Ammo sizes?

1) Yes, most times you see .308 or any number as a decimal less then 1.0, it's a bullet diameter in inches. If you see something like 7.62 (decimal greater then 5.0), it's the bullet diameter in millimeters. You may also see cartridges refered to as 7.62x51, which is the bullet diameter and case length, respectively, in millimeters. Also, for future references, many cartidges have multiple names and ways of being refered to. For example, the .308 is also refered to as the .308 Winchester, 7.62x51, and 7.62 NATO. Learning all the different names is a challenge unto itself, but most of the time, they're refered to by their most common name.

2) Yes, rifle bullets are designed quite differently then pistol bullets. Rifle bullets travel at much higher velocities, requiring them to be more aerodynamic to achieve sufficient range. As a result, they've longer and more sleek. Handguns, generally, have larger diameter, more 'stumpy' looking bullets that fly at much lower velocities. However, once you see the cartridges compared, you quickly realize that rifle cartridges are much larger then most pistol ammo.

3) When you say "grain" are you referring to the bullet weight in grains, or cartidge powder weight. Either way, rifle bullets tend to have much more powder and a bit more bullet mass for a comperable diameter. As always though, there are different bullet weights within a certain diameters, so you can find exceptions to this.

Kiwi: You're right in that the 7.62 NATO (.308) is still used in light squad support machine guns such as the m249. Also of note is that .308 is one of the prefered calibers for sniper rifles. You're also correct in that most assault rifles currently use the 5.56 NATO (.223) round. Isn't being one of the few countries in the world still using the English measurement system fun?

Also, bullets weights are typically refered to in grains, not grams, ounces or another "normal" unit of weight. Thus my confusion. However, my original statement is mostly true. For example, common pistol ammo for the 7.65 mm cartidge (Remington Express for the .32 auto caliber) uses a 71 grain bullet. 7.62 NATO sniping ammunition commonly uses bullet weights between 167 and 175 grains, which is over twice as heavy.

Of course, as I said, there are exceptions, like the huge .454 Casull pistol round which is loaded with 300 grain bullets. However, the .454 Casull can also be accurately classified as a hand-held anti-aircraft weapon. But to be accurate, the .454 Casull is also about .15" bigger then the standard .308. But, if you want something to compare the Casull round to, the .50 Browning Machine Gun (.50 BMG) round, which the Barrett .50 rifles use, is .05" bigger then the .454 Casull and fires bullets in the range of 700 grains.

well heres a visual comparison if ya want it
left to right:
.30-06 Springfield- older round adopted by the Army in 1903, popular hunting round today
bullets range usually from 150-220 grain
.308 Winchester (7.62*51mm NATO)- currently used by law enforcement and military snipers worldwide
bullets in this caliber usually range from 150-180 gr
.223 Remington (5.56*45mm NATO)- NATO's standard assault rifle cartridge
bullets usually range for this caliber from 50-80 gr
9mm- (9*19mm PARABELLUM)- NATO's standard pistol cartridge and a popular pistol round, fairly small but common with law enforcement agencies
bullets uslally range from 105-147 gr
.22 LR- common target round, low recoil, fairly accurate, cheap
bullets usually range from 32-40 gr

Here you go...



The image is available at this link, along with MANY other cartridges.
http://stevespages.com/page8d.htm

MEL