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Lehigh Extreme Penetrator

By Andrew Betts

LEHIGH EXTREME PENETRATOR
LEHIGH EXTREME PENETRATOR

No, it is not the title of a sci-fi themed adult movie, it’s the line of CNC machined solid copper bullets from Lehigh Defense. Their Extreme Penetrator line is reminiscent of a Philips head screwdriver and the projectile is available in a variety of calibers, both as loaded ammunition and as components. The company claims that it not only penetrates relatively deeply as the name indicates, but that the “progressive nose geometry” can create “a permanent wound cavity diameter exceeding that of most expanding bullets.” They go on to claim that this “magic” is due to some ambiguous fluid dynamics which they liken to “sticking your thumb over a garden hose.” They even go so far as to claim a permanent wound cavity that is 2-4 times greater than traditional solid projectiles and some unspecified amount greater than expanding ammo. These are some extraordinary claims. Does the product live up to the hype?

To rationally examine the claims that Lehigh is making, we should first consider whether the claims are consistent with what we know about the mechanics of projectile wounding. The best resource on that topic is a paper published by the FBI called “Handgun Wounding Factors and Effectiveness” which summarizes what the agency has learned through testing, examination of cadavers, and statistical analysis of shooting incidents. One of the fundamental points made in the paper is that, at the speed that handgun bullets travel, the temporary stretch cavity is not a significant wounding factor. This is in contrast to much higher velocity rifle bullets, which can produce damage through tearing caused by the sudden and violent stretching of tissue. In other words, rifle bullets impact at such a high speed that the temporary stretch cavity stretches past the elastic limit of the tissue, increasing the size of the permanent cavity beyond tissue that was in direct contact with the projectile. Pistol bullets are moving too slowly to cause this effect so tissue simply stretches and snaps back to normal with no substantive damage aside from some bruising.  The paper concludes that only tissue that comes in direct contact with the projectile can be damaged by a pistol bullet. That means that the claims that Lehigh is making are in direct contradiction to what is known about wounds caused by projectiles. To be fair, though, perhaps Lehigh discovered some new mechanism that was previously unknown. To rule out that possibility, we have to consider the results of independent testing.

There are two primary takeaways from this test. The first is that the bullet really is capable of some ridiculously deep penetration, especially for a projectile with such low sectional density. The deep penetration is most likely a result of the moderately high velocity combined with small frontal area and a hard material that simply does not deform. The second takeaway is that there is quite obviously no more tissue damage than is produced by a simple FMJ. The ball round actually produced more damage when it yawed and traveled sideways through the gelatin for a short distance starting around the 6” mark.

9mm ball does not exactly have a reputation for impressive tissue damage, yet it did destroy more “tissue” than the Extreme Penetrator in this test. There simply appears to be no support for Lehigh’s extraordinary claim. It should come as no surprise that the ammo fails to perform as advertised, though. Lehigh is essentially claiming that you can have your cake and eat it. Projectile wounding, like every physical action, is a dance of compromises. If all other factors (weight, velocity, projectile diameter, etc.) remain the same, varying the projectile’s design can only increase penetration if that design change also results in decreased tissue damage. Conversely, a wide swath of crushed tissue can only be produced at the expense of reduced penetration. In other words, the volume of tissue that can be damaged is relatively fixed. As the penetration goes up, the width of the wound track must necessarily decrease and vice versa. You can’t cheat Newton. As cool as Lehigh’s bullet looks, it does not defy the laws of physics.

(top) 9mm FMJ track, (bottom) Lehigh XP track
(top) 9mm FMJ track, (bottom) Lehigh XP track

A rare failure, the broken AR15 forward assist.

Broken AR15 Forward Assist

Pictured above is the broken forward assist from my Colt 6933.

I’ve see a few forward assists break. Every time it has come as a surprise to the shooter. Usually what happens is a shot is fired, and the action ends up locked closed, and no one is able to open it using normal clearing techniques. In my case the action locked open after ejecting a shell.

It can be hard to diagnose a jam caused by a broken extractor simply because you can’t see that is what is preventing the bolt carrier from moving.

The best procedure we have found to free up a stuck bolt carrier from a broken forward assist is to:
1. Remove magazine, keep muzzle pointed in a safe direction.
2. Hold rifle with the ejection port down, barrel parallel to the ground.
3. Shake rifle while attempting to move bolt carrier.

Then usually it wont take much to get the action moving again. Immediately clear the chamber and remove the bolt carrier group from the action and remove any loose parts(like the forward assist pawl shown above).

Over the years, I have come to believe that the forward assist should be reserved for emergencies. In practice or on the range if a round does not chamber discard the round or inspect the firearm. I have met many(most former Army) that hit the forward assist after every reload. If your rifle isn’t chambering the round under its own power, there is something wrong with either the rifle or the ammo. Forward assists very rarely fail, but there is no point in slapping it around unless it is an emergency.

Quick review of the Larue MBT trigger.

Recently LaRue Tactical ran a sale on his 2 stage match trigger called the “Meticulously Built Trigger”. I bought one for during this sale for $125.

2015-06-20 22.54.39

The MBT trigger came nicely packaged, it looks good and appears to be well made. The disconnector is riveted in place making the trigger a little easier to install than a Geissele SSA trigger.

AR15 Larue MBT Trigger

I noticed the pins that came with the my MBT trigger were slightly longer then the average trigger/hammer pin. This caused them to stick out from the lower just slightly. In the picture below you can see the trigger pin sticking out from the receiver. The hammer pin is reversed and is sticking out similarly on the other side.

2015-06-21 12.39.11

When I compared this trigger to the Geissele SSA, I found I preferred the SSA by a very small margin. I find the second stage to be just a touch stiffer than the SSA. When the MBT was new, it was noticeably stiffer and longer pull than the SSA, but after being greased and a few rounds fired it feels mostly similar to the SSA. The MBT used to be priced at $250, the SSA $220, at those prices I would always recommend the SSA over the MBT. At the sale price of $125, I don’t think the MBT can be beat. Now I see the MBT is priced at $200, which makes it better competition for the Geissele SSA.

The MBT appears to be a good trigger, but honestly I currently prefer the SSA a bit over it. The MBT is a very nice trigger and if you want one, get it. I am looking forward to seeing how it feels after it has more rounds on it and is better broken in.

A buyers market, AKA LaRue triggers cheap.

It is absolutely amazing how the firearm market has become super saturated and how much prices have dropped. Great deals are available all over the price.

For example, Larue is running a sale on his match trigger for $125 shipped. The deal can be found here.

I went ahead and bought one. This is a really nice deal if you are looking for a nice trigger.

Update: Looks like the deals over already.

Samson flip to side Aimpoint 3X magnifier mount

Samsun FTS Aimpoint

I pickup an Aimpoint 3X mangifer in a Samson Flip To Side mount to play around with.

Samsum FTS Aimpoint

The Samson FTS mount has a cross bolt so you screw it onto your rail. A lever is on the left side to flip the magnifier over.

I had to swap out the Matech rear sight I was using with a KAC 300m rear sight. The Samson mount did not have enough height to clear the Matech sight.

Samson FTS Aimpoint

The spring in the mount quickly pushes the magnifier out of the way. It also hold the magnifier off on the side pretty well. If you violently shake the rifle, the magnifier will move, but it stays out of the way pretty well.

Samson FTS Aimpoint

After playing with this mount a bit, I don’t like it. It appears to be well made, but it isn’t right for me. Flip to side mounts like the LaRue can be used by either hand while this one has its lever on the left side. I also don’t like how it screws to the gun, I would prefer to be able to take the magnifier off quickly. For me, this mount isn’t right, but I would recommend it to someone who wants a dedicated FTS mount.

Now may be a good time to buy

Colt Larue Aimpoint Surefire

With the new Aimpoint T-2s coming out and the super saturated AR market there are some awesome deals to be had on used Aimpoints. I purchased this T-1 used with the LaRue mount and IO cover for $425 off the AR15.com Equipment Exchange. I have seen several other good deals there on used T-1 Aimpoints. If money is tight and your looking for a top of the line optic, consider looking at used Aimpoints on the gun forums. Currently it is a buyers market.