Headshots.

[markonymous]

i thought the gas parts was to take some recoil force out and also the recoil moves the working parts back such as the bolt carry assembly and this is one reason why your shoulder does not shatter when firing weapons. mayby this is a load of ballony but im not too sure but just dont flame me for coming out with a load of bull

the reason your shoulder does not shatter is that the weight and area of the weapon is much larger then the bullet.. Therefor as much energy but much less pressure. And yes some of it does escape with gases and the mechanics but most of it doesnt since you still do feel quite a punch when firing.

[Sabre_tooth_tigger]

http://en.wikipedia.org/wiki/Muzzle_brake

http://en.wikipedia.org/wiki/Suppressor

[Dempsey]

Seen as though we are on subject, i will expand, and onto movies.

Quite a lot of gun scenes in films show people being shot and then traveling some distance, be it a cm or 10 metres, it just dosent happen, the bullet has no mass at all, which is what your all babbling on about i guess.

[Bringerof_D]

im no expert but im pretty sure the modern helmet can stop 7.62 rounds given right conditions. And you wouldnt be injuring your neck severely. If this were true anyone firing a gun would have broken their shoulder then the recoil hits because the power of the recoil is exactly the same as the power of the shot. For every action there is an equal and opposite reaction.

oh and yes behold the mighty m16
YouTube - M16 Blows up in Kids Face

ABSOLUTELY NOT! a kevlar helmet will stand no chance againts a 7.62mm round. since the begining of firearms helmets stood no chance. they have been since the early days been used to stop shrapnell from artillery and grenades. the only way a helmet can stop a bullet is if that bullet was a riccochette in which case it would be considered shrapnell. and yes modern kev helmets can stop 9mm rounds but only at mid to long ranges.

[Dempsey]

http://www.youtube.com/watch?v=WrjwaqZfjIY[/youtube]

ha ha very good, but im not wrong.

When i said a bullet has no mass, IT WAS A EXAGGERATION you keyboard warriors.

[Deadfast]

ha ha very good, but im not wrong.

When i said a bullet has no mass, IT WAS A EXAGGERATION you keyboard warriors.

When it comes to physics, you don't want to argue with Jonny, trust me

[markonymous]

ha ha very good, but im not wrong.

When i said a bullet has no mass, IT WAS A EXAGGERATION you keyboard warriors.

it was not an exaggeration it was stupid. No mass no force no force no kill no kill no happy soldier

The 4g bullet has enough mass to make it actually move your entire head and a 1.5 kg helmet backwards at around 0.6 m/s. So quite considerable mass at the speed it is going, I would say.

just wanted to add that this speed will not break your neck nor will it knock you out or cause serious injury.

[KP]

Most of the energy DOES go out with the round if it is not embedded.

Every action has an equal and opposite reaction is regerding forces, not energies.

Ah, well, my mistake. I was thinking about recoil being dependent on the mass and speed of the round.

[nedlands1]

Exaggeration means you screwed up bad.

The only allowable thing anything like it is safety margins, labelling a bridge as being able to take 10 tons when it can take a 50 ton load before failing. Your particular one would lead to deaths if actually used as an approximation.

The 4g bullet has enough mass to make it actually move your entire head and a 1.5 kg helmet backwards at around 0.6 m/s. So quite considerable mass at the speed it is going, I would say.

And you are wrong.

Even about people not being moved, the average human has a mass of ~80kg, I heard somewhere.

So would move at about 5 cm/s initially if the bullet from my previous post was picked out of the helmet, fitted back into a case, primed, loaded, shot at and embedded in the person.

80 kg? Are you thick headed?
Only joking.

Bear in mind that looks like an maximum speed of an inelastic collision that Jonny is talking about (*desperately tries to remember fancy terminology used in my mechanics unit from last year* ) . The bullet would penetrate the helmet and deform itself along with the helmet and possibly what is behind, in turn, dissipating a proportion (but not all) of it's forward kinetic energy as other forms. If the bullet keeps on going through and out the other end, the speed will be a whole lot less again.

[nedlands1]

Ah, well, my mistake. I was thinking about recoil being dependent on the mass and speed of the round.

It pretty much is, I would wager, except I would swap "speed" with "acceleration". If you were to keep everything constant then each of those things would be proportional to "recoil". For instance, if you increased the weight of the round being fired yet increased the powder charge accordingly, to maintain the acceleration, then the recoil would increase, compared to the default value.

[markonymous]

hmm im just thinking why not use steel alloy 1090 to make helmets its got a a tensile strength of .84 GPa and a yield strength of .64 GPa.

[turnpipe]

hmm im just thinking why not use steel alloy 1090 to make helmets its got a a tensile strength of .84 GPa and a yield strength of .64 GPa.

Cause it hurts to wear heavy stuff on your head.

[gclark03]

Doesn't it hurt more to get shot in the head without the proper protection?

[DerangedDingo]

The Personnel Armor System Ground Troops Helmet, also known as the "K-pot" and also the "Fritz" helmet for its resemblance to the World War II German army helmet is a standard infantry combat wear in the US Military. The shell is made from 19 layers of Kevlar, a ballistic aramid fabric treated with a phenolic resin system and is rated at a Threat Level II, and offers protection against fragmentation and ballistic threats. It meets the 1800 requirement of MIL-STD-662 E. It weighs from 3.1 pounds (size extra small) to 4.2 pounds (extra large).

The PASGT Helmet is said to have stopped rifle rounds on occasion, most commonly 7.62x39mm (AK) rounds (in one account the PASGT Helmet is credited with stopping an M43 round from approximately 25 meters). This performance would be closer to Level III or Level IV performance, though in a demonstration of the Heckler & Koch MP7 on the Discovery Channel show Future Weapons, a PASGT helmet suffered a catastrophic armor penetration when hit head-on with one round of the MP7's 4.6x30mm ammunition. Similarly, the firearms testing site The Box o' Truth has reported that a 7.62x25mm Tokarev fired from a ČZ vz. 52 handgun was able to penetrate the helmet at 25 meters. In the same test, both the 5.56x45mm NATO and the 7.62x39mm were able to yield catastrophic penetrations through both sides of the helmet.

This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) at a reference velocity of 367 m/s (1205 ft/s ± 30 ft/s) and 357 Magnum Jacketed Soft Point (JSP) bullets, with nominal masses of 10.2 g (158 gr) at a reference velocity of 436 m/s (1430 ft/s ± 30 ft/s). It also provides protection against the threats mentioned in [Types I and IIA].

1) The problems cited in the first post were due to network problems.
2) Headshots in PR are for the most part deadly, unless you're lucky.
3) Modern helmets will stop pistol ammunition and shrapnel 99% of the time, and sometimes rifle ammunition given special circumstances and, again, luck. Although helmets are primarily meant to stop shrapnel, having your head protected from small munitions is a comfortable feeling, and a comfortable soldier is a combat effective soldier. Whoever it was that said that most helmets won't stop a 9mm bullet, and even if they did, it would snap your neck, was, uh, misinformed.
4) I don't wanna get into the physics stuff. It's late and I'm hungry.

[M.0.D]

3) Modern helmets will stop pistol ammunition and shrapnel 99% of the time, and sometimes rifle ammunition given special circumstances and, again, luck. Although helmets are primarily meant to stop shrapnel, having your head protected from small munitions is a comfortable feeling, and a comfortable soldier is a combat effective soldier. Whoever it was that said that most helmets won't stop a 9mm bullet, and even if they did, it would snap your neck, was, uh, misinformed.

So I'm misinformed if I say, that a helmet will only stop a 9mm under very unlikely situation? Too bad i tried and that 9mm went through the helmet like it was a piece of paper even at a distance of 50 meters.. maybe you are misinformed ( Helmet - Bundeswehr issued helmet, Weapon H&K P8 )