Monthly Archives: March 2010

Auto-Ordnance M1 Carbine

Some of you may notice that this post is not filed under “firearms” or “reviews” or even “tests”. It’s filed under “Lies, Errors, and Omissions.”

Why is that, you ask? Well, this firearm is an error. The company that made it is an error. I might even go so far as to say that the ancestors of the people who founded the company were also errors.

But first, the firearm. It looks just like this. Yes, I stole Auto-Ordnance’s photo.

I had a pretty hard time finding .30 carbine ammo locally – I was very lucky that two boxes of S&B .30 Carbine had fallen behind some Winchester 5.56 at my local Sportsman’s Warehouse. I paid 50 cents a round for 100 rounds. Expensive, but not really all that horrible compared to brass cased 5.56mm ammunition.

So, with my new carbine and ammunition in hand, I headed for the range. I have to say, it was nice to be taking something other than an AR to the range for once. Don’t get me wrong, I love ARs, but variety is the spice of life, as they say.

I encountered problems before I even chambered a round. Seating a magazine was very difficult and required a firm smack on the baseplate of a loaded 15 round magazine to accomplish. With that task complete, though, I figured it was smooth sailing from there on out.

I was wrong. The next problem I encountered, after pulling the operating rod handle to the rear and releasing it, was that the bolt didn’t fully lock into battery. It went all the way forward, but it didn’t rotate into place. It could be forced into battery, but I was not comfortable with shooting the weapon in that condition – especially with thoughts of a kB encountered by a friend with his own AO M1 Carbine floating around in my head.

So I went to remove the round, but that’s when I found that the operating handle wouldn’t budge to the rear without a fight. I “mortared” the weapon and the handle came back nicely. The spent round flew out onto the shooting bench. I set it aside for later inspection and attempted to chamber another round. Miraculously, this time, the bolt rotated into position. I fired at a 3″ Shoot-N-C target placed at 25 yards and hit right at 9 o’clock. Unfortunately, the weapon had stopped working again. This time, it seemed to be magazine related – the round hadn’t fed straight towards the feed ramp, rather, it had veered off to the left side. I cleared this malfunction and attempted to fire again. This time I managed to shoot twice before encountering another round that wouldn’t go into battery.

At this point, I sat back and tried to think about what was going wrong. It was then that I realized the condition of the weapon – it was essentially dry. Cursing myself for making such a basic mistake, I found some oil and generously lubricated the appropriate areas. After a few more magazine malfunctions, I was able to shoot 3 or 4 times before the weapon wouldn’t go into battery again. I tried a different magazine – I had 3 – and encountered no more magazine related malfunctions. I did, however, continue to regularly encounter the aforementioned failure to go into battery.

Hoping that it was some sort of break in issue, I fired a total of 45 rounds – yes, a smaller amount than one would expect to call a “break-in period” – but this had no effect.

Several days later, after what California would call a “mandatory cooling-off period”, I grabbed the carbine out of its case and inspected it thoroughly. I noticed that there were several minor cosmetic issues, as well as issues that affected function. I categorized the functional issues as follows:

1. Loose upper handguard was rotating to the left and having a minor binding effect on the operating slide handle.

2. One of the magazines, the magazine original to the weapon, had feed lips that were approximately 1/10″ longer than the other two magazines’ feed lips, and very rough to boot. Incidentally, this was the magazine that did not work.

3. The action itself was simply a collection of rough surfaces that were already showing very rapid finish wear considering the low round count.

I could also not rule out the possibility that ammunition was to blame – that certain rounds were loaded long or that the cases themselves were too long. However, all cases were consistently 1.285″, within the maximum OAL for .30 Carbine cases.

The first item was easily corrected by tightening the screw that holds tension on the barrel band. I didn’t do this too much – just enough that the upper handguard couldn’t rotate too far to the right and rub the operating slide.

The second item was also easily corrected by discarding the junk magazine into my junk magazine bucket.

The third item would prove to be the most difficult to correct.

Initially, I figured that simply working the action would help “break in” the weapon – just like at the CZ factory, where a machine racks the slides of CZ pistols hundreds of times before the weapon leaves the factory. So I sat down in front of the TV and watched Fox News’ Red Eye while quickly working the action of the weapon. I did this hundreds of times before I attempted to chamber a live round (while the muzzle was pointed at my sand bucket). No change, the bolt wouldn’t go into battery. I also found that the weapon would regularly not go into battery even when a round was not present, which led me to believe that ammunition might not be a factor.

So my next step was to field strip the weapon, a task which is accomplished quickly and easily – especially if you get to do it a few times, as I did over the course of that day.

I started with lubrication again, thinking that I’d missed a critical area. No, that didn’t work. After a few more failed ideas, I simply took a very close look at the action under magnification as I slowly let the operating handle forward. I noticed several areas where the head of the bolt was binding against the slide as it rotated into place.

Thinking “This is the last chance you have to contact Kahr customer service about this rifle”, I took one of my polishing stones and carefully smoothed out the area on the inside of the op-rod where the finish had been worn away the most. I figured that if I messed anything up, it would make a nice wall hanging.

As it turns out, though, I don’t think I messed anything up. After reassembly, I noticed that the action was much smoother and never failed to go into battery, even if allowed to go forward slowly. I was also able to hand-cycle dozens of rounds without any problems.

At the range, I was also able to make it through a significant amount of ammunition (having ordered more via the internet since my first outing) without any failures of any kind.

At this point, I was able to appreciate the concept of the M1 carbine. It is light, handy, simple to operate, quite accurate, and has little more recoil than a 5.56mm AR-15. I have about $375 invested in it, not counting ammunition, and I’d say it’s a decent weapon for that price. I see this model on the wall in local gun stores, though, for $700. I wouldn’t pay $700 for one of these. If I wanted to pay $700 for an M1 Carbine, I’d get a USGI version from the CMP (Civilian Marksmanship Program) and have some money left over for ammo.

I have to wonder, though – did they actually test fire the weapon before allowing it to leave the factory? How could so many problems with the weapon have slipped by even the most inexperienced of QC inspectors? Does this company even employ QC inspectors? I could understand if one issue went by unnoticed, but a loose handguard that rubbed against the op-rod (AO’s manual calls it the “operating slide”, and I’m not educated on M1 carbines enough to call it either way), a faulty magazine, and an action so full of rough surfaces and sharp edges that it would hardly go into battery without a round being in the rifle?

That’s why this is in the “errors” section of the blog.

Heat Dissipation Update: Magpul MOE

This is an update to the earlier heat dissipation comparison between the single and double heat shield handguards.

Today, I tested the Magpul MOE handguards using the same protocol: 28 rounds fired in a rapid manner, with temperature measurements at specific locations and time intervals.

The MOE handguards have a single heat shield. By that, I mean a single heat shield. The “single heat shield” handguards have one heat shield in each of two handguard halves, and the double heat shield handguards have two heat shields in each of two handguard halves. The MOE has one heat shield in the lower handguard half, and no heat shield in the upper half. This might sound bad from a “protect the user” standpoint, but it has many more vent holes than the other handguard styles, and these holes are located to draw in cool air on the bottom and expel hot air up top.

As to the effectiveness of the design, I’ll let the results speak for themselves. I was pretty impressed. First, the handguard temperature averages.

And here are the gas block/barrel temperatures.

Based on the results of this limited test, it seems that the MOE offers a very good compromise between reducing heat transmitted to the user’s non-firing hand and allowing heat to escape, resulting in slightly faster barrel cooling.

Krylon How-To

I’ve received a fair number of requests for a tutorial or explanation as to how I painted the rifle you see at the top of this page. I have to say, I’m a little surprised, but thankful. I’m no artist – I used Krylon.

Why Krylon?

Well, it’s easy to do. You can paint a rifle in 15 minutes or less. You can also remove it fairly easily with common chemicals and a brush if you get tired of a brown or green rifle. You can paint over it if you need to. It’s also cheap – $15-20 max, depending on the number of colors you want to use.

Why should you not use Krylon on your rifle?

Well, if you want a durable, protective finish, Krylon is not what you’re looking for. It’s going to wear pretty fast if you use the rifle continuously. It won’t protect the rifle from anything but the weakest of scratches. It may help prevent rust, but if you’re worried about rust, have the steel parts of your rifle properly refinished with manganese phosphate, IonBond, etc etc. If you want to do a pattern with leaves, straw, or netting, you can definitely do that with Krylon, but when it gets worn, it’ll be difficult to “repair” the worn areas. Obviously, you could just redo the entire thing – but I’m throwing this out there so that you can make an educated decision.

So, now that I’ve covered that, here’s the how to. For this, I used my trusty – and very well used – S&W 5.45×39 upper on a Bravo Company lower receiver assembly.

First, and most important, degrease the rifle. I use a can of brake cleaner and some paper towels. Also, get some paint! I use “ultra-flat” camouflage spray paint – dark brown, dark green, light green, light tan.

After that, cover up anything that shouldn’t be painted – optics, flashlight lenses, night sights – and ensure that the ejection port cover is closed. You might want to paint a mag at the same time, this will kill two birds with one stone. I found some electrical tape to cover the optic lenses on this rifle.

Next, find a safe place to paint the weapon. I use the lid of my garbage can inside my garage. Remember to give yourself enough breathing room that you don’t pass out from the fumes and die.

The victim.

Next, start with a single solid coat of a dark color. I use dark brown. I contemplated stopping after this step and just calling the rifle “Chocolate.” If you haven’t painted anything before, don’t go too heavy; spray from 8-12″ away and roll your wrist as you spray in short bursts. This will help avoid runs.

Since this is a solid coat, let it dry for 10-15 minutes before turning it over and doing the other side.

I then use dark green. Not a solid coat – just what I’d call “misting”. Split-second hits from various angles and at least a foot away. I wanted to avoid the impression of any one solid color.

“Misting” dries almost instantly and you can turn the rifle over moments later with little to no consequence, or continue on to another color right away if you want.

After that, I move to light green. Again, misting.

Finally, I use the tan spray paint. You guessed it – misting. This is where you fine-tune the shade you want. Here you can see a comparison of the “new” paint job with the one seen above.

Here they are on the wall. Warning, it’s a big picture!

Double Heat Shield vs. Single Heat Shield Handguards

Heat shields.

This is one of the items on “the chart” that a lot of people gloss over – especially if they want to replace the standard handguards with some sort of railed handguard.

So, I don’t expect this article to get a whole lot of attention. Also, please note that I am not a scientist and this is not meant to be a scientific test.

However, I was frustrated with the progress of another project while at the range, and decided that a few mag dumps would raise my spirits.

Here’s how I conducted this test:

A Smith & Wesson 5.45x39mm upper with CAR type single heat shield handguards was placed on a standard lower. I recorded the temperature of the handguards in four locations, using an infrared thermometer, before any shooting was conducted. These four locations were the forward- and rear-most vent holes on the top and bottom of the handguards.

Then, I fired a magazine (28 rounds) of 5.45×39 surplus ammunition through the rifle as fast as I could. I recorded the temperature of the handguards in those four locations immediately after shooting, 1 minute after shooting, 5 minutes after shooting, and 10 minutes after shooting. I originally intended to measure the temperatures past 15 minutes, but they bottomed out and dropped very slowly after 10 minutes, so I didn’t see that it would be very valuable data. Between measurements, the rifle was laid ejection port cover up, with the bolt locked to the rear, as required by range regulations.

After the rifle was allowed to cool a sufficient amount, I replaced the handguards with M4 type oval handguards that had double heat shields and repeated the above process.

Here is the average of the four locations. Temperature is measured in degrees Fahrenheit:

As you can see, there was a drastic difference between the two handguards initially, although it narrowed after a minute or so, and the single heat shield handguards did shed heat faster than the double heat shield handguards. Interestingly, the double heat shield handguards actually got slightly warmer after a minute or so – the extra shield kept the heat in rather than allowing it to come out all at once, for lack of a better explanation.

One more note – the double heat shield handguards delayed barrel cooling. Here is the temperature of the barrel at the front sight base:

Again, this is probably because the double heat shield handguards didn’t allow the heat to dissipate as quickly as it could.

Based on this limited testing, I would recommend double heat shield handguards for those who want to keep heat away from their non-firing hand, but aren’t as concerned with barrel temperature, and single heat shield handguards for those who are more concerned with allowing the barrel to cool as quickly as possible. On the other hand, for the latter purpose, a free float handguard designed to dissipate heat is probably the best option.

Mike Pannone Tests the Bravo Company Upper Receiver Group

I know of no one who personally puts more rounds down the barrel of AR-15/M4 type weapons each year than Mike Pannone. I’ve had the honor of shooting with him several times, and came away from those brief sessions a better shooter. I greatly respect his opinion and experience on all things AR-15/M4.

He’s recently completed an exhaustive test of a Bravo Company 14.5″ M4 type upper receiver assembly. You can read the details here. In essence, he stripped away all lubrication, replaced critical items in the lower receiver, and proceeded to shoot 2400 rounds through the weapon with only magazine-related failures (he used USGI type mags to simulate as closely as possible the military M4).

POF R.D.I.K.

After my tour of the POF facility yesterday, I was temporarily loaned two POF upper receiver assemblies, one of which is photographed below.
The upper assembly has a 16″ fluted barrel with a carbine length gas system. It is built around the reinforced POF upper receiver and uses the POF modular rail system, which is equivalent to a 9″ free float rail in terms of length.
It’s remarkably light and well balanced – this rifle would have a neutral center of gravity with a lighter stock. For those of you who are not familiar with how I define various centers of gravity, and why this is important, click here. (Parts 2 and 3 are coming very soon, I promise).
It has a two position adjustable gas block – “normal” and “suppressed.”
The large barrel nut functions as a heat sink, shedding heat rapidly.
The gas key has been clearanced to allow for installation of the POF Roller Cam Pin….wait a second…the gas key?
That’s right, this upper has a gas tube, not an op rod!
This upper retains all the features of the POF P-415 uppers, with the important exception that it functions much like a standard AR-15. There are important differences – the gas tube is of a different design, is held in place using a dowel pin instead of a roll pin, and, of course, the gas plug regulates how much gas gets back into the action. Hence the name – Regulated Direct Impingement Kit. I’m told that it may be offered in various forms. As this is a prototype, details may change. I’ll be comparing this upper to a POF op rod upper as well as standard AR-15s in the next few days.

Inside POF-USA

Recently, I contacted Frank DeSomma of Patriot Ordnance Factory with a request for a T&E upper to be used for an upcoming SPR comparison.

Noting that I was in Arizona, Frank invited me to take a tour of POF’s facility before I tested one of their uppers. It should go without saying that this was an offer I couldn’t refuse.

Located in an industrial park devoid of any indication that a world class manufacturing facility lurks within, POF is composed of a machine shop – two machine shops, really – an assembly area, a shipping area, and a small front office. I was impressed when I saw that no employee seemed to be idle for more than a few moments during the entirety of my visit, which lasted nearly 3 hours. Everyone was doing something, and they all seemed to be doing that “something” in a very efficient manner.

Frank spent a good deal of time explaining the function of various components of the POF system. I’ll cover those as best I can, but I may revise details over the next few days if I find that I misquoted him or made a technical error. I’ll also probably expand on certain items in the next few days, but I have a lot of ground to cover here, so the initial post won’t be as detailed as I’d prefer.

Frank came from the aerospace industry, and he had certain objectives when he set out to design his new system. His first objective was heat dissipation. To that end, every POF rifle and upper has a fluted barrel and an aluminum heat sink barrel nut – aluminum because it dissipates heat 5 times faster than steel. Even the shortest POF barrels are fluted, he said, because he doesn’t believe in cutting corners.

On the left is a 5.56mm barrel nut. On the right is a .308 barrel nut.
Fluted barrels on POF short barrel uppers.

Frank gave me a lot of impressive figures about heat dissipation after big round counts. I can’t remember them exactly (I should have been writing this stuff down). He did tell me something very interesting that I can remember, though – although he uses standard bolts in his 5.56 firearms, he’s never had a broken or cracked bolt come back for repair/replacement, nor has he had one break in his own testing.

I also was shown cutaways of upper receivers, both standard M4 and POF. I’m familiar with the phenomenon of receiver flex – when forces are exerted on a long handguard, especially with a vertical grip installed, the forward portion of the standard M4 receiver can deflect by a very small amount. This deflection, however, can cause premature wear and failure of bolts. To this end, companies such as Vltor have designed the MUR and VIS, LaRue Tactical has designed the Stealth as well as the OBR, and POF has designed its own upper receiver, seen below in cutout form next to a standard M4 receiver. Although they’re facing away from one another, note how thin the top of the M4 receiver is compared to the POF upper.

Comparison of POF and M4 upper receivers.
Not only is the receiver thicker, but the barrel is supported, for lack of a better term, by the massive barrel nut.

After this “system overview”, I was shown some new POF products – a 7.62×39 SBR was among them. Here, from the top, are 6.8, 7.62×51, and 7.62×39 POF SBRs.

More shots.

There were additional items discussed at that time, but I’ll cut ahead to the manufacturing portion and cover those later.

Frank is very proud –  as well he should be – that he manufactures most of the components for the P-415 and P-308 in house. We’ll start with receivers.

Each P-308 lower receiver starts as a 7 pound “billet” of 7075-T6 aluminum. By the time the lower receiver is finished, 6 1/4 pounds have been whittled away. P-415 lower receivers start and end at a reduced percentages of those weights.

This CNC milling machine is where lower receivers take shape.

Magazine wells are wire EDM cut to precise tolerances – .0001 – that’s one ten-thousandth of an inch.

Wire EDM machine
These are the unused magwell portions.
P-308 lowers waiting for the EDM process.

Upper receivers come to life in two different buildings, but for the sake of organization, I’ll describe it all at the same time.

5.56/6.8mm uppers start as 7075-T6 forgings. Note that multiple parts are being machined at one time – production was being maximized whenever possible.

Upper forgings are prepared for machining.
Inside this big machine, midgets with chainsaws carve POF upper receivers.
P-415 upper receiver forgings being machined.
POF P-308 upper receivers start as large aluminum rounds.
Bolt carrier “blank” compared with machined bolt carrier.
P-308 bolt carrier being machined
Birth of a POF rail/handguard system.
Disconnectors are wire EDM cut.
Charging handles are manufactured on site.
P-415 and P-308 barrels start as Rock Creek 5R barrel blanks.
Initial machining operations ensure barrel concentricity.
Barrels are then contoured.
Barrel extensions are manufactured in house. It costs POF more to grind the inside and outside of the barrel extensions than it would to simply buy off-the-shelf extensions.
Here, the single 1911-style feed ramp is machined into a barrel extension.
Closeup of feedramp machining.
Barrel extensions are attached and headspace is set. Gas ports are drilled after this step.
The next step involves barrel fluting.
12″ .308 barrel, left; 11.5″ 5.56 barrel, right.
Production costs for each gas block include a beautiful TIG weld. It’s probably unnecessary, but again, Frank doesn’t like to cut corners.
The inside of every gas block is honed at this station to ensure a precise barrel/gas block fit.
Barrels awaiting their gas blocks.
Before nitride, gas blocks and barrels are drilled for taper pins. The two parts are then serialized, separated, finished with a nitrocarburization process, and reassembled with their “siblings”.
Barrel nuts are torqued to at least 40 ft/lbs.
Assembled uppers awaiting handguards.
Handguards awaiting their uppers.
Assembled uppers being prepared for shipping.
P-415 rifles in the final stages of assembly.
Every POF upper and rifle is test fired with a variety of ammunition before it ships.
I’ll be writing follow-ups and more detailed explanations shortly, but I think they deserve their own posts.

Bravo Company MFG Mk12Mod0 Upper Receiver Group

What do you get when you order an upper receiver group from BCM?

You get a box…

Inside the box are a hat and a shirt (you may not get a shirt)…

There are also some stickers and a catalog…

A generous amount of bubble wrap is also included…

Inside the bubble wrap is some sort of long, cylindrical shaped object…

It’s a faithful representation of the military Mk12 Mod0. For those of you not familiar with the Mk12 program, click here.

I’ll be getting many more close up shots of the upper later today and will have a range report by the end of this weekend, although I will be breaking the upper in according to strict procedures, so there may not be an accuracy report just yet.

Smith Vortex vs. AAC Blackout

I’m not going to lie. Before I completed this test, I thought the AAC Blackout was all hype.

I thought AAC had engaged in shady marketing practices in order to show that their flash suppressor was superior to the competition, namely, the Smith Enterprises Vortex. I figured that I’d be spending $50 to pick up a Blackout and that I’d lose $10 reselling it after I did the comparison (maybe more than $10, if I said really bad things about it).

I was wrong.

Now, if you’ve seen my previous video comparing flash suppressors (or someone else’s comparison of popular muzzle devices), you know that the Vortex was the most effective, eliminating nearly all visible flash. So it’s not as if the Blackout could improve on the Vortex by a great amount – it’s not as if the Blackout could create a black hole or anything. But what the Blackout could do – and, in my limited testing, did do – was eliminate what tiny bit of flash the Vortex couldn’t.

Here’s today’s video. I start out with the A2 flash suppressor to establish a baseline for comparison. The weapon used is a Spike’s Tactical M4 LE, a 16″ barrel AR-15 with a carbine length gas system. The ammunition used is Federal XM193F, which is, I feel, a fairly common round.

I haven’t sat down at the bench to determine if either device has an effect on accuracy, but if you’re looking for a muzzle device that eliminates as much flash as possible, I recommend that you strongly consider the AAC Blackout.

Note – I apologize for the poor quality of the night vision video compared to the previous test. I think my video camera may have been damaged during a recent outing, and it’s not taking video as clearly as it used to, especially in low light. My view through the PVS-14 was perfect, but the camera couldn’t keep up.

« Older Entries