Decimals v. Fractions

[Idobox]

I'm an engineer. I'd say decimals are fine in calculations as long as you take care to use full precision at every step, and only round your result. Rounding too early is a major source of errors.

Of course. What I meant is that you should try to use the least possible operations with them, as the error compounds.

That's why I was taught to solve in symbolic form first, to get the most compact equation possible. Think of something like x²/x, if you don't simplify it and do the computation in decimal, your error bar increases significantly.

[Seret]

Yes but then I would have to call my bullets something silly like 12.5mm instead of .50 cal, or even worse that horrid squib round called 9x19mm instead of a good proper hole maker like .45 cal.

.50cal is indeed known as 12.7mm in many places. It's no sillier than 5.56x45mm, which is itself no sillier a name than .223 Remington. The Germans, being precise types, are even in the habit of referring to things like 20mm autocannons as 2cm. That always just seems wrong.

I come from an aerospace weapons background myself, where metric and imperial is pretty much mix and match. You've got to be fluent in both IMO. Doesn't mean I don't fervently wish imperial would dry up and blow away. It's horrible. Metric is beautiful, all the different units slot together and it just works.

[drakesdoom]

Beautiful in the same way that antiseptic is effective. It works and it works well, just don't keep too much of it around for too long or it will smell the whole place up and make want to hurl. Just because metric works (sometime) and people like to daydream they live in a math book doesn't mean I wish it would pack up and take it's snobby self back to the bloody queen.

You are correct about .223 though, most ridiculous round to ever come out of the American continent. I can understand the use of a mid-range cartridge but chopping and necking a .30 down to a .22? The Russians actually got that bit right just take your normal .30 rifle round and shorten it up till you get the recoil reduction wanted, if you line it up right you could even get the same ammo cans to work for both.

[Seret]

Beautiful in the same way that antiseptic is effective. It works and it works well, just don't keep too much of it around for too long or it will smell the whole place up and make want to hurl. Just because metric works (sometime) and people like to daydream they live in a math book doesn't mean I wish it would pack up and take it's snobby self back to the bloody queen.

SI is the international standard, it's just you backwards types in Murka that need to modernise.

Resistance is futile, turn in your tools and prepare to be assimilated.

The Russians actually got that bit right just take your normal .30 rifle round and shorten it up till you get the recoil reduction wanted, if you line it up right you could even get the same ammo cans to work for both.

They nabbed the idea from the Germans. The Russians took one look at the StG-44, said "Nice gun, let's make one", and the AK-47 was born.

I don/t mind 5.56mm NATO too much as long as it's used in a full-length barrel, it's earned its stripes. And there's something to be said for being able to carry MOAR AMMO. I quite liked FN's 5.7mm round, the P90 is great and they have a pistol in the same calibre (although I've not fired it). A sidearm with 20 rounds of AP ammo sounds like fun. When you're a military user 9mm Para might as well be throwing rocks if the other guy has a helmet and body armour.

[drakesdoom]

The 5.56 is nice indoors but I can hardly call it a rifle round when it will reliably bounce off a human skull at 500 meters. The 5.7 is in all respects just an even slower and shorter bullet. The P90 seems like a good PDW, small, high capacity, high rate of fire. Doesn't even matter if they really do pierce Kevlar spray them down and you will hit the head at that point. The pistol I have serious doubts about though, it certainly could kill someone, but that is not what you want in a weapon. If you need to shoot a person you need them down 5 seconds ago, I cannot imagine semi auto fire of that caliber round being up to that task.

[Seret]

The 5.56 is nice indoors but I can hardly call it a rifle round when it will reliably bounce off a human skull at 500 meters.

Sure, it's not supposed to do a lot at that range. The full-power rifles everybody carried for the first 40-50 years of the 20th century were designed to be useful out to 800m or so. Turns out nobody fights at that range, analysis of actual combat showed almost all transactions happened under 200m. It's better to carry more of a round that's effective to that kind of range and leave the longer range stuff to SFMGs, MMGs, snipers, heavy weapons, etc. I know I couldn't hit a truck at 500m under combat conditions, and I don't think many other people can either.

The P90 seems like a good PDW, small, high capacity, high rate of fire.

It is, I've handled it on the range. As a rear-echelon type I liked the way it was designed with us in mind. It slung in useful positions (the length of the weapon was based on width of a man's chest, so you can carry it slung across your front while you drive, etc) it was handy, ambidextrous, accurate and had a 50-round mag. Just what the doctor ordered for everybody except the PBIs, really. I notice a lot of special forces seem to like it, so it's not just a tool for us spastics in the rear.

The pistol I have serious doubts about though, it certainly could kill someone, but that is not what you want in a weapon. If you need to shoot a person you need them down 5 seconds ago, I cannot imagine semi auto fire of that caliber round being up to that task.

Most traditional pistol calibre ball rounds get laughed at by military body armour. It'll generally stop 9mm as close as 5m, and even better rounds like 40S&W at only a little further. They won't have much stopping power even if they do penetrate. 5.7mm is a good defensive round for the targets you might face on the modern battlefield. You can't stop somebody if you can't punch through their armour, so you need a high-velocity AP round (or AP-ish like the SS109). I would be severely miffed at being made to defend myself with 9mm para, which is otherwise the default option for military users. We had 9mm Browning HPs and Sig P226s, but in opinion both were just noise makers.

[drakesdoom]

Yeah once you get in the cities a full size rifle round is pointless I agree, however there is combat outside of cities. Right now in Afghanistan when firefights break out in the mountains the m4 simply cannot reach far enough with the 5.56, the AK can reach slightly further. That is why so many M1s have been brought out of storage and touched up.

Pistols against body armor are a joke, even the brain bucket helmets they give the troops these days can stop them. I just don't see the 5.7 round out of a 3.5" barrel going through kevlar, not to mention military vests have plates and those will stop battle rifle rounds. If you know of any sources for video of live fire of the 5.7 round defeating kevlar that would be awesome, until then I will consider the pistol a fancy way to punch someone in the face on the modern battlefield.

[Seret]

Yeah once you get in the cities a full size rifle round is pointless I agree, however there is combat outside of cities. Right now in Afghanistan when firefights break out in the mountains the m4 simply cannot reach far enough with the 5.56, the AK can reach slightly further. That is why so many M1s have been brought out of storage and touched up.

The M4 isn't a good idea. That's why I said above:

I don't mind 5.56mm NATO too much as long as it's used in a full-length barrel

The M4 loses about 15% of the muzzle energy over the M16, for a pretty small reduction in length. If the US military wants a shorter weapon they should get a bullpup with a full length barrel.

It's not just built-up areas, where engagement ranges are short btw. Even out in the countryside it's pretty hard to effectively engage fleeting targets in combat conditions out beyond 200-300m. Realistically aimed fire at ranges longer than that are best left to snipers or heavy weapons. Suppressive fire obviously has longer legs. Most 5.56mm assault rifles these days are rated as being effective to 300m for individual fire, and and about 500m for section fire.

Pistols against body armor are a joke, even the brain bucket helmets they give the troops these days can stop them. I just don't see the 5.7 round out of a 3.5" barrel going through kevlar, not to mention military vests have plates and those will stop battle rifle rounds. If you know of any sources for video of live fire of the 5.7 round defeating kevlar that would be awesome, until then I will consider the pistol a fancy way to punch someone in the face on the modern battlefield.

The 5.7mm round is a steel-tipped AP round, it was specifically designed to part the weave of aramid body armours, instead of tearing it. It'll penetrate the CRISAT test target (1.6mm titanium and 20 layers of aramid) or Level 3A body armour at 200m. Level 3A is good enough to stop pretty much any handgun bullet, up to about .44 or .45ish. Basically it eats Kevlar for breakfast. Couple that to a nice flat trajectory, low recoil, and good soft-tissue performance and it gets a thumbs up from me.

Short range vs 9mm on 3A vest

Short range SS190 going through both sides of a 3A vest

Would like to see some longer range stuff myself, but you get the idea. Compared to handgun loads, this round rocks.

[drakesdoom]

For the military then that looks like a good sidearm, I had not seen tests on the AP rounds before. Unfortunately AP pistol rounds have been banned so the SS190 is out though the S4M might be available someday (manufacturer "out" of stock). For a civilian I think maximizing soft tissue damage is still the priority in pistol rounds, it is incredibly rare for criminals to be wearing a vest, unless it is under a blue shirt.

For the rifles out in the country around here most places you would be lucky to find a 200 yard vantage however the middle east is made mostly of mountains and desert. In that kind of terrain ranges can easily be 400+ for light rifle fire out too 1500+ for anything that can reach that far. If the enemy is firing from beyond the effective range of the average rifleman's firearm then he is only there as a potential wounded. Below are some videos showing some long range combat in the mountains.

[Seret]

For a civilian I think maximizing soft tissue damage is still the priority in pistol rounds

Absolutely.

If the enemy is firing from beyond the effective range of the average rifleman's firearm then he is only there as a potential wounded.

The enemy isn't likely to be carrying anything with much longer legs. You still get people lugging around old G3s and FALs, but most folks are carrying 5.56mm NATO, 7.62x39mm or 5.45mm rifles. They're all much of a muchness on effective range.

You've always got SFMGs, MMGs, sniper rifles, mortars, artillery, air, etc. I've seen videos of lads in Afghanistan using Javelin ATGMs as a long-range sniper weapon.

[Camacha]

Although they are a pain the the ass sometimes, fractions are a lot more pure. Decimals mean more in the human realm that fractions do, so for simple stuff, where precision is not essential or when trying to understand something they are preferred.

If you like the pure simplicity of math, fractions should be the way to go When I try to apply math to real world stuff decimals are often easier to work with.