Please school me on "grain"
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  1. #1
    Captain 1BIGMOFO's Avatar
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    Default Please school me on "grain"

    I understand the concept that grain refers to the weight of the projectile. I understand that 150 grain is lighter than 180 grain. (I hope I'm correct with that)

    I have a 30-06 and a 7mm rem mag that I'm trying to purchase ammo for both rifles just to have extra. Im currently shooting Winchester 30-06 180 grain and Winchester 7mm rem mag 175 grain.



    How much will a 150 - 250 yard shot be effected by going to a lighter or heavier grain with either of these 2 rounds?


    Im eager to learn, please school me.

    Thank you.

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  3. #2
    General VARMINT223's Avatar
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    A very very small unit of weight measure. 7000 grains in one pound of gunpowder/bullet lead.

    Bullet trajectory is affected by the ballistic coefficient (air resistance). Two equal grained bullets of equal diameter can have totally different ballistic coefficients and will have different down range bullet drop profiles. A good rifleman however w/ballistic tables can put them both on target. ( A good Marine scout-sniper could put them in the same hole.)
    Last edited by VARMINT223; 12-31-2013 at 12:02 PM.
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  4. #3
    General Camper4lyfe's Avatar
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    One thing you need to keep in mind is the twist rate of your barrel. Different twist rates will be able to handle (stabilize) different weight bullets.

    Typically, in my uneducated opinion, lighter bullets will travel faster with a flatter trajectory, while heavier will be the opposite.

    There's more involved, but better educated folks around here can help with that.

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  6. #4
    Colonel varmint's Avatar
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    It depends on whose ammunition it is...there is usually a bullet listing in the ammunition catalog. If you reload your own, look in the charts in the reloading manual.

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    Major Dawgkilla's Avatar
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    Also remember, "heavy for calibre" bullets retain their velocity better at longer ranges. There's a fancy name for it..."Ballistic Coefficient" I think? I might have that confused with another term "sectional density"? I've reloaded for 20 years and just work on getting loadings that shoot "minute of critter".
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  8. #6
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    1 grain = 0.002 285 714 285 7 ounce
    As you can see it's a small unit of mass, you don't refer to your weight in ounces, because it's cumbersome and hard to process in your head, same with bullets, comparing them in ounces and pounds would be a mess so grains give you nice whole numbers that you can relate to.

    So yes 150 grain is lighter than 180 grain, just like if they were in pounds. In your example 5 grains wouldn't make much of a difference, 175gr 7mm produces roughly same energy as 180 gr 30-06. It would come down to bullet design and other factors to determine their lethality, but trust me, they are both powerful enough to kill any game in NY.

  9. #7
    Captain 1BIGMOFO's Avatar
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    Quote Originally Posted by Cuomostein View Post
    1 grain = 0.002 285 714 285 7 ounce
    As you can see it's a small unit of mass, you don't refer to your weight in ounces, because it's cumbersome and hard to process in your head, same with bullets, comparing them in ounces and pounds would be a mess so grains give you nice whole numbers that you can relate to.

    So yes 150 grain is lighter than 180 grain, just like if they were in pounds. In your example 5 grains wouldn't make much of a difference, 175gr 7mm produces roughly same energy as 180 gr 30-06. It would come down to bullet design and other factors to determine their lethality, but trust me, they are both powerful enough to kill any game in NY.

    Thank you, how will switching from a 180 grain to a 150 grain effect my accuracy at 150-250 yards without re-sighting in my rifle? If I'm talking about 1/2" drop then it's obviously not an issue but if it could potentially drop 3+" or so I could get myself in a bad situation. I pride myself on being a very accurate shooter, and I'd hate to miss a big buck, or worse off, wound him and not be able to track him down.

  10. #8
    General Camper4lyfe's Avatar
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    Quote Originally Posted by 1BIGMOFO View Post
    Thank you, how will switching from a 180 grain to a 150 grain effect my accuracy at 150-250 yards without re-sighting in my rifle? If I'm talking about 1/2" drop then it's obviously not an issue but if it could potentially drop 3+" or so I could get myself in a bad situation. I pride myself on being a very accurate shooter, and I'd hate to miss a big buck, or worse off, wound him and not be able to track him down.
    You would have to sight in your gun to determine that. Barrel harmonics and other things can do strange things that ballistic calculators can't account for.

  11. #9
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    'How much will a 150 - 250 yard shot be effected by going to a lighter or heavier grain with either of these 2 rounds?'

    You need to get ballistic tables to get that answer, they make 7mm in 110 grain I believe it may not even make it to 250 yards, ok I'm being silly but you get the idea, lighter bullets don't travel as far as heavier ones and drop off faster in general. Ever been at the lake? if you throw rocks, you want a nice heavy rock to throw it far, if you get a light stone no matter how hard you throw it, it will not make it far.

  12. #10
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    Quote Originally Posted by 1BIGMOFO View Post
    Thank you, how will switching from a 180 grain to a 150 grain effect my accuracy at 150-250 yards without re-sighting in my rifle? If I'm talking about 1/2" drop then it's obviously not an issue but if it could potentially drop 3+" or so I could get myself in a bad situation. I pride myself on being a very accurate shooter, and I'd hate to miss a big buck, or worse off, wound him and not be able to track him down.
    Use this automated chart by Winchester.

    http://ballisticscalculator.winchester.com/

  13. #11
    Major pappasue's Avatar
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    This stuff can drive you batty, the best way is to buy ammo and take your gun out and shoot it at the different ranges then you get your answers ,have some fun and get practice shooting. Most ammo is way more accurate than the guy/girl pulling (squeezing) the trigger.
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  14. #12
    Captain 1BIGMOFO's Avatar
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    Thanks so much for the help guys.

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    Quote Originally Posted by 1BIGMOFO View Post
    Thanks so much for the help guys.
    Were you able to open that app?

    I ran 2 bullets for you, Winchester SilverTip 180 gr vs 150 gr, sight in range was 250 yards, max range was 325 yards, cross wind was 0 mph and sight height was 1.5 inches.

    The drop off between the 2 was less than .5 inches at 150 and 250 yards, actually 150 grain bullet dropped off slower due to design but it also has less energy at both 150 and 250 yards. So stick with a heavier bullet but to answer your question, going from 180 to 150 grains will not effect accuracy too much.

  16. #14
    Captain OnyxDragun's Avatar
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    Alot of very good info being pointed out here. As with any question in this hobby , The basic question of "Why" , will open the door to many more questions before one gets to an understanding of the answer they seek. Many factors can change accuracy. Those apps can get ya close but they are limited & they only know the info you enter.
    First off you need to define your expectations. Do you want bug-hole groups , minute of man or minute of moose ?
    Then you need to realize that the tighter the grouping you want , the more each small change will effect said accuracy.Now the OP asked about "ammo" , so I will try not to go too deep because once you go into hand-loading , you can really drive yourself wack-a-doodle.
    If you simply change manufacturer of ammo in the exact same weight , your POI will likely change. Heck even using a different lot # of the same exact brand/style ammo could effect accuracy. Couple the manufacturing variances with the individual personalities of each rifle & it is hard to give a specific answer of "If you use X ammo & zero at A you will pattern at point B using Y ammo" .
    Things that can effect POI are :
    Bullet weight
    Bullet type- bal tip , Soft point, fmj, hollow pt., etc..
    Ogive - length , shape, design.
    Primer choice- this depends on what the ammo maker wants their ammo to do. Each primer manufacturer makes their primers differently , plus they make different variations of those, (Std., Match, Magnum)
    Powder charge - manufacturers use their own recipes to obtain the results they want.
    All of these choices are combined in an effort to make a product that performs well within a range of rifle action styles, barrel lengths , barrel twists, etc.. Therefore , the best way for you to answer your question is for you to buy a box of anything you may want to try & head to the range . When there follow this process for each box of ammo:
    Start with a clean rifle.
    Setup to shoot just like you would in the field. If you shoot offhand when hunting , then do so for testing. Unless you shoot from a rest in the woods , don't use one here.

    To simulate cold bore / fouled bore - If you are one to foul your bore before season & hunt it that way all season. let rifle cool to ambient temps between every shot.
    If You always shoot from a clean bore then clean it between shots.
    You have to simulate (as best as you can) the conditions you want the rifle to perform in & how it will be shot. Shooting 5 or more shots in quick succession on a 95* summer day, out of a deer hunting sporter rifle, is not gonna give you the correct info.
    Shoot whole box for group on 1 target & document the results in order.
    Rinse & Repeat for each box of ammo . Try to do as much testing as you can without making any adjustments to the scope/sights . Then compare all your results/targets.
    The only way you will know 100% how Your rifle will perform with any given ammo is to shoot it.
    Sorry this was so long , Keep Safe , Aim True , Good Shooting !

  17. #15
    Major minderasr's Avatar
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    Quote Originally Posted by Dawgkilla View Post
    I've reloaded for 20 years and just work on getting loadings that shoot "minute of critter".
    This literally made me lol out loud. Thank you for the laugh this morning, and happy new year.
    Jim
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