bonanza
.400 member
Reged: 17/05/04
Posts: 2335
Loc: South Carolina
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When I took the mathematical equations (in excel) for muzzle energy and recoil, computed 5000 ft/lbs of energy for a 400 and 500 grain projectile in a 9 lbs rifle the recoil was 9 lbs more for the 500 grain bullet.
This was enlightening as intuitively one would think that the recoil would be equal for a specific ME.
Using this, I was able to play what-if with different bullet weights and velocities.
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Nakihunter
.375 member
Reged: 13/10/07
Posts: 588
Loc: New Zealand
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Interesting. I set up a similar excel formula in my reloading log file & I also found that the same bullet (225gr) with same velocity (2350 fps) in 358 Win gave different recoil with different powder / charge. A light powder like AR 2207 (H4198) versus AR 2206 (similar to IMR3031)- showed a noticeable increase in recoil with the AR2206.
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Always shoot through the target & not just at it.
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Omnivorous_Bob
.333 member
Reged: 03/10/05
Posts: 286
Loc: Montana
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"Recoil energy" will be equal for any two loads that have equal momentum (of bullet and powder gases) not ME. Equal momentun divided by the fixed weight of the gun give equal recoil velocity and therefore equal energy.
Personally, I've never put much stock in recoil calculators, because they don't reflect reality. Guns aren't free recoiling. As soon as it starts moving rearward it begins compressing muscle tissue and then moving the shooter. The huge additional mass (relative to the weight of the rifle) of your upper body radically reduces the gun/body velocity from what the calculations show. Since the recoil energy varies with the square of velocity, the exponentially reduces the energy. Intuitively we know this because it's the reason we hold rifles tightly to our shoulder lest you get clobered.
About the only way to make the formulas valid would be to suspend the rifle from a wire and stand a few feet behind it such that it strikes your shoulder just as the powder gasses and bullet exits the barrel and it is at that theoretical "recoil velocity". I'm not volunteering for that!
Bob
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"If we're not supposed to eat animals, how come they're made out of meat?"
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JPK
.375 member
Reged: 31/08/04
Posts: 734
Loc: Chevy Chase, MD
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Personal experience has always borne out that the heavier bullet recoils more in any given cartridge fired from the same rifle.
But powders can make a noticeable difference with the same bullet weight.
JPK
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Yogi000
.333 member
Reged: 02/03/06
Posts: 265
Loc: New York, USA
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Factory 220 grainer bullets always kick more than 180 in the same gun. No surprise there. And Omnivorous you make excellent points about how these recoil calculators provide free recoil which is of no value in the real world.
Why the heck did my 20 gauge double kick so much harder and sharper than my 12 gauge double? No recoil calculator would lead to that conclusion but that was how it was.
Only a Limbsaver Pad turned the tables on that hard/sharp 20 gauge kicker.
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Ripp
.577 member
Reged: 19/02/07
Posts: 16072
Loc: Montana, USA
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Quote:
When I took the mathematical equations (in excel) for muzzle energy and recoil, computed 5000 ft/lbs of energy for a 400 and 500 grain projectile in a 9 lbs rifle the recoil was 9 lbs more for the 500 grain bullet.
This was enlightening as intuitively one would think that the recoil would be equal for a specific ME.
Using this, I was able to play what-if with different bullet weights and velocities.
I would expect the results you described --the reason I would is that you will need to push the 400 faster than the 500 to reach the same ME--therefore increased recoil from the 400 grain bullet..
Having said that, I agree with the other posts..I feel a significant difference when I shoot 200 grs bullets versus 250 out of my 338 Ultra-mag..
Ripp
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ALL MEN DIE, BUT FEW MEN TRULY LIVE..
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DarylS
.700 member
Reged: 10/08/05
Posts: 27526
Loc: Beautiful British Columbia, Ca...
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Powder type, speed of burning and energy produced per grain weight also has a direct effect on recoil. Bullet wieght is not the only aspect of recoil energy.
; Felt recoil is another thing entirely. Stock fit, shape and weight also effects felt recoil.
; Ever shoot a 5-1/2 pound, 3" 20 bore Semi Auto - Franchie, I think it was. I had one that kicked more with it's 1-1/4 ounce loads than my 8-1/2 pound 12 bore Browning over/under with 3" factory 1-7/8oz loads. Stock fit and weight made the difference.
; Fired in the same gun, bullet weight makes the difference, even though the powder charge is usually less with heavier bullets. This, of course, depends on the case shape and capacity. The smaller cases might use a higher grain weight of slower powder with a heavier bullets. It all depends on powders used, but the heavier bullet will be found to kick more.
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Daryl
"a gun without hammers is like a Spaniel without ears" King George V
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