Differences in Recoil but Same Bullet Weight

[Rule3]

No it wouldn't, the break or comp is diverting gas. Not in burned powder. So one would have to determine which powder is putting out more "gas" of equal charge and velocity.

Kinda like Win Auto Comp claim of "filling the comp with gas" Which is all BS . If a powder produces more "gas" then it is gonna increase, pressure velocity and most probably be a slower burning powder. More Nitro perhaps??
Then of course is the length of the barrel and all kinds of other variables.

 

[Toprudder]

No it wouldn't, the break or comp is diverting gas. Not in burned powder. So one would have to determine which powder is putting out more "gas" of equal charge and velocity.

Kinda like Win Auto Comp claim of "filling the comp with gas" Which is all BS . If a powder produces more "gas" then it is gonna increase, pressure velocity and most probably be a slower burning powder. More Nitro perhaps??
Then of course is the length of the barrel and all kinds of other variables.

Since the powder contains its own oxidizer, then the mass of the gas coming out of the barrel is proportional to the mass of the unburned powder. So, the gas comes from the powder, plain and simple. More powder, more gas. The velocity, though, will be a little harder to pin down, but it should be related to the pressure achieved by the combustion. But everything coming out of the end of the barrel was contained in the unfired cartridge, except for the air column in front of the bullet.

 

[Blue68f100]

In most cases you do not get un-burnt powder. What you see is a residue that did not completely burn up, normaly due to lower pressure. If it's truly un-burnt powder you should be able to light set it off with a heat source. I have not been able to set any residue off.

 

[25-20 WCF]

The velocity of the powder gas exiting the muzzle varies with the muzzle pressure, but Lyman and others estimate around 4500-5000 fps. This elevates the portion of recoil energy the powder provides, especially with handgun cartridges and their low projectile velocities. I know that my .45 LC loads wiith BlueDot versus H110 (same velocity) recoil noticeably less, and muzzle blast is much lower too. Overall much more pleasant to shoot. Yes, velocity can be higher with H110, but then I don’t need the maximum possible velocity....


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[Rule3]

This thread is another Seinfeld Episode

 

[WrongHanded]

This thread is another Seinfeld Episode

Thanks for your contribution.

 

[Toprudder]

In most cases you do not get un-burnt powder. What you see is a residue that did not completely burn up, normaly due to lower pressure. If it's truly un-burnt powder you should be able to light set it off with a heat source. I have not been able to set any residue off.

What I meant by unburned was the raw powder before ignition.

But, yes, I have taken residue and ignited it. I helped a friend of mine at the indoor range where he worked, he swept up the brass in front of the firing line and dumped it in a bucket. I took the bucket and sorted the brass, there was an amazing amount of unburned powder in the bottom of the bucket and it did light up when I put a flame to it.

 

[fxvr5]

Here's an article that looks at the deal with gunpowders and compensators:

http://www.shootingtimes.com/editorial/compensators-pressure-gas/99170

It might address some points in previous posts.

 

[Walkalong]

In my comped .38 Super I have two loads, one with N320 (A 124 @ just short of 1200 FPS) and one with 3N37 using 2.2 Grs more powder (A124 @ just over 1300 FPS). The latter has more recoil but shots just as flat due to the higher volume of gas working through the comp. It takes gas to work a comp.

 

[Jim Watson]

Computed recoil is a momentum (not energy) balance that includes the bullet mass x velocity plus powder mass x (assumed) velocity. Some calculators take powder gas velocity as 4500 fps, others set it proportional to bullet velocity, I have seen 150%. That makes more sense to me, you are not getting proportionally the same "jet effect" from 5 grains of powder driving a pistol bullet at 1000 fps as 50 gr of powder propelling a rifle bullet at 3000 fps; muzzle pressure is very different.

Differences in felt recoil have to come from somewhere. Bullet acceleration down the barrel is the usual suspect, and is affected by bullet friction and powder pressure curve. You've got acceleration and you've got change in acceleration, "surge." Mr Davis worked on that a lot but it is over my head.

Of course if you start throwing in the feel of gun design with different weight, height of bore, grip/stock shape, and muzzle brake/compensator, a lot of fine physics goes out the window.

 

[mcb]

The first derivative of position with respect to time is Velocity
The second derivative of position with respect to time is Acceleration
The third derivative of position with respect to time is Jerk.
And amusingly enough the forth, fifth and six derivatives of position with respect to time are... Snap, Crackle and Pop. (not terrible useful for most calculations but amusing if you're a nerd)

The propellant velocity for recoil calculations is always a hard thing to estimate. As other have noted it is not constant and changes as the pressure drop at the muzzle after the bullet exits so methods usually try to come up with an estimate for the average velocity. SAAMI uses a multiplier based on the gun type and projectile velocity. The multiplier is 1.25 for long barreled shotguns, 1.5 for standard shotguns and handguns and 1.75 for center fire rifles.

https://saami.org/wp-content/uploads/2018/07/Gun-Recoil-Formulae-2018-07-9-1.pdf

This method along with most purely calculated recoil values are an estimate. In reality the portion of recoil due to propellant gases is hard to estimate accurately and really needs to be measured for a given cartridge and barrel length (and muzzle device if you have one). This is measured in one of two common ways.

The old school method of using a ballistic pendulum where the firearm in mounted on a 3-point pendulum that is free to swing in the direction of recoil. Fire the gun and record the velocity of the projectile and the motion of the pendulum. The equation of motion of a pendulum is extremely well understood and that motion results in a direct calculation of the momentum imparted by firing the gun. Subtract the easily calculate momentum of the projectile and you are left with the momentum imparted by the propellant gases. This method goes back to research done before the common use of electricity. The motion was recorded by stylist on paper laid on the ground under the pendulum. Though with modern high speed cameras this method is pretty easy and effective and getting cheaper everyday.

The more modern way is to build a recoil sled that measure the recoil force vs time curve. It can be a much more compact measurement system, though a bit more expensive. The recoil impulse is then the integral of force vs time curve (area under the curve). The caveat here is the actual level of force at any given time is sort of meaningless as the way the gun is supported will have a dramatic effect on the force magnitude and duration but the area under the curve should remain constant. ie if you hard mount the gun to the force gauge and shooting a fixed breach gun with a hard recoil pad your going to see extremely high force over very short time period. If you soft mount the force sensor on a spring dampened base and are firing a semi-auto with a soft squishy recoil pad the force vs time curve will have much lower peak forces spread out over a much greater time frame. This method requires moderately expensive force gauges and data acquisition hardware that can sample the data fast enough. 20,000 samples/sec or faster is typical. This method is great for comparing things like different recoil pads or different muzzle breaks you just have to be careful not to read too much into the magnitude of the force (due to the effect the support method has on that) and use it more as a relatively difference measurement than and absolute measure.

-Rambling

 

[Rule3]

Thanks for your contribution.

I gave it in post #23. Your contribution did not have enough information to go on.

 

[ATLDave]

I gave it in post #23. Your contribution did not have enough information to go on.

Is that the post where you said there was no data about variances in powder having an impact on recoil? Because there has been a lot of data on that, and some of it has already been provided in this thread.

 

[ATLDave]

The first derivative of position with respect to time is Velocity
The second derivative of position with respect to time is Acceleration
The third derivative of position with respect to time is Jerk.
And amusingly enough the forth, fifth and six derivatives of position with respect to time are... Snap, Crackle and Pop. (not terrible useful for most calculations but amusing if you're a nerd)

You know, I thought this was a joke (we didn't cover this in high school beyond the first two). Imagine my surprise! http://wearcam.org/absement/Derivatives_of_displacement.htm

 

[Jim Watson]

Found a reference citing G. Harry Stine:
G. Harry Stine [3] has noted several other, specific implications:
· The human body responds to rate-of-onset of acceleration, a third derivative force.

 

[WrongHanded]

I gave it in post #23. Your contribution did not have enough information to go on.

Well if we for a moment assume that the DT ammo is moving at very close to their advertised 1400fps, and that my load was at 1300fps, does that help? How about if the two loads were at the same velocity? You stated in a previous post:

.... Plus there is actual recoil and felt or perceived recoil. The OP "felt" something.

Is that not how we all notice recoil whilst shooting? Yes, I "felt" something. I felt less recoil with the DT load than with my reload. I "felt" the difference repeatedly, because after I first noticed it, I alternated loads specifically to confirm it.

And yes, the reality is that I did not chrono the loads. If I had a convenient place to shoot, where I was able to use a chronograph, I would own one and use it often. It's currently not feasible. But I've yet to see a reloading manual load that is equal to or greater in velocity (for a given barrel length and bullet weight) than manufacturers like Double Tap, Buffalo Bore, or Underwood. There may be some, but I have not personally seen any yet.

Could the DT ammo be performing at a much lower velocity than claimed? Yes. Could something be amiss with my reloads causing them to be much faster than those who test and record the data have found? Yes. But barring those two things, which seem unlikely to any great extent, I simply wanted to know if any other reasons could exist.

As it happens, I did find a few snippets of information floating around on the web. Apparently, blending powders to create a more sustained peak pressure (or at least greater pressure for longer), is part of how DT get the velocities they do whilst staying under pressure limits. How that would effect recoil I do not know. But it's quite interesting.

At any rate, you want velocities? You now have them. And the ones I made up are every bit as credible as anything I could chrono as far as you're concerned....because even if I told you I got them from a chronograph, how would you know?

 

[Walkalong]

He would trust you to be honest?

It really is hard to make a comparison or debate it without knowing both velocities.

 

[Rule3]

Is that the post where you said there was no data about variances in powder having an impact on recoil? Because there has been a lot of data on that, and some of it has already been provided in this thread.

No I do not believe I said that??


From the OP here is what info we have
I decided to shoot some Double Tap .357 Mag 158gr "Bonded Defense" (looks like Gold Dots) at the range recently, along side my reloads. They are an SNS 158gr coated LSWC with 14.5gr of 2400 and a CCI SPP. I can't currently remember what the manual was claiming for velocity on the reloads at that charge, but it is certainly less than the Double Taps claimed 1,400fps from a 4" GP100 (which happened to be what I was using).

Now I didn't chronograph these rounds, but I felt an obvious increase in recoil with my reloads to the DT ammo. And I'm wondering, other than velocity, what could cause that? Different powders, jacketed vs coated lead, or something else?

DT ammo, Do we know what powder or how much?? NO
Actual velocity do we know that? NO

OP loads
Bullet YES
Powder charge YES
Actual velocity? NO

So from that it is all just guess work as there is nothing to go on. Even using a simple recoil calculator is not an option.

So to determine something, facts are needed.
I am not going to debate this any more.

Recoil Energy Calculator
Use this calculator to calculate the recoil on you rifles, handgun, and other firearms. After you input the necessary data such as the bullet weight, bullet velocity, powder charge weight, and the firearm weight it will output the recoil impulse, recoil velocity, and the recoil energy of the firearm. With this data you can estimate the felt recoil of a specific firearm and cartridge. Remember that "felt recoil" may be a little different from these numbers because felt recoil depends on the design of the firearm, how you hold it, recoil pads, and other factors. Use the chart below to see the recoil energy of common cartridges. Also you may create your own recoil chart and share it with others.

The numbers calculated here do not relate to "felt recoil". Felt recoil is different for each person, what is excessive for me might not be for you and vice versa.

http://www.shooterscalculator.com/recoil-calculator.php

 

[ATLDave]

Then I must have misunderstood this:

Yes the physics show the weight of the powder in the calculation, but if there is only say a few grains of powder difference fast vs slower) no one is going to feel 3 to 5 grains of powder every thing else equal (including velocity)

Because, in fact, plenty of people will feel the difference between a charge of slow powder and a charge of faster powder that achieve the same velocity, but at different charge weights. That is definitely a thing, nor does it fall into the more subjective/individually-dependent realm of stuff like blast/flash-as-recoil, or spring rates on pistol slides, or the like.

You are correct that we cannot know whether that is what is going on with the OP, because, among other things, we don't know the velocities. But the OP asked "what, other than velocity, could cause that." "Could," not "did." A different powder can absolutely be the cause of something like what the OP is describing. Was it the cause? You're right, we cannot know based on the information available.

 

[WrongHanded]

He would trust you to be honest?

It really is hard to make a comparison or debate it without knowing both velocities.

My point is not really that the data (could I give it) would not be trusted. But certain things can be taken for granted. One thing would be that I did in fact feel a difference in recoil, and that feeling that difference is because one load produced more than the other.

My point, is that I don't see why the exact velocities are needed to answer my question: "....I felt an obvious increase in recoil with my reloads to the DT ammo. And I'm wondering, other than velocity, what could cause that?" Assuming that I did not imagine the difference, there either is a reason or there is not. If there is not another reason for it, then only two possibilities remain; I did imagine it; or my load is going faster.

At this point, it seems one plausible explanation has emerged thanks to some very knowledgeable individuals. And I'm quite satisfied with that. It does however seem unnecessary to claim my question simply cannot be answered because I didn't not chronograph the loads. To then try and dissaude others from taking part in the thread, is even more unnecessary. If someone does not want to discuss a topic it's simple to avoid doing so, not to mention being a polite course of action.

 

[ATLDave]

Just to be clear, WrongHanded, we cannot confidently answer why, in your specific case, one load recoiled more than the other. There are several possibilities, and a difference in velocity (contrary to expectations based on box or book numbers) is a very real one. Powder speed and weight differences are another. There's also the possibility that the two loads have similar overall mechanical recoil, but that you are perceiving your handload as having more because of the flash and/or blast.* There may be other explanations. There's no way to confidently pick one or the other based on the information available, but we can say that at least those explanations are possible.

* People's brains often synthesize different sensory data into a single perception. The golf industry alters the sound their clubs make in order to effect golfers' perception of how the club feels. Beverage makers know that there is no such thing as strawberry flavor. There is strawberry odor, and if you combine it with sweet flavor, your brain will "taste strawberry." This is normal human brain function.

 

[WrongHanded]

Just to be clear, WrongHanded, we cannot confidently answer why, in your specific case, one load recoiled more than the other. There are several possibilities, and a difference in velocity (contrary to expectations based on box or book numbers) is a very real one. Powder speed and weight differences are another. There's also the possibility that the two loads have similar overall mechanical recoil, but that you are perceiving your handload as having more because of the flash and/or blast.* There may be other explanations. There's no way to confidently pick one or the other based on the information available, but we can say that at least those explanations are possible.

* People's brains often synthesize different sensory data into a single perception. The golf industry alters the sound their clubs make in order to effect golfers' perception of how the club feels. Beverage makers know that there is no such thing as strawberry flavor. There is strawberry odor, and if you combine it with sweet flavor, your brain will "taste strawberry." This is normal human brain function.

Dave, I completely understand what you're saying. I didn't write the OP expecting a definitive answer. And I was (and am) aware that box and book velocities are not precisely accurate (or sometimes even that close at all). I also realize that what I perceive may not be a true representation of an event, such as in this case, recoil.

Part of the reason for the OP, was that between the theoretical velocities and the difference in recoil I felt whilst shooting the two loads, something was obviously not lining up. So asking what else it could be was a way to estabilish if the velocities or my perception we're the only two viable explanations.

I appreciate your input. Thank you.

 

[Walkalong]

Because, in fact, plenty of people will feel the difference between a charge of slow powder and a charge of faster powder that achieve the same velocity, but at different charge weights. That is definitely a thing

Yes it is, although we had a very spirited debate here with folks who did not believe some of us could.

 

[labnoti]

I know that when I load a 158 grain bullet on top of 14 grains of H110, the recoil is a LOT more than if I load the case with enough Longshot to get the same velocity, which is roughly half the weight. With the H110 load, 14 grains of mass is being accelerated to a much higher velocity than the bullet. Because the velocity of the powder (and gas) is not a constant (some bits of powder might be at bullet velocity while some of the gas could be going four thousand fps), most recoil calculation formulas use a factor of 1.5 times the muzzle velocity of the bullet. So if the 158 grains of bullet mass is being accelerated to 1000fps, the 14 grains of powder mass is being accelerated to 1500fps (for the purpose of calculation). If the differences of powder mass are as much as 7 to 10 grains, that much mass going 1500fps will make a noticeable difference in recoil. Of course this is not the only thing that can affect felt recoil, but given the same gun, same bullet (not just same bullet mass), and same velocity, it is a factor.

The way I understand ball powders at least, the propellant's bases (nitroglycerin and nitrocellulose) are coated in deterrent materials and the amount and type of deterents result in different burn rates at various pressures. A simplified way of thinking about two different powders would be to imagine adding the mass of the deterent to the mass of the bullet. If one powder has more deterent than another, more mass will be accelerated. This is ignoring how the deterent effects the pressure-over-time curve but the bottom line is that at the end of combustion, a greater mass was accelerated.

Besides deterent, I speculate there may be a perceptible difference in felt recoil when using single-base vs. double-base powders. H110, Li'l Gun and IMR4227 can generate very similar velocities with similar powder masses in some cases. I wouldn't be surprised if I could match powder mass and bullet velocity with the same bullet and yet still tell the difference between Li'l Gun and IMR4227. I speculate the nitroglycerin will make itself known. Now it may not be in actual recoil force, but "felt recoil" has a lot to do with perception and not just physical forces.

 

[murf]

murf, there's a lot of data out there to the contrary. See, e.g., http://www.shootingtimes.com/editorial/measure-relative-handgun-recoil/99442

As mcb mentioned, the weight of powder punches above its weight because the gasses that the powder turns into are generally of significantly higher velocity than the projectile. So they contribute more to the recoil than the difference in their weight.

Here's an excerpt of that article showing what was measured by tracking the movement of a ransom rest arm by various loads from the same gun. Note that, at any given point along the horizontal access, velocity is the same. The projectiles were the same. The gun was the same. The only difference is the type and amount of powder used to achieve the velocities.

View attachment 810723

As you can see, if you compare a mid-slow powder like HS6 to an faster powder like N320, you get equivalent recoil (the vertical axis) at velocities that are ~75-100 fps apart.

Throw in the blast/flash that most people process as being recoil, and it starts to make a BIG difference.

thanks for the extra info, atldave. i'm just skeptical that the force generated by the powder gases is twenty percent of the total force. i don't think a shooter can tell the difference in powder charge by feeling the difference in the recoil of the pistol.

murf