recoil reality

[nekshot]

If boolit or bullet of equal weight is fired in a given calibers (160gr fired in 6.5,7mm,30, 32, 35) at the same speed will the recoil be the same in all or less in the larger calibers because of less bearing surface. The weight of the gun we will assume is the same weight in all calibers for sake of discussion. I am starting to think and this sometimes leads to trouble or at least confusion!
nekshot

[MUSTANG]

If boolit or bullet of equal weight is fired in a given calibers (160gr fired in 6.5,7mm,30, 32, 35) at the same speed will the recoil be the same in all or less in the larger calibers because of less bearing surface. The weight of the gun we will assume is the same weight in all calibers for sake of discussion. I am starting to think and this sometimes leads to trouble or at least confusion!
nekshot


I believe that Newton's Third Law of Motion provides the answer in a pure theory perspective:


Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.

Felt recoil may be a different matter. The difference in bearing surface between larger and smaller caliber boolits/bullets; could cause a difference in the rotational force transferred to the firearm, which could result a difference in apparent (felt) recoil. As an example of this rotational force, consider the firing of a .45ACP 1911 in the old traditional one handed Target shooting stance - The shooter can not only feel the recoil, but also the twist of the pistol to the left as the bullet attempts to twist the pistol counter-clockwise in the hand as the round goes down the barrel.

Additionally, the pressures generated may be different given the variances in bearing surface and powder characteristics.

Mustang

[Pilgrim]

Close but a bit of over simplification me thinks. Newtons third law is sure enuf in effect, but the weight of the powder charge has to be added in to the bullet weight(mass) plus the jet effect due to the burning powder/expanding gases adds a fair amount of backward thrust in addition to the effect of the bullets equal and opposite reaction. Felt recoil will also be greatly effected by stock shape and fit. The slower burning rate powder you use, the more of it you generally use to get a given velocity, and the higher will be the recoil. The higher recoil is due to both more powder mass and the (generally) higher velocity of the powder gases resulting from the larger charge than that of a smaller charge of faster burning powder. I suggest the highest recoiling rifle will be the one using the most powder, all other factors being equal.

[MtGun44]

Weight of powder charge is included and RATE OF VELICTIY INCREASE will make a difference.
If you get the velocity in a 30" bbl vs the same in a 10" bbl, the recoil in the short bbl gun will
be greater.

However, both are secondary effects (smaller) - the main effect is exactly what you said.


NOW - FELT recoil is HUGELY affected by the weight of the gun. Light gun snaps back
quicker than a heavy gun, even with identical applied forces from recoil.

Bill

[olafhardt]

The recoil is not all applied at one instant. Recoil pads work and all they do is spread out the time that the recoil is applied. The force applied to the boolet is the pressure times the boolit base area. Since the pressure varies over the length of the barrel the instantaneous pressure x area product must be integrated over the length of the barrel to give the total force produced over the time of bullet passage. Other things such as resistance to boolit passageare also involved. These are all good reasons to leave your calculator at home when you go to the range. If the dang thing kicks to hard load it down.

[1Shirt]

Ya, I think you are trying to think on this subject, and it is probably a waste of your time. The reality of the issue is a moot point in my opinion. You are in all probability never going to be able to get as exact as you want with weapon, blts/wt of blts/wt of brass/wt of rifle/bbl length etc.
1Shirt!

[ku4hx]

I believe that Newton's Third Law of Motion provides the answer in a pure theory perspective:


Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.

Felt recoil may be a different matter. The difference in bearing surface between larger and smaller caliber boolits/bullets; could cause a difference in the rotational force transferred to the firearm, which could result a difference in apparent (felt) recoil. As an example of this rotational force, consider the firing of a .45ACP 1911 in the old traditional one handed Target shooting stance - The shooter can not only feel the recoil, but also the twist of the pistol to the left as the bullet attempts to twist the pistol counter-clockwise in the hand as the round goes down the barrel.

Additionally, the pressures generated may be different given the variances in bearing surface and powder characteristics.

Mustang

"All other things being equal" has relevance here as usual, but as a former Physics teacher, I'd give you an A+ on this response.

You can't negate the physics, but you can do things to "soften the blow" as it were: redirection vectors, increased surface area (larger butt stock end plate), inertial compensation devices and etc.. That's where "felt recoil" comes into play and as we all know, that's pretty much subjective.

[truckjohn]

My experience is that there's a big difference between Perceived Recoil and the Physics, 2nd law Recoil...

"Perceived" recoil is how unpleasant it is to shoot... and it includes MANY factors that aren't just the thump against your shoulder.... Muzzle blast, jump, noise, and all the like factor into what you Perceive....

Case in point...
30-06 loaded with 168 grain Match bullets. Loaded to 2,700 FPS MV.
1 is loaded with IMR or H 4350 powder
2 is loaded with IMR4895 or 4064

Your "Perception" is that #1 is a pretty "Hot" load... kicks like a mule and just beats you to death... It must be quite powerful.... and it Hurts to shoot many of these....

Your perception of #2 is that it's not a particularly hot load, easy to shoot, etc... You can shoot this one all day long, because it's a fairly soft shooting load... You would let your 13 year old kid shoot this one without too much worry...

BUT BUT BUT... THEY have EXACTLY the same Muzzle Velocity, same bullet weight, etc..... The actual Recoil push backwards must be the same... but your shoulder tells you otherwise....

What's the difference?
#1 is a case full of slow burning powder... It creates a GIGANTIC muzzle blast... At dusk - you can see a 6' fireball... There's a ton of commotion, blast wave, stuff kicked up, etc.... You will literally clear all the benches around you shooting this load...

#2 is Ye 'Olde GI Match Load... and it's an easy shooting baby of a load... Very minimal muzzle blast/commotion... No one around gives this one a second look....

That's when I understood why faster burning powders do in fact have a place in the world...

Thanks

[jonp]

If you have the same boolit weight and
If you are using the same powder and charge weight and
If the gun is the weight and
If the stocks are the same type then
The recoil will not differ as momentum does not care what you are doing or what caliber you are shooting. The bearing surface of the different boolits due to different shape will cause a difference in recoil but in all practical matters will not be discernible to you.
The various formuli for calculating this make no mention of caliber. It will make a difference in recoil pulse if the two, equal weight projectiles are of vastly different size and shape and the barrel is either extremely smooth vs extremely rough but for our purposes these can be discounted.

[DeanWinchester]

Shape of the stock can mean a LOT too.
I've fired 45/70's and a few belted magnums and none of them will pound you like an 8x56 Steyr straight pull.

[nekshot]

Thanks for your input, I'll never be accused of being a sheeple as I think alot on my own and do entertain various ideas. This has been a wonder to me(fortunatlely I didn't get lost) and now I can move on to other thoughts and ideas! Wow, getting old is interesting.
nekshot

[popper]

olafhardt - good one on the recoil pad, same for buffer in SA. Energy squashes the pad fast, pad springs back slow. Stock drop provides a torque about the shoulder and forces bbl up. Twist causes torque on the gun, as I found out the first time I shot a 45. Darned thing almost twisted out of my hand. Physical laws always work, we don't always consider everything. In the end it is what you can handle.

[LynC2]

Excellent responses! Two things that were mentioned were the jet effects of the high velocity gases exiting the muzzle being part of the equation and force vectoring. That comes into play with muzzle breaks and why installing one on a .300 mag. with it's higher muzzle pressure will make a much more noticeable difference than one on a 45/70 using loads that produce the same number of foot pounds of recoil. Oh, did I mention muzzle breaks are LOUD! :shock: