Why is .284 called a true 7mm?

LoneTraveler

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Today in the world only the United States, Burma and Liberia use a measuring system other than the METRIC system. The military in order to standardize with NATO gave the M-14 ammo a metric designation 7.62 X 51 NATO around the Vietnam War era. Winchester gave it the 308 Win. name when they commercialized it as a sporting round. The 223 Rem. is known as the 5.56 mm to the Military today.

Only U.S.A used world wide measurement today is 42 U.S. gallons = 1 Barrel of crude oil. 1 U.S.A. barrel of oil =158.987 liters in the world market measuring equipment.

7mm measurement is 0.275591" + .004 X 2 for rifling = .283591 or .284 rounded off to nearest thousandth.
30 cal. = .300 + .004 X 2 for rifling= .308 U.S.A.
Once SAAMI set the standards and the barrel and bullet manufactures use the standards its just that way.

Just thoughts of an old U.S. Army Engineer who hauled Kilo's of sand, Kilometers over France in a 5 ton dump truck. 1963-64
 

old_heli_logger

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Today in the world only the United States, Burma and Liberia use a measuring system other than the METRIC system. The military in order to standardize with NATO gave the M-14 ammo a metric designation 7.62 X 51 NATO around the Vietnam War era. Winchester gave it the 308 Win. name when they commercialized it as a sporting round. The 223 Rem. is known as the 5.56 mm to the Military today.

Only U.S.A used world wide measurement today is 42 U.S. gallons = 1 Barrel of crude oil. 1 U.S.A. barrel of oil =158.987 liters in the world market measuring equipment.

7mm measurement is 0.275591" + .004 X 2 for rifling = .283591 or .284 rounded off to nearest thousandth.
30 cal. = .300 + .004 X 2 for rifling= .308 U.S.A.
Once SAAMI set the standards and the barrel and bullet manufactures use the standards its just that way.

Just thoughts of an old U.S. Army Engineer who hauled Kilo's of sand, Kilometers over France in a 5 ton dump truck. 1963-64

Thank you very much for your service sir!
 

Oldschool280

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Jan 22, 2016
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Re: Why is a bullet that meaures .284 called a true 7mm?

Thanx for all of your help guys. I appreciate the time you spent reading and replying.
 

J E Custom

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Location
Texas
Re: Why is a bullet that meaures .284 called a true 7mm?

Thanx for all of your help guys. I appreciate the time you spent reading and replying.


A true 7 mm bullet, measure 0.2755 inches so there are no true 7 mm bullets and cartridges, just some that are called 7 mm.

The 270 Winchester is one that is very close @ .2770 diameter and the relatively new 6.8 spc also uses the .277 diameter bullets, but they named it the 6.8 SPC which is actually .2677 dia, when actually 6.8 mm is not 2770 but uses that bullet diameter.

It does get confusing, but whats new. o_O

J E CUSTOM
 
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