Every year when I go for reserve training we get an introductory speech from the current 18-year-old soldierette expert about the m16 rifle. It starts like this:

Her: This is the M16A2E3. Who can tell me what the weight of the weapon is...
Us: So, do you have a boyfriend?.....

Anyways, on alternate years we are told different versions of why the exposed end of the barrel is thicker:
1) Increases accuracy by reducing barrel whip
2) Prevent the barrel from bending when abused by soldiers (i.e. like stories about GIs using it as a crowbar)

Does anyone know the true reason for the (govt?) profile design of the A2 barrel?

Occasionally we are even told that the forward assist was put on for silently charging the weapon in Vietnam ambushes. I used to argue with them that it was bs but time has worn me out...

Pick up a copy of the Black Rifle - IIRC it's covered in there.

The most common issue I heard of was the abuse of the barrel.  Put a bayonet on the rifle and use it to cut the banding on a crate of ammunition-with an A1 profile barrel you'll bend it, but the thicker profile of an A2 barrel resists this particular abuse quite well.

Of course I'd be more in favor of issuing band-cutters, but that's just me.

Quoted: Pick up a copy of the Black Rifle - IIRC it's covered in there.

So I'm going to have to shell out $96 US greenbacks to Amazon in order to settle this issue? I doubt that any local library around here has the book. I'm really curious-but not that curious.

Maybe someone knows the answer?

It's crazy if they really added a half kilo to the end of the rifle just because soldiers were doing foolish things with the barrel.

The original reason, is pretty much as posted.  Barrels were being bent by all manner of abuse, including using the 3 pronged muzzle break as an ad-hoc band cutter on C-Rat and ammo cases.  

The thicker barrel prevents that, but it was kept thinner under the handguards to match the original profile so that the M203 could be mounted without change.  An added benefit was just a bit of felt recoil reduction and muzzle flip in burst and auto with more meat out towards the end.  

Although there are not many real world uses anymore, we are still taught rifle fighting techniques just in case you actually do have reason to fix bayonets and slash or jab your opponent.  A little thicker barrel ensures that when your done dancin, and clear that jam that got you on the dance floor to begin with (why your buddies didnt shoot the bastard is beyond me, quit fartin in the foxhole, ya might have more friends)  your barrel is still straight and shootable.  

I cant buy the bayonet item being true. the bayonet attaches to the barrel where the barrel goes thin. It would ber had to ben a barrel in the area where the bayonet is you would have to bend both the bayonet and barrel. That small increas in barrel dia would not slove the bending problem.

A long, long time ago...
I can still remember
How that gun used to make me smile.
And I knew if I had my chance
That I could make those targets dance
And, maybe, they’d be happy for a while.

I can’t remember if I cried
When I read about this thin govt. profile,
But something touched me deep inside
Cause I had wanted an HBAR for a while.

But that skinny barrel made me shiver
With every paper hole I’d deliver.
Bad news on the doorstep;
I couldn’t take one more step.

So bye-bye, my government profile.
Drove my Colt to the levee,
But the levee was dry for a while.
And them good old boys were drinkin’ whiskey and rye
Singin’, "the HBAR rules IPSC.
"The HBAR rules IPSC."

Did you write the book of love,
And do you have faith in Colt above,
If the Shooter's Bible tells you so?
Do you believe in rock ’n roll,
Can a heavy barrel save your mortal soul,
And can you teach me how to shoot real slow?

enough of that, years ago I bought my first AR15A2, a transition model.
Tear drop FA, Govt. Barrel and A1 sights. It actualy shot fine, BUT EVERYBODY who was ANYBODY had a HBAR. I had to be an EVERYBODY.

I have have quite a few HBARs and I still have a Colt 6520 pencil barrel. All I do is shoot IPSC with the Bushy 14.5 Heavy and CMP with the HBAR. If Iwas to walk around for days I'd pick up the 6520, or may the Bushy, but NOT the Service Rifle, that thing is probably 12 lbs.

Bill
From what used to be New Orleans

Bayonet stresses are, indeed, focused on the bayonet lug and flash suppressor, but you ignore that bayonet practice doesn't limit itself to just poking at things, the end for the barrel WAS bent often enough for somebody in the Marines to say, hey, there's a problem.  When you look at how they're trained, it's easy to envision the barrels bending all kinds of ways with a bayonet on the end.

That's a logical explanation if you ask me... Yeah, I realize that nobody did though so I'll shut up.

Quoted: I cant buy the bayonet item being true. the bayonet attaches to the barrel where the barrel goes thin. It would ber had to ben a barrel in the area where the bayonet is you would have to bend both the bayonet and barrel. That small increas in barrel dia would not slove the bending problem.

Simple physics defuncts the theory... an A2 would just bend under the handguard.

Quoted: Quoted: I cant buy the bayonet item being true. the bayonet attaches to the barrel where the barrel goes thin. It would ber had to ben a barrel in the area where the bayonet is you would have to bend both the bayonet and barrel. That small increas in barrel dia would not slove the bending problem. Simple physics defuncts the theory... an A2 would just bend under the handguard.

Wouldn't the newer round and stronger A2 handguards help with supporting the barrel more than the old triangle handguards?

Brett

Black Rifle II mentions the abuse that Airborne divisions put rifles through by landing on them during jumps, etc, and the bayonet as prybar issue. A heavier barrel was designed, tested, and then altered back to A1 profile so a new M203 front mount would not havr to be designed. One design just clashed with another.

Quoted: Heat trials by the Navy determined that a combination of the new handguards (A2) and the old (A1) barrel were the most economical combination for increasing dissipation of barrel heat. Their recommendation was that if the barrel mass was increased that it only be increased outside the handguards. The bayonet argument is patently stupid, the barrel is a lever, thickening one end just makes it bend at a different point.

So I understand that the physics and technical reasons rule out the A2 profile for preventing the bending the barrel by abuse (bayoneting/use as a crowbar).

By most economical combination for increasing dissipation of barrel heat do they mean for keeping the barrel itself cooler or for keeping the heat away from the user’s hands? How does the A2 hanguard play a role?

How does keeping only the last third of the barrel thicker, keep it more accurate when hot? I would think that an uneven profile would induce more flexing not less.

One shooting instructor who seemed to know more than others, once explained to me that it was thicker in the front to reduce barrel whip at the exposed part of the barrel. He said that it didn’t need to be thicker under the handguards because there the barrel was supported by the connection to the receiver and the handguards. I guess this would be sort of analogous to the barrel as a wet noodle. Does this sound right?

Also, I believe almost all assault rifles around the world have only thin profile barrels and this doesn’t seem to bother anyone else. I'm sure other armies' soldiers are just as enterprising when it comes to abusing weapons (ours certainly are hat
For me the A1 is much better balanced than the A2. The A2 feels too front heavy, especially with an attached Harris bipod. The bipod at least helps stability when you need to stay in position for an extended period or during times of physical exertion.

ok, so no body liked my song, but tonight I am a bit too lazy to do a search, so how much more or less does a govt profile weigh as opposed to 1) a HBAR and 2) the originial A1, ah la pencill barrel?

Bill

ps it was a stolen song anyway

Quoted: ok, so no body liked my song, but tonight I am a bit too lazy to do a search, so how much more or less does a govt profile weigh as opposed to 1) a HBAR and 2) the originial A1, ah la pencill barrel?

All right, you're honest at least:
20" Govt (A2) Profile 2.1
20" HBAR 3.1
20" 'Pencil' (A1) Profile 1.8

Weights are in pounds, and don't include barrel nut and related hardware, handguard cap, muzle device, nor front sight base (which would all weigh the same for each)

Thanks to everyone for their input, especially to Tweek for spending his valuable time and effort on suppling so much valuable information. I find it kind of amusing that the A2 (Govt) vs HBAR profile argument is getting so much attention recently, and yet the actual reasons for this unique profile are somewhat in doubt. Next time I visit the States, I’ll look for a copy of the TBR in the local library.

20" Govt (A2) Profile 2.1 20" HBAR 3.1 20" 'Pencil' (A1) Profile 1.8

I always assumed that most of the almost 1 lb weight difference between the A1 and A2 rifle,  2.97 kg (6.55 lbs) vs 3.4 kg (7.5 lbs), was due to the barrel. From the info above, I see that barrel weight difference is only 0.3 lbs so I guess it’s not a big deal after all. The harris bipod at the front weighs more than twice as much anyways. I wonder where the othe 0.7 lbs come from?

Chuck Taylor tells  a funny story about IDF Infantry troop and their ability to damage their rifles during some of his rifle classes. Said he knew something was up when they complained that the AK was too easily damaged. hr

It still is SOP to hit the catches that lock the back ramp of the APCs and are always getting stuck, with the rifle muzzle to free them so that the ramp can be lowered.

The problem with the "wet noodle" arguement is the same problem found on the M1919s (you're familar with them?) the barrels are supported only at the ends and when the barrels heat up they flex in the middle. The same would happen with the AR if the arguement were true only with the "the middle" being between the upper receiver and the front sight base.

If by M1919 you mean the Browning 30 cal. MG, I never trained or handled one (only MAG 58s in my time). The only one I saw in service was once when I was exploring the trenches of a large Golan Heights outpost we were stationed 20 yrs ago, I discovered one under a tarp. It was rusted bright orange! Being an experienced soldier, I quickly replaced the tarp before anyone could order me to go clean it. hat
Another-Bill,
Your song was-how should I put it-interesting. I just can't picture Madonna doing a rendition of it

Quoted: Every year when I go for reserve training we get an introductory speech from the current 18-year-old soldierette expert about the m16 rifle. It starts like this: Her: This is the M16A2E3. Who can tell me what the weight of the weapon is... Us: So, do you have a boyfriend?..... Anyways, on alternate years we are told different versions of why the exposed end of the barrel is thicker: 1) Increases accuracy by reducing barrel whip 2) Prevent the barrel from bending when abused by soldiers (i.e. like stories about GIs using it as a crowbar) Does anyone know the true reason for the (govt?) profile design of the A2 barrel? Occasionally we are even told that the forward assist was put on for silently charging the weapon in Vietnam ambushes. I used to argue with them that it was bs but time has worn me out...

Since The M16A2 Product Improvement Program (1980-1983) was my program, this is the down & dirty on the barrel thickness issue.
We (Marines) were replacing a lot of  "bent" barrels that were determined to be "bent" because the Armorer's Bore Drop Gauge would not freely pass through some barrels during Ordnance Inspections (LTI's).  So the Logisitcs people had "Barrels Bending" on their list of "M16A1" things to "Improve" right after listing "Handguards Breaking."
We "experts" thought this bending was from rough handling like during bayonet drills, etc., as an absence of any mid-barrel handguard damage in these rifles made one assume the fulcrum of such bending was the bayonet lug.  So we made that part of the barel thicker because we did not want the excess weight of a full length heavy barrel.  In testing using the bayonet lug as a fulcrum, and applying calibrated mechanical pressure to the muzzle, the new barrel was about 9 times more resistant to bend and take a set than an M16A1 profile.  So we went with this "improvement."
However, soon after I started using a bore scope with a video recorder and monitor to inspect "bent" barrels.  What I found was a mound of bullet jacket material at their gas ports.  This build up was caused by a burr left from drilling/reaming the gas port.  This was where the Armorer's Drop Gauge was geting stuck.  When we removed this "mound", the barrels would all pass the Drop Gauge.  We let Colt know what we had deduced, and that is one reason they kept models of "A2's" in their line-up with A1 profile barrels.  However, the A2 profile was already down the road for the US Military.  So about the only advantage of the A2 profile was to give the rifle a little more muzzle hang.  This was noted by most all the Operational Test paticipants, especially when they fired the standing/off-hand leg of our rifle qualification course.
So my advice to mlitary armorers is to never replace a bent barrel until you visually check the gas port, or at least scrub the hell out of the gas port area with a new bore brush and an electric drill.  And thank God for chrome bores!

Quoted: Since The M16A2 Product Improvement Program (1980-1983) was my program, this is the down & dirty on the barrel thickness issue.

Coldblue,
Incredible story! Thanks for sharing this piece of M16 history with us. I remember reading about the then new version of the M16 in an issue of Marine Corps Gazette in my High School library at the time.

With the benefit of 20+ years of hindsight, are there any features that you wish you had or hadn't added to the A2?

Quoted: Quoted: Since The M16A2 Product Improvement Program (1980-1983) was my program, this is the down & dirty on the barrel thickness issue. Coldblue, Incredible story! Thanks for sharing this piece of M16 history with us. I remember reading about the then new version of the M16 in an issue of Marine Corps Gazette in my High School library at the time. With the benefit of 20+ years of hindsight, are there any features that you wish you had or hadn't added to the A2?

Oh Yea!
1. Lose the burst control.  We were forced into this because the Logisticians who were planning on buying the M249 SAW were saying the rifleman did not need the auto option.  And the Ammo people made a great case of removong auto from the Rifleman because the 800 SAW rounds per case was going to significantly reduce the rifle ammo pack out per case at 1680 rds.
2. Ever wonder why Safe, Semi, and Burst are marked on the starboard side of the receiver? Well as the list of improvements increased to a point some 2 1/2 years into the program spilled over onto a second viewgraph, the last thing on the first page was the starboard side marking, the first thing on the second slide was a "mirror image" selector that pulged-in from the right side for us left-handed Marines.  
3. One Colonel who shall remain un-named insisted that I "lose everything on the second slide."  Well the second thing on that list was a "step" at the rear of the front large diameter barrel area to provide a more robust interface for the front of the M203 receiver.  (Something we sorely need today.)
4. An M203 Side Sling Adapter that would fit around the larger diameter barrel.  This one bit us in the ass when we fielded the A2's when everyone else on the planet discovered the old Side Sling Adapter would not fit.
5.  Then there was a railed uper receiver that eventually became the Picatinny rail (remember, I was stationed at Picatinny at the time), and then a receiver concept drawing that looks very much inspired by the then brang new AUG-1.
...the Colonel's reasoning: "Major, you were sent to Picatinny to Product Improve the current Service Rifle, not to develop the Futue Rifle--that is another program entirely, which the Marine Corps & Army are currently funding as you well know because Picatinny is doing it and you are monitoring in on-site."
Well, all I got to say is Future Rifle failed to deliver and improed rile, then became the Advanced Combat Rifle (ACR) that failed to deliver as well, then that was followed by the like ill fated OICW.
Oh, I guess I got one more thing to say, THANK YOU MR. STONER and f___ y__ Colonel.

Quoted: 2. Ever wonder why Safe, Semi, and Burst are marked on the starboard side of the receiver? ............ One Colonel who shall remain un-named insisted that I "lose everything the second slide."

So much for high-tech Test/Evaluation, huh?


Its uncanny how such simple things can change history.