m16 barrel

[deputy bruce]

Can anyone tell me about the m16.I had an army friend tell me that the m 16 keyholes and that what makes it so deadly.

 

[12Bravo20]

That is total BS.

If that was the case then how would any service member be able to hit the 300 meter targets to qualify.

I was issued the M16A1 and M16A2 while I was in the Army and if any key holed, it got a new barrel right away.

 

[ParallelCode]

I think what your friend was likely referencing was M193 taking an erratic path after impact and either not exiting or doing so in a non-linear manner.

 

[12Bravo20]

I think what your friend was likely referencing was M193 taking an erratic path after impact and either not exiting or doing so in a non-linear manner.

And even that is a myth told in basic training. And any tumbling would have been more prevalent with the very first M16 rifles with the 1-14 twist. But those were not in service very long before being replaced with 1-12 twist barrels.

 

[ParallelCode]

And even that is a myth told in basic training. And any tumbling would have been more prevalent with the very first M16 rifles with the 1-14 twist. But those were not in service very long before being replaced with 1-12 twist barrels.

To be clear I'm not saying it's accurate, just noting that it is almost certainly what his friend was referencing as opposed to keyhole behavior.

 

[citizenconn]

I don't know about it being a myth, but I personally did see a lot of keyholing on targets while I was in the Army. Sometimes the pop up range targets were arranged such that a shot would go through the 50 yard target and then strike the 150 yard target or other various distances. In those cases the 2nd hole was almost always a keyhole. I've also seen shots past 100 yards keyhole on the first shot.

This was 30+ years ago and some bases were still shooting 55 grain while some were shooting the newer 62 grain projectiles. As far as I remember the keyholing was with the 55 grain projectiles. These were from A1 and A2 rifles.

As a civilian I've shot a lot of 5.56 projectiles and about the only time I see keyholing is when the projectile hits some grass or other obstructions, which very well could have been the case in Vietnam. Are keyholing projectiles more deadly? I guess in theory they create a bigger entrance wound that might not exit. Otherwise the FMJ round will often go straight through the target.

My understanding of why the 5.56 was considered a better alternative is because it incapacitated the enemy soldier without killing him outright many times, requiring the enemy to exhaust more resources to save him. That seems like it might be more myth than the issue of keyholing.

All of my 5.56 barrels have twists of 1:7, 1:8 or 1:9, so they do quite well stabilizing my projectiles from 55-77 grain. I haven't tried smaller varmint loads under 55 grain. As 12Bravo20 indicated, the early barrels with 1:14 twist (which I think were pencil barrels) were more apt to have stabilization problems.

OP, I hope this helps.

 

[12Bravo20]

And you also have to remember that most unit armorers would let a barrel go until there was a significant problem with key holing before sending the rifle in for a new barrel. This was more true with basic training units. As long as the trainees could still hit the 300 meter targets and qualify the rifles usually stayed in service.

 

[Varminterror]

There’s nothing about the “M16 barrel” design or the ammo used therein which would elicit keyholing.

This is a prime example of the fact “military experience” doesn’t equate ballistic intelligence, or even ballistic knowledge. At BEST, this “army friend” is convoluting tumbling AFTER impact by bullets in tissue, or potentially mis-assigning the observation of keyholes on target from completely wasted barrels.

 

[entropy]

M885 will keyhole out of an A1 barrel between 200 and 300 meters. The twist rate didn't stabilize it well.

 

[12Bravo20]

M885 will keyhole out of an A1 barrel between 200 and 300 meters. The twist rate didn't stabilize it well.

And to add, the only reason for going with the 1-7 twist was to stabilize the even longer 64 grain M856 tracer rounds. 62 grain M855 stabilizes just fine in a 1-9 twist wheel the M856 tracers will not.

 

[lysanderxiii]

I don't know about it being a myth, but I personally did see a lot of keyholing on targets while I was in the Army. Sometimes the pop up range targets were arranged such that a shot would go through the 50 yard target and then strike the 150 yard target or other various distances. In those cases the 2nd hole was almost always a keyhole. I've also seen shots past 100 yards keyhole on the first shot.

Those holes are from ricochets.

Ricochets are caused by even minor disturbances in the projectile flight. Who would have thought that a watermelon or two could knock a 114 pound 6 inch projectile sideways . . . .(go to 00:14:30)

Are keyholing projectiles more deadly? I guess in theory they create a bigger entrance wound that might not exit. Otherwise the FMJ round will often go straight through the target.

If a projectile starts to tumble in flight, it will loose velocity rapidly and within a hundred yards or so, be harmless. (Except to a piece of plastic.)

 

[FL-NC]

Keyholing in flight is a thing that happens when a bullet path is disturbed between the muzzle and the target. It may come as a surprise, but this isn't just limited to the 5.56/223. It will also happen in the M16 family of weapons (and other 223 rifles) if the bullet is too heavy for the twist rate. Finally, it will happen at very close distances (less than 25 yards) if the barrel is worn out. 5.56/223 ball or OTM will tend to keyhole inside of a "soft organic" target too- but not necessarily every time. I have witnessed "banana shaped" exit holes from 223/5.56 in pigs, deer, and so on.

 

[deputy bruce]

Thanks for all your input,It is nice to be able to call apon you for information

 

[N555]

If the barrel twist isn't fast enough just going transsonic or using a silencer can cause a bullet to tumble in flight.

 

[Varminterror]

using a silencer can cause a bullet to tumble in flight.

Another wild an unsubstantiated claim.

 

[Destructo6]

We had about a dozen M16A1s at one time. Triangular handguards and all. After we switched from 55grain ammo to 62grain, we noticed that the targets displayed keyholeing at 50 yards.

We swapped them out for more M4s.

 

[N555]

Another wild an unsubstantiated claim.

I have discovered silencer and ammo combinations that cause bullets to tumble.
Try firing a 22wmr in a 22LR silencer, it will tumble after about 10 feet.
5.7x28 subsonic 62gr bullets, with a 1:9 twist, without the silencer they fly straight, put on the 5.7 rated silencer they tumble.
5.7x28 subsonic 55gr bullets are fine, that's probably why FN developed a 55gr and not a 60 or 62gr.
Load developing a subsonic 30carbine with 130gr "30-30 bullets" subsonic they flew straight, super sonic 1,250fps+ they flew straight. At transsonic I couldn't even hit the paper at 100 yards. It's something you will never encounter unless you are load developing subsonic ammo and/or using silencers.

When the bullet drops to subsonic it is hitting something, even if you can't see it so if there's not enough spin the bullet tumbles.
Just because you haven't experienced it doesn't mean it doesn't happen.
If you still have any doubts about transition from subsonic to supersonic and back again see the movie "The Right Stuff" that little hump at mach1 on that chart killed a lot of people.

 

[Varminterror]

Destabilization due to Transonic transition has absolutely nothing to do with suppressor use.

 

[herrwalther]

No. M16s shoot relatively light bullets that yaw inside a target that causes high wounding capability. Keyholing implies that bullets go into targets in an orientation other than straight on like sideways, backwards, or upside down. Either your friend doesn't know what he is talking about or you misunderstood.

There is much more to it with twist rates, bullet weight, distance to target, through barriers etc. But a properly working rifle with issued ammo is not designed to keyhole on a target.

 

[CapnMac]

The original "pencil" barrel on the M-16, made before more modern heat treating became standard, was prone to vertical stringing after heating up. Thi will make for ragged targets down range.

The M-16A2 barrel profile was thickened, to help prevent stringing (and it's final finish treatment had the benefit of a couple decades of procedural improvement, too).

There are any number of myths about the "M16" which ignore detail of version, era, and use--to call them half baked overestimates the "baking" about 4x.

 

[N555]

Destabilization due to Transonic transition has absolutely nothing to do with suppressor use.

I didn't say they were.

 

[C-grunt]

A few years back Franklin Armory made a short barreled "firearm" which was basically a shorty AR15 with no rifling.

Military Arms Channel on Youtube did some testing of the firearm using M855 and a rubber dummy target. The bullet would start tumbling in flight almost immediately after leaving the barrel and lose velocity rapidly. If I remember correctly the M855 struggled to penetrated the rubber dummy at around 100 yards.

Found it.

 

[Varminterror]

I didn't say they were.

Um… sure seems like you did…

using a silencer can cause a bullet to tumble in flight.

 

[Reloadron]

I trained in the Marine Corps with a M14 but when I got to Vietnam in '72 we were issued M16A1 as I recall. All of my future qualifications (one each year) till 1978 were with the M16A1 both shooting and pulling butts at 200, 300 and 500 meters and I never saw one keyhole. The only time I had anything keyhole was shooting my 1:7 twist AR15 and that was shooting something like 52 grain Hornady match bullets if I even recall correctly. They were hand loads and actually shot well in my 1:12 bolt gun. Anyway I never had or saw keyholing with any government issued M16A1 that I shot using GI ammunition.

Ron

 

[David Hoback]

Can anyone tell me about the m16.I had an army friend tell me that the m 16 keyholes and that what makes it so deadly.

The M16, or AR15 as it’s called in the civilian world, is a truly awesome platform. It’s one of the longest running platforms of ANY battle rifle in the World. The 5.56x45 round (again, 223 in normal speak), is a great round with a HUGE expanse of bullet styles, weights, velocities; lending to an ultra large range of uses. From Military application, but also Hunting, Defense, & Target duty. On 2-legged “critters”, the 223 is DEVASTATING! Any talk of it not performing is ludicrous. And before the latest & greatest armor is brought up, yeah… people aren’t walking around with that! At best they might be wearing some Level IIIA. Well, here is what 223 thinks of IIIA Armor.
(Yeah… it LAUGHS while it takes the IIIA’s lunch!)



As for what your friend told you, I believe he is thinking of this.


So if you are thinking about getting one, or better yet.. build it yourself… I absolutely recommend YES!! They are fun, accurate & dollar/performance/accuracy ratio they can’t be touched! (Some will argue that and I’ll gladly TAKE THIER LUNCH in a debate, LOL!)