Doctor! My brain hurts!

The Ammo-Oracle

A reader sends this:

I think the Army will have a problem with terminal ballistics (wounding/killing potential) with the XM8.

The 12.5 and 9 inch barrel lengths are generally too short to provide the velocity needed for bullet fragmentation in the target at reasonable combat ranges. Your site viewers might be interested in the excellent discussion of the 5.56mm round (history, ballistic performance, gelatin testing, etc.), which is pinned as the reference FAQ in the Ammunition forum at

I’ve just barely scratched the surface of that site. Tons and tons and tons of good stuff. You’d need an Energia super booster to put it in orbit, and even then you’d better hope they did the English-metric conversions right.

Go check it out. And a big time thanks to the reader who sent it in.

UPDATE: And I agree 100% (speaking as an armchair analyst) with the barrel length issues. The baseline carbine variant of the XM8, which would be the “standard” variant, has a barrel that’s two inches SHORTER than the current M4. Nicer to carry in a vehicle, I’m sure. But it’s supposed to be all the better to shoot you with, my dear.


  1. So if I memorize all that I can sound like a real gun-nerd…without even owning a rifle too. My chair needs arms! /me runs off to play counterstrike. /sarcasm ;)

  2. What? No arms on your chair? You are sitting in an unarmed chair? What kind of computer/internet geek are you? You should be ashamed of yourself, posing as a poser…

  3. I can’t even get Counterstrike (the new Source version) to work! Might the claws on my cat count as weapons?

  4. so sam i assume that you are some sort of an idiot if you are to truly understand your weapon and be a better marksman you should know the ballistics of your weapon like take me … I am a soldier in the ARMY and im in iraq right now 10min west of baghdad and ill tell you every soldier is requierd to understand the ballistics of his or her weapon.How to operate it and such these things are drilled into us in basic and then from there it really depends on how good you want to be at shooting your weapon and then you should know what type of ammo you are useing because you could cause a serious weapons malfunction otherwise. if u dont own a weapon or arent interested in one or how they work than u should stay off of this site and sites related to similar topics.

  5. soldier: Sam used ‘/sarcasm’ and ‘;)’ to show that he was being, well, sarcastic. I am not a soldier. I am not a weapons expert of any kind. I don’t understand a lot of what’s on that ballistics page. However, I don’t think that makes me an idiot. Sam comments here frequently, and I don’t think he’s an idiot, either. I don’t know about Sam, but I do know that *I* don’t know enough about ballistics to be a good soldier. I imagine that many of my readers are in a similar boat. That’s why I linked to that page. I also know that feedback from actual operators is part of what makes this site so much fun and informative. I thank you for your service to me and mine, and I pray that you have a safe and happy Thanksgiving.

  6. I didn’t mean to insult. It is a very excellent page about the 5.56 and .223. Ftr, I did go through basic in the army 12 years ago. (due to odd eyesight, had to shoot left handed though I am right handed…barely squeaked through :( ) I must try to keep my natural sillyness in check.

  7. I understand the standard issue rifle needing that sort of muzzle velocity. But its really mission dependant. If you’re going around in armored trucks escorting people all day the smaller the weapon the better. (its what the vast majority of soldiers are doing now) The likelihood of you popping out and engaging them is slim. It’ll be your top gunner lighting them up with whatever crew served weapon he has up there. Yeah yeah I understand sometimes your vehicle is disabled and you have to get out and engage while seeking cover. The XM8 sounds like it will be well suited for CQB and urban combat enviroments. The fighting we do here is really close and you need a smaller rifle (some of us are lucky enough to use MP5s) to manuver around with. HK isn’t so bad either because it shoots 5.56 rounds instead of 9mm, but they won’t be issuing those any time soon. Yeah I’m a soldier out here to, and I can say from my 1 1/2 years experience out here dealing with the enemy and situations that I’d rather have a more compact weapon. Thats one reason I enjoy having my M4 or MP5 and my 9mil as my sidearm. If I were to run around with my old M16/203 it would make what I was doing here much more difficult. Not all of us are soldiers that will be persuing the enemy, and actively engaging targets 300-600 meters away. The vast majority of us are now dealing with targets that are 50 meters to 250 meters away, and we’re in really cramped quarters. Like I said though its really all mission dependant, and weapons should be issued accordingly. If what I said didn’t make any sense to you let me know and I’ll try and clarify this a bit more.

  8. Boredsoldier, how would you feel about a bullpup weapon? (roughly same sizeof m4, but magazine behind the grip, 20ish inch barrel for more power; with some minor but botentially serious issues of brass ejection and switching magazines)

  9. Sam, I don’t know if you’ll get an answer from Boredsoldier anytime soon, unless he’s on a base with a huge computer bank, or a free DSN line. Can I talk about the whole bullpup thing with you from a soldiers perspective? I thought you’d say yes, so I’ll go ahead, and you can tell me if you think I’m wrong. There’s three main issues with bullpup configuration rifles. 1-ejection- we all know that this is an issue, solvable only with left and right ‘handed’ rifles (supply nightmare) or with a downward or forward ejection (complicated) 2-muzzle jump- due to the position of the action, in relation to the shooter, these weapons have a pretty serious ‘jump’. This could be engineered out, but once again, you get a complicated system. (remember that these weapons are made by the contractor that bids lowest, and that they have to be maintained by a soldier who may have never touched a weapon before basic training) 3-recoil- The M-16/M-4 series of rifles have a great recoil-reduction/operating system built in. Any bullpup configuration will not have the buffer/buffer spring behind the bolt in order to remove a lot of that felt recoil. You’d need a system that was a conter piston (The russians have this on some of their later AK experiments) or some kind of a counter-weight or some such. Meaning that, once again, you have a complicated weapon. Short-Good Relatively Long Barrel-Good Maintenance-Bad Recoil-Bad I think we need a whole new weapon (Say a P-90 type. (see FN) with a larger Diameter Bullet. Say .45 ACP. We could issue this to 2 or 3 per Squad, and that way you’d have fast moving, close-in firepower, while the rest of your squad dismounts. The army is addressing the issue with a new procedure for fighting from vehicles, something that hadn’t changed since Vietnam. The new procedure is based on lessons learned in Mogadishu, Afghanistan, and Iraq. Oh, and maybe we could just start arming some of our soldiers with H&K UMP’s in .45, and shotguns. Say 1 or 2 per squad. That’d be great close firepower, and the shotgun gives some serious versatility with the variety of rounds out there now. (flechette, accurate slugs, rubber rounds((EPW’s), and Dragon’s Breath, Bolos, etc.)