The Government Profile Barrel Is Dumb
BY Herschel Smith
5 years, 7 months ago
I was doing some research on barrels and was a bit puzzled to find that so many top flight manufacturers (e.g., Daniel Defense, BCM, etc.) are still putting “government profile” barrels on their guns. The best research I can find on why such a thing exists shows the idea to be extremely dumb.
Marine Lt. Col Dave Lutz was the program manager for the M16A2 project from 1980 to 1983. He was later the VP for Military Operations at Knights Armament Company. Some years ago he shared the story of the government profile barrel on AR-15.com.
It all started with a drop gauge test. The gauge wouldn’t pass through the bore, so the assumption was that the barrel was “bent.”
We (Marines) were replacing a lot of “bent” barrels that were determined to be “bent” because the Armorer’s Bore Drop Gauge would not freely pass through some barrels during Ordnance Inspections (LTI’s). So the Logisitcs people had “Barrels Bending” on their list of “M16A1” things to “Improve” right after listing “Handguards Breaking.”
AR-15 lore tells us that GIs were using their rifles as pry bars to open crates, and they were bending the barrels by the muzzle doing it. Another story tells us that aggressive bayonet drills were the source of bending. This is the one that Lt. Col Lutz ascribed to, at least somewhat.
We “experts” thought this bending was from rough handling like during bayonet drills, etc., as an absence of any mid-barrel handguard damage in these rifles made one assume the fulcrum of such bending was the bayonet lug. So we made that part of the barrel thicker because we did not want the excess weight of a full length heavy barrel.
The last line of that quote highlights something interesting. There was internal pressure to make the entire barrel thicker. The Marines have always prided themselves on their marksmanship skills. A lot of their techniques and choices of rifle components have origins in competition. The Marines were the driving factor in the adjustable rear sights of the M16A2 as well.
Lt. Col Lutz and his team realized that a heavy barrel all the way through was not a practical solution for a lightweight combat rifle like the M16. So they made only the front of the barrel thicker to increase strength.
In testing using the bayonet lug as a fulcrum, and applying calibrated mechanical pressure to the muzzle, the new barrel was about 9 times more resistant to bend and take a set than an M16A1 profile. So we went with this “improvement.”
With the problem solved, the new barrel design went into effect. Only later did the team realize the actual cause of the drop gauge failure was something entirely different.
However, soon after I started using a borescope with a video recorder and monitor to inspect “bent” barrels. What I found was a mound of bullet jacket material at their gas ports. This build up was caused by a burr left from drilling/reaming the gas port. This was where the Armorer’s Drop Gauge was getting stuck. When we removed this “mound”, the barrels would all pass the Drop Gauge.
Realizing that the “solution” they presented didn’t actually solve a problem, they tried to course correct. Colt listened, and even put out civilian M16A2 copies that still had the standard lightweight profile. But the government was already too far down the road. The new technical data package was already written and put into effect. There was no going back.
First, I question their testing of the resistance to bending of a “government profile” barrel. They obviously never got real engineers involved in this problem. The highest bending moment in a cantilever beam will be where it is pinned, which in this case will be at the receiver. As best as I can tell, not only didn’t they solve a real problem, they didn’t even solve the pretend problem.
Second, engineering resources would have performed a failure mode and effects analysis of the problem. A failure investigation team of engineers should have been commissioned, not a military team.
Third, if you believe the problem is that Soldiers or Marines are using their rifles to pry open boxes or crates, then teach them not to do that. That’s stupid. I remain unimpressed with folks who try to mistreat, abuse and beat up their guns only to complain when they don’t work.
The second law of thermodynamics says that entropy always increases. Fatigue, metal lattice stretching and deformation, metal creep, rust, corrosion and a host of other problems will affect any machine. I once read that someone complained that he had used the butt of his rifle as a hammer for tent stakes and other things, and thus wanted “Milspec” parts so they don’t break.
Listen to me. Milspec isn’t better. Milspec isn’t worse. Milspec means that something was fabricated and built according to a specification, nothing more and nothing less. Some guns and parts are better than Milspec, and some are worse. Some are just different than Milspec because the buyer wants a different machine for a different purpose or with different parts simply because that’s what he wants.
The takeaway is this: don’t use your rifle butt as a hammer. It isn’t a shovel, it isn’t a hammer, it isn’t a pry bar, and as for bayonet charges, you’re not going to do one. Ever. If you’re doing a bayonet charge, you failed to do whatever you needed to do to make it a stand-off fight. Your rifle isn’t a spear.
And the top end AR-15 manufacturers need to get away from fabricating “government profile” barrels. They’re dumb.
If you think I wrong or don’t know the full history of government profile barrels, you can weigh in with comments.
On May 12, 2019 at 9:46 pm, MTHead said:
Thanks Herschel, always wondered about those goofy looking things. thank god for the aftermarket!
On May 12, 2019 at 10:19 pm, Ratus said:
You about summed up the idiocy of the government profile barrel.
If anyone wants a deep dive on barrel making, InRangTV did a series of interviews with someone from Faxon as a supplement to their WWSD project.
On May 12, 2019 at 10:47 pm, Papa said:
What is a recommended barrel profile for 16-20″ AR/M16’s?
On May 13, 2019 at 3:38 am, Ratus said:
@Papa, it depends on what you want to do with it.
For general purpose, a new manufactured Nitrided pencil profile should be more than good enough.
Unless you need sustained fire, then a heavier profile and chrome lined would be better.
On May 13, 2019 at 8:16 am, Dean M Drews said:
I totally agree. Heavy barrels might be slightly slower to heat up with sustained fire, but they also retain the heat longer. From a competition standpoint, the front sling attachment is on the barrel of a standard rifle, so a tight sling does change POI. I remember that a switch to the heavy barrel was to alleviate that.. Both the USAMU and Marine rifle teams pioneered and drove the changes to the A1 rifle into the A2
I own a AR15A2 purchased in 1988 that I used in service rifle matches and saw this change in POI until I added a free float tube that moved the front sling swivel to it and off the barrel. The barrel profile is not significant any longer.
On May 13, 2019 at 8:46 am, Herschel Smith said:
@Dean,
If you saw a change in POI, that wouldn’t have been because of barrel deflection or bending. That would have been because of a change in barrel harmonics due to being pinned at the wrong point. The best point to pin a barrel is not at all, i.e., the floated barrel fixes all of that.
On May 13, 2019 at 9:04 am, Frank Clarke said:
I know next-to-nothing about barrels. “The bullet exits its forward end.” I just read you the book.
Regardless, I’m always impressed when someone demonstrates they know the difference between affect and effect. There are so few of us left…
On May 13, 2019 at 9:10 am, Herschel Smith said:
@Frank,
Many times writing professional papers editors want me to use the word “effect,” claiming that the word “affect” is used more in an emotive connotation. But “effect” is a verb (e.g., to effect a change). “Affect” isn’t just use in an emotive context.
On May 13, 2019 at 10:15 am, MTHead said:
Interesting that the problem was sloppy port drilling. not cleaning up the burr correctly. for all the money spent to bring those guns to field?
I read the Marines are paying H&K $3500 a copy for the M27. at that price they could have the finest aftermarket guns available.
The only thing that comes to mind is, prison time!
On May 13, 2019 at 10:34 am, Bill said:
I was in the Service when the -A2 came out. I thought the Gov profile was dumb on the face of it from the first moment. …There is so much idiocy talked about guns it’s nearly unbelievable. Viewed as machines, guns are really very simple mechanisms, even automatics. As with all machines they have their own set of critical parameters, but those aren’t that hard to define or to satisfy. ….Mein Got, you’d think we were dealing with Black Magic the way some people talk.
On May 13, 2019 at 10:36 am, brunop said:
There are many good barrel makers out there. I have had unbelievable success with the DD pencil barrels. I thought the pencil profile would sacrifice accuracy for some reason. Nope. I’ve got 6 or 7 16-inch “pencil” barrels from DD, and they all shoot MOA with 77s from Black Hills or Hornady, and they shoot 1.5 with bulk M855 Green Tip. All free-floated, of course.
No Gov’t Profile barrels over here.
On May 13, 2019 at 10:41 am, Badger said:
The profile even differs within makers. Many of the barrels sold now (and PSA sells container-ship loads of them) are “A2 profile.” On a gun whose role is one where ‘handy’ is in the job description, they are a beast, solution in search of a problem. All the more so when a Soldier adds IR/Visual lasers & lights on it. They shoot fine but are often simply a nose-heavy PITA.
Several com’l makers make what THEY call a “Gov’t profile” and it is something completely different than MILSPEC A2 (I know this from measuring & comparing an OEM A2 with a replacement gov’t profile), and lighter by about 8-12 oz. (maker dependent) & balancing much better in hand. My favorite is the .625″ at the gas “pencil” (pick your barrel length). It does sustained fire quite well (FA mag dumps not tested) and even with a 5 oz light & mount on the nose handles wonderfully. Unless something more specific needed I’ll be going “pencil” every time.
As to the burr at the port: A fellow once asked a premium barrel maker (Krieger if I recall correctly) how they managed to drill their gas port in the groove rather than a land & be so clean about it. The answer:
“Math”
Engineer types might appreciate that.
On May 13, 2019 at 10:55 am, John said:
A related story walking down memory lane at “Fort Lost In The Woods”.
The first A1 I was issued in basic had a bent barrel. We had 1 day to zero and qualify
for that first of several qualifying steps. On the 25 meter range I adjusted the sights
as far as possible and was still about 6 inches high and 3 inches left. I told the DI
and then he and then another both spent some time firing it and then went to the armorers
trailer. After a bit they issued me a replacement but the time to zero was over and we
had to qualify right after chow. My DI was a decent guy and took me to an unused range
down the road and I zeroed while the others ate. Got back and shot a 93 out of 100.
Just sayin.
On May 13, 2019 at 11:20 am, CC said:
Why not issue one of those small, flat, light-weight prybars that are made for the job of opening crates, and useful for many others?
Is that really the mentality of military leadership these days?
God help us.
On May 13, 2019 at 12:33 pm, warhorse said:
the only use I’ve ever actually had for a bayonet was on a shotgun for controlling unruly protesters around the time of desert shield stateside..as a “do not grab my shotgun” device. people think twice about grabbing a knife..for some reason grabbing a shotgun barrel, not so much.
On May 13, 2019 at 12:34 pm, Georgiaboy61 said:
@ Herschel
Re: “The takeaway is this: don’t use your rifle butt as a hammer. It isn’t a shovel, it isn’t a hammer, it isn’t a pry bar, and as for bayonet charges, you’re not going to do one. Ever. If you’re doing a bayonet charge, you failed to do whatever you needed to do to make it a stand-off fight. Your rifle isn’t a spear.”
Your statement is almost 100% correct, but not quite. The bayonet-affixed rifle as a combat weapon has been called extinct by some, but there have been occasional sightings.
In Basra in 2004, a force of around twenty British soldiers was ambushed and forced out of their vehicles by an enemy force of around one-hundred Shi’ite fighters. On the defensive and running out of ammunition, the British fixed bayonets and charged the enemy, routing them at no cost to themselves while inflicting twenty or so casualties upon the opposition.
I hope the British government decorated those brave men, not just for defeating a more-numerous enemy force who had the advantage of surprise, but for doing it largely with bayoneted SA80 bull-pup rifles. Talk about a tough job!
You are correct about the bayonet insofar as the fact that modern armies have largely moved away from their use and no longer teach bayonet skills as a significant part of hand-to-hand/close-quarters battle doctrine. However, cold steel still has its place in combat. Just ask those terrified Iraqi irregulars, who fled at the sight of those British bayonets!
Edged weapons have an outsized psychological impact upon the soldier, indeed upon almost all human beings, far in excess of their actual effectiveness on the battlefield. Although most soldiers, even in the heyday of the bayonet, rarely used theirs for anything other than opening rations or other jobs in the field, on those rare occasions when the bayonets were used as intended, the grunts were glad they had them.
Ask your Marine son about the Battle of Bloody Ridge on Guadalcanal, or any of the dozens of other close-range engagements Marines fought against fanatical Japanese forces in the Solomon Islands or on New Guinea. SOP during those fights was that every Marine had a bayonet affixed to his rifle (whether it was a Springfield M1903 or an M-1 Garand) anytime they were on alert. Surprise human wave attacks out of the jungle will do that to ya!
On May 13, 2019 at 1:21 pm, DAN III said:
ALCON,
I carried an M16a1 for more years than I care to divulge here. Never used it to pry open a case of 5.56, a Mermite can or anything else for that matter. However, I did use my carry Ka-Bar once to pry open the seal on a case of 5.56. SNAP ! ! ! Broke the blade of that Ka-Bar right in half ! Contacted Ka- bar. To their credit they replaced the knife and sheath no questions asked.
Go Ka-Bar !
BTW…I never had an issue with my iron sight equipped M16a1 accurately hitting 300m + targets. It is the shooter behind the weapon. Not the barrel profile.
On May 13, 2019 at 1:21 pm, Jorge said:
“As best as I can tell, not only didn’t they solve a real problem, they didn’t even solve the pretend problem.”
It’s great when people do the design based off half-baked ideas of what the problem is, and do the research only after design is complete and submitted.
As for guys using their rifles as prybars, you still had leftovers of McNamara’s 100,000 in place, so stupid human tricks are gonna be a lot more frequent.
On May 13, 2019 at 1:31 pm, Russ said:
I’ve often wondered about that. Both my M1A and G.I. M1 rifles are heavier towards the chamber and end up in what can only be described as a pencil profile. Which is what my favorite GM M16A1 had. If you want beef, it would seem better to have it where the heat is the highest and the Marines put it out towards the muzzle. Jarhead logik.
On May 13, 2019 at 2:10 pm, Cold Warrior said:
Interesting read, thank you. I can totally relate to-
“But the government was already too far down the road. The new technical data package was already written and put into effect. There was no going back.” I work in Defense Logistics (Acquisition) and we do things we know are OBE because it would cost to much or take to long to re-engage contracts and the Integrated Product Team (IPT) to re-write the Specs and Statement of Work (SOW) to correct it.
It is, quite correctly stated, dumb.
On May 13, 2019 at 2:31 pm, RSR said:
Ballistic Advantage’s Hanson profile barrels from online resellers like Arm or Ally are great values. I like the 16″ midlengths w/ .750 gas block journal diameter for higher rates of fire, or the .625 journal version where weight reduction is paramount. I personally opt for the chrome moly steel (“Performance Series”) over the stainless option (“Premium Series”) due to being less like to burst if ever need to run it red hot.
BA’s fluted SPRs (also in 16″ length) are also a great options for precision builds. Saves more than a pound vs unfluted IIRC and increases rate of cooling. I only buy the premium stainless options here. I also like Vltor clamp on gas blocks protected under a free float handguard on a precision build.
I’m not certain if BA’s barrels are stress relieved, or not (probably not). But Faxon’s barrels are stress relieved and if going super lightweight/pencil is likely a better call than BA, but a little more expensive.
Faxon also has precision profile barrels that are fluted w/ 5R rifling that weigh similar to BA, but are something like 30% more expensive IIRC.
Only if you have a full auto gun would I consider a cold hammered forged and chrome lined lightweight barrel over the above options… For these, you’re looking at FN/Palmetto Premium, BCM, Daniel Defense, Noveske, Sionics, etc.
Re 16 vs 20″ — you really only see differences in trajectory beyond 300 yards. 0-300 w/ a 100 yard zero are nearly identical. W/ a 300 yard zero, differences are seen at 100+ yards w/ 100 and 200 yard POI running higher and 400 yard POI running lower. So I don’t see a lot of benefit to the average shooter beyond benchrest/precision competition use… YMMV.
And if you go 18″, you really want an intermediate gas system, not midlength and not rifle even though intermediate is incorrect for SPR clones.
On May 13, 2019 at 2:37 pm, RSR said:
And to echo others, properly profiled barrels completely change the handling and balance of the AR15. Sort of an AK vs VZ58, or an M1 carbine vs an SKS comparison if you will.
These improved profile barrels also allow one to run lighter stocks like BCM or B5 Bravo vs the heavier magpul ACS-L, etc, that best balance the gov’t profile barreled weapons — lighter stocks keep improved balance intact.
On May 13, 2019 at 2:39 pm, RSR said:
And Palmetto offers a pencil nitride .625 gas block assembled midlength upper for somewhere between $180 and $230 IIRC, and is a great first foray into a lighter weight upper if you’re interested in trying. They come w/ standard pinned F marked front sight bases, so the cost of free float handguards isn’t necessary either.
On May 13, 2019 at 3:52 pm, Lionhound said:
I always assumed the reverse taper was to accommodate
the M203 grenade launcher, but I may be wrong.
On May 13, 2019 at 4:52 pm, Matt Bracken said:
The M-16A1 with (as I recall) a 20.5″ pencil barrel was meant to max out the velocity of the M-193 55 grain bullet at a nominal 3,250 fps. Vietnam combat vets I know well affirm that it was deadly stuff, hauling ass and barely stable in flight, ready to tumble and break apart on contact.
As far as “prying open crates” what folks are talking about is using the original open-prong flash hider to break open the steel “band-it” straps around wood ordnance crates. Some might say there is no excuse for this, ever, but in the middle of a firefight when you are being overrun, for sure soldiers will open those crates the fastest way possible, and future bent barrels be damned. The open-prong flash hiders worked great to break those steel bands! Who will wait around, saying, “Hey sarge, you got some cutters for this steel band?” Hell no. You’ll open that crate anyway you can, as fast as possible. Your next qualification score will be the LAST thing on your mind!
This is one of the reasons the open-prong flash-hiders went away. Another is that they liked to reach out and grab vines and branches, not an ideal feature while patrolling in a jungle!
On May 13, 2019 at 4:57 pm, Matt Bracken said:
RSR wrote: “Re 16 vs 20″ — you really only see differences in trajectory beyond 300 yards. 0-300 w/ a 100 yard zero are nearly identical. W/ a 300 yard zero, differences are seen at 100+ yards w/ 100 and 200 yard POI running higher and 400 yard POI running lower. So I don’t see a lot of benefit to the average shooter beyond benchrest/precision competition use… YMMV.
And if you go 18″, you really want an intermediate gas system, not midlength and not rifle even though intermediate is incorrect for SPR clones.”
The original 20.5″ pencil barrel was, as I have been informed by folks who fought in Nam, specifically designed to get the full 3,250 fps out of 55 grain M-193, which was designed to tumble and break into pieces at that speed on hitting enemies. And, they say, it worked as designed. I’m not trying to get into a debate, just passing along what I’ve been told through the decades.
On May 13, 2019 at 5:32 pm, X said:
While everything stated in the article above may well be true, I do not believe that the government profile barrel is “dumb.” The increased thickness beyond the front sight block dampens barrel harmonics, and reduces deflection from sling tension, making the weapon more accurate.
You can prove this by comparing the AR platform to the Mini-14. It is well-established that the Mini-14’s lousy accuracy in the earlier-production models was in large part due to the thin, whippy barrel beyond the gas block. Almost ANY government-profile AR/M-16 will outshoot a Mini-14 easily because of this. Accuracy systems has done a brisk business for many years retrofitting Mini-14s with .750″ barrels. On recent production models, Ruger has in fact thickened the barrel beyond the gas block to improve accuracy.
I had many years of experience shooting free-floated, national match ARs with full, 1″ profile barrels under the handguards before I acquired a cheap, government profile, non-floated 16″ midlength, and I was surprised at how accurate the latter was. It makes even the newer Mini-14 seem inaccurate by comparison.
On May 13, 2019 at 7:14 pm, Papa said:
Pencil barrel stress and heat zero testing.
https://youtu.be/QTovPt4weIs
On May 13, 2019 at 7:15 pm, Papa said:
Pencil barrel and carbon fiber free float tube.
https://youtu.be/beaBDC8iS-E
On May 13, 2019 at 8:30 pm, The Wretched Dog said:
Not withstanding anything written above, to what extent did the first 60% of the ‘government profile’ barrel remain ‘thin’ so as to be able to mount the M203 grenade launcher – without changing the mounting hardware?
Scuttlebutt was, in the 80’s when the M16 A2 was adopted, that the reason the main barrel remained thin was to mount the M203. The Army wanted a heavier barrel for improved accuracy (no intent to get into the merits of that solution), but had to accept making only the front portion of the barrel, outside the handguards so as to be compatible with the M203.
I could be wrong on that – but that was the longstanding explanation we received as to why the whole damn barrel wasn’t the thicker, heavier profile.
YMMV.
The Wretched Dog
Colonel, US Army (Retired)
Infantry, Ordnance, Logistics
On May 13, 2019 at 9:11 pm, Anonymous said:
This varies with manufacturer, production lot, and so on, due to differences in jacket thickness, jacket material, and cannelure pattern, but as a general rule of thumb, the 5.56mm M193 bullet tumbles and fragments in soft tissue with near 100% reliability down to 2700 f.p.s. From there down to about 2550 f.p.s., it fragments about half the time. Below 2550 f.p.s. it may still tumble or yaw in soft tissue but rarely fragments.
With a muzzle velocity of around 3240 f.p.s. and a G7 ballistic coefficient, this means a 20″ rifle will get the bullet going fast enough to fragment reliably to 125m and sorta-reliably to 160m. With a 16″ barrel taking 100 off the muzzle velocity, it’s 100m/140m. With a 14.5″ barrel like an M4, 80/115.
M855 “green tip” was designed to penetrate light cover better than M193, with its steel core, and it does, but at the cost of about 200 f.p.s. muzzle velocity as compared to M193, plus it overall seems to be more stable in tissue and does not yaw and fragment as reliably as M193, for reasons not fully understood (speculation currently revolves around rifling twist and bullet construction).
On May 14, 2019 at 12:48 pm, SGM Settles (Ret.) said:
The Army published Training Circular (TC) 23-11 in about 1981, in which The Army Research Institute (ARI) published results of their rifle marksmanship studies conducted over the previous several years. Among other recommended items (25-meter scaled-silhouette targets), the study showed that the pencil-thin M16A1 barrel flexed when used in the auto-rifle mode with the clam-shell bipod. The doctrinal method of use had the shooter pulling down on the sling under the hand-guard in order to keep the rifle steady, and this caused the bullet-strike to hit high.
I have a Bushmaster AR, 20-inch, 1-9 twist, with a thick profile under the hand-guard and the standard government-profile from the front-sight-assembly forward. I changed the standard A2 hand-guards out for a drop-in pic-rail, on which I mount an clip-on bipod. It has given me 1-MOA accuracy with 69 grain Match Kings at 300 yards from a bench. (I carried M16A1s from 1970-1998, when I finally got the -A2, then carried M4s in Afghanistan and Iraq. I have some experience with the Government-Issue items.)
Regarding bayonets: Don’t say “never.” They have been used in close combat up through near-current times. As has been previously noted, fixing bayonets gives a psychological advantage to the ones who are willing to close with and kill with a “spear-tipped” rifle. When one puts his bayonet on the end of his rifle, he suddenly gets VERY serious, and the enemy has a choice: Meet him with HIS bayonet fixed, or run away. (Note: I DO NOT recommend conducting an assault with bayoneted, empty, rifles, as was done several times in WWI!)
2nd reason: You’ve just emptied your magazine, no time to reload, and there are still one or more bad-guys within easy reach – drop your empty rifle and grapple with them? Or gut them with your bayoneted-rifle before they can do the same to you? How badly do YOU want to make it back home?
On May 14, 2019 at 6:31 pm, kevinH said:
As for bayonet use, am I wrong in thinking that a civilian 16″ barrel with a carbine length gas system and an A2 front sight, puts the bayonet lug in the wrong place, since the military M4 is 14″?
On May 14, 2019 at 6:47 pm, SGM Settles (Ret.) said:
KevinH: You are correct that the 16-inch barrel “M4gery” positions the front-sight assembly/bayonet lug too far to the rear on the barrel for a mounted bayonet to be of much use. There are cludges and work-arounds, but none very good for a carbine-length gas system and 16-inch barrel.
I favor a mid-length gas system which, with a 16-inch barrel, positions the front-sight/bayonet lug the same distance from the muzzle as the 14.5-inch M4 and the 20-inch M16A2/A3/A4. This also, with the same length firearm, slows the cyclic-rate (longer 9-inch gas tube, compared to 7-inches with the M4geries) which seems to be good for the rifle.
On May 14, 2019 at 8:58 pm, X said:
I think civilians need to start thinking more about the uses of the bayonet.
If you’re hiding in thick cover and your opponent sends a dog after you, it’s the ideal tool for dispatching the animal without firing a shot and betraying your position.
On May 15, 2019 at 11:15 am, DAN III said:
SGM Settles @ 1248,
“….Don’t say “never.”
My thoughts exactly Sergeant Major.
Never say never !
On May 15, 2019 at 11:39 am, Crew said:
Much better to make them dead at 200 yards or 100 yards than to have to get up close and personal.
You could get hurt that way.
On May 15, 2019 at 10:08 pm, RSR said:
Matt Bracken — Thanks for the reply. My grandfather was a Green Beret and A-Camp Team Leader within miles of both the DMZ and Laos, near Khe Sanh… Combat disabled before John Wayne’s movie ever hit theaters. Korea vet and most of his SF service was in Germany/Eastern Europe… CAR-15s were common among US SF at his time in Vietnam and M1 carbines for the indigs…
W/ CAR-15s, the open 3 prong wasn’t used AFAIK (unfortunately, the Gpa is deceased so can’t ask).
Regardless, w/ modern powders you DO NOT need 20″ of barrel in order to achieve full velocity.
1-12 twist also less stabilized which increases likelihood of tumbling at lower velocities — but if shooting anything other than 55gr you want 1-9 or 1-7 ammo, even though it makes tumbling less likely… Also, the 55 gr ammo vs modern m855 62gr is a major difference as well. And for us civilians using soft or poly tip ammo moves fragmentation velocity down to the low 1k range (arfcom has a good summary chart somewhere on that — I’m not an arfcommer).
The problem with longer barrels is that they result in reduced accuracy, albeit higher velocities. Beyond velocities, the greatest benefit of longer barrels is greater sight radius if using irons — if using optics this second-level benefit is no longer applicable.
On May 15, 2019 at 10:08 pm, RSR said:
Matt Bracken – Whoops, left out — big fan of your books.
On May 15, 2019 at 10:22 pm, RSR said:
Other posts since my previous:
-M203s mount to the Socom profile which is heavy under the HGs, but with flats milled.
-Thickness in front of the front sight is dumb. It doesn’t do anything to dampen harmonics, in fact all the right angles increase the effect of harmonics. Compare Hanson profile barrels to gov’t.
-The only benefit I see of gov’t is if mounting a suppressor on the gun — increased thermal mass due to add’l material is a benefit. Unfortunately very few dot gov folks use suppressors.
-Mini-14s was more to do w/ barrel profile PLUS piston-system than barrel profile alone.
-Anon at 5/13 #s and effects regarding M855 vs M193 are spot on.
-Sling bending 20″ pencil barrel and affecting POI is real — and the same bend applies to gov’t profile barrels since pencil under the HG.
-Bayonets — not saying never but as civilians we can carry sidearms regardless of “rank.” Bayonets are often used for soldiers prohibited from carrying sidearms. Since WW-2, bayonet charges have been about as pointless as cavalry charges in WW-1, especially if against peer forces.
-Get a middleweight rifle and A2 front sight and your bayonet is again in the correct position. Zero reason for carbine length gas on a 16″ barrel.
-Fighting knives, kukris, tomahawks, machetes, etc, are all superior for blade fighting to a bayonet.
-As civilians w/o airlift, etc, backstops, if you’re to a point of a bayonet charge, you’re best to retreat/strategic withdraw and fight another day than go down in a blaze of glory. Discretion being the better part of valor, etc.
On May 15, 2019 at 10:24 pm, RSR said:
*midlength rifle and A2 front sight on 3rd to last bullet.
On May 15, 2019 at 10:27 pm, RSR said:
**And on last point, meant medivac rather than airlift… Long day.
On May 15, 2019 at 10:52 pm, DAN III said:
RSR @ 2227,
You still did not get it right. The acronym is NOT “medivac” ! The acronym is MEDEVAC.
MEDEVAC = MEDical EVACuation
On May 16, 2019 at 10:28 pm, RSR said:
DAN III – Thanks for catching. Like I said — yesterday was a long day.