The folks at CMMG have come out with an AR-15 gas piston conversion kit.  It comes with a new gas block, piston and bolt carrier (so it works more like the AK).  As far as I know, before this conversion kit you had to buy a whole new upper for your AR if you wanted a piston-driven system.  It’s an attractive idea in some ways, especially for those who’ve had problems with carbon fouling in the bolt carrier.  The piston system keeps more of the carbon out of the receiver and it’s great for use with a sound suppressor, in which case it keeps more of the trapped gasses from blowing back into your face.  The conversion kit’s price is roughly equal to that of a new AK rifle and several spare magazines.

However, they call their piston kit a “direct impingement gas piston system.”  Anyone else see a problem here?  It may be nitpicking (and please correct me if I’m wrong) but “direct impingement” is exactly that one thing that a piston system is not.  When Stoner came up with his piston-less operation back in the day, he called it “direct impingement” to describe his system of channeling the gas back into the receiver where it “directly impinges” on the bolt carrier without an intervening piston rod or tappet.

At Blackwater last weekend we used ammo supplied by International Cartridge Corporation.

The ammo worked great. I have zero complaints about the performance of the ammo. Accuracy was excellent. We fired the ammo about five or ten feet from steel plates (that is what Tam was doing here) with only a hint of dust coming back when the wind was right. It is made of sintered copper and tin so it is non-toxic. Because there is no jacket the bullets can be made very accurate. The major factor in bullet accuracy is the jacket being of different thicknesses on one side than another. This puts the geometric center of the bullet at a different point from the center of gravity. As the bullet traverses the barrel the bullet rotates about its geometric center. As it exits it rotates about it’s center of gravity. If the two centers are not the same it will “jump” a little to one side as it makes the transition. This will cause the bullet to go in a slightly different direction than that which the barrel was pointed. Hence the homogeneous, sintered, bullet can be made more accurate.

The bullets are also made with a lubricant for release from the mold during the manufacturing process. This lubricant is part of the structure of the bullet and is still present when the bullet is fired. Along with the tighter diameter tolerances (about 0.0005″) the guns shooting these bullets run much cooler. Todd Jarrett told us of full auto guns having barrels cool enough to hold the gun by after emptying a complete magazine loaded with this type of ammo.

The ammo rep on-site with us said the price was about the same as hollow point ammo. He also said the bullets were not available for reloading. Something about them being too fragile and cracking in reloading presses. This seems a little odd. They didn’t crack when we dropped them on the gravel in the shooting bays. They didn’t crack when we dropped them on the concrete. The didn’t crack when they were fired.

I also found where they are sold for reloading. From their dealer page click on http://www.frangiblebullets.com/. There you can find prices, loading data, and lots of other interesting information.

One thing you will notice about the bullets is they are much lighter than the same caliber lead bullets. This is because the materials used, copper and tin, have a lower density than lead. They can, and are, loaded to higher velocities and can reach IPSC major power factor in .45 ACP, 10mm, and probably .38 Super. Minor PF can apparently be reached with 9mm. .40 S&W appears to be unable to reach major PF.

If my blood levels of lead were on the high end of normal I would probably buy the bullets and reload them in my pistols for practice and competition. As it is my lead levels are on the low end of normal and lead bullets are cheaper (in .40 S&W about $0.18 versus $0.11). And in any case I don’t think I would use the bullets for self-defense. I’m inclined to believe that heavy, deep penetrating bullets are better fight stoppers than light bullets that leave a lot of fragments behind upon entry.

Another reason I would be disinclined to use the light bullets is the recoil. For the same bullet momentum (Power Factor in USPSA terminology) you get more recoil. This is because more powder is used with the light bullets and the high velocity powder exiting the barrel adds to the total recoil. The recoil is also spread over a longer period of time with the slower moving bullet. Hence a light fast bullet causes a very “snappy” recoil which tends to be uncomfortable. I noticed this with the .45 gun I was shooting over the weekend. The recoil was much different than what I expected from a .45. I asked what the bullet velocity was on the 155 grain bullets we were shooting. About 1150 fps I was told. Normal .45 ACP velocities are in the range of about 750 to 925 fps and you feel more of a “push” than the “slap” I was feeling.

Still the lead free frangible bullets have their place. I could see indoor ranges requiring lead free bullets or steel plate competitions requiring frangible bullets. I remember taking a pistol class once and the instructor telling us that for every class they usually have, on the average, one injury from the back splatter from the steel targets. They had about 10 students per class and were firing about 1000 rounds each on steel so there were a lot of bullets going down range and eventually the odds would catch up with someone. The injuries were always minor and required nothing more serious than a Band-Aid but still the injuries did occur. Wrap around eye protection and either directly facing the targets or facing away was required. Those concerns would be eliminated with ICC’s frangible ammo.

The History Channel recently started running a program entitled, “The Works”.  The host, Daniel Wilson, has a PHD in “Robotics”.  I didn’t know you could get a PHD in robotics, thus becoming what, a “roboticist” or a “robotologist”?  I’d have thought you’d need three degrees for that– mechanical engineering, electrical engineering, and computer science, but I’m just a layman.  For all I know, there are degree programs for “Vending Machine Technology” too, you know, for those who don’t quite feel up to the work load associated with a major in “Roboticism”.

He did an episode on guns, which was pretty good.  It did however show an image of Superman flying “faster than a speeding bullet”, and as per the cliché, Superman was shown flying right next to a fully assembled, metallic pistol cartridge.  I’m not sure how one is meant to propel an entire cartridge through the air at the velocity of a speeding pistol bullet (which the host correctly described as about a thousand feet per second) but I’m sure that where there’s a will, there’s a way, especially if you have a PHD in robotics.

Anyway, the program was interesting.  Though the host talked down to us a little more than required, IMO, I can forgive him– he’s young.  He obviously had a lot of fun with the various guns too, and wasn’t afraid to show it.

Check out “The Works” on THC if you have the time.  I think you’ll like it.  Oh and;

Congratulations, Dr. Wilson.  Keep up the good works.