I told a chemistry joke once. Didn't get a reaction. Sorry, wrong thread. Right. On to grains and all that... While I have read a few tidbits about the meaning and effects of ammo of differing grain counts, I still don't really understand it. I don't even know if it's something simple like, "It affects velocity." Or "It affects impact." And "What is the relationship between velocity and impact?" Or "Impact has more to do with the weight of the round." As you can see, I understand the subject about as well as a village idiot understands quantum mechanics. At least I assume a village idiot doesn't understand quantum mechanics. For all I know, he could be Shecky the Amazing Village Idiot who taught Niels Bohr everything he knew. Maybe Niels Bohr was a village idiot. Any help, then?
Grains used in the measurement of weight. 7,000 grains equal one pound. This was actually derived from the volumetric weight of your average size of wheat berries, which was 7,000 wheat berries(grains) equaled one pound.
As for velocity and impact, well E=mc^2 pretty much explains what happens when an object in motion meets an object at rest. The heavier and faster the object in motion is traveling, the more energy is transferred to the object at rest when both meet up.
BIGGER and HEAVY = more grains. The scale below is set to measure in this way. I sometimes buy bulk match bullets that are seconds for range shooting, and I weigh every one of them and sort accordingly. This batch came in 185 and 190 grain and I had to sort them. For my more accurate loads, I will use premium match quality bullets that are all within spec. The size and weight of every bullet is important to know when reloading so you use the correct amount of powder. Too much and it goes boom in the wrong way, too little and it goes pop and doesn't give you the velocity you require. That's the dumbed down version. A reloading manual is an essential component to have for reloading and it will list the powder type and charge for every bullet with maximum and minimum amounts clearly defined for safe operation. Precision is important. Your ballistic coefficient is always a factor in accuracy. Think of it this way -a heavier object requires more energy to propel it...but you're using the same size case. More bullet lead equals less space which means more pressure, so the charge (powder) must be carefully calibrated for every bullet. There's some wiggle room with seating so you can seat a bullet deeper or more shallow, every manual will tell you the overall dimensions for a fully loaded round. But bear in mind, the whole premise relies upon all the laws of physics in order to safely control accuracy. Do not play around with reloading if you don't know what you're doing. From a simple average user's perspective who purchases premade ammunition only, heavier gr. bullets offer you more lead to make a bigger hole. A lighter grain bullet can travel at a higher velocity but will impact with less energy because there's less mass. Although not entirely true...that is the basic way of viewing it. Every bullet will have parameters that will determine various flight characteristics. And temperature has an effect on velocity, too.
