... Physics, coolness & Mforgerys

[ARCHIVED THREAD] - ... Physics, coolness & Mforgerys

Posted: 4/27/2002 10:25:32 PM EDT

... Ever consider the fact that the necked-down portion of an M4 barrel is a "weak link" in its bending strength?
Without an M203 it's really useless and in fact just cosmetic and a place for your barrel to fail first. It's not for me.

... Comments

Posted: 4/27/2002 11:18:20 PM EDT

[#1]

Yeah, I know what you mean. I don't have an M203 and mine fails (splits, cracks, blows-up) every time I shoot it. It really sucks. I'm really sick of getting steel in my face...but what am I gonna do. And then there is the "bending" issue. If only I didn't have to use it as a ladder rung every time I went to the range...

Actually I plan on getting a MasterKey setup this summer, so it does serve a purpose for me.

Honestly, how many M4's in the military are not equipped with an M203? And how many of them fail at the cut-down area? How many of them suffer barrel failures period?

Posted: 4/27/2002 11:30:35 PM EDT

[#2]

I have read that M4's should not be suppressed as there have been cases where the back pressure caused the cut down portion of the barrel to bulge.

Posted: 4/27/2002 11:46:52 PM EDT

[#3]

Quoted:
I have read that M4's should not be suppressed as there have been cases where the back pressure caused the cut down portion of the barrel to bulge.

... well, "knowing" you Imbroglio, I'm gonna call bullshit on this. The fact remains, there is LESS material there and if right amount of force is applied it will bend about the same as an old SP1 barrel.

... the strength of materials is constant on earth.

Posted: 4/28/2002 12:58:24 AM EDT

[#4]

Well, OK then. Everyone trade in your M4 barrels for H-Bars, since they will be so much stronger "bending strength-wise" when we use them to step on to scale walls or pry open doors & such...

Posted: 4/28/2002 7:05:42 AM EDT

[#5]

Quoted:
Well, OK then. Everyone trade in your M4 barrels for H-Bars, since they will be so much stronger "bending strength-wise" when we use them to step on to scale walls or pry open doors & such...

I have an H-bar if anyone wants to trade.

Posted: 4/28/2002 8:20:46 AM EDT

[#6]

come on now guys ..

You all know that the M16 was designed to assist you in putting your cot together so you could get a good nights sleep... (maybe the notch on the M4 style barrel interfaces better with the brace .. this I will have to check next time I am in an assault with my cot...)

It has a longer piece of barrel showing that allows you to get the cot stretched out to the full length thereby making it better supportive of your back when resting ...

Now you know why the M14 & M1 Garand were dropped from service ... they could not handle the newer model Aluminum Cots with the Nylon fabric...

Ted...

Posted: 4/28/2002 12:15:49 PM EDT

[#7]

It goes without saying that a thin barrel will bend more/sooner than a thick one under the same load.

That being said, I doubt the Army would buy off on an under strength barrel. The diameter of the thin portion of the M-4 barrel is the same as the barrels on the original M-16's. I've never heard about failures related to a lack of thickness (unless you include the barrels bent when they were used to pry open ammo crates).

Do they have a purpose for us 'civilians'? Only if you want to mount a 37mm tube.

Do they adversely impact accuracy? Darn tootin'

Do they scare the crap out of the anti's? Ohhh Yeaahhh!

I bought mine for no reason other than some piss-ant bureaucrat says I shouldn't. That's the best reason for owning an M-4gery that I know of.

Edited to add: I still have my HBAR for those long distance affairs.

Posted: 4/28/2002 12:15:51 PM EDT

[#8]

... Function over vanity. WTF good is a weak link on your rifle barrel?

I still haven't heard ONE good reason to purposely "build in" a flaw (and that's all it is if you're not hanging an M203 off it).

... Another thing you geniuses, just what spot on your M4 barrel do you think would fail from heat first during sustained fire?

Posted: 4/28/2002 12:21:49 PM EDT

[#9]

Quoted:
... The diameter of the thin portion of the M-4 barrel is the same as the barrels on the original M-16's.

... Humph, excellent observation. [sarcasm]I wonder why they designed the heavy barrel as a replacement?[/sarcasm]

Posted: 4/28/2002 12:53:33 PM EDT

[#10]

Winston_Wolf, I agree that the M4 barrel is unnecessary without an M203 or 37mm, but you have the solution backwards. I wouldn't modify an M4 barrel by filling in the cutout. I would modify it by removing all that extra material on the rest of the barrel.

Posted: 4/28/2002 12:55:15 PM EDT

[#11]

IMO, the "thin-lightweight" barrel is better than the HBAR. Is is more costly to produce the lightweight barrel, so that was probably a factor in the switch. Some will argue ehat the heavy barrel is more difficult to heat up (and that is true), but it also takes a lot more time to cool off. Most M4s are semi/full auto (as opposed to the semi/3round burst found on the typical M16A2), and both have the THIN profile under the hand guards - seems the better option was to make the M4 handguard with double heat shields - not to make the barrel of the M4 thicker.

As far as I am concerned, the HBAR barrel was only designed to add weight in making the AR15 into a target rifle.

Just my .02

Tyler

Posted: 4/28/2002 1:05:52 PM EDT

[#12]

The light weight of the M4 barrel makes it balance very nicely. It's short length makes it much more maneuverable. And it's also KEWL.
Regarding all the metallurgical and thermodynamic physicists' inquiries regarding design weakness- Not sure, but I believe the full auto variants used by various agencies have thoroughly tested the cooling/meltdown-blowup features of the barrel and found: it didn't...

Posted: 4/28/2002 1:22:29 PM EDT

[#13]

As an mechanical engineer to be, the first thing I was tought, is to dimention mechanical components by studying it's weakest portion. So, constraints due to pressure of an M4 barrel Wich have to be under 29 000 Psi (excluding the security factor) were calculated using the dimensions of the "cut down" part, I'm 100% sure of that.

Kid223

Posted: 4/28/2002 1:29:45 PM EDT

[#14]

I hope someone comes up with a definitive answer to this question.

I am going to be ordering a new upper from Bushmaster in a couple weeks. Have been trying to decide between a 16" M-4 profile and the new lightweight barrel they are offering. My guess is the M-4 profile upper will be light enough, and the 16" pencil barrel will be too light.

More barrel rise. Don't need that.

If you all decide the M-4 profile is passe, please do not deluge Bushmaster with orders for new barrels and uppers before I get mine.

Posted: 4/28/2002 1:38:22 PM EDT

[#15]

I have a preban Colt Carbine with the lightweight barrel - and I like it just as much, if not better than the M4 barrel.

Tyler

Posted: 4/28/2002 1:53:12 PM EDT

[#16]

Quoted:
... Function over vanity. WTF good is a weak link on your rifle barrel?

I still haven't heard ONE good reason to purposely "build in" a flaw (and that's all it is if you're not hanging an M203 off it).

... Another thing you geniuses, just what spot on your M4 barrel do you think would fail from heat first during sustained fire?

And how many of us have full-auto rifles that we should really worry about extreme heat build-up from sustained full-auto fire. As for Imbro's comments about suppressed rifles failing..... BS! until you can show me an example. Haven't heard anything from Gemtech regarding this and they should know.... they are the pro's in the suppressor industry.

Posted: 4/28/2002 1:55:29 PM EDT

[#17]

Quoted:
The light weight of the M4 barrel makes it balance very nicely. It's short length makes it much more maneuverable. And it's also KEWL.

hr

Agreed. The M-4 has the nicest balance that I've seen between it and a 16" heavy and a 20" or 16" lightwt.

Posted: 4/28/2002 2:06:41 PM EDT

[#18]

Ive yet to see a barrel that a paratrooper could not bend. A1s, 2s, M60s, I even bent the barrel of my M4 when I had my para accident. But accidents are accidents, not the norm. Everyone has/shoots an AR for different reasons. If you dont want the M4 profile, thats great, But I want it, because I want to be able to shoot something that is as close as possible to what I used to carry.

Posted: 4/28/2002 2:12:50 PM EDT

[#19]

Quoted:

... Another thing you geniuses, just what spot on your M4 barrel do you think would fail from heat first during sustained fire?

Hey genius, lets go back to my first post...how many M4's are failing? Mine sure as hell isn't. You want a good reason? How about for collection purposes.

If you have info on these things failing at the cut-down, please post it.

Posted: 4/28/2002 3:38:22 PM EDT

[#20]

The only reason HBARs are so popular is because the AR Industry said they were better and were inherently more accurate. The reason they said this was because they are much easier to machine than lighweight barrels = more profit for the amount of labor they put into them.

For most people, unless you shoot competition, there will be no appreciable difference between an HBAR, lightweight, M4, or gov't profile barrel in the accuracy department. I like lighweight barrels better because they make the rifle balance better and lighter, sure they heat up faster but they also cool down more quickly as well.

The only real reason M4s are so popular is because its what the spec ops guys are using, and thus looks cool. If the spec ops guys were using Super Soakers ine bright pink and yellow filled with battery acid, I bet a lot of people would go buy a super soaker and a bunch of bottles of battery acid.

I like M4s because they look cool. But I think a straight 16" lightweight barrel would better serve most of us. I have a 16" midlength lighweight barrel, that's about ideal as you can get for a civilian carbine as far as I'm concerned.

Posted: 4/29/2002 12:02:47 AM EDT

[#21]

Quoted:
Quoted:
I have read that M4's should not be suppressed as there have been cases where the back pressure caused the cut down portion of the barrel to bulge.

... well, "knowing" you Imbroglio, I'm gonna call bullshit on this. The fact remains, there is LESS material there and if right amount of force is applied it will bend about the same as an old SP1 barrel.

... the strength of materials is constant on earth.

Why are you people always so damn mean to me?

Tactical Shooter November, 1999 Vol. 2 No. 10

Setting Up The Tactical M16 For Law Enforcement
By Mark White

From page 57:

"The military designates the weapon with it's flawed 14.5" barrel the M4-A1. Curiously (and unfortunately) the rear portion of the standard M4 barrel is turned quite thin, at a touch over 5/8". We view this reduction in diameter as a real mistake, as the thinner barrel lacks the ability to remain rigid and absorb heat like the H-BAR."

"...Phil at Gemtech used such a barrel in the testing of his cans, and had his barrel bulge at the groove in front of the sight tower. Heat was probably a factor, combined with pressure."

Posted: 4/29/2002 9:41:32 AM EDT

[#22]

I'm just glad to hear that I'm not the only one who has trouble putting a G.I. cot together!

I never thought about using my carbine barrel.

Posted: 4/29/2002 11:59:56 AM EDT

[#23]

Quoted:
...
I like M4s because they look cool. But I think a straight 16" lightweight barrel would better serve most of us. I have a 16" midlength lighweight barrel, that's about ideal as you can get for a civilian carbine as far as I'm concerned.

Who makes a 16" (or 14.5") lightweight barrel with midlength handguards? I don't see one in either the Bushmaster or RRA catalogs.

Posted: 4/29/2002 12:31:26 PM EDT

[#24]

Quoted:
Winston_Wolf, I agree that the M4 barrel is unnecessary without an M203 or 37mm, but you have the solution backwards. I wouldn't modify an M4 barrel by filling in the cutout. I would modify it by removing all that extra material on the rest of the barrel.

I agree. What was wrong with the barrel on the Colt 653 compared to the M4? Not a thing.

With the possible exceptions of the brass deflector hump and the flat top (it's not an A3, it's M16A4 or M4A1) upper, this is the pinnacle of carbine development.

Posted: 4/29/2002 3:02:10 PM EDT

[#25]

Quoted:

... Why are you people always so damn mean to me?

Tactical Shooter November, 1999 Vol. 2 No. 10

Setting Up The Tactical M16 For Law Enforcement
By Mark White

From page 57:

"The military designates the weapon with it's flawed 14.5" barrel the M4-A1. Curiously (and unfortunately) the rear portion of the standard M4 barrel is turned quite thin, at a touch over 5/8". We view this reduction in diameter as a real mistake, as the thinner barrel lacks the ability to remain rigid and absorb heat like the H-BAR."

"...Phil at Gemtech used such a barrel in the testing of his cans, and had his barrel bulge at the groove in front of the sight tower. Heat was probably a factor, combined with pressure."

... I apologize Imbroglio, sometimes it's hard for me to sort your sarcasm from seriousness.
I'm really not a mean person.

Posted: 4/29/2002 9:38:26 PM EDT

[#26]

Quoted:
Quoted:
...
I like M4s because they look cool. But I think a straight 16" lightweight barrel would better serve most of us. I have a 16" midlength lighweight barrel, that's about ideal as you can get for a civilian carbine as far as I'm concerned.
Who makes a 16" (or 14.5") lightweight barrel with midlength handguards? I don't see one in either the Bushmaster or RRA catalogs.

Mine is a Rock River, it is an older one, maybe they are no longer in production. It did have the large diameter front sight (it was crooked) so we turned down that one larger diameter portion of the barrel and put a small diameter front sight post on it.

Posted: 4/29/2002 10:21:48 PM EDT

[#27]

Doesn't Armalite make a carbine with midlength hand guards?

Posted: 4/29/2002 10:37:14 PM EDT

[#28]

Quoted:
Doesn't Armalite make a carbine with midlength hand guards?

Yes but to my knowledge, they don't make them with lightweight barrels.

Posted: 4/30/2002 5:31:03 AM EDT

[#29]

Quoted:
I'm just glad to hear that I'm not the only one who has trouble putting a G.I. cot together!

I never thought about using my carbine barrel.

Ditto!!!

Posted: 4/30/2002 1:36:41 PM EDT

[#30]

Quoted:
Tactical Shooter November, 1999 Vol. 2 No. 10

Setting Up The Tactical M16 For Law Enforcement
By Mark White

From page 57:

"The military designates the weapon with it's flawed 14.5" barrel the M4-A1. Curiously (and unfortunately) the rear portion of the standard M4 barrel is turned quite thin, at a touch over 5/8". We view this reduction in diameter as a real mistake, as the thinner barrel lacks the ability to remain rigid and absorb heat like the H-BAR."

"...Phil at Gemtech used such a barrel in the testing of his cans, and had his barrel bulge at the groove in front of the sight tower. Heat was probably a factor, combined with pressure."

The part you didn't mention is that the above only applies when shooting high volumes of full auto, which most of us don't do.

For those who DO regularly shoot high-volume full-auto, I'd agree: get an HBAR.

-Troy

[ARCHIVED THREAD] - ... Physics, coolness & Mforgerys

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