In AR15 / M16, as you go up in twist rates and bullet weights, accuracy goes way up. Why did the military settle for 55 gr when the higher weight bullets seem to be so much more accurate? I.E. real match bullets are around 77 gr. Does the extra velocity 55 gr cause more damage than a heavier, slightly slower bullet would?
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Read The Black Rifle and 5.56 Timeline by D. Watters. http://www.thegunzone.com/556dw.html
Short answer is arbitrary steel helmet perforation test that was changed from 400yds to 500yds to try to kill the SCHV Rifle, so the AR15 developers blew the shoulder forward on the .222 Remington, used a different powder under a 55gr FMJ Boat Tail, and pushed the pressures higher than the AR15 was meant for, creating 5.56x45.
I will politely point out that the premises are flawed, namely bullet weight and rate of twist having something to do with accuracy by going tighter and heavier with them.
Short answer is arbitrary steel helmet perforation test that was changed from 400yds to 500yds to try to kill the SCHV Rifle, so the AR15 developers blew the shoulder forward on the .222 Remington, used a different powder under a 55gr FMJ Boat Tail, and pushed the pressures higher than the AR15 was meant for, creating 5.56x45.
I will politely point out that the premises are flawed, namely bullet weight and rate of twist having something to do with accuracy by going tighter and heavier with them.
Outside of stability being necessary for accuracy, how do you figure?
OP. It's likely cause lighter is easier and cheaper. But the mil is using the heavies and has been doing so for years. Mk262 is just not standard issue for every Joe.
OP. It's likely cause lighter is easier and cheaper. But the mil is using the heavies and has been doing so for years. Mk262 is just not standard issue for every Joe.
Do elaborate, please?
M855 is on its way out, M855A1 is on its way in. Both are 62gr but the new stuff performs a hell of a lot better terminally, and has an increased accuracy advantage as well. I've only done some small testing with the A1 ammunition, but even at 100yds with an Aimpoint I noticed a difference. It was shooting around 2-3 moa with a 2moa dot, unsupported prone and a 8 year old Bushmaster M4A1 that I had done a good bit of hard semi and also FA fire from over the years. For comparison, M855 would do about 4-5 moa with me on the trigger. M855A1 does some nasty shit on a large chunk of beef as well, much more than M855.
55gr FMJs haven't been issued widely for battlefield use since the 80's, and I NEVER saw it once across my AD years (92-06). I doubt they even used it at all over the recent wars for actual mil use, but I'm not everywhere at once. Some contracting firms have issued it with less than optimal performance, but it is good training ammo for el Presidente drills and the like.
55gr FMJs haven't been issued widely for battlefield use since the 80's, and I NEVER saw it once across my AD years (92-06). I doubt they even used it at all over the recent wars for actual mil use, but I'm not everywhere at once. Some contracting firms have issued it with less than optimal performance, but it is good training ammo for el Presidente drills and the like.
The op suggested that when going up in in twist and bullet weight, there is a direct correlation to better accuracy. This is simply not true. A lighter bullet and slower twist can be just as accurate as a heavier bullet and faster twist as long as they are matched correctly. Extending range leads to heavier bullets and faster twist to maintain stability as velocity decreases and wind becomes a factor.
Good idea. Original M16s in the 1960s were 1:14/1:12 twist and switched to 1:7 to handle heavier bullets in the early to mid 1980s.
You can't overstabilize a bullet, but you can understabilize one.
I just believed the statement to be broad in scope because there is a correlation between twist and bullet weight.
Why doesn't military use heavier bullets in 5.56 AR style rifles ?
62 is the minimum. 77 is widespread. 100 is uncommon, but I've seen it.
OP, your info is dated: At least twenty years behind the times.
The answer is: The military does use heavy bullets and it doesn't use 55gr. .223 at all.
62 is the minimum. 77 is widespread. 100 is uncommon, but I've seen it.
OP, your info is dated: At least twenty years behind the times.
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Accuracy is not dependent on twist and bullet weight. A slower twist and 45-55gr bullet can still absolutely be a tack driving combo.
The issue with military ammo is that you have to balance barrier penetration, body armor penetration, and terminal effects in soft tissue, oh, and cost. 55gr ammunition hasn't really been used in the military for a long time. M855 is a 62gr FMJBT with a tiny little steel "penetrator". In combat zones, you will often see Mk262 77gr HPBT "match" ammo issued, also. It isn't a complete replacement, however, and honestly because of the increase in cost, I wouldn't expect it ever to be.
Another thing to consider when talking about small arms accuracy in the military, is the weapons themselves. We've finally just about got everyone picatinny rails, but they're not free float tubes (and often are not mounted correctly, and wiggle all over hell), so you still shoot yourself in the foot, accuracy wise. The Marine Corps is introducing M27 IAR's increasingly, which are very solid platforms, but are also very expensive. Most of the Marine Corps is still using a 20" M16a4.
Then there is the subject of how well trained the troops are to take advantage of whatever accuracy is there. In the Marines, we shoot for a 12" black circle at 200-300yd for slow-fire. 4-6 MOA target. You'd be blown away at how many people can't reliably hit this in a tight, slung up position (never mind that the sling is probably hurting accuracy because it's mounted to a non-FF rail....).
Sooo, with all of that in mind, ammo choice is pretty low on the agenda, even moreso that we're drawing down and getting out of Afghan. We've got V22 Ospreys and whiz-bang rocket systems to worry about.
Very much behind the times.
As has been stated, your info is clearly outdated, they are wide spread in use.
The other conclusion you drew is incorrect as 55gr loadings can be damn accurate when loaded properly. The advantage that comes with the heavier bullets is that most of them are better suited for use at distance due to the higher BCs they tend to have. Also, the twist rate is largely irrelevant as long as it is suitable to properly stabilize the bullet.
The other conclusion you drew is incorrect as 55gr loadings can be damn accurate when loaded properly. The advantage that comes with the heavier bullets is that most of them are better suited for use at distance due to the higher BCs they tend to have. Also, the twist rate is largely irrelevant as long as it is suitable to properly stabilize the bullet.
I have two different takes-
1- you can over stabilize a bullet. If you speed one up faster than needed, you accelerate throat erosion.
2- back to bullet weight.
I believe the "average soldier" does not kill with a rifle at any distance.
Most killing is from range- designated marksman, artillery, rockets, tanks, mortars, aircraft.
Inside of 30-50 yards, a hit is a bit from a rifle with FMJ or green tip ammo.
Past 100 yards the heavier bullets are the way to go.
If you look at all of the stats on the dead in war, it is a small percentage that are killed by a grunt.
As we did not sign onto The Hague convention, switching to soft point or hollow point would be a better change than switching to a heavier bullet.
If a helo can fire HE at the enemy, why are we still stiching them with green tip????
1- you can over stabilize a bullet. If you speed one up faster than needed, you accelerate throat erosion.
2- back to bullet weight.
I believe the "average soldier" does not kill with a rifle at any distance.
Most killing is from range- designated marksman, artillery, rockets, tanks, mortars, aircraft.
Inside of 30-50 yards, a hit is a bit from a rifle with FMJ or green tip ammo.
Past 100 yards the heavier bullets are the way to go.
If you look at all of the stats on the dead in war, it is a small percentage that are killed by a grunt.
As we did not sign onto The Hague convention, switching to soft point or hollow point would be a better change than switching to a heavier bullet.
If a helo can fire HE at the enemy, why are we still stiching them with green tip????
I wouldn't say that the military doesn't use 55 grain at all.
I managed an ammo account database that was the issue point for teams in Afghanistan and Iraq (06-07).
I maintained a stock of 55 grain ball ammo, as well as 62 grain green tip and 77 grain.
Some one, I don't know who, thought the 55 grain (for CQB) from the short barrel (14.5") tended to perform better than the M855 from the short barrels at close range (read inside dwellings) against skinny guys with no body armor.
I will tell you, that I never issued any 55 grain when I was there, but then again, I never issued any 77 grain either. But all three were available in theater.
The USMC has been issuing an improved 62 grain load for a considerable time (SOST load)
Bingo. There's a reason the short range benchrest like the light bullets with very slow twist rates.
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