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Old July 18th, 2019, 09:16 AM #221
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This post makes me lol
No kidding...
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Old July 19th, 2019, 08:04 PM #222
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From Quora:
The most common interpretation of “HBAR” is “Heavy BARrel”, sometimes called a “bull barrel” or “target barrel”. It’s most commonly seen as a marking on the AR-15 family of rifles, on specific models designed for high medium-range accuracy (300–500 yards) where it refers to a specific “two-step” barrel design, though the concept of the heavy barrel is by no means limited to that design.

Your typical rifle will have a barrel engineered to be just thick enough to withstand the pressures in the chamber and barrel, with a reasonable buffer to increase safety margin and prolong barrel life. As the bullet travels down the barrel, the pressure behind the bullet decreases as the pressurized volume increases (Boyle’s law). This allows the barrel to be tapered along its length; thick at the receiver, thin at the muzzle. This has basic practical advantages as well, by placing most of the mass between the shooter’s hands, thus lowering the “moment of inertia”, requiring less force to aim the rifle and less strength to hold it on target. Overall, shooters spending most of their time with their rifle in their hands (or over their shoulder), like stalk hunters, will generally prefer this style of barrel for its lighter weight and easier maneuverability.

However, ultra-high-speed photography shows a drawback. The stark pressure differences in the barrel cause many of these types of barrel to undulate or “whip”, almost snakelike, as the bullet exits. This reduces accuracy, as you might expect, since the muzzle’s not pointing where the scope says it is. A free-floated barrel (where the forend of the stock does not touch the actual barrel) reduces inaccuracy but mainly does so by allowing a consistent undulation from shot to shot, unaffected by contact between the barrel and forend.

A heavy barrel reduces barrel movement and undulation simply by being thicker. The resulting barrel is more massive, and more of that mass is further out from the anchor points at the shoulder and hands. However, many are no longer considering that a disadvantage, because the increased moment of inertia this creates helps to quiet the little “yips” that even the best shooters have. Many shooters interested in real long-range accuracy will shoot from a benchrest or bipod anyway, so this style of barrel is perfect for the shooting range or a prearranged deer stand.
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Old July 19th, 2019, 08:05 PM #223
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HBAR stands for heavy barrel. During the US involvement in Vietnam and the M16 was introduced, they made a prototype of the M16 called the M16 HBAR which actually meant it was in 7.62x51 AKA .308. It took the same capacity magazines as its 556 brother of 20 rounds. HBAR just mainly means a heavy profile barrel.
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Old July 20th, 2019, 08:31 AM #224
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The reason target rifles have heavy barrels is not due to whip.

It is due to POI changes due to heating. A heavy barrel has more mass, and therefore can absorb more heat before bending. Also, the larger surface area means the heat is dissipated faster. Simple black body radiation.
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Old July 20th, 2019, 08:33 AM #225
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Quote:
Originally Posted by bobwilley View Post
HBAR stands for heavy barrel. During the US involvement in Vietnam and the M16 was introduced, they made a prototype of the M16 called the M16 HBAR which actually meant it was in 7.62x51 AKA .308. It took the same capacity magazines as its 556 brother of 20 rounds. HBAR just mainly means a heavy profile barrel.
And how would you fit a 7.62x51 round into the mag well of an M16?????

And how would it cycle with the a round longer than the bolt stroke?????

The 7.62x51 rifle was the AR-10, which looks like an AR-15/M-16, but it pretty much totally different parts, except the fire control group.

Oh, the HBAR comes from the Colt HBAR Match Sporter rifle. It was the target model of the standard AR-15. And it is specifically exempted in the ban list.
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Old Yesterday, 01:50 PM #226
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Originally Posted by Pinecone View Post
And how would you fit a 7.62x51 round into the mag well of an M16?????

And how would it cycle with the a round longer than the bolt stroke?????

The 7.62x51 rifle was the AR-10, which looks like an AR-15/M-16, but it pretty much totally different parts, except the fire control group.

Oh, the HBAR comes from the Colt HBAR Match Sporter rifle. It was the target model of the standard AR-15. And it is specifically exempted in the ban list.
I don't think that is what he is saying... I read the post as, Colt made a 308 caliber prototype M16 that they branded HBAR and also came with 20 round magazines.
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Old Today, 10:08 AM #227
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I don't think that is what he is saying... I read the post as, Colt made a 308 caliber prototype M16 that they branded HBAR and also came with 20 round magazines.
How is it an M16 if it is totally different?
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Old Today, 12:23 PM #228
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Originally Posted by Pinecone View Post
How is it an M16 if it is totally different?
I have no idea if they ever prototyped an m16 in 308 and called it an HBAR. What I do know is that the AR-10 was the first rifle to incorporate Stoner’s gas system and that the AR-10 prototype was chambered for 7.62mm . Later the AR-10 was scaled down to what became the ArmaLite Rifle model 15 (AR-15 M) officially designated the M16. Like I said, I have no idea if the M16 rifle (m16 I assume being the military's designation not Armalite's) tested prototypes in various calibers before settling on the 5.56X45.
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