Look at the end of the barrel and you will have import information on the end. Normally they come in the obscure cartridge of 8x56r (r for rimmed) hungarian. This ammo is extremely rare and I suggest you reload for it. You can also convert the common existing 7.62x54r into it for reloading purposes, to which you can find out at surplusrifle.com. Some of these rifles have been exported to other countries earlier in the 20th century and therefore have undergone many conversions, many in 8mm Mauser, which is also a common round. They are great rifles as I enjoy mine.
50-350 usd
Heckler & Koch G3 Steyr AUG M-16 AK-47 Heckler & Koch MP5 Heckler & Koch MP5K-PDW Heckler & Koch G3 Steyr AUG M-16 AK-47 Heckler & Koch MP5 Heckler & Koch MP5K-PDW
5.56x45mm
The M16A4 assault rifle is chambered for the 5.56x45mmNATO cartridge, which is of the .223 caliber.
7.62x51 NATO
Yes
It's ammo for the very first version of the "30-caliber machinegun" M-1919, which is the smaller version of the M-2 HB (means either 'heavy barrel' or 'hydraulic buffer') .50-caliber machinegun.
Impossible to answer without knowing who made it and what the caliber is.
No
30.06 or (30-ought-six) same as springfield M-1908
A Smith and Wesson M&P 40 is a .40 caliber hand gun.
ww1 french mle m16 was 8mmx50mm lebel.