I have a couple of rifles (30-06 and 280ai) that use N560, and when compared to the two rifles I have that use Retumbo (280ai and 30 Nosler) I swear the Retumbo rifles are both more enjoyable than the N560 rifles. They are different weights, shoot different weights bullets, etc, but the recoil calculator says both Retumbo guns have the most recoil of any of the rifles I own. The 280's and 30-06 are all similar and the 30 Nosler has by far more recoil. They all have brakes (although some different brands) so that should equal out.
I feel like slower powders produce less felt recoil, spreading the impact out over a longer time. As many folks have described it, it sounds like a shove while the N560 rifle feels more like a punch.
Is this just me or do others notice a noticeable difference in recoil with some powders?
I don't think it's just you by yourself since many of us have described the same action using the same terms. The difference being that we used the word 'feel' instead of 'sounds'...
Retumbo is an Extreme Powder which as described by Hodgdon means that there is less variation from Temperature and Lot# batch to batch. Less spiking if you will from changes in Temperature and Lot#.
VVN-560 is a Double Base powder which uses Nitroglycerine as an added component to increase Energy and Temperature from the burning powder. You are able to achieve higher velocities than from Single Base powders without Nitroglycerine.
It stands to reason then that Retumbo feels more like a punch and VVN-560 feels more like a punch.
In calculating recoil, the components in the equation include the weight of the powder, often referred to as 'Ejecta'. Here is a calculator as an example:
https://shooterscalculator.com/recoil-calculator.php
Here is an explanation of the formula:
Recoil Calculation Formula
Recoil in Ft- Lb =
((((Wb+(Wp x 1.75)) x Vm)/Wr)/7000)^2 x Wr / 64.4
Where:
Wb = Weight of Bullet in grains
Wp = Weight of powder in grains
Vm = Muzzle Velocity in fps
Wr = Weight of Rifle in pounds
Ga = Acceleration of gravity 64.4 fps/sec
This formula can be placed into a spreadsheet if you like and you can play with the variables of Bullet, Powder, Muzzle Velocity and Weight of your rifle. Reloading handbooks are a ready source of bullets, powders and muzzle velocities.
Here is an example for a 243 Winchester:
Wb=100 grains
Wp=43 grains
Vm=2900 fps
Wr=8 pounds
Take the weight of the powder and multiply by a factor of 1.75 = 75.25. Add this to the weight of the bullet 100 + 75.25 = 175.25. Now multiply this by the muzzle velocity 175.25 X 2900 = 508225. Take the 508225 and divide it by the weight of the rifle in pounds. 508225/8 pounds = 63528.125. Now divide this by 7000 grains per pound. 63528.125/7000 = 9.075. Ok, we are almost there. Now square this result 9.075^2 = 82.355. Multiply this by the weight of the rifle in pounds, 82.355 x 8 = 658.845. Finally divide this by the acceleration of gravity 64.4 fps/sec = 10.23 ft-lbs Recoil. I rounded these numbers a bit in my spreadsheet and got 9.9 ft-lbs recoil, a tenth of a pound difference. Or use this calculator below which does it easily and includes products like recoil velocity and recoil impulse. This is a great way to validate the formula findings. If you round your intermediate data it may vary slightly from the on-line calculator.
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Checking the idea of the weight of the Ejecta is simple by substituting lesser or greater weight of the powder in the calculator. This surprises most shooters.
Enjoy!
