AR Question

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dreppucci007

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So I'm still learning about ARs...

Can someone tell me what difference an HBAR is from any other AR? Are they not made as well? I only say that because I see on the Four Seasons website that there are a couple Colt ARs for sale, and the HBAR is significantly less, and it seems as though it's that way for other shops, too. When I was at Four Seasons the other day, I tried asking the guys there about ARs, but they said that Carl knows best about them (Carl wasn't there of course) and they didn't seem to be able to answer my questions. I held the HBAR and it seemed pretty nice.

TIA
 
From what I know, which is not much, the HBAR seems to be a barrel which is the same thickness all the way down, and that is pretty thick. I think it is supposed to be more consistent for target shooting having less expansion as it warms up. I also think it might be cheaper because it means they don't have to turn it on a lathe to get off all the material like they do on the profiled barrels. The downside is that it is heavier than it would otherwise be, which is a pain if you are going to be holding the thing off of a bench for any length of time.

But I could be full of s**t here, I'm just going on what I read on AR15.com once upon a time.
 
dave...from my limited experience ill try and tackle this...the hbar models are the full size rifles as opposed to the carbine with the shorter barrel and folding stock...also...the hbar line i believe has a flash suppressor but no bayo lug...and the hbar i believe if the carry handle which is not removeable on the sporter models but is removeable on the carbine models allowing you to mount optics on the receiver flat top...i think this is right but im sure some else can clarify better than myself...in my advice the hbars that are out there are some of the better deals because theyre preban...the one on 4 seasons is $999, and the sp1 listed $1699...in my opinion buy the hbar, and with the money you saved by not buying the sp1 you can get yourself a brand new preban upper of your choice for less than the extra $699 and essentially have 2 rifles in one...a fullsize and a carbine...thats what im doing...i got a bushy carbine and my next adventure is a colt sporter hbar...becase its preban you can swap out the buttstock and get a telescoping one too

hope this helps and if im wrong anywhere someone will correct me

by the way...whos the new girl workin at 4 seasons???? i dont know if you saw her but she was there thursday when i was there...pretty lil lady
 
I’m kinda surprised that they were a cheaper than the rest of the AR rifles. When I got mine, years ago they were a $100 premium and if you wanted the A2 sight, you had to get it. The standard A2 & A4 rifle has a tapered barrel under the handguards. The barrel tapers down to what the old A1 barrels were so the military could hang M203s. The HBAR is just a straight barrel or in some instances it steps up a little. It’s just heavier. If you are talking about Colt specific, I think they are both 1/7 chrome lined barrels. Although I think Colt had a Super Delta Elite that was a HBAR with a 1/9 barrel and a crap scope and silly cheek rest. I may be wrong on the twist.

As far as quality (if you are talking Colt), they are all about the same. If you are talking about other manufactures, it depends. Some make good stuff, and others make good stuff some of the time. There shouldn’t be any difference in accuracy with the heavy barrel, but it is stiffer if you want to put a sling on; it will not move as much as a regular barrel. Unfortunately it will still move if you put a real tight sling on it. The competition rifles have handguards that float the barrel and the sling attaches to the handguard.

I bet with the current hostilities every one sees military guys running around with M4 carbines on the news; and that is what is selling.


Brian
 
oh...another thing for the difference in price...the older the rifles are...usually the more they cost...collectors had a few sp-1s from '69 and '71 and they were more money than the later production ones
 
The heavy barrel is thicker to absorb more heat so the barrel does not distorted in anyway during continous heavy firing, remenber the barrel is air cooled.I seen a m60 barrel glow red from heavy continous firing. Hope this helps.
 
This may be verging off topic a tad, but I believe that the reason that a HBAR, or any heavy barrel on a rifle, improves its inherent (or machine) accuracy has nothing to do with heat -- and on that point, our objective with any barrel is not to "absorb" heat but to dissipate it.

All steels have a degree of plasticity. A hollow steel tube, subject to the proper forces, is a bit like a piece of wet spaghetti. As a result, the barrel begins to vibrate shortly after the bullet leave the case neck, and long before it leaves the muzzle. The degree of this vibration and its concentricity define the ultimate in repeatability that the barrel can achieve when firing multiple rounds.

The cross-section of the barrel, on the other hand, while not changing its plasticity, will affect the magnitude of its deflection under a given set of load parameters. So thicker wall barrels, though they vibrate, tend to swing the muzzle through a smaller circle. And if the barrel is free-floated, this circle will be concentric to the no-load point of aim.
 
I have the HBAR 20" and HBAR 16". I find the 20" is too heavy for me to hold for any extended period. If I were to buy again, I'd buy something lighter.

The 16" is pretty comfortable though.
 
RKG I argee on what you say, maybe absorb is not the right word, but the thicker the metal the better the barrel can perform at high temperatures to prevent high temperature stress put on the metal under continous firing.I am no expert by any means but high temps cause all kinds of metal failures in all things made, again I am no expert but all metals have a temperature where failure or distortion will happen.
 
RKG said:
This may be verging off topic a tad, but I believe that the reason that a HBAR, or any heavy barrel on a rifle, improves its inherent (or machine) accuracy has nothing to do with heat -- and on that point, our objective with any barrel is not to "absorb" heat but to dissipate it.

All steels have a degree of plasticity. A hollow steel tube, subject to the proper forces, is a bit like a piece of wet spaghetti. As a result, the barrel begins to vibrate shortly after the bullet leave the case neck, and long before it leaves the muzzle. The degree of this vibration and its concentricity define the ultimate in repeatability that the barrel can achieve when firing multiple rounds.

The cross-section of the barrel, on the other hand, while not changing its plasticity, will affect the magnitude of its deflection under a given set of load parameters. So thicker wall barrels, though they vibrate, tend to swing the muzzle through a smaller circle. And if the barrel is free-floated, this circle will be concentric to the no-load point of aim.
Click to expand...

You are correct in describing how the heavy barrel reduces barrel "whip".

However, the heavy barrel also slows the heat build up during sustained fire. As the barrel heats, the harmonics "whip" changes thus causing a point of aim shift. The upside is that a heavy barrel can take more rounds during a shorter period of time before becoming overheated. The downside is that once you get it that hot, it takes longer to cool.
 
Well, I probably shouldn't have started this:

Now we have to distinguish between heat and temperature. All other things being equal (which, in this example, is impossible), of two barrels of the same bore, the one with the thicker walls must absorb more heat in order to raise its temperature by the same amount, because its thermal mass is greater. Once the heat source is removed, the barrel with the thicker walls will retain some of its increased temperature longer, for the same reason. At the same time, though, the thicker-walled barrel will dissipate heat more quickly, because its surface area to the heat sink is larger.

As to whether a change in a barrel's temperature will affect its harmonic response -- and, in particular, the amplitude of that response (since for present purposes the frequency of response is considered to be random), I'm not so sure. A barrel that is 140F is not twice as hot as a barrel that is 70F, because to compare two temperatures, you have to use the Kelvin scale. 140F =~ 330K, while 70F =~ 294K; this is only a 10% increase in temperature. I suspect (but cannot prove) that in this scenario, the effect of this increase in temperature upon the bullet's internal coefficient of friction (i.e., impact on lube, jacket material, etc.) would have far greater an effect on machine accuracy than any change in harmonic amplitude.
 
Last edited:
Sorry about that.

Every fall I get a bunch of calls to help out folks who want to "sight in" their deer rifles, and one of my pet peeves is someone who has a 6-1/2 lb. M700 with a thin wispy 22-in. barrel who expects it to shoot like a 40X. I vent by giving them a physics lesson. Sorry to have inflicted that on innocents.
 
Ok, one more question (not physics related I think)...

What is the difference between say a Colt HBAR and the Colt Match HBAR? Is there a significant difference? Again going to different pre-owned websites, Four Seasons Colt Match HBAR is $999 w/o any accessories. Gun & Sport North has a Colt HBAR with a 20 & 30 round mag in 98% condition for $899. Is there really a big difference?...or is this just a really good deal from G&S or bad deal from FS?
 
from what i understand the match hbar has a barrel with a different twist rate that allows you to shoot heavier bullets...so that will come into play if you look at distance and ammo
 
Another AR Question!

Ok, so what's so special about the Government model of an AR? I've been looking around, and the carbines seem to go for more $$$ than the HBARs...Ok fine, more lightweight, etc. I see that these Gov't models (i.e. Zero Hour Arms has one posted on their website for $2150!) are just a lot more expensive! What's the big deal that makes it so much more $$$?
 
dreppucci007 said:
Ok, so what's so special about the Government model of an AR? I've been looking around, and the carbines seem to go for more $$$ than the HBARs...
Click to expand...

The carbines have more of that high speed low drag look. It's just fashion on the civilian side of things.

If you have to actually haul the dam thing around and use it for work, you would appreciate less weight and handier/adjustable features.

Brian
 
bpm990d said:
The carbines have more of that high speed low drag look. It's just fashion on the civilian side of things.

If you have to actually haul the dam thing around and use it for work, you would appreciate less weight and handier/adjustable features.

Brian
Click to expand...

So the Government is a carbine model that's got all sorts of adjustable goodies, and is more lightweight than other models?
 
I could be wrong, but I think the government model is a full 20" barrel that tapers down under the handguards so the military can hang the M203 with the existing brackets used on M16A1s.

The carbine should be a 16" barrel with an adjustable stock.

B
 
That seems like a lot of $$ for a Govt. model, my guess is it probably has lots of bells & whistles on it. Freefloat rails, maybe a Magpul stock etc.

As bpm990d said, generally a govt model has a reprofiled barrel to accept the M230 Grenade launcher. It's also desirable because of it's lower weight. That was what I first got for my wife before I got her and SP1/A1 upper.

CD
 
The "Govt Model" that Zero Hour has is a Colt Govt Model carbine - 16" bbl, A2 configured upper, collapsible stock. These are very nice carbines but they are pricey.
 

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