Easily, the most adaptable rifle in the world!
The Smoke Composites stock I received, allows the gas key of the carrier to strike the thread embossment on the lower receiver, even with a rifle length buffer. My fix was to cut a piece of carbon fiber sheet and place in in the buffer tube, then cut the urethane on the buffer to still allow the rifle to hold the carrier back on the last round.
You know how you can "freeze time" by dropping a strong magnet down a copper pipe? Why don't they make eddy-current magnetic buffers for ARs? The buffer tube is already a metal that would work. Maybe a project in the works...
Lately the CMMG .22 Conversion kit. It's a great kit, it will fully control the rounds too, if you move the magazine further up and forward. It will even fire fully submerged underwater, round after round. (of course you must use some SuperLube or other silicon grease on the crimp of the rounds or they water log.)
The kit can be found here: CMMG It should be noted that the bolt catch does not work with this kit, for a standard bolt catch to work you would need an intire upper like the military uses. (I should say, I have not yet seen a bcg replacement kit that will do this. Maybe it's out there!)
The best thing I have found for cleaning the Bolt and Bolt Carrier is a Chore Boy brand copper scrubbing pad (for dishes and household cleaning). Make sure it is a pure copper scrubbing pad and not a copper plated one. These things are cheap and really make short work of the BCG (Bolt Carrier Group). You can find them at the dollar store or any supermarket. That tip came from Frank Porch, a park ranger and life long member of the gun culture.
Never put any wet lube on your firing pin. You may get away with it in fair weather, but cold or dirt will cause failure to fires by light primer strikes. If you have to put something on your firing pin, use BreakFree-CLP, Smooth-Coat, or Mil-tec 1 and make sure it is wiped DRY and the firing pin chamber is DRY before reassembly.
Brownells and www.gunpartscorp.com have all the supplies needed to maintain an AR. I was recently given one that was burned in a fire. The stock, hand guard, and grip were completely disintegrated. However, the springs still had some "spring" left in them so I'm betting that the aluminum and the barrel did not loose their temper since the springs should go at a lower temperature than anything else. I have decided to rebuild the rifle, so we'll see if that theory is correct. Anyway, all parts needed were found on the two sites above.Note on Firing Pin protrusion
Another great tip found HERE is a way to keep your AR's gas system from blowing in your face. The idea is to put some Permatex (silicone gasket maker) in between the charging handle and the upper receiver. They already make charging handles that do this i.e. the Gas Buster charging handle, but this way is cheap!M-16 Manual
You calculate twist by simply knowing that a 1-7 imperial barrel will induce one rotation of the bullet every 7 inches of travel. Likewise, a 1-12 twist barrel will induce one rotation every 12 inches of travel. Different twist rates are required for different activities, and the higher the twist, the harder it is on your barrel, so high twist barrels need to be made of good steel (4150,4150cmv, and to the mil spec.). Companies like Spike's Tactical build their LE barrels right, and Noveske chrome lines their barrels to twice the military specification.
So how fast is that bullet spinning anyway? Well RPM = (12/T) * V * 60 where V is velocity in feet per second and T is the twist rate expressed in length required for one rotation (1:10 would be 10). So let's find out what this means. Lets take this ammo and shoot it through a 1-7 twist barrel and see what kind of RPMs where looking at right out of the muzzle. (12/7)3000*60 = 308,571 RPM!
We can put some algebra on this to shorten the formula to RPM=720V/T for RPM with imperial numbers. It should also be noted that the RPM of a projectile decays much more slowly than it's velocity. The geometry, moment of inertia, and surface qualities of the projectile also determines this decay. One site grabs an estimate from the Ballistics Research Lab at Aberdeen, that a 147gr 7.62 NATO round only looses around 10 percent of it's spin at 400 yards and it takes 1000 yards to slow the spin to 75% of the initial rpm. In short for the AR a 1-7 will stabilize anything you can put through it. In fact, the original 1:14 twist M-16 barrels would not stabilize the NATO 55gr projectiles below 40 degrees, and the 1-7 is only needed to stabilize the extra long tracers. It could in fact, over stabilize very light rounds at very long distances, but you would want to be shooting heavy rounds at long distances anyway.
This is for informational purposes only, it's illegal for an unlicensed (Class III I believe) to own a machine gun.Lightning Link Plans
There are many different bolt carriers for AR's that possess different geometries, they can all be purchased online for less than 100 bucks, but you can reduce your perceived recoil if you match your bolt carrier to your buffer and spring. There are Carriers for auto and semi auto (AR) both can be used in an a semi auto AR but they are different components. Bravo Company (link below) sells both. You want one that covers the firing pin as well (see above link for buyer's guide). Also to be noted, you must check your lower on Colt AR's/M4s some of them use different pin sizes, not a big deal, but you need to know so you can purchase upgrades accordingly. Colt further tries to control the buyer by changing other geometries in their lowers. It's a real shame too, they make a great AR.
The gas system of an AR can become pretty complicated, very quickly. The distance of the cartridge to the gas port, the distance of the gas port to the end of the barrel, and diameter of the gas port, the weight of the cyclical components, and the spring rate of the recoil spring all play integral and important parts in the reliability, durability, and shoot-ability of your AR. Plus, the wonderful and confusing world of buffers that still perplexes me. However, as long as you don't stray too far from what the original design intent was for your particular setup you'll be OK. If you add a suppressor for instance, the pressure increases, and for a longer duration. This is because you have essentially created a longer barrel. If your setup was not designed for a suppressor then you'll get a face full of gas and will beat on your AR harder than it was intended to be beat on. Further, this may speed the action to the point of feeding problems. The solution is to design the gas system to work with a suppressor, but what if you run your AR with and without a can? Enter the adjustable gas block. They are not only for cans, perhaps you wish to run lower powered ammo AND high powered NATO stuff. Or you want a setting for an extremely dirty AR.
Another word on front sight bases and other gas-blocks... You want pined not set-screw types if you can. Further, the pins are tapered. Looking down the rifle, they go out left to right and in right to left. If you get a new barrel, you will need to drill AND TAPER the holes through the gas-block or front sight and the barrel. It's not the end of the world just know you have to taper the holes. If you are replacing a front sight with a previously used barrel, you will have alignment issues with the previous holes in the barrel. You can just use a set screw type gas-block or front sight to get around this or you can re-drill the barrel (1/8" (.125") drill) then buy the AR Taper reamer from Midway USA. If you are going to be cutting into previous holes, you can either use over size pins or just put a wield on the old holes. I actually wielded the front sight to the barrel just so I could keep the alignment right while I drilled into the barrel/front site base. After tapering the holes, its probably a good idea to grind off the wield so the taper pins can produce a tight seal for the top of the gas block when you install them. This of course is not the way to do this. The proper way is to let a gunsmith with a mill and lathe wield the barrel, align the gas-block and drill and taper the pin holes.Noveske Switch Block
The AR platform has a couple of really big faults. All machines fail at some point, however it is the job of the engineer to try and get them to fail in a non catastrophic way. For instance I owned a Jeep that cracked a piston and lost all compression in another cylinder (straight 6) and it still managed to be drivable. In a firearm, you want the same type of engineering. The AR can fail to eject (or feed) in such a way that the cartridge becomes lodged between the charging handle and the top of the bolt carrier. This type of malfunction is called a bolt-override. Because the round is between the charging handle and the carrier, when you pull the charging handle the cartridge moves with the bolt (if you can pull the charging handle back at all). You cannot separate the upper from the lower because half of the carrier is in the stock. The way you fix it, is to take a squib rod, magazine, knife butt, etc. and manually pull the bolt back from the ejection port; then put your fingers in the ejection port and pull the cartridge out. This is a tough maneuver when you're not getting shot at, so I would guess it can only get worse from there. There are a few companies that have worked on this problem. The fix is to put a charging handle directly on the bolt carrier. There are many companies out there now that provide this, but most of them take the rear charging handle away. JP hos engineered one that does not do this (link below). This does not mean it's fail safe, a bolt-override can still occur (and crush the gas tube putting you at very least out of auto/semi-auto commission). However, this gives you a way to get the bolt back to try and fish out the round.JP Rifles
When looking for a muzzle device, a Brake stops the rifle/pistol from pushing back, a compensator stops the rifle/pistol from pushing back and flipping up. There are trade offs, the more gas that is directed to stop the movement of the firearm, the more muzzle blast and flash will come from the barrel. A flash suppressor will negate the flash, like the A2 birdcage that comes on most ARs but it will not do as good a job at reducing recoil or flip. The A2 however does to a great job at hiding the flash from the shooter and would be assailants, however it only helps a little for muzzle flip. Most compensators and brakes you could use as signaling devices, and some of them are quite bone jarring to the person next to you.Miculek AR Compensator
There are many different types of hand guard materials and designs. Phenolic, aluminum, thermosets, carbon fiber, and plastics are the usual materials of choice. Personally I do not like aluminum hand guards because they get hot, and the accessory rails that are usually milled into them are heavy and sharp. I suppose though, if you need lights, lasers, vertical grips, etc. you've got to go with them. There is a company that is selling a set of high performance thermoset (plastics you can only melt once) hand guards that don't even get as hot as the bake-lite hand guards that work great! Link below. There are stronger materials such as G10, a material originally designed for extreme temperature circuit boards for the aerospace industry. These do a pretty good job of keeping the heat down while still maintaining a relatively high strength to weight ratio. For super weight reductions and a hot hand you can always go carbon fiber.Alexander Arms G10 Hand Guards
Midway USA is Great for parts, Brownells takes longer and might mess up your order but they WILL TREAT YOU RIGHT! Numrich sucks.Midway USA
An ambidexterous magazine release is a must for lefties and righties as well. I picked up a Troy Industries one (as pictured). However, after only a few matches the pivot (roll) pin started to drift out! BAD PRODUCT! Especially for something my life relies on. I ended up chucking a center punch in a vise and hammering another center punch into the pin (on both sides at the same time) to flair the ends of the roll pin. So far so good it's staying put, but only time will tell.
Magpul has great magazines for a great price, and they just got better. You need to make sure they fit in your lower before you buy a stack of them, but the Gen-3 magazines have an over-travel stop that prevents the magazine from getting slammed too far into an AR with the bolt locked back. It's not a great idea to "slam" an AR mag into an AR anyway because of the risk of a bullet hopping out and creating a double feed (only an issue with the bolt locked back" however, it is one more level of tuned operation for your AR. The lip in the image is more pronounced on the Gen-3 mag than the Gen-2. Pay no attention to the "window" feature, you can get the windows on gen-2 or gen-3 mags.Lancer