Sunday, July 20, 2014

The 9mm AR15 conversion

As I covered in my last post, the 9mm carbine is a nice alternative to the 5.56x45mm standard rifle round. Cost of ammunition, recoil, and noise, are all lower when you switch to 9 mm. Some ranges only let you shoot pistol calibers and will not even allow a rifle caliber on the premises.Penetration, overshoot, and backstops all have to be taken into consideration as well. Whatever your reason, the 9mm carbine just makes sense in a lot of scenarios.
I've been looking into a pistol caliber AR15 for some time, but due to the excessive cost, I've never gotten too serious about them. Just from a glance online, the prices are insane:
1. Bolt, about 200 bucks
2. Barrel, another 150-200 bucks
3. Magazine block, 50-200 bucks
4. Heavy buffer and heavier buffer spring, 50-75 bucks.
And this doesn't cover mags, or even the dedicated upper receivers.

No matter how you look at it, the cost of converting a standard AR lower to 9mm is almost the same price as an entry-level AR15. While you will eventually save that much money by shooting the inexpensive 9mm ammo, it might take you a long time.

Longtime readers of this blog will probably remember that I am
1. A cheap bastard frugal man.
2. Resourceful
As such, I felt it was time to look into caliber conversions on a budget. My ideal weapon conversion would of course, have to be inexpensive, reliable, and perhaps even adaptable to different pistol calibers, such as .45 acp, 40 S&W, and 9mm luger.
I think I have managed to put something together that will accomplish all of the above.

The magazine is from a Sten, and these mags have been used to feed 9mm, 40, and 45, so it's capable of being swapped from one upper to another.

Starting with a normal Anderson lower, I added a few parts.

A standard stripped upper, no forward assist or ejection port door are attached. They're not needed, and I will probably either machine a "featureless" upper down the road, or I'll get an Anderson upper that has no provision for a forward assist or a port door.

The barrel is a given, I started out with a "gunsmith blank" from Green Mountain Rifle Barrel. I have used dozens, if not hundreds of these barrels in different calibers, and have never had a problem with the quality.
The barrel set me back about 30 dollars, then it needed to be chambered and profiled (turned to shape on the lathe)

The "mag block" is a piece of cold roll scrap I had laying around. It takes up the remainder of the room in the magazine well, and has a release lever for keeping the mag in place.

An ejector was attached later, but here's the basic spacer block attached to the lower.

The bolt was a heavily modified Suomi bolt with a floating firing pin installed. This bolt was almost too light in this configuration, so I came up with a quick, easy, and cheap solution that uses the original buffer and recoil spring. I found some 1" round bar stock and cut a section of it to put in front of the buffer. It acts as a weight to slow bolt movement, and also shortens the stroke of the bolt by that amount. We'll see how it runs.

After slapping the gun together, I liked the way it looked with the plastic forearm and carry handle, but figured a free-floating handguard and a cheap red dot sight would look even better.

I think I was right.

The final tally of expenses revealed that I had spent well under what a normal aftermarket kit would run, and I may have actually assembled a kit that can be configured in multiple calibers.

Range report coming soon.

Thursday, July 17, 2014

Powder coating: It's an electrically charged awesome.

One of my biggest hurdles in gun building, believe it or not, has been coating the finished product. While there are a variety of different products on the market, each one has it's own issues for a garage builder like me. Bluing, parkerizing, duracoat, cerakote, spray paint, and a number of others, each with their own inherent benefits and detractions. Most of my guns have been coated with the Krylon touch, but that leaves a lot to be desired. My shop is almost too dirty to do spray coatings like Duracoat in, plus the fumes would get to be an annoyance.

Recently, I was in Harbor Freight, and saw that they had their powder coating set up on sale, and I had a 20% off coupon, so I walked out a happy man. I figured I could afford to lose that much money if it didn't work out, or I couldn't get the hang of it. I already have a sandblasting cabinet, so that part of the equation was covered. All I needed was an oven that could reach 450 degrees.
A quick stop by my local Chinese wholesale mart (also known as Wal Mart) netted me a toaster oven for about 50 bucks that is large enough to cook most of my powder coated parts in.

Powder coating is a pretty cool process, in that it sprays a positively charged cloud of colored powder at an object that has been grounded. The powder is attracted to the part like a magnet, and the powder is held in place via static electricity (more or less). The part is put in an oven and the powder is melted and fused to the part. It requires a very clean surface, and media blasting the part beforehand to get some "tooth" for the coating to adhere to.

I've been working on a 9mm conversion for the AR15 that is inexpensive and doesn't require any modification to the rifle. Most of the conversion kits out there are very expensive (200 bucks for a bolt, 100-200 for a barrel, 50-200 for a mag adapter, etc) and since I can build a complete AR rifle for less than 400 bucks these days, that just didn't set well with me.
So, I needed a conversion kit, and true to my typical nature, I don't want to spend much money. A starting point would be magazines. The Colt mags are great, but expensive, and are really just Uzi mags with a mag catch milled in, and require an adaptor. After digging around, I found a reasonable solution: Sten mags. They're cheap, hold plenty of ammo, and can even be used with other calibers. The best part? They fit in the magwell quite nicely, and only require a filler piece on the rear of the mag.
I took 3 mags out of the stack of Sten mags that feed my Sten, and dedicated them to this purpose. Since they were rusty, greasy, and altogether cruddy looking, I figured they would be good fodder for this project.

The mag block, fresh out of the mill.

A Sten mag in place with the block. The block is held in place by the AR mag release.

Mocked up right purty.

They are a good fit for the AR pattern rifle. A bit of a bitch to load, but there are plenty of mag loaders on the market that will work with the Sten mag.
Since the rifle was going to get refinished, why not the mags?

Now, these mags were all military surplus that had been dunked in cosmoline and stored for years in a vault in somewhereistan. The oil from the cosmoline had soaked in pretty good, and made life a living hell. I couldn't get all the oils out, no matter how hard I scrubbed. I finally media blasted the mags, then put them in the oven at 450 degrees for 20 minutes.
Turns out, the oil seeped out of all the hidey-holes, and I was finally able to remove it all. I put the mags on a fan to cool, before dunking them in solvent.

After the mags had cooled, were degreased again, and blasted again, I put them in my hi-tech powder coating booth (the box the powder coating rig came in, with a metal hanger stuck through it) and sprayed some Harbor Freight matte black powder on them. That stuff is about 6 bucks for a pound, and it takes about a spoonful to do a mag or three.

Believe it or not, this is the coated mag.

While they're getting powder coated, I turn the oven on to 450 and let it warm up. I then hang the three mags from a rack that came with the oven, and set the timer to 20 minutes.

Within a minute, the powder melts, and gets a very glossy and orange-peel-ish look. After 10 minutes, it's very evenly coated, with a nice gloss. As it cools, it dulls slightly.

Giving the floor plates the same treatment.

The finished, unassembled product. Ignore the water droplets on the floor plates.

Assembled, with a light coat of gun oil spread on with a towel.

Finished, and installed in the blurry gun.

The finish is very tough. It does not scratch easily, and solvents won't touch it. The best part? Over 6000 different colors available, and it's cheap.
I don't know how it would hold up on a barrel or a similar object that gets hot, but so far the mags and receivers I have coated have held up well, and still look good despite a few trips to the range and a lot of shooting.

This weekend, we will find out how well my 9mm conversion works; more on that later.