ronlaughlin

You experienced more recoil burning Blackhorn, because the bullet had more velocity than it did when burning an equal charge of black powder.

Simple physics. Conservation of Momentum
















_______________________

sabotloader

Simple physics. Conservation of Momentum


I was going to say Ron that you were incorrect with your assertion, but since Bronko did not say which FFG powder he was burning you could be correct if he we shooting a BP or sub that was not T7 or real Swiss BP. It was my assumption (which I should not make) that Bronko was shooting T7.


If he were shooting T7 or Swiss the velocity difference would depend on the weight of the projectile because of the progressive burning nature of the powder.

Again this can be verified when comparing the pressure curves on the posted chart.

bronko22000

That's pretty much what I said. Equal amounts of BP & BH the BH will give more velocity (AKA more pressure) resulting in more recoil. Maybe the words didn't come out as such but that's what I was trying to say.

sabotloader

Yes your words were read wrong be me... In today's modern world I made an assumption, and you know what happens when you assume! So the final results should be the BH, T7 or Swiss would give you a 10-15% boost.. so yep! you should have felt it.


Bronco, sorry for my assumption

bronko22000

Not a problem Sabotloader. Miscommunication or misinterpretation has lead to many an argument. Just ask my wife! But its nice when such things can be worked out in a civil manner. Even if it comes down to agreeing to disagree.

lemoyne

Now according to that, if you load Blackhorn to the same pressure as 777 the longer pressure peak will give you a lot more velocity.

bronko22000

I was shooting Goes FFg and then BH209. There was a noticeable increace in the recoil with the BH209.
Those charts were very enlightening Sabot.
And from what I gathered from the first one is that at 100gr by volume there is no significant velocity increase between T7 and BH. With that in mind someone would have to justify to THEMSELVES is the cost of BH is worth the not swabbing between shots and slightly easier cleaning aspect of BH. Even going up to a 120 gr charge there is only a 100 fps (+/-) difference between the two.
As for me I'm in the process of working with Alliant Black MZ (on the back burner now while I'm in FL for the winter). I'll have to dig out the chrony and see what results I get using it. Initial result are that this powder also burns pretty clean.

Olde NE Hunter

What is confusing is that we have a volume measurement and a mass measurement with the same label. We use grains by volume and grains by mass and they are interchangeable only when dealing with real black powder.
This is because the densities are different. Density is a ratio of mass/volume and could be thought of as “measure of compactness.” In the old days when there was only black powder a simple method was needed for reloading in the field. This was a volume measure calibrated to deliver a certain mass of powder. And if you define the density of black powder as 1 grain/volume unit then a volume measure would produce masses equal to the volume. Along come the BP Subs. There densities are different than real black now that 100 unit volume measure will not deliver 100 grains of mass.
It appears that the density for BH209 is 0.7 grains/volume unit, 777 is 0.777 grains/volume unit, and (I think) Pyrodex RS is about 0.68 grains/volume unit.
Powder is sold by mass. If you want to know how many shots per bottle you have to know the mass not the volume of each load. A one pound bottle contains 7000 grains by mass. An eighty grain by volume of Goex should have a mass of 80 grains. Therefore, (7000 grain/bottle)/(80 grains/shot) equals 87.5 shots/bottle. Both BA and RonL did this calculation earlier.
RonL states that 80 grains by volume of BH209 is 56 grains by mass. A ten ounce bottle of BH209 contains 4375 grains. Therefore, (4375 grains/bottle)/(56 grains/shot) equals 78.125 shots/bottle.

I hope I didn't confuse everyone even more.

top_prop

To through another wrench in the works... recoil... is not simple momentum... its really impulse (which is related to momentum, but not the same)... impulse is basically force over time... we like to think of the projectile instantly going down the barrel, but it takes time... and its that transfer of momentum over that time that we feel as recoil plus (once the projectile leaves the barrel) the escaping gasses continue to push the rifle back into our shoulder just like a rocket pushes and its that which is felt as recoil... that is why muzzle breaks and suppressors reduce recoil as well....

ronlaughlin

Force of the impulse on the shooter can be reduced by increasing the time. Time can be increased by utilizing a recoil pad. As the recoil pad compresses, time of the impulse is being increased; this forces the force to decrease.

Momentum is a vector. A brake redirects the gases of ignition so the gases carry some of the momentum, and this reduces the momentum/impulse of the rifle.

Recoil happens because momentum is conserved. There is zero momentum before the trigger is pulled. This means there will be zero momentum after the trigger is pulled. Wait............what about the momentum of the bullet, and the exhaust gas?? Answer: The total momentum adds to zero, because the rifle gets momentum in the opposite direction. The sum of all the momenta after the trigger is pulled, must add to zero; momentum is conserved. The impulse is a vector and equals the change of momentum vector; all changes of momentum add to zero; all impulse adds to zero.

An interesting side note: The momentum of the rifle is about equal, but opposite to the momentum of the bullet, however, the energy of the rifle is far far less than the energy of the bullet. Luckily, or we each of us, would only shoot our rifles but once.



















____________________