The AR as originally presented

[GGALLIN1776]

Have any of you ever tried building an original spec 1/14 rate barrel with 40gr bullets as it was presented to Curtis Lemay?

If so, what are your thoughts? Would you rather have that than a 1/12 (or any other rate) along with the other bullet weights or does the tumble on impact make it worth the limitations?

[imashooter]

No.
The twist rate and grain never caused twist. Urban legend.

[Screwball]

I bought an H&R 604 clone… Air Force rifle. Lightweight, accurate and handy.

Options for twist were 1:12” and 1:7”. I got 1:7” because the lightest I shoot is 55 grain… with heavier being more used. Why set up a gun to a twist rate for ammo I’d never use when I can get one that uses the standard for what is currently shot? It isn’t like you can see the differences visually.

[GGALLIN1776]

Originally Posted by imashooter

No.
The twist rate and grain never caused twist. Urban legend.

I'm going from a video interview with Eugene Stoner, the one with the chalkboard behind him on YouTube.

The man himself said the 40gr combined with the 1/14 twist rate caused the extreme tumble, initially was against the change to 1/12 & 55gr.

[GGALLIN1776]

Originally Posted by Screwball

I bought an H&R 604 clone… Air Force rifle. Lightweight, accurate and handy.

Options for twist were 1:12” and 1:7”. I got 1:7” because the lightest I shoot is 55 grain… with heavier being more used. Why set up a gun to a twist rate for ammo I’d never use when I can get one that uses the standard for what is currently shot? It isn’t like you can see the differences visually.

Sure it wouldn't be very practical unless you roll your own. Just curious if anyone has built one & loads rounds in that configuration, also how it performs.

[bamaranger]

Can't speak to a 1-14" twist, but..........

I have a Mini-Mauser bolt rifle that I believe is twisted 1-12" and have a load using the 40 gr V-Max Hornady bullet, selected because the rifle for whatever reason, delivers relatively low velocities with heavier bullets (52-55 grains) despite its 20" bbl.

The 40 grain pill with modest charges is faster than the 52 MHP I wanted to use. Additionally, it actually groups better (at 100). I expect great results on varmints.

[Jim Watson]

Have any of you ever tried building an original spec 1/14 rate barrel with 40gr bullets as it was presented to Curtis Lemay?

A 40 grain bullet is new to me. But then I haven't recovered from it being asserted that the .223 was designed by a gunzine writer.

[44 AMP]

Have any of you ever tried building an original spec 1/14 rate barrel with 40gr bullets as it was presented to Curtis Lemay?

The original AR 15 was a .222 Remington. That's what LeMay got to check out. The .223(5.56mm) didn't exist at that time.

LeMay was in a bind, his security forces used the M1 carbine. The Army was dropping the carbine. That meant no more carbines or parts for LeMay's SAC guards and SPs. HE thought the AR 15 would be an adequate replacment.

When he pitched the idea, the "whiz kids" in the MacNamara defense dept thought it would be a good choice for the general service rifle.

Factions in the Army objected to that. They got a requirement in the specs that the .222 Rem could not meet. They hoped this would kill the entire idea. It didn't. A different faction created the 5.56 (.223) which could meet the spec and fit in the AR 15, and that was what the Army was required to adopt.

The original AR 15s don't have all the features of the M16A1 or later variants.

The triangle handguards, the three prong "wait a minute" flash suppressor, NO forward assist, no brass deflector block, and no "fence" guards around the magazine catch. These are the primary differences. There are a few others...

[Shadow9mm]

Personally, never shot one. But the idea of a bullet that is on the razors edge of being stable so that, with FMJ ammo, it should destabilize and tumble after striking a target, seems like a VERY limited use case with a LOT of drawbacks.

Using Bergers bullet stability calculator here https://bergerbullets.com/twist-rate-calculator/ gave me a stability of 0.939, with anything under 1.0 being unstable.

For data I used the 40g v-max
BC of .2 https://www.midwayusa.com/product/1165189058?pid=692022
Caliber .224
weight 40g
Length .686 https://jbmballistics.com/ballistics....shtml#Hornady
Velocity, 3650fps https://www.midwayusa.com/product/1836223300?pid=533596
Twist rate 1:14
air temp 59F
Altitude 0

Berger quantifies stability using this scale based on their calculations
under 1.0 unstable
1.0 to 1.5 marginally stable
1.5 or more comfortably stable

using the bullet above changing the twist rates
1:14 0.939
1:12 1.28
1:9 2.27
1:8 2.88
1:7 3.76

[Jim Watson]

Interesting, considering that a .222 is darned accurate with a 52 gr SMK at 3200 fps from a 14 twist even though the calculated stability is only 1.11.

The story at the time was that the cheap 55gr FMJ BT was not stable or accurate in cold weather testing. As Jeff Cooper put it, rumor has it that it gets cold in Germany. So they increased the twist from varmint rifle 14 to service rifle 12.

An old gunzine showed an M16 with an early tubular free float foreend and a 10 twist barrel. Work done by the USMC to try to squeeze some accuracy out of M193 hardball. Of course now everybody shoots non-GI match ammo in their "service rifles."

[zukiphile]

Originally Posted by Shadow9mm

Personally, never shot one. But the idea of a bullet that is on the razors edge of being stable so that, with FMJ ammo, it should destabilize and tumble after striking a target, seems like a VERY limited use case with a LOT of drawbacks.

One of the first ARs I made had a 20" Green Mountain 1:12 pencil barrel. It's just over six pounds with sling and optic and does great things with 50gr polymer tipped rounds. It's neat and so long as the cheapest rounds are 55gr, I won't worry too much about being able to find rounds that work.

On the other hand, it won't keep 62gr green tipped rounds inside a one foot circle at 50 yards. For some people that would be a considerable drawback. If I had to find and shoot only 40gr rounds for a barrel, I'd find that unduly limiting.

[44 AMP]

Personally, never shot one. But the idea of a bullet that is on the razors edge of being stable so that, with FMJ ammo, it should destabilize and tumble after striking a target, seems like a VERY limited use case with a LOT of drawbacks.

Regarding the M16 and its ammo, and "designed to tumble" statements are mostly BS.

Yes, the bullet will tumble after impact. EVERY BULLET LONGER THAN IT IS WIDE DOES THAT!

What differs is the degree of yaw, how soon (in terms of distance traveled) it happens, and how noticeable it is.

The .26-.32 caliber bullets used by the world's militaries for most of the major 20th century wars all tumble after impact. Eventually. If they aren't stopped by something before full tumble happens.

Those long, heavy "stable" bullets still tumbled. The difference being it mostly happened AFTER the bullet exited the enemy soldier's bodies, so no one really SAW it happen.

The short, light .224 frequently tumbled while it was going through the enemy. This did cause wounds out of proportion to its small diameter, and this factor was seized upon by advocates of the small round, and this became the myth that it was designed to do that, rather than what it really was, a fortuitous benefit of physics.

The round and its rifling were designed to be accurate. The rapid tumbling after impact was an unexpected military benefit, claimed to have been the idea all along.

Take a look at the history, people were shooting .22 centerfires for some decades before the .223 came along. NEVER any mention of the tumbling and how it enhanced the wounding effect. Why not??

Couple of reasons. First, no one was shooting people (enemy soldiers) with .22 centerfires. Second, what they were shooting were varmint bullets, intended to expand rapidly (even explosively) on targets with very light resistance, compared to the human body or big game animals.

There were some "big game" (deer, primarily) bullets, and no mention of their "tumbling" is found in period literature, either.

The other "myth" one frequently hears about the 5.56mm is that its "horrific wounding power" actually makes it a more effective military round because a wounded soldier takes 2-3 other soldiers "out of the fight" to care for the wounded man.

Sure, that happens, sometimes, WE DO THAT, and so do many nations, who have the resources, and care about individual soldier's health. Doesn't work that way when the enemy doesn't fight the way we do. Nations that treat their troops as cannon fodder, and also those "insurgent" groups without the resources to care for their troops the way we do, generally don't take many, if any guys "out of the fight" to care for their wounded. What frequently happens is the wounded get what care is available, if they are still alive AFTER the fighting is over.

[Jim Watson]

Early smokeless military bullets were jacketed roundnose, as used for deep straight penetration on megafauna. The British went through a whole series of expanding bullets for “stopping power” against enraged savage tribesmen. Those were barred by The Hague conventions. But they and everybody else had the last laugh when spitzers became standard.

[NWPilgrim]

Very informative discussion! I learned a few things. Thx. I only shoot 1:8 and 1:7 barrels in ARs so none of this has been relevant to me. But it is fascinating to read the background.

[44 AMP]

For those of us who lived through the havoc created by the MacNamra defense dept, and its aftermath, most of the memories are more bitter than sweet.

The nickname "whiz kids" was not given out of admiration, rather the opposite.

If the whiz kids every had any really good ideas, I don't recall what they were. Seemed like about everything they wanted done wasn't a good idea (though it could be done) and I remember some that were barking stupid.

Don't know if they were Lord of the Rings fans, or even if they knew the stories existed, but they were hard into "One Ring to Rule them ALL" as a concept. They pushed hard to get the military all using the same equiptment, one rifle, one plane, etc. On paper that looks good, in the real world, not so much.

One fellow I remember reading claimed that the MacNamara Defense Dept actually took more weapons and weapon systems out of action than a Soviet nuclear first strike would have. That's probably overstating things a bit, but most of us felt it wasn't all that far off.

There are probably entire books written about the actions and the power struggles that went on between various factions in the military and the govt during those years. One thing I do know, with certainty is that the poor line troops were "lab rats" having each new idea tested on us, and blamed if we couldn't make it work, by one group and blamed by another faction if we could make it work, no matter how badly it did work.

And, tragically, soldiers were killed and injured that didn't need to be, while the various factions did things to "prove their point".

The story of the M16 isn't the only place this happened, but its probably the best known and most tragic.