PDA

View Full Version : How accurate were Vietnam-era M16A1s?


23 Blast
10-10-2012, 6:07 AM
While the accuracy of the AR platform is well known, particularly in its current 1:7 and 1:9 iterations, IIRC, the twist rate on the original M16s was 1:12. For those who know, and those who have used them, how accurate (or precise, for you members of the terminology-enforcement police) were the original M16 and M16A1 rifles? How about the original CAR-15's as used by Special Forces?

moulton
10-10-2012, 6:12 AM
I have a m-16a1 retro build and can do 2" groupings at 100 yards and can hit the gong at 500 yards 8 out of 10 shots while prone and with sand bags.

gun toting monkeyboy
10-10-2012, 6:42 AM
My retro build uses an old SP-1 rifle upper. It IS one of those Vietnam-era rifles, just the civilian version. Same parts as the military m16A1. It is just as accurate as my modern ones. The 1-12 twist is more than enough for the 55 grain bullets, and seems to do just fine with the 62 grain bullets as well.

-Mb

OldShooter32
10-10-2012, 7:21 AM
Way we found when shooting on a military "composite team" (NM M14's and rack M16's) was that we had to learn not to "muscle" the M16's due to the flexibility of the barrel-receiver attachment -- we could pull a couple MOA out of it. The front arm had to just be a support and to use no sling pressure. Then they'd shoot pretty well.

jmzhwells
10-10-2012, 7:26 AM
Prone, about 1-2" at 100 yds w/ iron sights. I use these at work.

tdyoung1958
10-10-2012, 8:06 AM
While the accuracy of the AR platform is well known, particularly in its current 1:7 and 1:9 iterations, IIRC, the twist rate on the original M16s was 1:12. For those who know, and those who have used them, how accurate (or precise, for you members of the terminology-enforcement police) were the original M16 and M16A1 rifles? How about the original CAR-15's as used by Special Forces?

more accurate than 95% of the people shooting them. Even though it wasn't really that hard to shoot them good, most people in the military have no real basic shooting skills until they joined the military . . . and most of their instructers suck, the ranges we shot at the "range" personell were there because they pissed someone off and got detailed to it

Siebler
10-10-2012, 8:15 AM
yea, accurate enough to hit communists. :D

docsmileyface
10-10-2012, 8:23 AM
Way we found when shooting on a military "composite team" (NM M14's and rack M16's) was that we had to learn not to "muscle" the M16's due to the flexibility of the barrel-receiver attachment -- we could pull a couple MOA out of it. The front arm had to just be a support and to use no sling pressure. Then they'd shoot pretty well.

best to just not touch the front of the rifle at all, was taught at SDM school to hold the rifle by the magazine well pushing it directly back into the shoulder pocket and let the barrel do its thing on its own without interference.

joker70
10-10-2012, 8:26 AM
I was just reading the book Weapons of the Navy Seals and it claimed that the Navy Seals were the first to use the M-16. I had thought it was the Air Force. Also it did mention the twist rate but nothing to note about accuracy or lack thereof. Mostly it mentioned the tumbling effect of the round once it hit flesh.

smle-man
10-10-2012, 8:40 AM
Good enough to qualify 'expert' at FT Knox in 1975! Three issues with the rifle as a range rifle: skinny barrel, combat sights, quality of the ammo. Fine as a combat rifle though.

angrypeccary
10-10-2012, 8:47 AM
i qualified with one at fort sill in 03' got to shoot it full auto at night too its accurate and was also lighter than my current ar 15.

frankm
10-10-2012, 9:06 AM
more accurate than 95% of the people shooting them. Even though it wasn't really that hard to shoot them good, most people in the military have no real basic shooting skills until they joined the military . . . and most of their instructers suck, the ranges we shot at the "range" personell were there because they pissed someone off and got detailed to it

Obviously, you weren't a Marine.

akjunkie
10-10-2012, 9:14 AM
My retro build uses an old SP-1 rifle upper. It IS one of those Vietnam-era rifles, just the civilian version. Same parts as the military m16A1. It is just as accurate as my modern ones. The 1-12 twist is more than enough for the 55 grain bullets, and seems to do just fine with the 62 grain bullets as well.

-Mb

Not recommended.

http://ammo.ar15.com/ammo/project/perf_112.html

1911su16b870
10-10-2012, 9:25 AM
Had the opportunity to do armory work on M16A1s. They are more than capable of excellent accuracy with irons when running XM193.

bighead
10-10-2012, 9:53 AM
I don't know about accuracy but my father's car-15 in 69-70 regularly failed to operate in firefights.

gun toting monkeyboy
10-10-2012, 10:05 AM
Not recommended.

http://ammo.ar15.com/ammo/project/perf_112.html

You need to clarify next time. Not just put up the link to a one-sentence post elsewhere. :p

The longest range I have tried the 62 grain bullets at is about 50 yards. I didn't have any issues with them, but at that range, who knows? I went with the Retro build because I wanted the 1-12 twist barrel specifically for the 55 grain FMJs. It is plenty to stabilize them in flight, but they supposedly tumble and come apart when they hit things. That was one of the reasons it was noted for such horrific wounds early in the war. With the early 1-14 twist that the experimental rifles, it looked like the enemy had been hit with a buzzsaw. The wounds I have seen documented for the standardized 1-12 twist guns were almost as bad.

-Mb

Plisk
10-10-2012, 10:48 AM
You need to clarify next time. Not just put up the link to a one-sentence post elsewhere. :p

The longest range I have tried the 62 grain bullets at is about 50 yards. I didn't have any issues with them, but at that range, who knows? I went with the Retro build because I wanted the 1-12 twist barrel specifically for the 55 grain FMJs. It is plenty to stabilize them in flight, but they supposedly tumble and come apart when they hit things. That was one of the reasons it was noted for such horrific wounds early in the war. With the early 1-14 twist that the experimental rifles, it looked like the enemy had been hit with a buzzsaw. The wounds I have seen documented for the standardized 1-12 twist guns were almost as bad.

-Mb

If you ever try to push the 62gr in the 1-12" out past 80-90m, you'll start to see them fly wild off target. Those heavy rounds aren't being stabilized well enough by that twist.

23 Blast
10-10-2012, 10:59 AM
I was just reading the book Weapons of the Navy Seals and it claimed that the Navy Seals were the first to use the M-16. I had thought it was the Air Force. Also it did mention the twist rate but nothing to note about accuracy or lack thereof. Mostly it mentioned the tumbling effect of the round once it hit flesh.

From what I've read/seen - the first to use the AR in combat were Green Berets and CIA guys who got them through unofficial channels (i.e. they acquired them as private purchasers, not through government funding/procurement)

As far as the "tumbling" aspect - I think the 1:12 twist rate provided less stability such that the bullet more readily yawed when it struck a target compared to the faster twist rates.

Holescreek
10-10-2012, 12:38 PM
We used hand me down Vietnam era M16's in USMC boot camp Parris Island in 1977. No problem keeping the rounds in a pie plate circle shooting prone at 500 yards. In fact I didn't see a "new" rifle until they came and gathered up all the well worn weapons to ship off to the Afgans who were fighting the Russians later in '78.

tiger222
10-10-2012, 1:36 PM
M193 is more accurate than M855 out of a 1/7, in a 1/12 you'll do just fine.

gun toting monkeyboy
10-10-2012, 1:56 PM
You do know that Green Mountain barrels still makes 1-12 chrome-lined M16A1 barrels, right? So if you ever get the urge to try one out, they cost around $160 last I checked.

-Mb

Mikeb
10-10-2012, 2:06 PM
I can't compare accuarcy but the less stable bullet made devastating wounds.

Dave07997S
10-10-2012, 2:19 PM
While the accuracy of the AR platform is well known, particularly in its current 1:7 and 1:9 iterations, IIRC, the twist rate on the original M16s was 1:12. For those who know, and those who have used them, how accurate (or precise, for you members of the terminology-enforcement police) were the original M16 and M16A1 rifles? How about the original CAR-15's as used by Special Forces?

My first rifle issued to me in the early mid 80s was a Vietnam era M16A1 and it was very accurate shooting M193 Ball. In fact my favorite rifle is still the A1s over the A2s and other newer models. Loved the full auto, it was light and very maneuverable. Remember it was only when the A2s came out and the 62gr. M855 and M856 tracer round came out did they switch to the 1/7 twist.

Dave

6mmintl
10-10-2012, 2:27 PM
Mostly two moa in 1969, no one used a sling except for carrying as we new the barrel tension drifting POA problems. Reliable and good cleaning gear, did pick up a clogged gas tube one from an ARVN but was older three pronger FH one.

6mmintl
10-10-2012, 2:29 PM
Free float tube the older G.I. skinny 12" twist barrel and they will shoot just over 1MOA all day with M193.

killshot44
10-10-2012, 2:48 PM
Can't add to the discussion of accuracy of issued arms 40yrs ago but a 1 in 12 twist is more than adequate for a 55gr projectile.

The 12 twist is nearly universally used for varmint rifles using sub 70gr bullets at velocities over 3,000fps. It's also preferred (along with a 14 twist) for 6PPCs in short range Benchrest.

sigstroker
10-10-2012, 11:30 PM
You need to clarify next time. Not just put up the link to a one-sentence post elsewhere. :p

The longest range I have tried the 62 grain bullets at is about 50 yards. I didn't have any issues with them, but at that range, who knows? I went with the Retro build because I wanted the 1-12 twist barrel specifically for the 55 grain FMJs. It is plenty to stabilize them in flight, but they supposedly tumble and come apart when they hit things. That was one of the reasons it was noted for such horrific wounds early in the war. With the early 1-14 twist that the experimental rifles, it looked like the enemy had been hit with a buzzsaw. The wounds I have seen documented for the standardized 1-12 twist guns were almost as bad.

-Mb

I've shot M855 out of a 1 in 12 at 100 yards and the targets looked normal with no sign of keyholing.

Standard
10-11-2012, 7:19 AM
I never understood claims of "1 moa all day" using 3-4moa ammo, regardless of rifle.

jwkincal
10-11-2012, 7:28 AM
I never understood claims of "1 moa all day" using 3-4moa ammo, regardless of rifle.

What ammo is that? The NATO spec actually is 1 MOA isn't it?

The A1 I ran in OSUT at Ft Benning would shoot one hole at 50 meters; the platform itself has always been accurate in every iteration I've ever handled.

m03
10-11-2012, 7:38 AM
What ammo is that? The NATO spec actually is 1 MOA isn't it?

M193 is not NATO SS109 spec.

Looks like the requirements for M193 are roughly 3 MOA according to this:

http://www.ak-47.net/ammo/ss109.txt

SS109 isn't 1 MOA either, though:

NATO specifications for SS109 (U.S. M855) Ball require a 61.7 grain
(q 1.5 grains) with a hardened steel penetrator at a velocity of 3,025 fps
(q 40 fps) from a 20 inch barrel 25 meters from the muzzle. Typical
velocity 15 feet from the M16A2's muzzle is around 3,100 fps. The accuracy
requirement from a test fixture equates to a maximum of approximately four
MOA over the 100 to 600 yard range.

jwkincal
10-11-2012, 7:53 AM
OK, but you can download MIL-C-9963F at the link below:

http://www.everyspec.com/MIL-SPECS/MIL-SPECS-MIL-C/MIL-C-9963F_25766/

...in which we learn that:
Military Specification, Cartridge, 5.56mm, Ball, M193

Section 3, Requirements
3.5 Accuracy -- The average of the mean radii of all targets of the sample cartridges, fired at 200 yards, shall not exceed 2.0 inches.

...which sounds like 1 MOA to me?

Maybe the NATO spec is weaker and the m193 is on the DOD spec which is tighter?

m03
10-11-2012, 8:01 AM
...which sounds like 1 MOA to me?

Maybe the NATO spec is weaker and the m193 is on the DOD spec which is tighter?

I don't think the math works out like that.

I seriously, seriously doubt that the requirements for an infantry service cartridge were that stringent.

Manolito
10-11-2012, 8:11 AM
I did two tours in 66,67,68. Time does a lot to memory but reliability was the first concern and the bolt had a cotter key that sheared all the time once replaced with a nail it worked great. The round often deflected with a leaf sending the round all over the place. I have had tracer rounds come back towards me after hitting jungle clutter. The weight was the big advantage. Carry a M-14 and 200 rounds of ammo for a day walking through duck ponds and you will get the idea. I chose the m-14 because of its penetration but I was on PBRs so I didn't have to carry in the brush. As far as accuracy I attended weapons training at pendleton. The range instruction and accuracy required to graduate were pretty thorough. We had a Gunny that could run 100 meters and hit at 200 meters off hand no problem. He loved what he did and loved running Navy guys and if you don't know pendleton is pretty big place.

This round made some very messy holes in humans.

jwkincal
10-11-2012, 8:18 AM
I don't think the math works out like that.

I seriously, seriously doubt that the requirements for an infantry service cartridge were that stringent.

Actually, looking a bit more closesly, by selecting for radius rather than diameter, the DoD appears to have specified a 2 MOA precision in this case.

Still, for me the rifle consistently shot one hole at 50 meters in a 6-shot string, so one would expect that the standard deviation is pretty small in most cases.

donw
10-11-2012, 12:16 PM
i don't know about the m16...i was using an M1 Garand And M1 Carbine during that time...i was there before the M16 came into issue...

the average firefight was at 40 yards...

chino
10-11-2012, 6:17 PM
Original twist was 1:14; however its accuracy under arctic conditions was unacceptable. With the 1:14 and the 1:12 (less) the projectile twist was not optimal for stability, hence the large wounds creating when the projectile tumbled, fractured on impact. This is the most likely source for the myth of th M16 bullets "tumbling" through the air

Fate
10-12-2012, 11:55 AM
My M16A1 clone has a Colt upper on it that was NIW when I got it. Original bolt/bc/charging handle and has the correct birdcage flash hider. It's far more accurate than I am and outshoots my "modern" AR-15 carbine.

gun toting monkeyboy
10-12-2012, 12:49 PM
My M16A1 clone has a Colt upper on it that was NIW when I got it. Original bolt/bc/charging handle and has the correct birdcage flash hider. It's far more accurate than I am and outshoots my "modern" AR-15 carbine.

OK, I'll bite. What is NIW condition?

Plisk
10-12-2012, 1:08 PM
OK, I'll bite. What is NIW condition?

New in Wrap.

DasBoost
10-12-2012, 7:36 PM
Never really been interested in ARs, but this one has piqued my curiosity. Fulton Armory Legacy Upper (http://www.fulton-armory.com/fariflecal556mmupruniversalprecisionrifle-3-2-2-7-2-2.aspx):

http://i430.photobucket.com/albums/qq23/VeeDubberGLI/FAR15LegacyRifleUpper_zps051c3c07.png
-20" Pencil contour 1:8 barrel
-Slick-side receiver
-Chrome BCG
-Hybrid match .223/5.56 chamber (doesn't say Wylde, figure it's FA's own chamber)
Thoughts?

I like the idea of a classic look AR but able to shoot the heavier weight/longer bullets; working on pricing out a build.