 Carbines Compared With 12 ga. Shotguns and Pistol Caliber Weapons Using 10% Ordnance Gelatin as a Tissue Simulant", Gary K. Roberts, The Police Marksman, pp. 38-45, July/August 1998.[/i]
View Quote


BH 68gr 2615fps, 53.6% fragmentation, don't have time to type out the rest.  As I recall, people have posted wildly different numbers for BH ammunition over the years, seems their velocities go up and down sometimes.
Link Posted: 12/23/2003 9:10:04 AM EDT
I wish Brou and Tat would do a fragmentation test on a selection of BH factory loads.  Will there ever be another fragmentation test from B&T labs?
Link Posted: 12/23/2003 12:19:33 PM EDT
I dont even know if Tat is in the US anymore.  I think Brouhaha is more interested in doing tests on the 6.8 than 68 and 69 grain.  I am pretty sure all his 5.56 barrels are 1/7 so he wont have to shoot those loads anyway. [;)]
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