Building The Mujahadeen AR-15

How to finish an 80% AR lower receiver using hand tools. Says the author;
"I'm not a machinist, tool maker or mechanic. I was a tank mechanic in the Army, but most Army mechanics are only parts changers. I was a good parts changer. I am now a human resources manager for a computer hardware manufacturer. I am also a patriot and a pretty good jury rigger. (Someday I'll with a book called "Doing the Job Right With the Wrong Tool!") Before I started this project, I set limits on the tools, power, equipment, supplies and outside help. I have less than the average amount of tools; a 3/8" drill, a set of bits up to 1/2", a set of files, sandpaper, a hacksaw, a Handy Clamp clamp (my vise), a package of JB Weld (good stuff), a DPMS lower, a Model 1 parts kit, a pack of Red Man and a box of Band-Aids."

Read more

AR-15 Pistol Rifling Twist

I recently built this AR-15 pistol from a virgin lower receiver that had never been assembled into a rifle. In reading the gun forums concerning AR pistols, one of the recurring themes is that only a fast 1:7" rifling twist should be used in the shortest common AR pistol barrel length of 7.5 inches, because that barely allows over one full rifling turn.
By that thinking, it should be impossible for the typical .38 Special revolver to shoot accurately. One turn in 18 inches is a common twist rate for .38 Special and .357 Magnum, and even a 6 inch barrel only provides one third of a turn to the projectile.
I bought my AR-15 pistol barrel with a 1:9 inch twist. So far, it seems to shoot just fine.
 

Inexpensive AR-15 Pistol

I built this AR pistol for less than $500. This was a virgin stripped lower receiver I bought awhile back and had never gotten around to building. So when I got the itch to build an AR-15 pistol, this was the perfect lower to build it on since this lower has never been built into a rifle. Check your local and state laws before you do this, but according to federal law and the laws of my state, this is legal. I had a full-length buffer, spring and tube that wasn't being used. The stock attachment threads were stripped, so I bored out the threads and used it. Cheaper and more reliable than the short pistol tubes.

WECSOGing a 9mm Olympic Arms AR barrel

I've been thinking about building a 9mm AR-15 carbine for awhile now. 9mm has a reasonable power level when fired from a carbine-length barrel, and it also makes for some cheap shooting. Powder usage is minimal, brass can be had for free if you know where to look, and the cartridge does well with cast bullets.
Several months ago I began studying the different approaches to building a 9mm AR. Leaving aside the possibility of building the bolt from scratch, there are two basic options: Colt and Olympic. Both operate on the simple blowback principle. Included under the Colt heading are bolts and barrels by Rock River Arms, and barrels by a few other manufacturers. The Colt-design bolt is one-piece and shares nothing, as far as I can tell, with a standard AR bolt carrier. The design is such that the chamber end of the barrel is flat. Therefore, any barrel blank can be made to work. The ejector is a steel "finger" that extends upward from the magazine adapter block. This Colt system uses modified Uzi magazines.
The Olympic bolt, on the other hand, is a piece that fits into a modified regular AR-15 bolt carrier, and secured by the standard bolt pin. The firing pin is also a standard AR part, with a rebound spring added to prevent slam-fires. The ejector is a coil spring bridging the lower section of the upper receiver, with a crosspin holding it in place. One end of the spring extends out to catch the head of the extracted case and flip it out of the ejection port. The Olympic system uses Sten magazines.
At first glance, the Colt system appears simpler and thus better. The ejector, especially, looks better; the Olympic ejector looks pretty hokey. However, anecdotal evidence indicates that the Olympic system works more reliably, requires less tuning to get working, and may even be more durable, or at least cost less to maintain in the long run. I have not only heard of many Colt 9mm owners who had problems with proper functioning; I have also personally witnessed a full-auto Colt 9mm which not only could not make it through a match, it actually drew blood from its owner in the process. Even the MAC-10s that were there worked better than that particular Colt, on that day.
On the other hand, a "friend of a friend" has a full-auto Olympic 9mm AR that he claims to have put tens of thousands of rounds through, with only the occasional malfunction. That's what I'm looking for.
Of course, I don't have any full-auto stuff, nor do I plan to have any. These days you have to be rich to own those things, plus I'm not into the whole government registration thing. But I would like to have a reliable semi-auto 9mm carbine. So when awhile back while researching the options, I ran across a used Olympic 9mm bolt and carrier on AR15.com for a reasonable price, I took the plunge and bought it.
My original intention was to buy an off-the-shelf barrel, screw it in, drill my standard non-forward-assist upper for the ejector pin, and have a functional 9mm carbine. That hasn't happened though, for several reasons including the over-$200 price tag on a barrel and my interest in WECSOG (Wile E. Coyote School Of Gunsmithing). So recently, I bought a cheap .357 Magnum chambered barrel blank. The barrel shank was quite a bit too small for my AR receiver, so I cut a one inch piece of rusty iron pipe that had been rolling around in the back of my truck, to use as a bushing/trunnion. The pipe was a bit too large both inside and outside, so I split it lengthwise along one side with a hacksaw, squeezed the slot back together in my vise, and then used a cutoff wheel in a Dremel to enlarge the slot. I ground the inside with a stone in the Dremel, ground the outside on the bench grinder, then did the open/squeeze thing again. You will notice that I am not using a lathe. That is partially because I want to retain the whole WECSOG thing, and partially because my Chinese lathe is in storage right now.
That is about as far as I have gotten, so I will have to take up from here in a later installment...