Tim Harmsen Of Military Arms Channel Begins An Interesting Run-To-Failure Test Of AR-15
BY Herschel Smith
5 years ago
Like me, Tim is a champion and fan of the AR-15 design. He begins an interesting test with a BCM rifle.
He shot 1000 rounds in 35 minutes. We’ll see how far this goes before it gives up as he tracks this over time without cleaning or maintenance.
The guys at Wanat claimed that their Colts gave up after shooting 800 rounds in 30 minutes. My bet is that they were firing in 3-round bursts. Although I still can’t see how they managed to put more rounds downrange than Tim.
When Tim posted this a few minutes ago, I heard that Bob Scales puked in his cream of wheat. His contract with H&K stipulates that no one can perform any more run-to-failure tests proving that no one really needs a piston system.
“Rifle is fine.”
On April 12, 2019 at 10:04 am, BAP45 said:
I really don’t understand Scales appeal. As far as I’ve seen the main reason for pistons was shorty barrels and suppressors. If the barrel is a normal length there’s really no need for them. But I’m no expert so if I’m wrong feel free to correct me.
On April 12, 2019 at 10:06 am, sobiloff said:
BCM typically sells with mid-length gas systems. (I didn’t see Tim specify in the video which length gas system this specific rifle has, so I’m assuming a bit here.) The Colt M-4 carbines in Wanat would have used carbine-length gas tubes, so what we’re probably seeing here is how over-gassed Colts will fail sooner than properly-gassed DI rifles.
On April 12, 2019 at 10:17 am, MTHead said:
Iv8888 got 830 rounds full auto before it spit one out the side of the barrel. Shooting semi, he’s going to have a hard time killing it. DI is lighter in the front and what the make AR platform the most accurate semi known to man.
The only argument against AR’s is some general trying to get a “backdoor” retirement from H&K.
On April 12, 2019 at 10:29 am, George said:
I always thought the 20″ barrel and rifle length gas tube was the way to go. Just like Eugene Stoner intended.
I bet the outcome of the early 2000’s testing results against the H&K, SCAR and some others would have been different if an A4 was used.
On April 12, 2019 at 10:58 am, Bill said:
A little speculation in regards to Wanat; the GIs there had no motivation to mis-report their weapons failures so I take them as accurate. Given the time and theater I am confident they were issued 62gn M885. The combination of a heavier bullet and a shorter gas system, and tighter rifling (1/7) will produce more heat. I think that is what killed those M4s. There’s a very good reason mid-length gas systems are more prevalent today. At Wanat we also know that for various reasons their belt-feds either weren’t there or were out of action, so those guys were trying to fill that gap with thier personal weapons …the M4s.
Key point: the AR designs reliability has been demonstrated repeatedly. What happened at Wanat was NOT due to a design flaw. Rather, it was mismanagement by the DOD. The combination of site selection, OPSEC, logistic support, set the battle in motion. The combination of poor weapons upgrade management (gas system), and ammunition selection set up conditions for the weapons failures under the demand of battle.
Now my personal prejudice: too many G-D Ring Knockers and Lawyers involved at all levels, and not enough NCOs.
On April 12, 2019 at 11:08 am, MTHead said:
Gas tube length makes little difference. as the amount of gas is regulated by the hole diameter. tube length only affects the “timing” of when the gasses start activating the bolt toward extraction. If the chamber is still pressurized, it over works the bolt lug/extraction system. which makes it prone to fouling.
One of the ways you can tell is to look at the case head after extraction, if there’s a bright smudge. your timing is to advanced. that smudge is the extraction plunger being twisted against the case head while the case is still pressurized. its very noticeable on 308/ carbine length systems. thus the big move toward mid-length gas systems, even in starter barreled rifles and “pistols”.
On April 12, 2019 at 12:20 pm, MTHead said:
Shorter barrels.
On April 12, 2019 at 1:56 pm, Pat Hines said:
When I was gathering parts for my first AR-15 build, I examined every piston system available and solicited input from lots of folks. I also read many evaluations of piston systems, including the infamous bolt carrier tipping issue.
I finally rejected going to a pistol system and built using the tried and trusted DI system. I have no regrets at all. My first AR build was one in 6.5 Grendel, no regrets there either, though I’ve build a number of ARs in standard 5.56NATO, too.
In several slow-mo videos you can see the DI system blow dirt, sand, and debris out of the action, a sort of self cleaning feature. No, I do NOT want to see one more moron quip, “it shits where it eats”, either.
I’d love to see a side by side firing to destruction of an AR-308, FAL, and a M1A. Expensive, yes, but well worth while. I don’t have a spare $6000.00 right now, or I’d do it.
On April 12, 2019 at 2:01 pm, Pat Hines said:
@MTHead,
That’s one reason I don’t built AR-pistols with less than 10.5-11.5 barrel lengths. That first AR build I mentioned had a mid-length gas system. I talked to the man at Sabre Industries (before ATF put them out of business) and he explained the mid-length versus the carbine length gas set ups.
On April 12, 2019 at 5:18 pm, MTHead said:
I picked up a 8″ upper for next to nothing. Dropped a CMMG 22 LR conversion in it. it had A2 front sights, so I slapped an old carry handle sight I had laying around on it. What a hoot that thing is! Great for pest control, teaching the grand-kids. If I ever need full horsepower from it, 10 second bolt swap back to 556. That’s the thing about AR’s. Pure American versatility!
On April 13, 2019 at 1:36 am, Jorge said:
Wanat is like the Miami Shootout: multiple levels of awful decisions and idiocy are explained away by saying “our guns just weren’t good enough” so we can whitewash all the endemic leadership/management problems that caused the disaster (which people predicted for years beforehand) and pretend it’s just a technology problem, so we give more money to a defense contractor to make this new technology and everything will be fine.
Grifters like Scales are a dime a dozen.
On April 13, 2019 at 8:31 am, Ned said:
I have had one failure with an AR. It was early on, when I had someone else work on one. The gas tube was bent and the key was striking it going into battery. Could have “fixed” it with a stick. That’s the only failure I can think of in various AR platforms.
On April 13, 2019 at 10:33 am, John said:
The Colt gun had the worst failure rate of all of tha M4 type rifles during the Army adoption
trials several years ago and they chose it anyway. It’s a piece of junk.
On April 13, 2019 at 10:41 am, John said:
Look up the info. Here is just part: “The M4/M16 family is both praised and criticized for its current performance in the field. In recent years, the M4 finished dead last in a sandstorm reliability test, against 3 competitors that include a convertible M4 variant. Worse, the 4th place M4 had over 3.5x more jams than the 3rd place finisher. Was that a blip in M4 buys, or a breaking point? The Army moved forward with an “Individual Carbine” competition, but as the results started to show the M4 again lagging – even with ammunition changed to a round specially formulated to make the M4 shine – the Army abruptly stopped the process once again, stating that the performance superiority of the competing gun was not better to a degree making it worthwhile. The Army stated after the tests that only a result that was twice as good external link as the existing gun’s performance would signify an actionable performance difference.”
On April 13, 2019 at 12:17 pm, DJ said:
All good things must come to an end.
On April 13, 2019 at 1:50 pm, =TW= said:
Gas is contained in the barrel behind the projectile. Pressure bleeds into the gas tube when bullet passes the port, and drops significantly only after the bullet clears the muzzle.
It seems that distance (volume) between gas port and muzzle is a variable that would affect timing.
On April 13, 2019 at 7:01 pm, Gryphon said:
“Run to Failure” with a lightweight Carbine is IMO somebody showing that they have More Money than Sense. OF COURSE a Lightweight, Air-Cooled Carbine isn’t going to Eat a Pallet of Ammo like a Water-Cooler Belt-Fed Machine Gun. Sure, in Desperate Combat Situations, Soldiers are going to Abuse their Weapons, until they are just a Handle for the Bayonet.
Just Like Aircraft Design, Weapons Design is the Art of Engineering Management of Compromise to produce the Best Possible Product FOR A SPECIFIC PURPOSE. Would those Guys in Wanat have done Better with Browning BAR’s ? (given sufficient Ammo) Sure. Again, it always comes back to Mission Failure due to Piss-Poor Planning, and if anything, the Failures these poor Troops encountered were probably well Outside the Design Limits of the Weapons as Produced.
If one Reads the Manual for most Closed-Bolt Firing Weapons, the Manufacturer will give a Warning about how many Rounds Fired Continuously will result in “Cook-Off” Rounds, and that probably represents a “Reasonable Limit” on that Weapon’s ability to handle Excessive Heating. Did these M4’s Fail before or after the number of Rounds that would produce Cook-Off?
Those Guys may have been Lucky that their Guns held up to Abuse as well as they Did…
On April 13, 2019 at 11:56 pm, MTHead said:
TW, your right. from gas port to muzzle is called the “dwell” time. and it does push more gas into the system. But AR’s are engineered to vent excessive gas/pressure. so pressure spikes won’t damage the gun.(within perimeters of course).
The standard answer to “over pressure” for a piston gun is to enlarge the port. make a massive operation rod,(so it won’t bend), with a strong spring to match. and let it bang. works great. but all that forward pressure on the barrel tweaks the accuracy out of the gun. That’s why Stoner designed the DI system. all the gas pressurizes is the bolt. nothing to bend. and once the bolt moves passed about a 1/2″ of power stroke. excessive gas gets vented.
But, by the same token if any power is robbed , such as early extraction. the gun won’t cycle properly. and you stress the bolt lugs/extractor.
On April 14, 2019 at 11:56 am, =TW= said:
MTH- The piston systems on my M1 Carbine and my Mini 30 have worked fine for many years. (Aftermarket mods for the Mini are available. But that’s a whole ‘nother topic.)
My AR was built before piston systems or “boutique” ammo were widely available. I chose 7.62X39 to share ammo with the Mini and my CZ527.
Matched Aero Precision upper and lower, 16″ bbl, carbine length DI (port size as supplied), M4 BCG, A2 device. I tweaked the feed ramps slightly. M4 spring and buffer used, so I can mount a similar 5.56 upper if necessary.
This carbine runs fine though I’m keeping an eye on the bolt.
I don’t need a piston system, better to spend for a nice drop-in trigger instead. Or optics…
On April 14, 2019 at 11:44 pm, MTHead said:
TW, your rig should run for years. no problems. but that’s the wonderful part about AR’s. grab a new BCG an throw it in your kit. like I use to tell people who came in the shop with a problem. all mechanical systems break. with an AR I can generally fix it in 10 min. and fewer moving parts means less to break.
A good trigger is so worth the cost. I’ve been using the POF-USA 4.5 lb. modular triggers for years. about $175.00. sometimes cheaper. but they come with a $35.00 KNS locking pin set. so it’s a good value. very crisp for an AR trigger.