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Edditty
02-02-2010, 2:35 PM
Can someone explain grainage to me please? I thought that it was a measurement of weight, but then I see 5.56 at 75 gr, .308 at 180 gr and .45 ACP at 230 gr? Is handgun powder denser? So even if takes up less space it's heavier, or is gr a measurement of weight per volume? I'm confused....

edditty

-hanko
02-02-2010, 2:40 PM
Can someone explain grainage to me please? I thought that it was a measurement of weight, but then I see 5.56 at 75 gr, .308 at 180 gr and .45 ACP at 230 gr? Is handgun powder denser? So even if takes up less space it's heavier, or is gr a measurement of weight per volume? I'm confused....

edditty
"Grainage" as a word does not exist. A grain is a unit of weight.

A grain is 1/7000 of a pound, a very light weight. Your posts shows bullet weights in the caliber's shown...Powder weight will typically be a lot less;).

-hanko

i1800collect
02-02-2010, 2:41 PM
Can someone explain grainage to me please? I thought that it was a measurement of weight, but then I see 5.56 at 75 gr, .308 at 180 gr and .45 ACP at 230 gr? Is handgun powder denser? So even if takes up less space it's heavier, or is gr a measurement of weight per volume? I'm confused....

edditty

the weights (in grains) you mentioned are the weights of the bullets not the gunpowder.

MasterYong
02-02-2010, 2:45 PM
I was confused about this as well when I first got into shooting. I thought that when a box of .45 was marked "230gr .45 ACP JHP" that the 230gr was the powder measurement, since I used to do black powder shooting in civil war reenactments.

When I had bought more than one firearm I thought about reloading, and looked into it. That's when I realized that the word "grain" was a unit of measurement used to refer to two different aspects (at least) of a cartridge. Typically what's marked on a box of ammo is the bullet weight. I've only ever seen one box of ammo (at least that I noticed) that actually stated the powder load. Even then, different powders burn at different rates, so it can be relative to a certain extent.

Probably makes more sense now, huh? A .45 bullet weighing more than a .308?

Edditty
02-02-2010, 3:11 PM
Geez, I always thought that the grains measured the amount of powder in the round. So then when I look for ammo, am I supposed to assume that all .308 rounds have the same amount of powder and that just the weight of the bullet is different? If not, is the weight of powder listed as well?

I'm still confused. I was looking at a chart on sniper central that listed distance from zero a round was averaging at http://www.snipercentral.com/308.htm (i.e. if a rifle is zeroed at 600yards the at 100 yards it would be +17.2" and at 1000 yards it would be -243.1"). I was looking up 168 gr and 175 gr Federal Gold Medal Match BTHP rounds. The 178 gr round seemed to have a flatter trajectory (less difference at 100 yards and 1000 yards).

Both rounds leave the weapon at 2600 FPS... So wouldn't a heavier round have more movement in its trejectory?

EBR Works
02-02-2010, 3:33 PM
Powder charges are measured in grains AND bullet weights are measured in grains. It's just a unit of measure. An ounce is 437.5 grains and a pound is 7000 grains. Powder charge weight depends on caliber, bullet weight, desired velocity, pressure limits etc. That's what reloading manuals are for.


Here's a conversion program you can play with:

http://www.onlineconversion.com/weight_common.htm

TKM
02-02-2010, 4:31 PM
Same unit of measure measuring two different things.

My car weighs about 2600 pounds but my gas tank will accept about 66 pounds of gas.

There is no single standardized nomenclature for ammunition. Over 500 years of development in many different languages.

All we can do at this point is try to learn everything. Good luck.