larue rail: heat sinking the chamber

[TheJawn]

I could not find the answer to my questions with searches.

http://www.laruetactical.com/larue-tactical-90-handguard-lt15-9


Additionally, our Free-float Rail system provides an excellent heat-sinking feature that pulls throat-damaging heat away from the chamber area. Another heat-sinking benefit is the elimination of pressure-spikes, which some feel is the cause of a large part of pre-mature bolt failures.

Does excessive heat on the chamber necessitate a heat sink? Does heat in this area necessitate larue rails for all ARs that aren't exclusively fun guns?

My feeling is that most quality rails are adequately ventilated enough to keep much of the upper (including the chamber) adqeuately cool for medium-hard use, and that the problem that larue is trying to solve only applies to m4 ribbed handguards.

[mkmckinley]

Considering that the vast majority of ARs that aren't considered fun guns don't have Larue rails I'd say the answer is no, you don't need a Larue rail. That said they are nice rails, you won't go wrong with one.

[TheJawn]

Okay.

Forget larue for a moment. Does an excessively hot chamber cause throat erosion and pressure spikes? Does heat build up at the same rate somewhere else and cause a more serious problem?

Also, are other rails capable of performing a function like this? Is stripping heat away from the chamber even necessary?

[vicious_cb]

I could not find the answer to my questions with searches.

http://www.laruetactical.com/larue-tactical-90-handguard-lt15-9



Does excessive heat on the chamber necessitate a heat sink? Does heat in this area necessitate larue rails for all ARs that aren't exclusively fun guns?

My feeling is that most quality rails are adequately ventilated enough to keep much of the upper (including the chamber) adqeuately cool for medium-hard use, and that the problem that larue is trying to solve only applies to m4 ribbed handguards.

The larue is not special in this case. All railed forends will act like a heatsink to some extent. The barrel nut will absorb heat from the chamber, the barrel nut will transfer that heat to the rail. There is nothing about the larue design that makes it a better heatsink than any other rail.

[GrumpyM4]

Another "questionable" claim from mark larue......sigh.

[rob_s]

Okay.

Forget larue for a moment. Does an excessively hot chamber cause throat erosion and pressure spikes? Does heat build up at the same rate somewhere else and cause a more serious problem?

Yes, guns wear out from use. As do cars, boats, shoes, vaginas...

[5pins]

Aluminum is a better conductor of heat then steel so any aluminum rail is going to be a heat sink. The larger the rail the more heat sinking benefit.

[Eric D.]

Heat buildup in the chamber does not necessitate a heat sink. Most of the heat is dumped at the gas port/fsb area anyway.

[VIP3R 237]

Also, are other rails capable of performing a function like this? Is stripping heat away from the chamber even necessary?

Just like in cars and electronics I cant see how less heat is a bad thing, but I doubt by just adding a free float rail you will see significant decrease in wear. The hogan/pof design adds a heat sink along with the rail in order to reduce operating temp.

[Markasaurus]

deletion of duplicate post

[Markasaurus]

There have been many attempts at engineering better air cooling of rifle barrels, this isn't one of them. The only thing that even comes close is the new US Marine modified M4 and that is supposed to replace the M249 SAW. This weapon is designed to fire with a closed bolt when set to "semi". When set to "auto" it fires from an OPEN bolt (bolt stays to the rear when trigger is released).

Anything else that small arms engineers have tried through the years, such as finned barrel and/or chamber, usually proven to be of marginal help in barrel cooling.

I live in the PRK (California) and we have 10 round mag limit. Even so the barrel on my Stag 2 gets plenty hot for me. I replaced the stock handguards with the tapco aluminum ones for $40. I like the way they look and they have 4 rails, and huge slots for barrel cooling. I got them from Amazon.

[vicious_cb]

There have been many attempts at engineering better air cooling of rifle barrels, this isn't one of them. The only thing that even comes close is the new US Marine modified M4 and that is supposed to replace the M249 SAW. This weapon is designed to fire with a closed bolt when set to "semi". When set to "auto" it fires from an OPEN bolt (bolt stays to the rear when trigger is released).


No, the M27 IAR does not do that...

[mike_556]

The only thing that even comes close is the new US Marine modified M4 and that is supposed to replace the M249 SAW. This weapon is designed to fire with a closed bolt when set to "semi". When set to "auto" it fires from an OPEN bolt (bolt stays to the rear when trigger is released).


You sure on that?

[bp7178]

You sure on that?

The gun he was talking about was the LWRCi one that lost out to the HK one.

[sinlessorrow]

No, the M27 IAR does not do that...

Its also not set to replace the M249, its more of a force multiplier to be used in conjunction with.

The M27 basically replaced the BAR.

[crazymoose]

Okay.

Forget larue for a moment. Does an excessively hot chamber cause throat erosion and pressure spikes?

The hotter the barrel gets, the softer the metal gets, and the more quickly it wears out. This is why sustained auto fire can wear out a barrel in a few thousand rounds, whereas with slow semi auto fire, you might get 20,000 rounds out of a barrel (some claim that you might get 30, with some accuracy degradation, before the throat erodes to the point that it's unsafe).

[Casull]

The gun he was talking about was the LWRCi one that lost out to the HK one.

Yup, it's the LWRC that did that. There's a segment on Discovery on it as most of us know.
http://youtomb.mit.edu/thumbnail/YouTube/L/X/LXD5q4QkpTQ/56aee011693c51adb0e0f39ce010d9ed.jpg

Although, FN had a similar approach with the HAMR

http://media.defenseindustrydaily.com/images/ORD_FN_SCAR-IAR_lg.jpg

Now, I was under the impression the barrel as a whole was typically the same heat end to end. Wouldn't that justify Colt's design?
http://www.colt.com/ColtMilitary/Products/ColtInfantryAutomaticRifleIAR.aspx
http://www.defensereview.com/wp-content/uploads/2009/04/Colt_IAR_6940.jpg

It states on the Colt webpage that their IAR featured a, "unique heat sink system significantly reduces risk of cook-offs during extended periods of firing"

[Markasaurus]

No, the M27 IAR does not do that... My Bad....that's what I get for relying on an old episode of "Futureweapons"....