Happiness Is A Warm Belt Fed & Designated Marksman Platforms

Here is a great piece regarding the designated Marksmen Rifle for the home turf defender and partisan: THE AREA DENIAL WEAPON

Linked over to WRSA: The Area Denial Weapon

Do link over and read, the Designated Marksman Rifleman and area denial tactics have much going for us mere citizen partisans and defenders of Home and AO. Resources are always thin. Combat grade belt fed weapons rare as hens teeth. Care and feeding, ammo and parts, an intensive, to prohibitive, for a majority of us dirt people, where life, land & Liberty defense is all important.

The whole idea based out of improvisation and adaptation at the civilian self defense small unit infantry combat level, with no prospect of materiel re-supply as a state military enjoys, is a driver of ideas and uses of resources at hand. It is a concept which definitely suits the ingenuity and industrious of many with home gunsmithing experience, for workshops equipped with basic machine tools, or access to such excellent resources. Along with the modular design and unlimited adaptability of the AR platforms, their affordability, the mind blowing scale of the AR component market, it doesn’t get any better. The world could be going to shit, but all this things AR is a bright spot with unlimited prospects. It is a grass roots movement in no uncertain terms. And a very American thing.

In two ways, I’m thinking the AR phenomenon is only getting started. We aint seen nothing yet. (They really believe they are taking our guns?). Are there any limits? Not yet. Lot of ingenious creative people out there. Refinement and innovation is essentially without limits. The most adaptable, proven, greatest small unit infantry combat rifle ever devised? For us civilians? You fuckin’ know it.

The tactic and weapon here has practical merit certainly for the citizen fighter. Its your AO, you know it like your wife’s body, you caress the land, know every fold of the terrain, have every kind of rally point, cache, observation point, interdiction route, emergency routes and trails. But no belt feds.

The author linked above has written a most worthy dissertation and deserves reading on his merits. It also alludes to my post here in a couple of respects, regards upgrading certain limitations of an off the shelf built area denial/designated marksman rifle.

In my previous post: Practical Personal Observations On The AR Platform .300 Blackout Truck Gun (update 5-28 with photos and minor revisions) We discussed one guys truck/tractor “minuteman rifle”.

In that iteration i used a “chambered blank” from the guys up at Green Mountain Rifle Barrel, who produce these fine, underrated and affordable military barrels. They offer all sorts of turned and unturned traditional barrel blanks, but the addition to their products with the AR platform chambered blanks is a real game changer.

The ballistic results so personally conclusive I’ve upgraded all my AR’s to this barrel configuration.


Image 1

In their product photo above you can visualize what their chambered blanks are about. Barrel extensions, chambers, stress relief, high accuracy turned outside diameter, superb weapon grade vanadium alloyed chrome-moly steel, anti-extractor blowoff pin, chrome lined, better than mil spec features. Any barrel features you want within the dimensions of OD and length can be turned using a basic accurate lathe and basic barrel turning techniques.

All for around $100 bucks. I’ll say it outright. These make $200 and up grade high quality combat barrels. GMRB has added a number of variants in length, cartridge, twist rates, coated barrel extentions. I have turned their 1-7 twist 5.56 and 1-7 twist 300BLK, along with a number of conventional barrel blanks, and can attest the accuracy I’m getting is crazy insane awesome. Like I personally can not shoot as good as this kind of accuracy. Im no great shot, but I am a life long snap shooter of reasonable success rate from hunting all my life in the boreal close cover forest of the North East. So what I have discovered, the inherent accuracy of these barrel blanks are giving me an edge in my practical ability to increase my accuracy under real life conditions I never had. Its awesome in a word.

They recently added a 7.62 x 54 Nato Chambered Blank. Hello affordable AR-10! Up armoring the AD/designated Rifle.

The pic below taken from GMRB product page, a “5.56 mm, 1:7 twist, 21″ long, 41V50 steel, weighs 3.65 lbs., Gunsmith Edition chambered blank, chrome line bore and chamber, phosphate extension (with M4 feed ramps), button rifle, air gauged, and stress relieved.”


The advantage in this line drawing should be self evident: Thick rugged barrel. Good length for obtaining potential of high velocity for the .223 cartridge. Thermal mass for high rates of fire. Enough materiel to add shallow cooling fins for barrel to air heat transfer. A cool barrel is a happy barrel. Relatively simple lathe work.

Based on the AD weapon concept of the linked above author’s, this is a raw GMRB chambered blank blue print. The plan is to retain the OD, employ cooling fins,  machine a gas block out of 4140 Chrome moly round stock, rifle gas port location, match 11 degree crown, 5/8-28 threads, for a larger, higher volume, heavier caliber, belt fed rated suppressor in the .30 caliber range, (a good suppressor design is not dependent on bullet diameter clearance being as close as possible as one would think). A suppressor gives your AD weapon concept another edge, more difficult for the enemy to locate and return effective fire on your position.

The reason for retaining the large barrel OD is due to the archived failure of the M4 barrel with its particular profile to first become irreparably damaged, in a sustained burst fire rate with no time between shot strings to properly cool down, to a characteristic, longitudinal rupture fail just behind the carbines gas block, when heated under sustained rapid fire, in the 350-750 round count, respectively.

The present configuration:

I like the idea of a carry handle ala FAL’s swing down design. Ditch the sling, one less item to get hung up or entangled in weapon. No messing with getting a strap over your gear in a desperate movement to another location. A solid handle to grab and run low with is all but instant. Grab & Go. KISS principle.

Matt Brackens Duplex Magazine rig he used as a Navy Seal: In Praise of Duplexed AR Mags. I swear by this set up. It really works. Its cheap, down & dirty. I’m working on a 4130 chrome moly sheet metal clamp design which duplicates Matts Duplex rig. The V makes all the difference. Duplex couplers which hold mags parallel for some reason don’t cut the mustard. This V system cant be judged by appearances only.

( The V configuration with the mags joining at their base plates is particularly slick method. I used it at Max Velocity’s live fire small unit infantry combat course. I watched everyones mag swaps, and this system was faster by orders of magnitude. It ain’t fancy, its down and dirty. It works. Cheap. Effective. Battle proven. Essential to surviving an ambush. You don’t got time to reach in a mag pouch for a refill. In this case of the area denial weapon, duplexed 40 round Pmags, thats eighty rounds on the rifle. Closer to the magic 100rd belt count. These duplex mags also tuck real sweet over your battle belt, pants top, stuffed into a vest shoulder strap when proved out, jam one mag feed lips down in a single TACO pouch, let the other mag dangle. Pmags have those awesome dust/spring detention covers, so debris entry in the exposed mag is much limited. Dust cover on the “left” mag looking down at your mag well, so its easy to reload a new duplex.)

Pmag bipod. Solid pod for a working mans wallet. Pmag quality. All good.

Top Shelf Iron Sights: Scalar Works Peak The Rolls Royce of AR iron peep sights Sights. These guys stuff is weapons art. Their red dot mounts are beautiful.

Trijicon Accupoint  1-4x24mm tritium/fiber optic powered green triangle post reticle, Superb glass. BIDON Aiming concept. Uncluttered view. Rugged. Built for combat. Uses all of Trijicon’s proven technology throughout. Don’t need a ranging reticle, or fussing with that, with a 20 inch barrel shooting the flat ballistic battle field zero of the 55 grain 5.56. No batteries. Adjustable reticle intensity. Green is much easier for the eye to pick up, less contrast in low/no light enhancing target ability acquisition in low light. Looking thru Trijicon’s glass lenses is believing.

Precision Steel Rings to mount the above. No broke aluminum alloy scope mounts for me in the middle of combat. It happens. Shit Happens.

Alternative optic: Trijicons Green Dot MRO, with a flip to the side magnifier. Or Aimpoints brutally robust Patrol Optic, with flip to the side magnifier. Both are combat grade. Both have 5 year battery life if left constantly on standard daylight setting. Both fast acquisition sight picture optics, parallax free, night vision capable, come with rugged flat top mounts. Reasonably priced for world class product. I use both and can’t imagine not running either on a combat rifle.

Very effective flash hider for when no suppressor. No need for a muzzle break with this rifle.

ALG Advanced Combat Trigger: Use the 6lb hammer spring for reliable mil spec primer ignition. These are a total must have on all AR’s. No exception on this rule. A good trigger contributes more to rapid fire accuracy than any rifle part. A combat spec trigger enhanced, still provides the legendary reliability and safety factors the AR trigger group possesses.

Full A2 Stock. buffer, and spring. Upgrade the buffer spring to a combat enhanced product, some really good choices there. The trap door is a must have for spare complete bolt carrier assembly. Bolt problem? 30 second swap. Back in business. This is a long controlled fire weapon.

Spare Bolt: Both bolt carrier assemblies of high quality. Cant skimp here. Money saved on GMRB chambered blank goes into at least a top shelf bolt. Mil Spec carrier more OK. They don’t have much problems. Why a complete bolt assembly is a must. JIC.

Free float forend of course. All that M-Lock or Key-Mod real estate. Some fantastic choices here. Need a solid mount for the Bipod. And carry handle.

Gas block: Rule #1 Must Be Pinned. Rule #2 Must Be Pinned. Colts AR’s are pinned for a reason. You heat a barrel enough the expansion stretches the gas block. Cools down, your gas block leaks or comes flying off from gas pressure. Ever see your gas tube glow red? Now we have expensive bad design caveman club. Spiffy lookin’ canoe anchor you got there. Adjustable gas block? Maybe one more component to fail and more complications. See Rule # KISS. The stock gas port size has worked fine for decades. Why mess with something don’t need fixing?

Moe Grip: Improved trigger pull position. The added thumb web is very comfortable. Improved angle. You might have to hold onto that grip for a very long time. Best of all more, nifty storage: Extra batteries. Spare firing pin and bolt storage. Or lube bottle accessory. Choices Choices.

Dedicated Ammo?: At least print some groups. Set aside best shooting out of the mountain of ammo you bought over the last ten years for this weapon.

Charging handle? I don’t know. I always used the mil spec handle. Works fine by me. Maybe I’m missing something?

Red & Blue Locktite: Same rule as Areo Space and motorsports safety wire. Anything you don’t want come loose, use it. Parts come off you die is the GP rule on aircraft.

Photo’s soon as I get going with the project.

Praxis Bitchez


Oh yeah, almost forgot. Update completely later. The gist of it:

The PO Ackley barrel turning high speed steel lathe bit that defies all normal lathe work convention of turning long small diameter stock. How does as heavy a cut as your lathe can handle without a follow rest strike you? .035″ to .050″ passes? No harmonics, no change in diameter over length of pass? Yes. The guy was a genious.

crazy Like A Fox, PO tricks you in his pencil line drawing, only gives you two views of a cutting tool that requires 3 axis surfaces to function. Did it on purpose to make you think outside the box. Great time saver. The other trick is you worry about surface finish on your last pass and use the usual methods of barrel polishing. Its a combat barrel bitchez. Not a safe queen right? I leave mine fairly rough. hit it with a lath file to take the sharper hi spots down, and sand paper. Put Brownell’s cold blue to it, hot water soap bath, and rattle can it. You do camo your weapons right? Black rifles might as well have lights lit up on them seen in NV optics. Stick out like a sore thumb.

For that, this guy has a great piece: Spray-Painting Things

While your there, this gent has a gold mine of exterior ballistics, Zeroes, devices and Apps for long range shooting. Great stuff. Real deal.













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