AR Sponsor
Posted: 7/8/2007 10:56:41 AM EDT
|
From the ammo oracle. The primary advantages of the intermediate power 5.56×45mm NATO cartridge are summarized as follows: (1) the penetration and power of the SS-109 version are superior to the 7.62mm NATO and more than adequate for the 300-meter average combat range documented in actual battle (ORO studies): (2) the lower recoil generated by the 5.56mm cartridge allows more control during full automatic fire and therefore provides greater firepower to the individual soldier; (3) the lesser weight of the 5.56mm ammunition allows the individual soldier to carry more ammunition and other equipment; (4) the smaller size of the 5.56mm ammunition allows the use of smaller, lighter and more compact rifles and squad automatic weapons and; (5) the lethality of the 5.56mm projectile is greater than the 7.62mm projectile at normal combat ranges, due to the tendency of the lighter projectile to tumble or shatter on impact. In summary, the 5.56mm NATO provides greater firepower and effectiveness than the larger and heavier 7.62mm NATO. 5.56-mm NATO ammunition weight only 47% as much as 7.62 mm NATO ammunition. It also says M855 rounds will not frag. below 2500fps. Out of a 16" bbl with a muzzle vel of 2900fps the M855 slows to 2500fps around 110yds. How is the 5.56 more lethal than the .308 ? At 600 yds with a 5.56 one can "poke a hole" in an enemy but is that enough? (Yeah, Yeah I already hear the head shot remarks) As assualt rifle rounds - The 5.56 may be minimal out of a 14" bbl but any 5.56,7.62x39, 6.8,6.5,or 308 should do nicely. As a DMR out to 500 yds you can't depend on head shots at moving targets. If the 5.56 loses its terminal lethality at 100yds where does the 6.8, 6.5 or 308? Nosler ballistic tips work great on p dogs out to 400yds but how would they perform on something larger? Doc, have you done any long distance testing? |
|
What exactly do you want to compare here? You say "At what velocity do other bullets of different caliber lose their terminal effectiveness? At 600 yds with a 5.56 one can "poke a hole" in an enemy but is that enough?" This sounds like it should be in the AR Discussion forum, granted you want to compare it to other bullets in different calibers...vague but it fits. Specifically, which ones were you curious about, there are SO MANY guys on here with a plethora of knowledge, and a whole host of others who can comment, but its pretty vague, care to toss out which rounds you meant to focus on? I can add my thoughts on the 300 WBY MAG with the 180 grain Barnes X bullet, but its not exactly relevant to discussion.... |
Cold, I edited the post to show primarily military rounds and AR varients. Thanks for moderating This has to do with showing at what range the 5.56 loses its effectiveness and why the 6.8 was developed but also to show all calibers lose their performance at longer distance. Just because I can poke a hole in paper at 800yds doesn't mean it'll kill something that far away without it being a headshot. I assumed most know that any big game load would work fine. The 5.56 has no big game loads. I've tumbled several coyotes at 3-400yds with 55 gr Nosler ballistic tips. It is Illegal here to shoot big game with anything under .243. |
|
Generally 223/556: 1. M855 ammo with a muzzle velocity of 2970fps, will fragment from 2600+ fps, which leaves a maximum performance range of 125 yards. 2. MK262 ammo with a muzzle velocity of 2700fps, will fragment from 2200+ fps, which leaves a maximum performance range of 215 yards. 3. Hornady 55 Gr. TAP (V-Max) with a muzzle velocity of 2910fps, will fragment from 1900+ fps, which leaves a maximum performance range of 315 yards. 4. Federal 55 Gr. Soft Point with a muzzle velocity of 2774fps, will fragment from 2000+ fps, which leaves a maximum performance range of 240 yards. 5. Federal 55 Gr. BTHP with a muzzle velocity of 2815fps, will fragment from 2100+ fps, which leaves a maximum performance range of 165 yards. 6.8 ammo: 1. Sierra 110 Gr. Pro-Hunters with a muzzle velocity of 2500fps, will expand from 1700+ fps, which leaves a maximum performance range of 330 yards. 2. Hornady 110 Gr. V-Max with a muzzle velocity of 2550 fps, will fragment from 1900+ fps, which leaves a maximum performance range of 305 yards. 3. Sierra 115 Gr. SMK with a muzzle velocity of 2500fps, will fragment from 2100+ fps, which leaves a maximum performance range of 160 yards. Theoredically the M855 ammo may not fragment below the 2500fps mark, but it most likely still tumble, which still causes a lot of damage. Just look at the reports on the MK262 ammo being used out in Afghan and Iraq, they are making kills out to 600 meters. Theoredically, the MK262 doesn't fragment out to that range, but with good SHOT PLACEMENT, it will get the job done. The same applies to the 6.8 ammo, although the fragmentation threshold appears to be even slower, which is good. |
Did you get these from your friend or a site that has more info?
|
. I honestly obtained that information from doing tons of research. Some of it was from my "Friend", but a lot of it, such as the fragmentaion thresholds were from contacting the manufacturers and speaking with the engineer guys. Once I got the thresholds, the rest was easy by using the JBM program. I actually had to do a presentation for work a while ago and I learned alot from doing the research.www.ar15.com/forums/topic.html?b=3&f=16&t=281405&page=1 |
I figured you were going that route... Well, as usual, this should get interesting. Personally, I wouldnt want to hunt whitetail with 223/556 but some people do. Depends what state etc. While in TX, people used 223 and 22-250 ALOT. Im sure DocGKR could shed some light on your discussion as he seems to be someone who could whip out the sort of facts your looking for. |
|
Keep in mind that while the 55 gr PT, JHP, JSP's may have good fragmentations thresholds, they concomitantly often offer inadequate penetration depths and poor intermediate barrier penetration characteristics. The use of .308's out of barrels shorter than about 16" results in a significant decrease in terminal performance--you might as well be running a 7.62x39mm. There is NO free lunch. |
Thanks, I get alot of the 5.56 with a 77gr is better than the Bla Bla Bla but they forget about velocity and energy loss. I haven't done any research on the frag thresholds. I am not going to shoot a trophy mule deer in the head so I can't rely on head shots. I'd like to know how a 155 scenar out of a 308 compares to a 180 gr Nosler BT out of a 300 win mag. because I know they will do the job well past 500yds. |
If you know the velocities and the velocity at which the expand/fragment, it is easy to figure out. |
A 5.56 is not even in the same league as 7.62 NATO in terminal performance. Now having said that. You cannot depend on head shots at LR with a DMR. The head is a small hard to get target that is often in motion. You are not going to get any frag out of either @ 600 yds. Combat is not the same as game hunting. When you are hunting an animal you should not risk a shot beyond you & the weapons abilty to place a humane killing shot with a good chance of certainty. In combat though where fragmentation matters is up close, where you need to shut the enemy down quickly, he is a threat to you & your fellow soldiers. Sometimes in combat though you might have nothing to lose by taking a long shot. If you hit him @ 847 yds & the bullet doesn't give a quick kill, so what? That enemy with a 5.56 hole drilled through his arm, buttocks, hand, guts or wherever is a lot less combat effective than he was before you drilled a 5.56 hole through him. You are most likley out of effective AK range, so he is not the threat he would be at 50 yds. Any longe range hit you put on the enemy is a good one. M9 |
AR Sponsor