Armed Polite Society
Main Forums => The Roundtable => Topic started by: zahc on July 29, 2013, 05:50:18 PM
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So, most AR15s have flash hiders. I understand the purpose of flash hiders. However, I don't understand their popularity. For the extra 1.5 inches of length, you could get extra velocity if you just had another 1.5 inches of actual barrel.
I have actually see people who build ultra-light ARs, when they don't want to have a SBR, they get a 14.5 inch barrel and weld a flash hider on it so the barrel length is 16". But I thought we shortened barrels so they were handy, so the idea of putting a permanent flash hider on your barrel so that you can make the real barrel shorter...it does not sense. Is it majorly bad luck to have an AR with just a normally-crowned barrel?
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The flash hider is cooler looking. Can't overstate the value of cool.
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It's a combat gun.
As such, it's of greater defensive (or offensive) utility to have a carbine at 16" with 1.5" of flash hider to protect your night vision when engaging bugaboos in your house (or elsewhere in the dark), than to have an additional 25fps and a fireball that is visible when looking through your sights or EOTech or ACOG or whatever.
I see lots of "service rifle" AR's at High Power matches with no flash hider. Full 20" barrel. They seem to think the exposed/recessed crown is greater value than the flash hider, especially since the 15+ pound rifle only gets used during peak sunlight hours in the middle of the day.
Anyways, back to the 16" issue: 16" is the arbitrary magical ATF number "thou shalt not have a barrel less than." So, go 14.5" and weld a 1.5" flash hider on it. 16", with the efficacy of the flash hider. Maximum shortiness.
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So, most AR15s have flash hiders. I understand the purpose of flash hiders. However, I don't understand their popularity. For the extra 1.5 inches of length, you could get extra velocity if you just had another 1.5 inches of actual barrel.
That 1.5 inches doesn't add enough velocity benefit to overcome the dramatically increased muzzle flash. My friend, Lisa, has a photo of her Bushmaster AR15, without a flash hider, creating a huge, donut-shaped fireball. This was in broad daylight, which didn't affect her vision, but using that in a low light environment could cause problems.
I have actually see people who build ultra-light ARs, when they don't want to have a SBR, they get a 14.5 inch barrel and weld a flash hider on it so the barrel length is 16". But I thought we shortened barrels so they were handy, so the idea of putting a permanent flash hider on your barrel so that you can make the real barrel shorter...it does not sense. Is it majorly bad luck to have an AR with just a normally-crowned barrel?
Light rifles are good, but some states don't allow SBRs, and some owners don't want the extra cost or hassle of getting the tax stamp.
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Many "Flash Hiders" act as a muzzle brake, and make it easier to keep on target with rapid fire or a happy switch.
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Many "Flash Hiders" act as a muzzle brake, and make it easier to keep on target with rapid fire or a happy switch.
Yup.
I have the YHM Phantom on mine, which acts as both.
I did do research into which hider... uh... hid... the most.
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May not be a big issue but for a combat rifle that may get banged around a bit I thin the flash hider might also offer some protection to the muzzle.
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May not be a big issue but for a combat rifle that may get banged around a bit I thin the flash hider might also offer some protection to the muzzle.
I think so, too. Probably not likely a crown would be damaged, but it seems like it would help.
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Don't forget it's a political statement to have it as well.
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I still want to get one of Bogie's "Zombie Brain Core Sampler" units for my AR... :D
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Don't forget it's a political statement to have it as well.
It's as American as the thing that goes up.
jim
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This all started because I decided it would be neat to have an ultralight AR15 "for the wife". I have seen some non-SBR builds under 5 pounds, including red-dot.
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FHs weigh less than barrel material.
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I have a new 16" unthreaded barrel setting here that has never been installed. I'm not going to pull my threaded barrel to compare weight but I don't think the difference would be much more then that of the velocity. Little to none.
jim
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So, are there any opinions as to the accuracy of "lightweight" barrel profiles? According to The Internet, the thinnest safe profile is about .56 inches in diameter, not counting the bits at the barrel nut and gas block, which have to be bigger to be compatible. Can I expect MOA accuracy out of a thin barrel like that, at least for the first couple rounds?
From what I understand, the M4A1 barrel profile is like .625 out to the gas block, and designed to fire some 500 rounds sustained full-auto before catastrophic failure, vhere the A2 is .75 inches out to the gas block, and goes over 900. Of course the M4 has a dinky 14-inch barrel, so I'm not sure how that plays in.
None of this matters for a gun that would be used to kill groundhogs and coyotes, with maybe 5 rounds fired.
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Buddy shot in a 3gun match last weekend, I videoed the rifle portion. Afterwards: "What the hell were you shooting? Some had no flash and some had a real fireball!" He had an ammo can of mixed Fed & PMC. I was shooting PMC w/ no noticeable flash in daylight, both of us using hider/brakes. Gotta think it was his Federals flashing.
Stay safe.
Bob
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the 20 inch govt profile is quite nice
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Farfcom.jetlag.us%2Ffnmi_govt_small.jpg&hash=282b43047c25134a8015648b043d77f4527c5fd6)
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I was actually thinking about getting a 20-inch govt, chopping 3.5 inches off, and turning the end (past the sight block) down to match the beginning (just past the barrel nut). That would probably be as light as all the featherweight barrels, only cheaper (given that I have a lathe). I suppose it would rust, though, after I took off the coating. I would either get a different gas block or chop down the front sight post.
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a govt 20 AR15 with the PRI carbon fore arm is light enough
super light is building something up on a CAV arms lower
a full 30 round mag adds a pound
http://www.ar15.com/mobile/topic.html?b=3&f=118&t=527546
Cav Arms Lower
Carbon-15 Stipper Upper
Bushmaster Super Lightweight Barrel
5 lb. 1 oz. (without magazine)
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Does magpul make a 10-round PMAG (or 5-round, for states with retarded hunting laws)? I really like their 20-round PMAG and use them all the time. 30 is just too big.
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Does magpul make a 10-round PMAG (or 5-round, for states with retarded hunting laws)? I really like their 20-round PMAG and use them all the time. 30 is just too big.
http://store.magpul.com/product/MAG559/PMAG
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Any folk build 20" bbls with the front sight assembly way out near the muzzle break to increase the sight radius?
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bloop tubes
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fpuuloa.com%2FKevin%2520Pictures%2520Movies%2Fnramtch.jpg&hash=7cccd021b1028a69ec541b290253a35ee16fe99e)
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May not be a big issue but for a combat rifle that may get banged around a bit I thin the flash hider might also offer some protection to the muzzle.
Unless you stick it in something really deep a flash hider is also easier to clean mud out of than a target crowned barrel.
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So, are there any opinions as to the accuracy of "lightweight" barrel profiles? According to The Internet, the thinnest safe profile is about .56 inches in diameter, not counting the bits at the barrel nut and gas block, which have to be bigger to be compatible. Can I expect MOA accuracy out of a thin barrel like that, at least for the first couple rounds?
From what I understand, the M4A1 barrel profile is like .625 out to the gas block, and designed to fire some 500 rounds sustained full-auto before catastrophic failure, vhere the A2 is .75 inches out to the gas block, and goes over 900. Of course the M4 has a dinky 14-inch barrel, so I'm not sure how that plays in.
None of this matters for a gun that would be used to kill groundhogs and coyotes, with maybe 5 rounds fired.
Thin profiles can definitely be accurate. This one is a CAV MK2 lower, Clark carbon handguard, 16" Ko-Tonics barrel, and Weaver 1-3x20 scope. It's right at 6 lbs as pictured. The barrel is 6.8 SPC (.277), and it's .7" diameter under the handguard, .750 gas block, and .6 between the gas block and muzzle. The second pic was 3 rounds of 100gr Nosler Accubond over 30.0gr of AA2200 at 100 yards from that gun.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi328.photobucket.com%2Falbums%2Fl342%2F1k_wayne%2Fguns%2F68spc-1.jpg%7Eoriginal&hash=2adcf5555e9853cb5ebdeb481e6ac8afcc799da4)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi328.photobucket.com%2Falbums%2Fl342%2F1k_wayne%2Fguns%2F68-100accubond_zps6d348240.jpg%7Eoriginal&hash=012e14debb9ac0d21f3cfdbc76881cc3d1e9249c)
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When you handload for the AR15, do you have to crimp the bullets any different than you for bolt-actions?
It seems like there isn't any room in the AR15 mag to adjust OAL. I guess you just have to load to a "factory" OAL and forget trying to tune your OAL for rifling set-off, is that right?
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When you handload for the AR15, do you have to crimp the bullets any different than you for bolt-actions?
It seems like there isn't any room in the AR15 mag to adjust OAL. I guess you just have to load to a "factory" OAL and forget trying to tune your OAL for rifling set-off, is that right?
Not really any different than bolt actions. There is the usual disagreement about which is best, taper, roll, Lee FCD, or none. I've tried both Taper and Lee, and found no crimp to be more accurate, and haven't had any problems with bullets moving with just neck tension. YMMV.
Some AR magazines allow length up to 2.3". I've found that 2.26" works pretty good in both of my 6.8 rifles, and I don't recall the length I load to in 223, but you should be able to find a length that is accurate.
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I see lots of "service rifle" AR's at High Power matches with no flash hider. Full 20" barrel. They seem to think the exposed/recessed crown is greater value than the flash hider, especially since the 15+ pound rifle only gets used during peak sunlight hours in the middle of the day.
Bare muzzles are only allowed in the 'Service Rifle' category because of the 1994 AWB. You don't see M-14s without them.
There really isn't any evidence to suggest that an A2 muzzle attachment does anything to harm accuracy if installed and timed with peel washers, Crush washers can distort the rifling/bore causing minor loss in accuracy.
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Whether or not a particular muzzle device negatively or positively affects accuracy depends on a lot of variables, harmonics, barrel profile, barrel stress for a given heat, whether it's hammer forged, or button rifled, cryogenically stress relieved, how hard it's torqued down, how hard the barrel is torqued into the receiver upper, the crush or peel washer used for timing it, as mentioned above. Then there's ammo weight, the speed and pressure curve characteristics of the particular load and powder, the differences between NATO spec and SAMMI .223 brass, primer strength... goes on and on...
I'm sure having or not having one matters if you're going for absolute bench-rest accuracy, or competition, but the individual variables get to be so diverse, it's one of those black-arts kind of things where there's no broad conclusions to be drawn.
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Bare muzzles are only allowed in the 'Service Rifle' category because of the 1994 AWB. You don't see M-14s without them.
I don't understand any part of this statement. Can you please explain to someone not familiar with the categories?
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I don't understand any part of this statement. Can you please explain to someone not familiar with the categories?
In highpower 'Service rifle' class matches, whether they be CMP or NRA, the rifle must outwardly resemble a military issue M1 garand, M14, or M16, with some modifications that cannot be seen allowed such as a heavy contour barrel, free float tube under the handguards, precisely machined and fitted sights, weights under the stock and handguards, and a modified trigger. The rules are sort of NASCAR-ish, where the rifles have to look and and have the same external dimensions. The '94 AWB, made threaded barrels difficult to come by or illegal to own for those buying a new rifle, so the rules had to be modified so that civillians could buy/build AR-15 rifles for this competition. If I'm not mistaken, 'pre-ban' barrels still cannot be purchased in some states.