tat and brou are both young and healthy...the little brats.

Tatjana, Brouhaha, et al...

Nifty charts.  One question.  I see that the Gree/Yellow/Red coding is based on various velocities for the rounds, i.e. the 55 gr ones go with a 2700fps/2500 fps threashold, the "heavies" for a 2300fps, etc.

Is this based on testing in gelatin for "ideal terminal effects" and "marginal terminal effects", on an energy claculation based on velocity and weight of the round, or on some ancedote numbers i.e. "2700 is good"?

Dawg

Wait a minute...

I thought that Fed/LC XM193 and Winchester/IMI Q3131A wre both M193 derivatives and should therefore be using essentially identical bullets. So how's come we end up with Q3131A having a much hgher BC than XM193?

Thanks.

SD

Quoted: Wait a minute... I thought that Fed/LC XM193 and Winchester/IMI Q3131A wre both M193 derivatives and should therefore be using essentially identical bullets. So how's come we end up with Q3131A having a much hgher BC than XM193? Thanks. SD

Q3131A's BC is directly from Winchester's catalog.

Lots of things on M193 can be different. Size and shape of cannelure... etc.

Ah ha...

One more thing added to the seemingly infinite library of things I either don't know or misunderstand.

Thanks.

SD

We don't have any clue WHERE these BCs apply.

Are they averages of the BCs at velocities between muzzle and the supersonic line?
Are they averages of the BCs down to 2500fps?
Are the BCs just at the muzzle velocity?

Actually, Sierra publishes a series of BC's for various velocities for each bullet. These aren't perfect tables as I've seen the numbers for various bullets changed from time to time; apparently the result of data correction. However, they do seem to me to be the most reliable of the commercially available data.

www.sierrabullets.com/bullets/index.cfm?fuseaction=Ballistic

Dang it! Can't remember how to make a link hot and the Board Code thingy isn't working.

SD

.272 @ 3000 fps and above
.245 between 3000 and 2400 fps
.235 @ 2400 fps and below

Wow, that extra 1.5" makes a big difference, huh?

How would I calculate fragmentation out of an 18" barrel? Would I just take the average of the 16" and 20"?

Quoted: 18" velocities

Much appreciated

Mavrick and I had a discussion a few months ago (here) where we used a Powly Calculator to extimate M193 muzzle velocities out of multiple barrel lengths.

Here's what we came up with:

A'ight, I downloaded an excel worksheet for the Powley Calculator and plugged in data and measurements to get what appears to be M193 out of it. I had an unknown variable (Water Capcity of Case), so I fiddled with it and calibrated it to both the BM and blickbok data.
Here's what I got:

BBL   BM    PC    Orig BM  Orig PC   BBL   BM    PC    Orig BM  Orig PC
2     1035  1003  983                13.5  2972  2881
4     1925  1866  1888               14    2998  2906  2909
6     2324  2253  2275               14.5  3022  2929  3064     2931
8     2575  2496  2513               16    3087  2993  3132     2992
10    2753  2668  2739     2680      18    3163  3066  3063
11.5  2858  2770  2872     2779      20    3229  3130  3259     3123
12    2889  2800  2808               22    3272  3172  3176
12.5  2918  2829                     24    3337  3235  3315     3223
13    2946  2856                     26    3382  3279  3391     3265

Granted, these numbers are estimated based on a rough calibration to blikbok's data, and measuring ammo specs from a diagram, so they're not perfect, but they're also probably not too terrible, either.

and

here's a graph of calculated muzzle velocity to barrel length in 0.5 inch incriments from 1.5 to 24 inch barrels with M193 ammunition:

Barrel length to velocity from 16 to 24 inches actually looks prettty darn linear. Anything shorter than 14.5" unreliably fragments past 75 yards (yes, we knew that before this little experiment). I would love to see similar data with the Mk262 mod 1 ammunition, though. I'd also love to see it corroborated with field testing. Now, if only I have rifles in those configurations and about 150 rounds each to test it ...

Quoted: <snip>

Thank you for brining this great XM193 data up

Yes I do hope this kind of data is available for BH 68/75 or Mk262 loadings.

Generally it seems to me that carbines tend to benefit more from higher velocity than higher BC, while rifles benefit more from BC. (if both are high, then best of both worlds; which is what Mk262 Mod1 is. I really hope BH makes this a standard carry item)

16" data for Black Hills 75gr and Mk262 Mod1 has been corrected.

Thanks to brouhaha for posting Mk262 Mod1 MV from 14.5", 16" and 20" barrels.

The chart here is still "simulated" until I can get a more concrete data on BH 68 and BH 75gr. All others are backed by real world experimentation figures.

So, uh ... anyone have data how those higher-weight loads (68, 75, and 77gr) perform out of a 9, 11.5, and 12.5 inch barrel (to relate it to the XM-8 and M4 Commando)?

Quoted: 2.  A pointer to the best ballistic calculator software out there right now.  We've been using java junk for too long.  Anyone have any suggestions as to what is best and why?  Something that actually knows that using one BC out to 500 is a bad idea.

I use JBM Ballistics Calculator.  It's still web based, but seems to be pretty complete.  At least it lets you specify the drag function for the BC, and also allows for atmospheric conditions.  It has the BC calculator from velocities too.

great for referrence!!

Funny how changing ammo changes frag range so differently for different barrel lengths.  Like Q3131A gains 5 yds over M193 in a 20" but loses 5 yds in the 16 & 14.5".  But even weirder is that the 77gr gains just 5 yds over 75gr in a 20" but 35yds in a 14.5"!  Must be powder rates or something changing the releative velocities....


I did some chrono testing this weekend:
Gun was a 16" RRA upper, 1/8 twist.  Screens at 10 ft.  Upper 80s and very humid.  

Q3131A
lot:  TG61
2 shots
Avg: 3167.6,  SD: 2.6,  ES: 3.7
Hi/Lo: 3169.5/3165.8

Black-Hills 68gr
lot:  2606171283
5 shots
Avg: 2694.7,  SD: 13.3,  ES: 34.3
Hi/Lo: 2706.3/2672.0
10 shots
Avg: 2699.5,  SD: 16.0,  ES: 45.5
Hi/Lo: 2721.0/2675.5

Black-Hills 75gr
lot:  1701120783
5 shots
Avg: 2632.2,  SD: 41.8,  ES: 111.0
Hi/Lo: 2680.0/2569.0
10 shots
Avg: 2641.2,  SD: 13.9,  ES: 45.5
Hi/Lo: 2667.5/2642.0

The two rounds of Q3131A were all I had with me, they were leftovers from a different day.  The two different strings for the BH ammo is because I shot 5 over the chrono without worrying about groups, then since I had time I shot 2 groups of 5 at a target and left the chrono set up.

Somewhere I have some numbers for 68gr out of a 20" barrel.  I'll post them if I can find them.

Thanks Mike_L :)

I'm getting convinced more and more that BH 68 gr seems loaded lighter than other SAMMI loadings.

Mav-
Nicely done. We should send this info out to all the USMC and SF grunts who are slugging it out in Iraq and Afghanistan right now and reissue them some of those millions of surplus M-14s until the new 6.8 SPC round is issued. Good job, dude. Phoenix 27

Howabout something for the 308?

Ben

voilsb: Glad I could help.  I think the Powley calculator takes some incredible shortcuts, and doesn't jive well when I use small, high-pressure rounds.

www.mindspring.com/~sfaber1/powley.htm

The calculator assumes a fixed loading density of 86% of the case volume and a peak pressure of 45K psi. ... In summary the Powley velocity equation is a simple instantaneous burn, frictionless, adiabatic expansion solution, where the constant K is adjusted to suit an average of experimental results.

The page has some basis for the actual math, and we might be able to tweak the Powley with different assumptions.

Great info.

But one thing appears to be missing from the discussion.  If it's there and I missed it, I apologize.

What about barrel twist?

I guess since most of the new ARs have 1/9 or 1/7 twist, that is the basis for most of this data.  But as I understand it, barrel length and resulting velocity are not the only hardware factors affecting fragmentation of M193; rifling twist has an effect as well.

I've read that 55g M193 coming out of an old 20-inch, 1/12 twist M16, will fragment more than the same round coming out of an M16A2's 20-inch 1/7 barrel, because the round will be less stable.  That's why some guys thought they made the M16 "less deadly" when they went from the 1/14 twist to the 1/12.

I guess it doesn't make a world of difference but I just wanted to mention it.

Personally, since M855 is likely to be more available in a future SHTF scenerio, my "grab and go" rifle is my 14.5-inch AR15 with a 1/9 twist.  On my ammo belt I have three mags full of M193 for 100 yards and less and three mags full of M855 for "long range" or vehicle/heavy cover work.

Good shooting.

Tissue is way too dense for the bullet to remain stable after impact, no matter what twist rate it started at.  That's an old myth from before terminal ballistics were studied scientifically by people like Fackler that just won't die.  Read more about it here: www.ammo-oracle.com/body.htm#tighttwist

Thanks for the info!

2 questions if I may:


First,  I noticed that you recommended the 155 AMAX for .308.  

AMAX are plastic tipped, aren't they?   So, in a .30 caliber,  the plastic-tipped rounds, though designed to fragment rapidly, must have pretty good penetration as well, right?  (as opposed to a .223 with plastic tip, which I've been told does not penetrate adequately for targets larger than woodchucks.)  Is any .30 caliber data available on the Oracle?  

Q #2:

When a .223 bullet which has traveled beyond its reliable fragmentation range strikes ballistic gelatin,  assuming no fragmentation, it will still de-stabilize and ...I hate to say "tumble" , but... its path of travel will no longer be concentric or parallel to it's longitudinal axis.  Right?  It will keyhole or something....  Is that a correct assumption?

Thanks in advance.

Quoted: Well, I was bored so I put together some fragmentation graphs. Let me know what everyone thinks: Fragmentation Graphs

Excellent!

I just have to ask now.. I notice that even the heavy OTM loads don't fragment reliably beyond 250-300 yards.  (Plinker skims the Ammo Oracle to avoid making a complete fool of himself)  What is the best round to use at 250 yards and beyond?  Especially if you aren't bound by the Hague convention.

Winchester 64-grain Powerpoint?  
Keep a mag loaded with Hornady  V-Max?  (doesn't penetrate enough at CQB ranges, but at 300 yards?)

Buy a .308 or a 300 Mag and leave the mousegun at home?

Great data. I guess our folks in uniform need a better cartridge if they are going to pop someone at more than 150-yards or so. Hopefully they will convert all of the M-16s and M-4s over to the 6.8 SPC round. I'd love to see some of that 5.56mm US Surplus ammo come out on the aftermarket, but I hear that there's a law that prohibits this. What a waste!
Phoenix27

T-
Nice colorful charts. I guess our men and women in uniform need a better service round, like the 6.8 SPC. Hope they convert over soon. What's the law that prevents the US DOD from selling US military surplus ammo on the aftermarket? It would seem like a good way to get the funds to resupply the new 6.8 SPC caliber. What do you think?
Phoenix27

Quoted: Quoted: Quoted: Well, I was bored so I put together some fragmentation graphs. Let me know what everyone thinks: Fragmentation Graphs Excellent! I just have to ask now.. I notice that even the heavy OTM loads don't fragment reliably beyond 250-300 yards.  (Plinker skims the Ammo Oracle to avoid making a complete fool of himself)  What is the best round to use at 250 yards and beyond?  Especially if you aren't bound by the Hague convention. For what purpose exactly? Lone actor/small unit?  Area/point defense?  What kind of targets?  What are the tactical issues?  If you can give me a general idea I can get a good answer for you.

Best past 250 -->  Mk211 Raufoss  

Quoted: Quoted: Excellent! I just have to ask now.. I notice that even the heavy OTM loads don't fragment reliably beyond 250-300 yards.  (Plinker skims the Ammo Oracle to avoid making a complete fool of himself)  What is the best round to use at 250 yards and beyond?  Especially if you aren't bound by the Hague convention. For what purpose exactly? Lone actor/small unit?  Area/point defense?  What kind of targets?  What are the tactical issues?  If you can give me a general idea I can get a good answer for you.

Hmmm... Just asking the right question could take some pondering, but here goes...

Uncle Sam (or at least Plinker's faulty memory of him) says the "maximum effective range" of an M16A2 with M855 is 500 meters against "point targets" and 800 meters against "area targets."  (I've never seen an "area target" myself, but Uncle Sam told me that they do exist)

IOW, Uncle Sam thinks that a skilled rifleman can reliably hit a man-sized target at 500m with the issue rifle and ammo.  And nobody who gets hit with a 5.56 round at that range is going to feel happy about it.

But within fragmentation distance (100-150M), the M193/M855 round is much more likely to incapacitate or kill the enemy immediately -- taking the fight out of him in a hurry -- something very important if that enemy is likely to shoot back.  And the heavy OTM loads extend that range to ~200-250M.

Anyhow here's the question, as best I can phrase it:

Lone actor/small unit?

Lone actor or fire-team size unit.  

Larger units typically have a wider variety of larger weapons (M240, M40, M21 etc) at their disposal, or call in air strikes and artillery to deal with more distant threats -- which makes discussing what is the best  AR15/M16 rifle round kind of pointless)  

Area/point defense?  What kind of targets? What are the tactical issues?

I'm too lazy to dream up a detailed tactical scenario, and it might turn it into a "why-the-hell-would-you-do-it-that-way" question instead of an ammo selection question.   So here goes.

Tactical situation -- taking potshots at "point targets" (human or human-like, as distinguished from prarie dog or deer-sized animals) beyond 200 Meters.  For whatever reason - offense, point/area/zone/man-on-man defense, Red Dawn, zombie hordes, bad hair day... anything.

Targets are either wearing regular clothing, PASGT/ComBlock-equivalent flak vests, or NIJ level II / IIIa soft body armor.  (level III and IV body armor probably would require upgrading to a larger weapon)

Weapon is a (to make it relevant to folks here, and not in Afghanistan with real M4's) 16" M4gery.  Or alternatively a 20" A2 clone.

Ammunition choices are M193/Q3131A, M855, the issue OTM loads (Hague convention loads already discussed) versus 64 grain PowerPoint, 55grain Nosler Partition, various Hornady TAP and VMAX loads, Nosler Ballistic Tip and any of the other soft-point non-Hague convention loads.

Questions to ponder:

The Ammo Oracle says that M193 is superior (because it penetrates farther but still fragments) to the TAP and other soft-tip loads at CQB distances.  Is it still superior beyond its fragmentation range? or do the hunting/varmint bullets become a better choice past a certain range?  (and what would that range be?)

Is the military giving up some "effective incapacitation range" (as opposed to mere "effective range") by using M193/M855/OTM rounds instead of, say, a controlled-expansion round like the Win PP or Nosler Partition?   In other words, what what is the cost of the Hague convention in terms of 5.56mm rifle range and effectiveness?

Is there a 5.56 round that would fragment/expand reliably at 500 meters?  Would it be "better" (considering BC and penetration) than OTM at that distance?

Quoted: For what purpose exactly? Lone actor/small unit?  Area/point defense?  What kind of targets?  What are the tactical issues?  If you can give me a general idea I can get a good answer for you.

How about this.  This is quoted from a report given from one of the Platoon Leaders in Iraq to MG Byrne, ORARNG, describing the events in the Battle of Najaf 08AUG2004 - 29AUG2004:

Outside room-to-room fighting, which indirect [fires] preparation largely prevented, targets were engaged primarily at ranges from 300 to 900 meters.

These tables are great.  Can anyone put one together for barrel lengths corresponding to the XM8?  I think it will be a terminal ballistics nightmare for our troops if current ammo and rifling twist rates are assumed.

The XM8 shorty will have a 9.5 inch barrel and the 'standard' version is a 12.5 inch barrel!  The sharpshooter and SAW versions will have 20 inch barrels.

I cannot believe the Army would adopt such apparently ineffective ammo/barrel length combinations!

I have to say something about fragmenting .30 caliber bullets.  Simply put, they may not be the best overall choice.  .30 caliber fragmenting bullets will cause a massive amount of blood loss in a relatively short amount of time, and that is great, but .30 caliber softpoints will create a wave of tissue that will strike the spinal column and knock the victim unconcious, and in several seconds he will be dead.

The important difference is that when struck in the torso the victim hit by a softpoint will not be able to fight back, wheras the victim struck by a fragmenting bullet may theoretically have a chance to fire back.

I have a question about 5.56mm hollow points though....
At what range will the average .223 hollowpoint mushroom in gelatin?

Thanks!

Odd, I am almost positive I read it off of either Firearms Tactical or a Dr. Fackler paper...

Errr... whats false, that a person hit by a softpoint as opposed to a fragmenting will not be able to fight back?  I didn't quite understand what you were saying there.

I did read ammo-oracle, and it was chock full of answers to most of my questions...  It really cleared some things up for me.  I will go back through it and try to find stuff on hollowpoints.

Thanks!

I don't believe in hydrostatic shock except in dangerous game hunting, it is an accepted fact that hunters using small caliber (relatively) rifles of high velocity will down a lion in 1 shot more often than a hunter using a .458 Lott or similar cartridge.  This does not apply to bears or elephants.

But I don't believe that it is hydrostatic shock that causes motor function to become disrupted, I believe it is tissue disruption in the form of a very large temporary cavity sort of wound that hits the spinal column.  This would disrupt the CNS enough to knock somebody unconcious according to the article I read.

I know the temporary cavity doesn't kill people, its either blood loss, brain loss or unconciousness tha stops the fight.

Maybe that's why in those old WW2 films taken on a battlefield when someone gets hit with an 8mm Mauser or .303 they just drop down dead.

P.S. I am not a troll I swear!  I still prefer the 5.56 for actual battlefield applications, please don't flame me...

They are studies in combination with hunting footage.  Bullet performance on animals can easily be tested in the field, and I get this information from hunting videos, hunting stories etc.  I researched this about a year ago and lost all my link when my computer crashed.

You can sometimes shoot a lion 4 or 5 times with a .458 Lott where one well placed .308 will do the trick.  There is a certain velocity the bullet has to be at, I believe 1900 FPS at impact to create this effect.