Smaller, lighter, faster

It seems that trend in automatic weapons continues to be smaller, lighter, and faster. You could (convincingly) argue that this was started with the introduction of the 5.56 NATO as the standard service round, and continued in handguns with the adoption of the 9mm.

The latest and greatest in the smaller-lighter-faster club seem to be the Personal Defense Weapons, or PDW. Defined as being smaller and lighter than an assault rifle such as an M4, yet having better armor piercing capabilities than a pistol or pistol caliber submachine gun.

I remember being fascinated by PDWs when FN Herstal introduced the 5.7mm cartridge. Getting a Five-seveN pistol is still high on my “want list”, but I’m constantly deterred by the (usually out here) 4 digit price tag. I can’t really justify dropping $1,100 on a gun for the sheer novelty of it…yet. Like I’ve said, if someone (can you hear me Ruger?) decided to knock a semi-automatic carbine chambered for the round, then maybe. Or even a pistol chambered for the round *coughGlockcough* so that I’d be more able to justify purchasing a pistol chambered for 5.7mm.

Now, thanks to that godawful show Futureweapons on the Discover Channel, I’ve come to know of a (relatively) new PDW, which started production in 2001. It’s the H&K MP7, and quite frankly it looks pretty cool. I know that there’s no hope of one coming out for the civilian market, but maybe the pistol that H&K is planning on chambering in the unique 4.6mm round will hit the US market.

When I saw what the diameter and specifications of the MP7’s cartridge were, I started thinking and doing a little comparison. The 4.6 x 30mm round as chambered in the MP7 fires an .18 caliber, 25 grain projectile at 2200-2400 fps. Now, those numbers got me thinking, so I hopped quick as an Ahab can over to CCI’s website.

Much to my surprise, the .17 HMR, with a 20 grain bullet has a muzzle velocity of 2375 fps, which is exactly 4 feet per second less than the quoted muzzle velocity for the 4.6mm out of the MP7. Hornady quotes their 20 grain XTP bullet at the same speed of 2375 fps.

Now, the 4.6mm has the advantage of a steel core under the jacket, which obviously the .17 HMR lacks, additionally the 4.6mm has about 5 grains of weight on the little .17. However, all that leads me to the desire to go buy a bunch of 20 grain .17 HMR FMJ and see exactly what they’d do to different types of Kevlar vests.

Currently, the German Armed Forces have actually issued the MP7 to some of their special forces units, and it has been used in action in Afghanistan. Of course, I don’t have access to combat reports on the effectiveness of the round; but I sure would be interesting in seeing them.

I’m sure that somewhere I had a point about the trend towards smaller and faster rounds for the military; I honestly don’t recall what it was. I don’t think I was going to do something crazy like advocate the .17 HMR for personal defense; despite the fact that doing so would probably generate all sorts of blog traffic.

I think that what I was getting at was while I understand the military’s desire to offer a weapon and chambering that can defeat soft body armor while remaining compact enough for personnel to use in cramped conditions, going down to a sub-caliber like 4.6mm or .17 cal seems a little…silly. Especially when your latest and greates tactical bug-zapper doesn’t seem to run much hotter than a rimfire varmint round.

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