Recoil impulse vs felt recoil

[kujuak]

While working up some new loads for my 300WM hunting rifle using Nosler Partition bullets. My load using H1000 powder (a full case, not maximum) load gave me an average velocity of 2930fps. The recoil was quite sharp (not sure if that's the right term, but the recoil torqued the rifle in my hands). On the other hand my H4350 load gave me a velocity of 2975fps. The recoil was quite noticeably less and smoother (mor eof a push rather than a violent shove).

Does this reflect different pressure curves in between the two powders or the case fill % difference? Without the chrono data i would have assumed the H1000 was the "hotter" and presumably faster load.

 

[JEFFPPC]

Can not answer your question but I do agree with you. I hear folks with a 9mm dropping to a .380 handgun for less recoil. Recoil impulse of a .380 to me is much sharper than a 9. I learned this from my wife years ago. She told me and I frowned. Then I shot her 380 and my 9 back to back. She is correct.

 

[6.5 forever]

Can not answer your question but I do agree with you. I hear folks with a 9mm dropping to a .380 handgun for less recoil. Recoil impulse of a .380 to me is much sharper than a 9. I learned this from my wife years ago. She told me and I frowned. Then I shot her 380 and my 9 back to back. She is correct.

Some of that may relate to the difference between the handgun weight and barrel length.

 

[Laurie]

Remember that recoil impulse is also determined by the charge weight on top of bullet weight / MV. Your powder charge is converted to high-speed gas that exits the muzzle just like the bullet, but is travelling faster. That's why all recoil calculators ask for propellant charge weight alongside the other variables. Presumably your H1000 charge was considerably heavier than that of H4350.

 

[rijndael]

Remember that recoil impulse is also determined by the charge weight on top of bullet weight / MV.

I have a 139 Scenar load, 2950 fps, that seems to recoil a bit less than a 130 Berger going 2900. The Berger feels much sharper. My shooting buddy confirmed my findings too. I suspect the feel of it involves some nuances not captured in just MV and Grains. Perhaps it's the interaction with the brake, possibly having higher muzzle pressures, making it feel different.

 

[Laurie]

Perhaps it's the interaction with the brake,

Muzzle brakes change everything and it's long been known that they work best with a small calibre high MV load due to higher gas speeds. Back in the days of Practical Pistol using specialised custom 'race guns', the arrival of brakes encouraged the move from 45ACP to 38 Super and IIRC a 38/45 ACP wildcat.

 

[RegionRat]

When starting out in ballistics, it takes lots of experience to make good assumptions, so let the real data lead your choices and don't make a habit of guessing for now.

Yes, powder characteristics make a distinct difference in your perception of recoil and discomfort when shooting just about any type of human supported weapon, even when all other things are equal.

It just happens much faster and depending on the energy level and the weight of the rifle, the damping etc., it can be severe.

 

[markm87]

I've noticed the same thing with H1000 vs Reloader in our 300WM loads. Got more velocity with Reloader with less pressure signs and recoil.

I tried to search an old post by someone on M4carbine.net, but couldn't find it. The guy mentioned that H1000 was a little dirtier and yielded more build up in the rifle suppressor too.

We run RWS brass which is much beefier than FC for example. It holds up to 10+ loadings with the Larry Willis collet die for belted mag brass.

We'd dump H1000 completely, but the ammo is accurate, and we have a big stash of the powder.

 

[wboggs]

While working up some new loads for my 300WM hunting rifle using Nosler Partition bullets. My load using H1000 powder (a full case, not maximum) load gave me an average velocity of 2930fps. The recoil was quite sharp (not sure if that's the right term, but the recoil torqued the rifle in my hands). On the other hand my H4350 load gave me a velocity of 2975fps. The recoil was quite noticeably less and smoother (mor eof a push rather than a violent shove).

Does this reflect different pressure curves in between the two powders or the case fill % difference? Without the chrono data i would have assumed the H1000 was the "hotter" and presumably faster load.

I don't know the answer to your question but I agree it exists. A .416 rem with a 400 gr bullet at 2400 fps has a sharper recoil than a .416 rigby with the same bullet/ velocity in the same weight rifle. I always thought it was the difference in pressure of the two loads. The worst rifle I ever shot was a friend's .378 wby with a 300 gr factory load in a factory rifle with iron sights. It was awful.

 

[kujuak]

I don't know the answer to your question but I agree it exists. A .416 rem with a 400 gr bullet at 2400 fps has a sharper recoil than a .416 rigby with the same bullet/ velocity in the same weight rifle. I always thought it was the difference in pressure of the two loads. The worst rifle I ever shot was a friend's .378 wby with a 300 gr factory load in a factory rifle with iron sights. It was awful.

Complicated stuff indeed. A little looking found this gem (for me)..."The average pressure applied to the bullet in the barrel determines the velocity. The problem is keeping that average pressure high while making sure the peak pressure stays within limits. Average pressure gives velocity, PEAK PRESSURE BLOWS THINGS UP. (Capitals are mine.). Reading about chamber pressure/velocity/recoil impulse was very confusing with some conflicting views. Maybe a sage, learned ballistic engineer or physicist could unravel this matter for a dense , cell biology major .

 

[wboggs]

Complicated stuff indeed. A little looking found this gem (for me)..."The average pressure applied to the bullet in the barrel determines the velocity. The problem is keeping that average pressure high while making sure the peak pressure stays within limits. Average pressure gives velocity, PEAK PRESSURE BLOWS THINGS UP. (Capitals are mine.). Reading about chamber pressure/velocity/recoil impulse was very confusing with some conflicting views. Maybe a sage, learned ballistic engineer or physicist could unravel this matter for a dense , cell biology major .

This needs to go to another pay grade but after 80 years of shooting and 75 reloading I've noticed it many times

 

[Doom]

Felt recoil is due to the acceleration of the rifle in reaction to the bullet and powder acceleration. This acceleration is not constant and changes with time and pressure. This rate of change in acceleration is called jerk. The greater the jerk the stronger the impulse will be felt. I assume that is what we feel in instances like described and it would imply that the bullet and powder acceleration is different which implies the combustion and pressure curve are different.

Several years ago I read a paper on this and yes, jerk is term used in physics. If I find that paper I'll post a link

 

[AGSHOOTER]

While working up some new loads for my 300WM hunting rifle using Nosler Partition bullets. My load using H1000 powder (a full case, not maximum) load gave me an average velocity of 2930fps. The recoil was quite sharp (not sure if that's the right term, but the recoil torqued the rifle in my hands). On the other hand my H4350 load gave me a velocity of 2975fps. The recoil was quite noticeably less and smoother (mor eof a push rather than a violent shove).

Does this reflect different pressure curves in between the two powders or the case fill % difference? Without the chrono data i would have assumed the H1000 was the "hotter" and presumably faster load.

No experience with them powder bit will have to say its the difference burn rate what you are feeling

 

[kujuak]

Felt recoil is due to the acceleration of the rifle in reaction to the bullet and powder acceleration. This acceleration is not constant and changes with time and pressure. This rate of change in acceleration is called jerk. The greater the jerk the stronger the impulse will be felt. I assume that is what we feel in instances like described and it would imply that the bullet and powder acceleration is different which implies the combustion and pressure curve are different.

Several years ago I read a paper on this and yes, jerk is term used in physics. If I find that paper I'll post a link

Thanks, that makes alot of sense. For my purposes in this case (hunting load) the less the jerk , the better. Fascinating stuff indeed. The Zen art of reloading/shooting

 

[SteveOak]

The feel of recoil, snap or more push, is related to the burn rate of the powder.

 

[dellet]

It’s a combination of many things, but pressure over time is what you’re looking at. That will certainly vary with powder burn rates. But burn rates change with load density. You find yourself in an endless circle until you can mange to come up with multiple loads, where the only difference is powder burn rate. Same charge weight, bullet and loaded length.

Then you can start to see the time in barrel, where, when, length and peak of the pressure curve. That will start to give you some numbers to look at.

After crunching all the numbers, it all comes down to feel. So all the math in the world becomes something subjective. The torque is different than the recoil. The torque is more the rifle trying to spin with the bullet, that will have more to do with acceleration of the bullet. In some ways how hard it is driven into the lands, starting speed and pressure.

I played with the exact thing a few years ago with a 45-70 with interesting observations.

Powder choice/burn rate and recoil. How are they related, How do you predict or measure effect?

After a few years of ignoring them, I started shooting my single shot rifles again. Two things have happened in that time. I've gained some knowledge about loading, and I have gained some years. It did not take too many shots to remember why casual competitive shooting was too many rounds in a...

forum.accurateshooter.com

 

[ASbobcat]

Felt recoil is due to the acceleration of the rifle in reaction to the bullet and powder acceleration. This acceleration is not constant and changes with time and pressure. This rate of change in acceleration is called jerk. The greater the jerk the stronger the impulse will be felt. I assume that is what we feel in instances like described and it would imply that the bullet and powder acceleration is different which implies the combustion and pressure curve are different.

Several years ago I read a paper on this and yes, jerk is term used in physics. If I find that paper I'll post a link

My physics is a little old (53yrs), but as I recall:

Velocity is the first derivative (rate of change) of displacement.
Acceleration is the second derivative (rate of change of velocity).
Jerk is the third derivative (rate of change of acceleration).

Albert may wish to correct me.

 

[Doom]

My physics is a little old (53yrs), but as I recall:

Velocity is the first derivative (rate of change) of displacement.
Acceleration is the second derivative (rate of change of velocity).
Jerk is the third derivative (rate of change of acceleration).

Albert may wish to correct me.

Albert says you have it right.

 

[Tommie]

I’ve always felt that a 308 jabs more than a 30-06.

 

[kujuak]

It’s a combination of many things, but pressure over time is what you’re looking at. That will certainly vary with powder burn rates. But burn rates change with load density. You find yourself in an endless circle until you can mange to come up with multiple loads, where the only difference is powder burn rate. Same charge weight, bullet and loaded length.

Then you can start to see the time in barrel, where, when, length and peak of the pressure curve. That will start to give you some numbers to look at.

After crunching all the numbers, it all comes down to feel. So all the math in the world becomes something subjective. The torque is different than the recoil. The torque is more the rifle trying to spin with the bullet, that will have more to do with acceleration of the bullet. In some ways how hard it is driven into the lands, starting speed and pressure.

I played with the exact thing a few years ago with a 45-70 with interesting observations.

Powder choice/burn rate and recoil. How are they related, How do you predict or measure effect?

After a few years of ignoring them, I started shooting my single shot rifles again. Two things have happened in that time. I've gained some knowledge about loading, and I have gained some years. It did not take too many shots to remember why casual competitive shooting was too many rounds in a...

forum.accurateshooter.com

Very insightful observation! Indeed it was not just recoil but the rifle twisted in my hands also. The twist was so severe as to impact my follow through after the shot. The change was quite notable. One load gave the expected back push of a magnum round, the other a violent twist. I had a similar experience with a Sako finnlight in 300 WinMag, hence my recent ac