Two engineers at the U.S. Army’s Combat Capabilities Development Command (CCDC) Armaments Center have invented a new helically fluted M4A1 barrel that reduces risk of barrel failure or premature cook-offs during high rates of fire for extended periods. The design was created by Thomas Grego and Adam Foltz at the Picatinny Arsenal in New Jersey.

The barrel features spiral fluting in three distinct areas that increase exterior surface area to increase heat dissipation during firing. Fin height gradually tapers but widens toward the muzzle end, providing an unusual profile to the design. Barrel weight is a quarter pound less than that of the currently issued M4A1 version.

CDCC indicated the design may be applicable for other weapons systems currently fielded by the U.S. Military. Enthusiasts may soon see versions available on the commercial market because, “The patented design is available to companies that would make, use, or sell the barrels,” according to the announcement.

Testing by the CDCC found the unique fluting pattern does not compromise accuracy, yet sustains fire “…at temperatures as high as 909.5 degrees F” without barrel drooping. The improved heat transfer also increases life expectancy of those barrels wearing the pattern.

Concerns about U.S. troops experiencing melting barrels and cartridges pre-maturely cooking off in combat were widely reported after the Battle of Wanat, which took place in 2008. A well-coordinated attack by at least 200 Taliban terrorists on the forward operating base in Afghanistan neutralized heavy guns and munitions at the disposal of the 49 U.S. Soldiers defending it early in the fighting. M4s then became their primary battle weapon on the ground during the engagement.

Many of the survivors reported stoppages, malfunctions and drooping barrels during the high rate of fire required to successfuly repel the attack. Nine U.S. Soldiers died and 27 were wounded during the battle.

American Rifleman

first thing I thought of,


had one thru the shop 25 yrs ago, the machine work on the barrel was amazing

Is this a lot different than the spiral barrels on the LWRC guns? It looks like there might be more and tighter spirals but . . .

LWRC DI

The US Patent office basically relys on the Applicant to do their due diligence in determining if this is a "new" idea. As a result they'll grant patents on stuff that has been common practice for 100 years or more.

One example is Whirlpool. They applied for and received a patent in 1992 or 1993 for serrated tube bends. Anyone who has been around factory exhaust systems 50's, 60's, 70's and 80's is quite familiar with serrated bends because at that time is was much less expensive to produce than a full mandrel bend. Heard that some company sued Whirlpool over this and won the lawsuit, so that patent was revoked and Whirlpool had to pay the piper.

Yep, whats old is new again. Of course this isn't a spiral ... my Yugo RPK

It's surprising that barrels with built in heat sinks aren't standard, especially with machine gun barrels.

Just because it's been used before doesn't mean you can't get a patent for it. The GPAC negative air patent is a good example of this.

Also, JP Enterprise has been selling a clamp-on barrel heat-sink for at least a couple decades, that's what the red color is under the handguard.

I built the 223 on the bottom back in 98 or 99 and on top is the 6.5 Creedmoor ...

It looks to be more than just a heat sink. They are spiral, in three places, and with a different barrel contour. If the barrel can be 900° and not droop, there’s more to it than just the presence of some fins.

quote:

Originally posted by sigcrazy7:
It looks to be more than just a heat sink. They are spiral, in three places, and with a different barrel contour. If the barrel can be 900° and not droop, there’s more to it than just the presence of some fins.

I..would say maybe the fluting opposite of rifling would possibly act as a truss? Otherwise, more surface area for cooling could be done rather more simply.

quote:

Originally posted by sigcrazy7:
If the barrel can be 900° and not droop, there’s more to it than just the presence of some fins.

That seemed clear from the article.

quote:

Originally posted by sigfreund:

quote:

Originally posted by sigcrazy7:
If the barrel can be 900° and not droop, there’s more to it than just the presence of some fins.

That seemed clear from the article.

I'll bet that when hot the barrel droop is within specs. There is no such thing as zero barrel droop when dealing with a rifle.

Time will tell if this patented barrel design makes it to the field. My thoughts, which may be more guesses than anything.

Spiral fluting isn't new. I have an LWRC upper, with their regular spiral fluting -- I'm uncertain if it does anything special. This LWRC barrel is the least flexible with ammo that I have owned. Furthermore, it's really only accurate with a 69 SMK bullet, even though it has a 1/7 twist. LWRC's flutes appear to be shallower, wider, and with a slower twist rate than those in the patent diagram.

I own both unfluted and straight-fluted Wilson Combat barrels. I don't think there are significant differences in accuracy among them. Well, maybe better accuracy of .1 or .2 MOA from the fluted barrels. For most users, that level of accuracy is immaterial. I don't find better life from either type, nor have there been significant differences in barrel operating temperatures. If anything, the unfluted barrels are a little slower to heat up and a little slower to cool down -- but without IR heat sensors and double-blind tests, there is no definitive proof. I've pushed both barrel types pretty hard in competition, with enough rounds that the handguards got pretty hot.

My gunsmith borescoped 2 of the 4 barrels I've shot out. He said the throats were badly cracked, looking similar to alligator skin. The lands were worn out for the first inch or so, meaning the bullet moved forward for quite a bit before rotation started. However, the rest of the barrel looked pretty good. This situation is supposed to be pretty common for shot-out barrels.

To me this means that the efforts to cool the barrel, extend its life, and maintain its accuracy should be concentrated on the chamber and the first few inches forward of the barrel. I don't see how fluting or heat-sinks or magic ju-ju further down the barrel will significantly change what's occurring at and right next to the chamber.

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Spiral fluting increases the cost of manufacturing a barrel. Multiple types of fluting means even more machine time. Will the military be willing to absorb the extra cost?

Fluting of any type increases stresses in the remaining barrel metal, and these stresses must be relieved. If the stress isn't relieved properly, the barrel will be more susceptible to stringing as the barrel changes temperature.

I have no idea what temps of 900 F does to a barrel's straightness, but such temps are pretty much guaranteed to rapidly deteriorate the barrel's throat. Possibly enough deterioration of any steel barrel -- made in any contour, made from any type of steel -- that's it's toast right then and there.