explain 'grains'
- Thread starter N3rday
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To answer your questions:
a) A grain is 1/7000 of a pound (it is a measure of weight or mass); therefore, for example, a 230 grain .45 ACP bullet weights 230/7000 of a pound.
b) Obviously – given identical propellant charges – a lighter projectile will have a faster muzzle velocity (and greater muzzle energy, too, since E = .5 M V V).
c) Certain weapons are designed for an ideal point-of-aim with a defined bullet mass; for example, some .357 magnum revolvers were designed for a 158 grain projectile.
However, with regard to “câ€, weapons are routinely “sighted in†for a wide variety of cartridges, bullet weights, powder charges, and so forth.
a) A grain is 1/7000 of a pound (it is a measure of weight or mass); therefore, for example, a 230 grain .45 ACP bullet weights 230/7000 of a pound.
b) Obviously – given identical propellant charges – a lighter projectile will have a faster muzzle velocity (and greater muzzle energy, too, since E = .5 M V V).
c) Certain weapons are designed for an ideal point-of-aim with a defined bullet mass; for example, some .357 magnum revolvers were designed for a 158 grain projectile.
However, with regard to “câ€, weapons are routinely “sighted in†for a wide variety of cartridges, bullet weights, powder charges, and so forth.
Jim March
Member
With a 5" barrel, the 1911 is optimum with 230s, at least in most people's opinion (incl. mine).
BUT: shorten the barrel up, and the 230s may not move fast enough to expand. That's why Speer for example makes 230, 200 and 185grain JHPs for 45ACPs...4" barrel, use a 200, 3", use a 185. Keep your velocity up, at the cost of some penetration (not a WHOLE lot).
Cor-Bon has a very nice 165 design that rocks in shorter barrels.
We have a THR member who actually had to use his 230s out of a short-barrel (3.5" Glock). He was using Speer Gold Dots as I recall, which is a SUPERB hollowpoint design, but they failed to expand (several good chest shots on the maniac who was definately about to murder him and several co-workers...this was a VERY clean shoot). The bad guy was "psychologically stopped" versus physically...the outcome was good but this was a definate "ammo failure" and the bad guy lived for trial (he'll never get out). The hero in the situation has since swapped ammo.
Lesson: JHPs are "speed sensitive", which means barrel length sensitive. Rule of thumb: 50fps extra for every inch of barrel, but that is NOT always accurate (75fps isn't unheard of, 100 isn't impossible depending on how fast burning the ammo's powder is). The same ammo that will work at 850fps may fail at 775...or if driven too fast (out of a carbine or monster-barrel handgun) may fly apart on impact and that isn't good either. Some JHP designs can take "overspeed" better than others and are preferred in situations with abnormally long barrels - the Gold Dot is good at holding together, the Hornady XTP is another "high speed compatible" critter. Whenever you have a gun with a barrel either shorter or longer than most in that caliber, stop and think about what you feed it if you're going in harm's way.
(This ain't just handguns, either, although that's where this crops up first for most of us. The US Military has been playing with 14" or shorter barrels for 223 rifles and it's had a big effect on ammo performance and effective range.)
BUT: shorten the barrel up, and the 230s may not move fast enough to expand. That's why Speer for example makes 230, 200 and 185grain JHPs for 45ACPs...4" barrel, use a 200, 3", use a 185. Keep your velocity up, at the cost of some penetration (not a WHOLE lot).
Cor-Bon has a very nice 165 design that rocks in shorter barrels.
We have a THR member who actually had to use his 230s out of a short-barrel (3.5" Glock). He was using Speer Gold Dots as I recall, which is a SUPERB hollowpoint design, but they failed to expand (several good chest shots on the maniac who was definately about to murder him and several co-workers...this was a VERY clean shoot). The bad guy was "psychologically stopped" versus physically...the outcome was good but this was a definate "ammo failure" and the bad guy lived for trial (he'll never get out). The hero in the situation has since swapped ammo.
Lesson: JHPs are "speed sensitive", which means barrel length sensitive. Rule of thumb: 50fps extra for every inch of barrel, but that is NOT always accurate (75fps isn't unheard of, 100 isn't impossible depending on how fast burning the ammo's powder is). The same ammo that will work at 850fps may fail at 775...or if driven too fast (out of a carbine or monster-barrel handgun) may fly apart on impact and that isn't good either. Some JHP designs can take "overspeed" better than others and are preferred in situations with abnormally long barrels - the Gold Dot is good at holding together, the Hornady XTP is another "high speed compatible" critter. Whenever you have a gun with a barrel either shorter or longer than most in that caliber, stop and think about what you feed it if you're going in harm's way.
(This ain't just handguns, either, although that's where this crops up first for most of us. The US Military has been playing with 14" or shorter barrels for 223 rifles and it's had a big effect on ammo performance and effective range.)
Kentucky Rifle
Member In Memoriam
I've been embarrassed to post this. However, when I went from a 124gr bullet to a 135gr bullet in my PM9, I actually felt that the pistol was heavier on my hip. Odd huh? Had to be imagined because it's just a minimal amount of weight.
Sheesh-I'm STILL embarrassed to admit that!
Will
Sheesh-I'm STILL embarrassed to admit that!
Will
KR - Maybe when you added the 100 or so grains of extra weight, the center of gravity shifted ever so slightly and you started feeling some pressure in a new spot. It's not at all unusual for extremely small changes in pressure on the skin to be very noticeable (ever felt a small hair on your face, or a tiny ant crawling on your skin - of course you have). It's a protection mechanism from the old days when anything foreign on our skin could be trouble.
Kentucky Rifle
Member In Memoriam
Thanks Mal..
I didn't think of it like that.
I feel a lot less silly.
Will
I didn't think of it like that.
I feel a lot less silly.Will
Balog
Member
Jim March: Good heavens, I hadn't heard about the THR member having to defend themselves. Who was that, or do they prefer that their identity be kept out of the public domain? I completely understand if they prefer to not discuss it, and I completely respect their right to privacy. Has anything been posted about the shoot on THR?
Nero Steptoe
member
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- Dec 30, 2002
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- 461
Lighter bullets require more, not less powder.
Nero, are you sure that lighter bullets require more powder? While cartridges with lighter bullets are loaded with more powder, this is not necessarily a requirement to reach equal velocities to heavier bullets.
Less mass means that it is easier to get it moving. The smaller bullet also leaves more room for powder. Because the bullet is lighter, you can also load more powder without building pressure to dangerous levels - the bullet movement decreases pressure faster than a heavier bullet would.
Less mass means that it is easier to get it moving. The smaller bullet also leaves more room for powder. Because the bullet is lighter, you can also load more powder without building pressure to dangerous levels - the bullet movement decreases pressure faster than a heavier bullet would.
Croyance, in general Nero is right. The main reason more powder is needed to reach the same velocity is due to the last point in your post. Because the lighter bullet can gain speed faster than the heavier one, the pressure increases at a slower rate and therefore the max pressure can be lower resulting in a lower velocity. However, there are so many variables involved, that it can't be stated that this is true all the time. Probably the biggest variable to affect the velocity is the difference (or sameness) in surface area and resulting friction in the barrel of one bullet vs another.
clubsoda22
member
Supposedly The winchester Ranger Talon 230gr .45+p work well out of shorter barrels. They also don't fragment and the do retain their jackets, unlike the corbon loads.
As a side note, those Ranger Talons are HOT. 990fps out of a 5" barrel At 230gr, it's gonna kick.
As a side note, those Ranger Talons are HOT. 990fps out of a 5" barrel At 230gr, it's gonna kick.
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