Lanark, IL—What’s the difference between 7.62 NATO and .308 Win? Between 5.56 NATO and .223? Although the average gunsmith who deals primarily with sporting guns and firearms chambered in commercial calibers might not grasp the difference, military and law enforcement armorers certainly do, and they understand the critical importance – from both a safety and performance perspective – of proper headspacing of firearms chambered in military calibers.
In the early 1950’s, the U.S. government researched and developed a cartridge to replace the 30/06. The end result was the “T-65" cartridge which was later re-named 7.62 x 51MM NATO. The chambering produced a cartridge with shorter and lighter cartridges than the 30-06, yet it had good power and velocity. The improved ballistics for this shorter case were largely made possible because of better ball powders and primers on the market.
Winchester saw the market potential and quickly introduced the .308 Winchester to the commercial market. Although all other case dimensions of the two cartridge cases remain the same, one important difference exists: The 7.62 NATO chambering has a longer headspace dimension than the commercial .308 chambering. Hence, the need for rifle chamber Headspace Gages specifically designed and manufactured to check the slightly longer 7.62 NATO chambers.
There can be great differences between the chambers of military rifles based on the type of
action (FN, Garand, Ishapur, etc)) and also based on the amount of use the rifle has seen. Forster
Products’ new NATO Minimum rifle chamber gages will check to see that the rifle will accept the longest (headspace dimension) NATO ammunition cases that are currently manufactured. The Forster NATO Maximum rifle chamber gage checks to see that the rifle does not have excessive headspace, which could lead to dangerous pressure problems.
Similarly, the 5.56 NATO caliber requires a slightly longer headspace than the commercial .223 caliber, which are commonly thought to be identical. For that reason, Forster Products is also offering 5.56 NATO Headspace Gages. For any gunsmith or armorer working with military firearms in these two calibers, these NATO Headspace Gages can make a huge difference in both performance and safety.
Two gages (Minimum Headspace and Maximum Headspace) are available per caliber
Part number Description Price
HG556NATOMin 5.56 NATO Headspace Gage - length is 1.4636" plus
(minimum chamber) .0003" minus zero $26
HG556NATOMax 5.56 NATO Headspace Gage - length is 1.4736" plus
(maximum chamber) Zero minus .0003" $26
HG762NATOMin 7.62 NATO Headspace Gage - length is 1.6355" plus
(minimum chamber) .0003" minus zero $26
HG762NATOMax 7.62 NATO Headspace Gage - length is 1.6455" plus
(maximum chamber) Zero minus .0003" $26