Recoil impulse vs felt recoil

[kujuak]

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 purchase of a used Sako 75 standard rifle. I have been very pleased with how comfortable this rifle is to shoot. So now I have two new parameters for rifle behavior "jerk" and "torque".

 

[wboggs]

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

In my illustration of the .416 Rem mag vs the .416 Rigby y, I was using a slower powder in the Rigby and your theory fits.

 

[ASbobcat]

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

Torque and it's effects on accuracy are not discussed enough. I always select the slowest rate that will serve my purpose.
In addition to movement of the firearm, there are negative effects on bullet jacket stress and bore friction.

 

[Coyotefurharvester]

I went to H380 in my 338wm, slower push. Same bullet and velocity. It's a hunting rifle, type of recoil is also part of a follow up shot.

 

[Wild Bill IV]

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 .

You ask for a physicist, how about 105 HR of pure applied science credits (mostly physics, then math)

Most of the felt recoil is the reaction of the sum of the bullets momentum and the unburnt powder momentum packed behind the bullet! Those momentums are increasing as the powder/bullet accelerates. Plus, the thrust of the exhausting gases add to the felt recoil!!! Felt recoil is an increasing reaction!

Impulse is a time factor!!!! Just think of the term PULSE!!! Impulse is the duration of time with respect to the acceleration of the changing momentums down the barrel!!!

Why do some slightly lower velocity loads kick harder than another load with different powder and higher velocity loads??? A faster burning powder will peak faster than a slower burning powder!! The faster burning powder will generate hydrostatic pressure faster, but will also loss the hydrostatic pressure and ideal gas laws take over sooner and longer!!! This results in a really fast acceleration and then a coasting acceleration!!! Slower burning powders tend to have a slower but consistent acceleration and can have little or no coasting effects from gas pressure!! Thus, the slower burning powder could have less felt recoil, slightly higher MV, with a drawn out Impulse!!

Bill!!!!!!!!!

 

[chop house]

There is another variable not yet mentioned - that would be the velocity of the ejecta. Would that not relate to muzzle pressure, amount of unburnt powder, and back past the pressure curve to ultimately burn rate?

I am playing with a very light weight 20" 7 mm-08. I have some lower energy hunting loads with speer 130 and h414. Pretty manageable. My Supply of those bullets is limited. So I tried using 110 tnt for practice, but the fireball with h414 is just too much. Was just thinking of going faster powder (varget) but would I be trading fireball for sharper recoil???

 

[Doom]

There is another variable not yet mentioned - that would be the velocity of the ejecta. Would that not relate to muzzle pressure, amount of unburnt powder, and back past the pressure curve to ultimately burn rate?

I am playing with a very light weight 20" 7 mm-08. I have some lower energy hunting loads with speer 130 and h414. Pretty manageable. My Supply of those bullets is limited. So I tried using 110 tnt for practice, but the fireball with h414 is just too much. Was just thinking of going faster powder (varget) but would I be trading fireball for sharper recoil???

You are correct that the gas/unburnt powder is a significant portion of the recoil. Whether its powder or gas is pretty much a moot point since the powder contains all of the ultimate combustion products. In fact the ejecta can run about 40% or more of the recoil.

https://saami.org/wp-content/uploads/2022/11/Gun-Recoil-Formulae-2018-07-9.pdf

 

[chop house]

You are correct that the gas/unburnt powder is a significant portion of the recoil. Whether its powder or gas is pretty much a moot point since the powder contains all of the ultimate combustion products. In fact the ejecta can run about 40% or more of the recoil.

https://saami.org/wp-content/uploads/2022/11/Gun-Recoil-Formulae-2018-07-9.pdf

Yes. Just went to @dellet ref thread and while not wading through the entirety of the sidebar pissing match he did a great job of designing an experiment with equal masses, equal velocities, but unequal burn rates.

I then wonder if my muzzle flash contributes more to perceived recoil than actual. I shall proceed with trying varget in my specific case but any results will only be anecdotal since I don't have velocity data.

 

[chop house]

Which brings me to another mostly academic question. Does bullet seating depth have any bearing in any of this, assuming equal mv? Perception being deep seating having smoother acceleration (or vice versa?)

 

[Doom]

Which brings me to another mostly academic question. Does bullet seating depth have any bearing in any of this, assuming equal mv? Perception being deep seating having smoother acceleration (or vice versa?)

I would think that with a good choice of powder it would not make a noticeable difference as long as the bullet has a run to the lands. If it is jammed then the pressure is higher when the bullet begins to move so it accelerates faster hence more jerk. Perceivable? I don't know.

 

[searcher]

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

Yeah - while stock configuration (and weight) plays a large part in felt recoil between different rifles, the WORST kicking medium bore cartridge I ever shot was a friend's wood-stocked sporter .308. It had a significantly worse bite than my 7 MM Rem. Mags.

 

[divingin]

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.

Not rifle related:

Pistol weight may come into play here; weight goes a long way in reducing felt recoil, as does a larger grip. As lot of other factors, too, recoil spring weight being a prime candidate.

If pistol a is sprung lighter to the point where the slide is moving smartly backwards at the time it is stopped by the frame, you'll get a much sharper recoil impulse than one where the slide is slowed by the spring compression before hitting the stop.

Reacting to the impending shot will often soften the felt recoil as well (easiest to see with a 22 pistol: Breaking the shot cleanly results in a feel like someone popped the muzzle with a hammer, while moving first results in softer, more prolonged felt recoil.

 

[JEFFPPC]

Recoil is recoil. What you feel is what you feel. While you are no doubt technically correct that does not relate to the crux of this post. Of course your entitled to your opinion just as I am.