Shouldn't a one ounce load of bird shot fired at the same velocity as a one ounce slug have about the same recoil if shot from the same gun? Shouldn't an ounce of eight shot fired at 1200 feet per second have similar recoil to an ounce of four shot fired at 1200 FPS? That is if fired from the same shotgun?
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Recoil Question
- Thread starter roy reali
- Start date
Quite possibly... Makes fine sense... But show me a 1,600 fps quail/dove shot load... I think most of the bird shot seems, IIRC, about 1,000-1,200 FPS. That is a massive difference. A pellet gun of decent power is 800 but a right powerful one is 1,000 fps. So like 2/3rds increase explains alot more felt recoil.
Brent
Brent
There are different gas release characteristics. This is especially true of slugs, since there should be less gas leakage around the projectile. I do not know how significant this is (as there are only about a thousand factors that influence recoil, and most of them are imperceptible effects).
-Jephthai-
-Jephthai-
Because energy is proportional to the square of velocity, a 200 fps, or 25% increase in velocity represents a 56.25% increase in energy!hogdogs said:A pellet gun of decent power is 800 but a right powerful one is 1,000 fps.
TerminalVelocity16
New member
pellets have more of a combined surface area then a slug does. therefore during the acceleration down the barrel and directly after, the total air resistance in increased yielding a lower muzzle velocity if the same powder charge is used in both cartridges. Long story short, it takes more powder to accelerate pellets to the same velocity as slugs.
-Term
-Term
Shouldn't a one ounce load of bird shot fired at the same velocity as a one ounce slug have about the same recoil if shot from the same gun? Shouldn't an ounce of eight shot fired at 1200 feet per second have similar recoil to an ounce of four shot fired at 1200 FPS? That is if fired from the same shotgun?
Yes, the recoil should be exactly the same, however, one ounce birdshot loads are usually loaded to 2 3/4 to 3 dram equivilent while slugs are almost always loaded to MAX dram equivilent. Slugs usually go about 1600 fps out of the muzzle while the birdshot load usually goes 1150 to 1250 fps so the premise of equal velocity is not easily realized with commercially loaded ammo.
Also, birdshot is usually shot at flying birds or clay pigeons. Take the same ammo you shoot skeet with and try shooting a shot at a patterning board, carefully aiming and squeezing off a shot like you are shooting a rifle and notice how much more the gun seems to kick when shot that way.
Jephthai is pretty close with his
External muzzle ballistics are not the full story. The recoil reaction starts the moment the shot/slug starts to accelerate down the barrel (it's essentially over when the shot/slug clears the muzzle). The greater the acceleration, the greater the reaction.
Newbies:
If you've never done this before, get a box of Federal Gold Medal Papers* and box of the cheapest** equivalently loaded plastic shells. Then have someone else load your gun. The two loads have equal ballistic energy at the muzzle; however, shooting blind, you'll probably notice a significant difference in the kick. This difference is all do to with internal ballistics. You can't use just the ballistic energy at the muzzle to determine kick.
Reloaders, wanting reduced recoil, peruse the data tables to find the load with the lowest average chamber pressure. The lower the pressure, the longer it takes the load to attain maximum velocity. Reducing the acceleration will reduce the kick.
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hogdogs
Brent, the time (T) shot is traveling down the barrel is roughly:
T = Distance divided by the average velocity. The average of rest and 1,200 is 600 fps
T = 2.5 ft. / 600 fps = 0.0042 seconds.
Most shooters are concerned with the effectiveness of what they are throwing down range (How hard will it hit the target?). The "mass times velocity squared" gives a good reference point. It's also a reasonable ball park reference for recoil and relative kick....there are only about a thousand factors that influence recoil, and most of them are imperceptible effects.
External muzzle ballistics are not the full story. The recoil reaction starts the moment the shot/slug starts to accelerate down the barrel (it's essentially over when the shot/slug clears the muzzle). The greater the acceleration, the greater the reaction.
Newbies:
If you've never done this before, get a box of Federal Gold Medal Papers* and box of the cheapest** equivalently loaded plastic shells. Then have someone else load your gun. The two loads have equal ballistic energy at the muzzle; however, shooting blind, you'll probably notice a significant difference in the kick. This difference is all do to with internal ballistics. You can't use just the ballistic energy at the muzzle to determine kick.
Reloaders, wanting reduced recoil, peruse the data tables to find the load with the lowest average chamber pressure. The lower the pressure, the longer it takes the load to attain maximum velocity. Reducing the acceleration will reduce the kick.
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* The Fed papers are known for their low pressure and low recoil.
**cheapest: Manufacturers buy their powder by the pound. So, they want the minimum charge weight that will deliver. The lighter charge will probably have significantly higher pressure than the more expensive target loads.
[/SIZE]**cheapest: Manufacturers buy their powder by the pound. So, they want the minimum charge weight that will deliver. The lighter charge will probably have significantly higher pressure than the more expensive target loads.
hogdogs
Brent, the time (T) shot is traveling down the barrel is roughly:
T = Distance divided by the average velocity. The average of rest and 1,200 is 600 fps
T = 2.5 ft. / 600 fps = 0.0042 seconds.
hogdogs
Brent, the time (T) shot is traveling down the barrel is roughly:
T = Distance divided by the average velocity. The average of rest and 1,200 is 600 fps
T = 2.5 ft. / 600 fps = 0.0042 seconds.
__________________
This formula assumes constant acceleration along the whole length of the barrel, something that's not realistic. I can pretty much guarrantee that if you sawed off that barrel to 1/2 its original length, you will see way higher velocitys than 600 fps.
I recently chonographed some .38 special loads shot out of a 24 inch rifle barrel, this long barrel only increased the velocity of the bullet by about 120 fps over the velocity of the same ammo out of a 5.5 inch revolver. Most of the acceleration happened in the first few inches of barrel travel.
The true barrel time will be somewhat less than the formula predicts. The lower the peak pressure, the more the gun uses the entire barrel to accelerate the shot. It's hard to beat good old black powder for maximum velocity with minimum peak pressure which is why black powder loads have a longer barrel time than smokeless loads of the same velocity, and also why the muzzle blast is louder, there's still pressure accelerating the shot at the end of the barrel.
B.L.E.
You're absolutely correct about acceleration not being uniform for the full length of the barrel and your other observations. That's why I used the word roughly. I was trying to give Brent a ballpark number on how long the shot/slug is in the barrel. The formula I used assumes a linear acceleration curve, which we know is not the case. Solving for non-linear acceleration, the numbers would become unnecessarily complicated for unneeded accuracy.
What I was trying to point out, in response to the OP: Different powders give different burn rates and pressures, different accelerations, and different recoils all with the same exterior ballistics. Therefore, the exterior ballistics are an indicator, but not the only factor to be used when evaluating kick.
When trying to anticipate a load's kick, I look at the exterior ballistic energy and the chamber pressure. It works for me, but your method may differ.
Pete
You're absolutely correct about acceleration not being uniform for the full length of the barrel and your other observations. That's why I used the word roughly. I was trying to give Brent a ballpark number on how long the shot/slug is in the barrel. The formula I used assumes a linear acceleration curve, which we know is not the case. Solving for non-linear acceleration, the numbers would become unnecessarily complicated for unneeded accuracy.
What I was trying to point out, in response to the OP: Different powders give different burn rates and pressures, different accelerations, and different recoils all with the same exterior ballistics. Therefore, the exterior ballistics are an indicator, but not the only factor to be used when evaluating kick.
When trying to anticipate a load's kick, I look at the exterior ballistic energy and the chamber pressure. It works for me, but your method may differ.
Pete
Zippy 13, after re-reading my post, I find I must correct myself. I indicated that if the acceleration was constant, the shot would be going at half its terminal velocity at the halfway point of the barrel, that is wrong. What is true is that the shot would have gained half its terminal kinetic energy at the halfway point or 70.7 percent of its terminal velocity. The average speed formula you gave would be correct because the shot spends just as much time below 600 fps as it does above 600 fps.
Old Guard Dog
New member
Don't forget the type of wad. Most shot wads have a built-in cushion, which will reduce felt recoil.
Actual recoil of 1 oz over 3 drams will recoil the same whether it is slugs, buck or bird because the starting weight is the factor...has to do with Newton's First Law of Motion...
"Felt" recoil is a significant different matter...I can, just by sheer mass (6' and 225 lbs) absorb more recoil then my 16 yr old daughter (5'8" and 125 lbs)...
The reason slug shoot "heavier" then bird is because they have to--they have to drop a 225 lb deer not a 20 lb goose/turkey so they are loaded with more powder to make a bigger boom--just read the labels and compare the dram weights...
Bore/shell.....Shot Oz......Velocity fps......Drams Equivalent
12 - 2-3/4".....1 1/4.....1220.....3 1/4
12 - 2-3/4".....1 1/4.....1330.....3 3/4
12 - 2-3/4".....1 1/2.....1260.....3 3/4
"Felt" recoil is a significant different matter...I can, just by sheer mass (6' and 225 lbs) absorb more recoil then my 16 yr old daughter (5'8" and 125 lbs)...
The reason slug shoot "heavier" then bird is because they have to--they have to drop a 225 lb deer not a 20 lb goose/turkey so they are loaded with more powder to make a bigger boom--just read the labels and compare the dram weights...
Bore/shell.....Shot Oz......Velocity fps......Drams Equivalent
12 - 2-3/4".....1 1/4.....1220.....3 1/4
12 - 2-3/4".....1 1/4.....1330.....3 3/4
12 - 2-3/4".....1 1/2.....1260.....3 3/4
One more question... how many powder formulations are implemented in factory loads? Like rifles have a ton of different powders for different burn rate etc... So a slower lighting powder might not give such a felt recoil as a super fast lighting powder? I am askin' as I am not a reloader... rather a free loader of some of the reloading posts....
Brent
Brent
Brent,
There are a lot of powder variations in shotshells - within one product line or between companies. In general, they formulate the powder to meet their specs / and custom mix components to get what they want - and in general, we as reloaders cannot buy the same mix or the same powders they use these days in factory loads.
Recoil is primarily a function of velocity and weight of shot charge and wad ( for any given gun ) - so if it burns fast or slow, it isn't really part of the equation - even though if you could quantify it - you could determine the effect. The way I think about it in the real world, a real fast burning powder seems to give more of a "smack" as it gets the shot up to speed vs over a longer curve - so it "thumps" as opposed to smacks you - but the pure recoil formula doesn't allow for burn rate - only velocity. Zippy gave you a better technical explanation of the burn rate issue / and he's right about looking at pressure as an indication of burn rates - and taking them into account along with velocity is important.
Most of us that reload - pick powders that are clean burning, give reliable drops on our presses, give good consistent performance in all kinds of weather - and are available. Personally, in shotshells, I use Hodgdon powders - Clays for 12ga, International for 20ga, Universal for 28ga, Lil Gun for .410 ... but some of my buddies are still using Unique, Red Dot, Blue Dot, etc ....
We are constantly debating best powders, wads, hulls etc - and once in a while it will come up on some powders seem to "smack" us vs thump ...but for the most part all of us shoot guns in the
8 1/2 lbs - 10 lbs range for clay target games / and burn rate really isn't a big deal. If someone is recoil sensitive - they drop the amount of shot down in a 12ga to 1 oz, or 7/8oz and pick a recipe that slows it down to 1150 fps / to reduce it as much as possible. So if you look at a combination of factors including velocity and pressure - in the reloading tables, it'll give you a better idea of the recoil a load will give you for any given gun.
There are a lot of powder variations in shotshells - within one product line or between companies. In general, they formulate the powder to meet their specs / and custom mix components to get what they want - and in general, we as reloaders cannot buy the same mix or the same powders they use these days in factory loads.
Recoil is primarily a function of velocity and weight of shot charge and wad ( for any given gun ) - so if it burns fast or slow, it isn't really part of the equation - even though if you could quantify it - you could determine the effect. The way I think about it in the real world, a real fast burning powder seems to give more of a "smack" as it gets the shot up to speed vs over a longer curve - so it "thumps" as opposed to smacks you - but the pure recoil formula doesn't allow for burn rate - only velocity. Zippy gave you a better technical explanation of the burn rate issue / and he's right about looking at pressure as an indication of burn rates - and taking them into account along with velocity is important.
Most of us that reload - pick powders that are clean burning, give reliable drops on our presses, give good consistent performance in all kinds of weather - and are available. Personally, in shotshells, I use Hodgdon powders - Clays for 12ga, International for 20ga, Universal for 28ga, Lil Gun for .410 ... but some of my buddies are still using Unique, Red Dot, Blue Dot, etc ....
We are constantly debating best powders, wads, hulls etc - and once in a while it will come up on some powders seem to "smack" us vs thump ...but for the most part all of us shoot guns in the
8 1/2 lbs - 10 lbs range for clay target games / and burn rate really isn't a big deal. If someone is recoil sensitive - they drop the amount of shot down in a 12ga to 1 oz, or 7/8oz and pick a recipe that slows it down to 1150 fps / to reduce it as much as possible. So if you look at a combination of factors including velocity and pressure - in the reloading tables, it'll give you a better idea of the recoil a load will give you for any given gun.
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Brent,
Looking over a reloading manual, I like a 12ga shell, 1 oz of shot, at about 1235 fps....
so as one example, using STS hulls:
using CCI 209 primer, wad is Win WAA12SL, 17.5 gr of Clays = 1235 fps / with 11,200 psi.
using REM 209P primer, Win WAA12SL wad, 18.7 gr of Clays powder = 1235 fps with 9,400 psi or about a 20% drop in pressure ( with different primer ) same wad and more powder ...
Using the recoil formula - you will get exactly the same recoil.
Books says you will get the same muzzle velocity at 1235 fps / but with less pressure, I think the 2nd load will "smack" you less / even though recoil formula will tell you its identical... and the difference is the primer and how it affects the burn rate of the powder ....
But the one with less pressure / and more powder might be a little dirtier in your gun ( and it uses 1.2 grains more powder )... while every grain of powder is about $ 0.0019 cents per grain / but you'll get 200 more shells off of the lighter powder recipe - so 8 more boxes vs how much more recoil ... and we can go on and on ...
Looking over a reloading manual, I like a 12ga shell, 1 oz of shot, at about 1235 fps....
so as one example, using STS hulls:
using CCI 209 primer, wad is Win WAA12SL, 17.5 gr of Clays = 1235 fps / with 11,200 psi.
using REM 209P primer, Win WAA12SL wad, 18.7 gr of Clays powder = 1235 fps with 9,400 psi or about a 20% drop in pressure ( with different primer ) same wad and more powder ...
Using the recoil formula - you will get exactly the same recoil.
Books says you will get the same muzzle velocity at 1235 fps / but with less pressure, I think the 2nd load will "smack" you less / even though recoil formula will tell you its identical... and the difference is the primer and how it affects the burn rate of the powder ....
But the one with less pressure / and more powder might be a little dirtier in your gun ( and it uses 1.2 grains more powder )... while every grain of powder is about $ 0.0019 cents per grain / but you'll get 200 more shells off of the lighter powder recipe - so 8 more boxes vs how much more recoil ... and we can go on and on ...
The "felt" or perceived recoil is what I was getting at... Like a Hornady leverevolution in .30-30 right smarts and sounds different than a standard .30-30... and i reckon they have to be careful with that round as they claim it is safe in any .30-30 chambered rifle... Folks who are using that round feel it is more the powder used than the addition of a rubber pointed tip that gets the far improved trajectory. Then there are the sedate feeling .30-06 and the BRUTAL ones...
Brent
Brent