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Posted: 11/14/2002 3:31:51 PM EDT
I know, I know.... fight like you train and train like you fight. I was an old fighter pilot and we made every hop count as if it were the real thing. When the call came, there was no big change from a training hop. Been there, done that, got the T-shirt too.

That said, very few of they guys on this board are going to combat with our AR-15s. This is a hobby and a great self defense weapon. I am not going "down town" with my Oly. I do kill lots of paper with mine. I have also been known to kill many a tin can!

For shooting paper and cans, there is zero need to fire hot military loads. It is a waste of good ammo and it causes a huge increase of wear on the weapon. The highest pressure military load is still a light round when compared to most centerfire rounds. Hence, the idea that I need to be ready for the recoil in a combat situation seems a bit silly to me. I have done rapid fire drills with mil spec. and civil rounds and this 210 pound man doesn't feel much in the way of recoil in either round. They are both light. Perhaps it takes a 1/10th of a second longer to get the dot back on the target, but not much more than that.

Why not use the civil stuff to train and use the good stuff for your stash? That's what we do at our range and we still have as much fun as anyone else. ;) That IS the idea....right?...to have fun?

Cheers,
D/D
Link Posted: 11/14/2002 4:19:54 PM EDT
Maybe you can afford the civilian stuff..... Give me 11c ammo over 25c ammo any day .

These rifles need milspec ammo to function well. There are specific port pressures needed for the gas system to work and this is often unattainable with weak ammo or non military powders.

The "hot" military loads put minimal strain on the rifle as long as you stick with the sustained rate of fire, which is 12 to 15 rounds per minute maximum.

We're still awash with good milspec ammo.

-- Chuck
Link Posted: 11/14/2002 4:37:37 PM EDT

Originally Posted By Chuck:
Maybe you can afford the civilian stuff..... Give me 11c ammo over 25c ammo any day hese
The "hot" military loads put minimal strain on the rifle as long as you stick with the sustained rate of fire, which is 12 to 15 rounds per minute maximum.

We're still awash with good milspec ammo.

-- Chuck


If your weapon doesn't function when you knock off 150 fps, something is very wrong with your equipment. I can swap from mil. spec. to civil all day long without any feed/extraction problems.

I don't do anything special other than keeping my weapon clean, but almost everyone does that. :)
Link Posted: 11/14/2002 4:59:49 PM EDT
I've never heard of an AR wearing out. Could it happen?
Link Posted: 11/14/2002 6:07:57 PM EDT
"12 to 15 rounds per minute maximum"

oh, oh, I'm in trouble....
Link Posted: 11/14/2002 7:56:30 PM EDT
To me the best way around this is to just shoot Wolf.
Link Posted: 11/14/2002 10:11:04 PM EDT
[Last Edit: 11/14/2002 10:19:38 PM EDT by Troy]
Link Posted: 11/15/2002 3:24:33 AM EDT

Originally Posted By Troy:
David,

I personally agree with you (GOOD ammo for defensive use, lesser ammo for the bulk of your practice). Of course, if you can find cheap surplus ammo that's too old to trust for duty ammo, it still makes great range ammo, which is what Chuck is saying.

As far as wear on my rifles, for me, that's the least of my concern. Spare barrels aren't that expensive given how long it takes to wear one out, and the barrel is the only major component that really wears out. But know this: despite the fact that 7.62 and larger rounds have more "power", the 5.56 ammo has higher velocities, and THAT (high-speed gas erosion) is what causes the most barrel wear.

-Troy


I shoot old mil surplus stuff too. That isn't a combat round in my mind. If it is expired by one military, I'm not going to trust my life with it.

There are guys that shoot current production mil spec. ammo ONLY because the loads are a little bit hotter than the civil stuff. It just seems like a waste of good ammo to me. Shoot the light stuff at the range and save the good stuff for your stash.

I will agree that a new barrel isn't a big deal. Hence, you are right, that isn't a very important factor. On the other hand, the supply of good mil. spec. ammo is tight because guys are running it through their weapons at the range killing paper. It just seems silly to me.

D/D
Link Posted: 11/15/2002 3:26:14 AM EDT

Originally Posted By markm:
I've never heard of an AR wearing out. Could it happen?


Yes, it can happen. Of course, we are talking lots of rounds and then you can replace the barrel and shoot for another ten years. Hence, it was sort of a stupid point on my part.
Link Posted: 11/15/2002 4:02:07 AM EDT

Originally Posted By Joe_556:
"12 to 15 rounds per minute maximum"

oh, oh, I'm in trouble.... hr

Me too! We do our 30 in :60 drill several times each trip to the range. My Oly match barrel must be toast! Not only that, but we do our rapid fire drills with Wolf!!! Now I'm going to hell for sure.
Link Posted: 11/15/2002 4:19:34 AM EDT
I am somewhat new to AR's and agree with you. I find that some of the newbies seem to want the very best ammo to shoot. (I know I did)Thus they get new production M193 and blast 30 rounds as fast as they can in the dirt. What a waste. I have since learned of the SA mil surplus and that what I use for range ammo. Thus my range ammo is M193,just 15 years old. I stash my new M193.
Very good point.
SugarD
Link Posted: 11/15/2002 5:22:42 AM EDT
David --

150fps? There's no assurance of any muzzle velocity with non-spec ammo. There's certainly good commercial ammo out there, but it's expensive and unless you chronograph it or have a way to determine chamber and port pressures you're just guessing it's softer on the rifle.

Federal Eagle .223 55gr is good commercial ammo, but it's a lot more expensive than South African M1A3 Ball and provides no better terminal ballistics.

Going to cartridges containing bullets like the 75gr and 77gr TAP has potential for personal combat use, but these cartridges still lack the sealant and milspec primers needed for sustained use or storage. In your house or truck gun where there's little chance of weather getting to them go for it. But don't plan on a lot of trigger time at these prices. The Army is still testing these and the initial results look very good.

You're absolutely right about recoil. There is no recoil in a real shooting situation, not that you notice at the time.

For you "unload the magazine" guys note that it only takes about 150 rounds thru these rifles to heat them to the point they'll cook off. Harder to do in SEMI, but guys will try it! The 12-15 rounds per minute sustained fire is still 720 to 900 rounds in an hour -- shooting a case of ammo in 66 minutes.

-- Chuck
Link Posted: 11/15/2002 7:49:29 AM EDT
[Last Edit: 11/15/2002 8:51:52 AM EDT by DavidDetroit]

Originally Posted By Chuck:
David --

150fps? There's no assurance of any muzzle velocity with non-spec ammo. There's certainly good commercial ammo out there, but it's expensive and unless you chronograph it or have a way to determine chamber and port pressures you're just guessing it's softer on the rifle.

Federal Eagle .223 55gr is good commercial ammo, but it's a lot more expensive than South African M1A3 Ball and provides no better terminal ballistics.

Going to cartridges containing bullets like the 75gr and 77gr TAP has potential for personal combat use, but these cartridges still lack the sealant and milspec primers needed for sustained use or storage. In your house or truck gun where there's little chance of weather getting to them go for it. But don't plan on a lot of trigger time at these prices. The Army is still testing these and the initial results look very good.

You're absolutely right about recoil. There is no recoil in a real shooting situation, not that you notice at the time.

For you "unload the magazine" guys note that it only takes about 150 rounds thru these rifles to heat them to the point they'll cook off. Harder to do in SEMI, but guys will try it! The 12-15 rounds per minute sustained fire is still 720 to 900 rounds in an hour -- shooting a case of ammo in 66 minutes.

-- Chuck


Chuck,

That 150fps number was me just tossing out what we have seen as an average in various testing we have done between civil and new military production ammo. I have seen a big range between the various companies, so you are right, you don't know if you don't test.

When we are serious about shooting paper, we hand load every round. We do own and use a chrono and one of our guys is an engineer in the field, so we get more serious than is healty for for something that is a game.

The SDs we have found from some surplus ammo is very bad. Other lots seem to be good, even as new. I assume some of the ammo has been too hot during storage. My problem is that I like a constant supply of good stuff to train with without doing a test on each lot. I get a little tired of finding out which lot is good and which is bad.

Of course the new Military stuff is great, but it is expensive and in tight supply. That is the stuff to save for a bad day. No sense burning it up shooting paper and cans.
Link Posted: 11/15/2002 2:18:39 PM EDT
I don't think there's a right way or a wrong way, perhaps just a common sense way. Shoot what you can afford. I've shot many brands thru my Bushy and have never had a failure. Unless you have a SAAMI chamber I wouldn't worry about different brands or pressures (unless of course you know a particular brand will give you trouble). Commercial ammo costs more, but surplus mil-spec may give better performance; guess it's depends on what you want for a particular application. I don't shoot surplus at paper simply because the surplus I buy is relatively new and I prefer to store it. If I shoot surplus, I use the oldest I have on hand and rotate my stock.

I don't forsee surplus ammo drying up. There will always be unpurchased lots available unless they outlaw it's sale to civillians.
Link Posted: 11/15/2002 3:53:59 PM EDT
The most common thing for people to do is use a NEW M193 type ammo for defensive use and practice with SA ammo. The SA is inexpensive and gives the same external ballistics because its loaded "hot" like the Lake City or Q3131A or whatever they have the rifle sighted in with.

If it was 150+ fps slower it would not track reliably out past 100 yards.
Link Posted: 11/15/2002 4:13:28 PM EDT
In general, the SA stuff seems to be good for range work. Too bad, but like all surplus ammo, it will run out.

Most of the civil stuff is sub 3000fps from my PCR3 (16" target barrel)while the current mil spec stuff is just sub 3200fps.

My point is not anti surplus. I shoot it quite often and alway look for a bargain. My point is...why do guys need to shoot only current military production rounds because the MV is high enough to provide one shot kills? That is what you need for combat, but it is a waste of good ammo on the range.

Shoot the cheap and old stuff on the range and save the good stuff for your stash.
Link Posted: 11/15/2002 4:29:41 PM EDT
[Last Edit: 11/15/2002 4:30:47 PM EDT by DavidDetroit]

Originally Posted By DevL:
If it was 150+ fps slower it would not track reliably out past 100 yards.


All our target loads are sub 3000fps out of my PCR 3 (16" target barrel) and it holds great groups out to 300 meters. Even better yet out of my 24" upper.

I am by no means a ballistic engineer, but I fail to understand the point. Faster doesn't always mean tighter groups.

I do have a solid grasp on fluid dynamics (military pilot/engineer backgroud). The reason .223 is such a wicked round is the speed of sound in water and the shock wave produced from a slug above it. 2700fps seems to be the magic number where 1/2MVsq is no longer the entire story. Above that magic number, the effect on the tissue is shocking for such a little slug with less engergy than larger rounds. It is obvious that the civil and target rounds with sub 3000fps MV would not be a great combat round beyond 100 meters due to the speed falling below the magic number. Still, it can group just fine well below 2700 fps and we do it all the time.

I have no doubt that most of you know more on this subject that I do. Still, I fail to see the reason to shoot current mil spec. stuff at paper and cans. Of course, my wife thinks I'm slow too.
Link Posted: 11/15/2002 5:13:37 PM EDT
David:
Velocity is important, but not for the reason that you think. The "shock wave" does little or nothing. The velocity is important in the military round because the 25-2700 fps line is the threshold at which the projo will yaw and fragment. Go check out the 5.56 ammo FAQ. It will be made clear.
Link Posted: 11/15/2002 5:30:52 PM EDT

Originally Posted By DavidDetroit:

Originally Posted By DevL:
If it was 150+ fps slower it would not track reliably out past 100 yards.


All our target loads are sub 3000fps out of my PCR 3 (16" target barrel) and it holds great groups out to 300 meters. Even better yet out of my 24" upper.

I am by no means a ballistic engineer, but I fail to understand the point. Faster doesn't always mean tighter groups.

I do have a solid grasp on fluid dynamics (military pilot/engineer backgroud). The reason .223 is such a wicked round is the speed of sound in water and the shock wave produced from a slug above it. 2700fps seems to be the magic number where 1/2MVsq is no longer the entire story. Above that magic number, the effect on the tissue is shocking for such a little slug with less engergy than larger rounds. It is obvious that the civil and target rounds with sub 3000fps MV would not be a great combat round beyond 100 meters due to the speed falling below the magic number. Still, it can group just fine well below 2700 fps and we do it all the time.

I have no doubt that most of you know more on this subject that I do. Still, I fail to see the reason to shoot current mil spec. stuff at paper and cans. Of course, my wife thinks I'm slow too.



You too can know more about .233 and 5.56 ballistics than 99.995% of all shooters by visiting: www.ammo-oracle.com
Link Posted: 11/15/2002 8:24:52 PM EDT
Higher velocity means increased fragmenting range in your defense ammo. That is why its used for defense.

Use ammo that is slower than this for practice and your long range shooting will be off if you sighted in your rifle with the high speed stuff.

You will be hitting low at all ranges and much more so the further out you are. Its about how much your bullet drops at a given distance. The speed has nothing to do with accuracy. In fact the commercial loadings are often more accurate than the military "hot" loadings.

If you get used to making hits at 300-400m with one ammo and switch to another you will miss a prone target every time if you use the same hold over/zero.

If you were doing nothing but close in CQB type drills then slower ammo would be fine for practice. But with SA available why use anything else?
Link Posted: 11/15/2002 9:00:32 PM EDT
Because you can't get 600rds of civillian ammo for $60-80....
Link Posted: 11/16/2002 5:21:37 AM EDT
[Last Edit: 11/16/2002 6:56:07 AM EDT by DavidDetroit]

Originally Posted By m24shooter:
David:
Velocity is important, but not for the reason that you think. The "shock wave" does little or nothing. The velocity is important in the military round because the 25-2700 fps line is the threshold at which the projo will yaw and fragment. Go check out the 5.56 ammo FAQ. It will be made clear.


I haven't done much engineering since my ol' fighter days, so hang with me. If someone else knows more on the subject, please chime in.

As you near the speed of sound for the tissue (we will call it water), the resistance is not linear. The reason you see fragmentation above the magic number (I will call that the speed of sound in water) is due massive g loads. The increased drag above 2700fps cause the bullet to slow at a greater rate and rips the copper right off the lead while below that speed the bullet might travel through soft tissue and exit the other side. So, going faster than the speed of sound in the fluid makes the bullet stop faster. Very odd indeed, but close to the perfect effect.

To add to the wound is the effects of the shock wave. Above the speed of sound, the fluid builds up pressure in front of the bullet and will move out of the way of the slug faster than the slug is going. Much like hitting a grape with a hammer on a flat hard surface. The fluid in the grape will travel many times faster than the face of the hammer as it exits the sides. As the speed drops below the magic number, we see this effect drop off and the .223 round makes a hole rather than the blender effect we all know and love. {;)]

To close, the fragmentation you see in quality military rounds is due to their higher velocity. The Civil stuff is just above this speed and most of it is below the magic number beyond 100 meters.
Link Posted: 11/16/2002 6:50:44 AM EDT

Originally Posted By Dave_A:
Because you can't get 600rds of civillian ammo for $60-80....


I don't know where I can get current production mil spec. ammo for $60 for 600 rounds. I seem to only see it for the 20 to 25 cents/round price. If you know something, please share! he
Link Posted: 11/16/2002 7:15:15 AM EDT

Originally Posted By DevL:
You too can know more about .233 and 5.56 ballistics than 99.995% of all shooters by visiting: www.ammo-oracle.com



Guys, I have read that page. Very good info there. In that page, there is great info on what happens but the "whys" are a little lacking. Fragmentation is a result of the drag spike above the speed of sound in water. Hence, the effect isn't from fragmentaion as much as the fragmentation is a result of the drag spike (if that makes any sense).

Just remember this....
For .223/5.56 NATO to have the effect we love, it needs to be going fast! If the speed of the round is below 2700 fps at impact, you have the wrong round for combat. In the case of civil rounds, this is only 100 meters from the muzzle or less.

I shoot 7.62x54 in a 200FMJ. It has twice the energy of 5.56 NATO at the muzzle and even a higher percentage down range. Yet, if I were to shoot a one gallon jug of water with 7.62x54, the round would simply pass through it. Shoot the same jug with a good mil. spec. 5.56 NATO round and the jug will explose with bullet fragments contained inside the jug after all the water drains. Why, you ask? The drag isn't linear as we see speed increase above the speed of sound in water. Even if the 5.56 round didn't fragment, the jug would still explode! Animal tissue and balistic gel is mostly water, hence you can base your numbers on water and be close.

For the guys that took the photos of the balistic gel, thanks! They are simply fantastic demonstrations of why .223/5.56 NATO is such a great combat round.

Cheers,
D/D
Link Posted: 11/16/2002 7:51:54 AM EDT
You can certainly judge fragmentation (or bullet expansion with JHP bullets) on their performance in water, but hydrostatic shock has a nil effect on wounding in large animal targets unless a non compressible organ is struck.

The large temporary cavity is petty harmless otherwise, but does make impressive permanent holes in clay and will explode watermelons and gallon milk jugs to the delight of Air Force generals . Too bad it's a very low level wounding mechanish.

The major benefit of fragmentation is to turn the relatively harmless temporary cabity into a massive permanent cavity.

This effect has been well documented since 1988, but it's taken the Army until this year to start testing other bullets to push this effect to lower velocities to increase range, or allow shorter barrels.

-- Chuck
Link Posted: 11/16/2002 8:40:39 AM EDT
Thanks for all the feedback guys. I know many of your have much more knowledge on this subject that I do, hence I enjoy your help.

Cheers,
D/D
Link Posted: 11/16/2002 7:22:02 PM EDT

Originally Posted By DavidDetroit:

Originally Posted By m24shooter:
David:
Velocity is important, but not for the reason that you think. The "shock wave" does little or nothing. The velocity is important in the military round because the 25-2700 fps line is the threshold at which the projo will yaw and fragment. Go check out the 5.56 ammo FAQ. It will be made clear.


I haven't done much engineering since my ol' fighter days, so hang with me. If someone else knows more on the subject, please chime in.

As you near the speed of sound for the tissue (we will call it water), the resistance is not linear. The reason you see fragmentation above the magic number (I will call that the speed of sound in water) is due massive g loads. The increased drag above 2700fps cause the bullet to slow at a greater rate and rips the copper right off the lead while below that speed the bullet might travel through soft tissue and exit the other side. So, going faster than the speed of sound in the fluid makes the bullet stop faster. Very odd indeed, but close to the perfect effect.



Not exactly. Bullet fragmentation depends primarily on construction. The reason M193 and M855 fragement when they do and how they do has nothing to do with the speed of sound/etc. Two factors contribute to the onset of fragmentation.

1. The propensity of the round to yaw.
2. The construction of the round.

You typically see fragmentation in lighter 5.56 rounds (M193/M855) associated with the yaw of the round. While the round penetrates and passes through gel just fine if it travels nose first, once it yaws around 90 degrees and increases the frontal area of the round the forces on the bullet are too high for the construction to resist and the integrity of the bullet is compromised. Thus there are three ways to keep most bullets from fragmenting:

1. Don't permit them to yaw.
2. Construct them stronger to resist the forces of high speed passage through dense mediums.
3. Slow them down to the point where the forces on the bullet do not exceed the structural integrity of the round.

(Wow, that sounds like a Star Trek Voyager episode!).


To add to the wound is the effects of the shock wave. Above the speed of sound, the fluid builds up pressure in front of the bullet and will move out of the way of the slug faster than the slug is going. Much like hitting a grape with a hammer on a flat hard surface. The fluid in the grape will travel many times faster than the face of the hammer as it exits the sides. As the speed drops below the magic number, we see this effect drop off and the .223 round makes a hole rather than the blender effect we all know and love. {;)]


It's more do to with the forces on the round than it is actually on a magic speed number. Different rounds have different magic numbers. There is no "total" magic number. 7.62x39 doesn't really fragment at all. Some FMJ 7.62x51 fragments like crazy, most doesn't.


To close, the fragmentation you see in quality military rounds is due to their higher velocity. The Civil stuff is just above this speed and most of it is below the magic number beyond 100 meters.


Not really. Most civilian stuff fragments MORE dramatically than military rounds- often too much for their own good and at the expense of penetration- despite lower velocity. Examples: any softpoint or ballistic point rounds. Light FMJ rounds like 50 grain and 45 grain.

The magic number (2700 fps) is very specific to M193 and M855. Other 55 grain FMJ doesn't exhibit the same fragmentation (or any in some cases) even at 2900 fps.
Link Posted: 11/18/2002 7:22:53 AM EDT
I use Winchester Value Packs at the range. Just buy three boxes when I am going to shoot. Gives me 120 rounds, at $.20 a round, and lets me hold onto the hot stuff for a bad day.....


Scott

Link Posted: 11/19/2002 6:38:29 PM EDT
I'm new to the AR crowd. I'm reading all these post on "hot" ammo and "range ammo". I got a Colt preban with a 16" barrel. Not sure what twist. All I really want to know is what is recommened to stash away for "the rainy day" and what is recommened for just shooting at the range. Where can I find these rounds at and about how much do they run?? Thanks.
Link Posted: 11/19/2002 11:57:22 PM EDT

Originally Posted By shawnster:
I'm new to the AR crowd. I'm reading all these post on "hot" ammo and "range ammo". I got a Colt preban with a 16" barrel. Not sure what twist. All I really want to know is what is recommened to stash away for "the rainy day" and what is recommened for just shooting at the range. Where can I find these rounds at and about how much do they run?? Thanks.



www.ammo-oracle.com
Link Posted: 11/20/2002 2:36:53 AM EDT
The reason so many of my posts deal with combat rounds is the serious nature of self defense. If I am plinking or shooting paper, it doesn't so much matter what I use. Remington UMC, Winchester white box, or whatever's on the shelf at Wal-Mart will work just fine. If it doesn't it's no big deal. I will just buy something else the next time. But in a self defense situation, the moment of truth is short. You want the best round you can possibly have. I think that's why there's such a heavy focus on combat rounds here in the ammo forum. Shooting tin cans on the other hand is much more a fun and less intense situation and therefore just doesn't spark the same amount of interest when it comes to ammo.
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