effects of fast/slow powders on felt recoil

dgang · March 22, 2017, 02:46 PM

A question to those who might know: If I were to load a cartridge with say a 158 gr. .357 dia.bullet with a fast burning powder like Bullseye to produce 1000 fps, would the felt recoil be the same as , less than, or greater than that same cartridge loaded with a slow burning powder like 2400? Same bullet @ the same velocity, Same recoil?
Thanks in advance, dang

NoSecondBest · March 22, 2017, 03:01 PM

You wouldn't notice any difference. The time difference in the burn is too minute for you to notice anything. I've shot .357mag for fifty years and I've used, and use, just about every powder that's been available. After several hundred thousand rounds I haven't noticed anything different.....when they're loaded to the same velocity.

jmr40 · March 22, 2017, 03:45 PM

Recoil is calculated with mathematical equations with the following factors.

Weight of projectile
Weight of firearm
Weight of powder charge
Velocity of the projectile

The rate of burn isn't a factor.

If you can find a powder (or cartridge case) that will achieve the same speed with less powder you will have less recoil. In some cases there enough difference to be noticeable. If a 308 and 30-06 are loaded to shoot 150 gr bullets at 2850 fps, the 30-06 will need more powder to achieve that speed and will recoil more. Some case designs are more efficient.

I think you could very easily see the same speed with 357 Sig and 357 mag and notice a difference in recoil.

Recoil speed is also a factor not always understood. You could load the 357 mag with 158 gr bullets and 125 gr bullets and mathematically have exactly the same recoil. But the heavier bullet with the slower speeds means recoil is spread out over a few milliseconds longer time. The actual recoil may be exactly the same, but most people would find the 158 gr load more comfortable.

Reloadron · March 22, 2017, 04:31 PM

If you want to read about FREE RECOIL ENERGY here is a link to the SAAMI Data and formula. Hatcher's notebook also covers it pretty well.

There is the actual calculated FRE (Free Recoil Energy) and there is also "felt recoil" the latter being how the free recoil energy feels to each individual shooter.

A Google of free recoil energy calculator will bring up several online calculators. What is interesting is with the same data put into several of these calculators you can often get different results. There are also several Excel Spreadsheet examples out there to be had. The data from Hatcher's Notebook is pretty good stuff.

Ron

Nick_C_S · March 22, 2017, 05:44 PM

Quote:

Same bullet @ the same velocity, Same recoil?

Nope. Definitely not. I have proven this to myself out at the range countless times. It is especially true with short barreled guns.

All else being equal, the slower propellant will have a lot more "thrust recoil;" that is, the effect of the propellant pushing back on the gun via residual thrust, once the bullet exits the muzzle. There's probably more technical terms for all of this, but it's basically the same action/reaction that propels rockets into space.

Faster powders are more "expended" than slower powders, when the bullet exits the muzzle. i.e. the faster powder will have less thrust.

This fact of physics is important to understand when loading ammunition proper for shorter barreled guns in particular (unless you like recoil). I've been down this road countless times.

**44 AMP** · March 22, 2017, 05:48 PM

After getting lost in a couple of discussions about recoil energy and how to calculate it, I have decided that it is essentially a waste of time.

Finding the numbers might be useful as a comparison, for some folks, but what matters to me more is what I FEEL, and that involves a LOT of factors, both objective and subjective.

You might notice a difference in recoil from a slower powder, you might not. Loaded to the same speed, the slower powder will use more powder, and produce more muzzle blast. And that might make the recoil seem like more than a faster powder which at that same speed might seem more like a "pop" than a "blast".

Or you might not.

Calculate all you want, two different people can have two different opinions about the "feel" no matter what the numbers say.

Personally this issue never comes up for me, as I don't load fast powders up to the velocities I load slower powders to get.

Nor do I down load slower powders, to me that's just a waste (the exception being if a certain gun shows a clear preference for a certain powder).

In other words, I don't use Bullseye when I want 1200fps nor do I use 2400 when I only want 850fps.

briandg · March 22, 2017, 06:54 PM

Even if there was a tiny bit of acceleration difference, which is what people always think would lessen the "punch" of the recoil, if your slow powder charge is 10 _ 20% heavier, the total impulse, or recoil energy, will be increased. Some.

May not be all of the proper terminology, but the basics are that combined powder and bullet charge factored with velocity determines the actual recoil energy, and that the acceleration of the charge up the bore can't possibly make a noticeable difference.

What the individual feels is obviously an individual experience. When that round goes off, perceived recoil will be affected by the noise, flash, size and shape of the gun, any of these may make a bigger perceived difference than other factors.

When I run a series of pistol rounds upward, I notice increases in noise and flash and that makes it feel like the recoil itself has increased. But, for example, if I push the charge up two grains on a 158 grain bullet, raising the velocity 150 or so fps, that's really almost insignificant as far as actual recoil energy.

FITASC · March 22, 2017, 07:19 PM

Quote:

Recoil is calculated with mathematical equations with the following factors.

Weight of projectile
Weight of firearm
Weight of powder charge
Velocity of the projectile

The rate of burn isn't a factor.

EXCEPT, the OP stated.....

Quote:

would the felt recoil be the same as

ACTUAL recoil and Felt/Perceived/Kick are different. Actual is - as you pointed out, a math equation. The other is more a matter of gun/grip fit, sensitivity to loud noise and flash, etc.

**Unclenick** · March 22, 2017, 09:29 PM

The standard calculation is limited. The assumption about what velocity the gas is accelerated to after the bullet clears the muzzle is usually fixed. SAAMI uses approximations that are multiples of muzzle velocity. But a moment's thought will reveal that the higher the muzzle pressure is, the greater the actual gas velocity will be. It will change with powder quantity and barrel length. This determines "rocket effect" or "after-effect" (meaning after the bullet has got out). It's also the reason a muzzle brake works with a heavy load: it lets the gas pressure release in a direction that is not forward, and thus the recoil portion due to rocket effect is reduced. But when you shoot mild, low pressure loads, the brake doesn't make much apparent difference.

Another factor not considered is that muzzle velocity as measured includes some acceleration of the bullet by muzzle blast for a short distance after it clears the muzzle. Harold Vaughn measured a .270 Winchester picking up 84 fps out of about 2800 fps from muzzle blast. About 3%. I looked at a continuous Doppler radar readout of a 40 S&W fired from a 4" barrel, and it gained about 35 fps out of 1050 fps after clearing the muzzle, so it happens with pistols, too. That part of the bullet's momentum should be discounted in the recoil calculation, but it isn't. And it's another factor that changes with muzzle pressure.

Felt recoil is a whole other animal. Jeff Cooper taught pulling a rifle hard into the shoulder to minimize this, and it works. It causes a portion of the body mass to be tied to the rifle firmly enough that the recoil is accelerating that body mass as well as the rifle mass. Despite the equal and opposite momentum, accelerating that larger total mass reduces the recoil velocity of the rifle, and since recoil energy is proportional to the square of velocity, it reduces the recoil energy as the inverse of the square of that velocity difference. You still feel it just fine, but the energy determines much of what the smack to the body feels like. If you don't believe it, fire a rifle held hard into the shoulder, then again with a little gap to the shoulder. A sixteenth of an inch is enough. Caution: don't try this with a hard recoiling magnum.

Another factor in felt recoil is psychological. A lot of people feel the old 1911 in .45 Auto kicks like a mule. Well, fire a dozen full power rounds of 44 Magnum, then pick up the 1911 and tell me it still feels like it recoils hard. It won't. What most people are really experiencing is a startle response to the muzzle disturbance in conjunction with the noise and suddenness of the event. 1911 equal and opposite momentum is transferred to the wrist first by direct recoil, then by the slide slamming into the frame, and then even more as the slide is pushed forward by the recoil spring. It doesn't stop jumping up until the slide locks the barrel up, at which point it transfers its momentum from the recoil spring pushing the slide forward back into the frame, which actually helps move the sights back down on the target. But how high the sights jump altogether still gives the impression of a lot of recoil when it isn't anything special.

Nosler guy · March 23, 2017, 04:19 AM

I notice a substantial difference in felt recoil between h1000 and retumbo, same bullet, same rifle and similar velocities. Retumbo wins the mares leg competition every time.

Sent from my SM-N920V using Tapatalk

ZenShot · March 23, 2017, 08:57 AM

Bullseye feels harsher to me than Universal. The harshness with Bullseye is more like a vibration pulse than a "push" type of feel with Universal.

briandg · March 23, 2017, 09:04 AM

In the really early years,people who grew up shooting the .38 calibers thought that .45 hurt. Years later, the .357, .44, and such hurt. Then along came the contender came out with rifle cartridges, then the casull and larger, recoil has reached new levels Nd the .45 is thought to be modest at best.

Nick_C_S · March 23, 2017, 09:53 AM

Great read Unclenick. Thanks.

reynolds357 · March 23, 2017, 03:04 PM

Where you will notice a difference is when you go to extremes. A powder too fast vs a powder too slow.

March 22, 2017, 02:46 PM	#1
dgang Senior Member Join Date: April 14, 2000 Location: Colorado Posts: 204	effects of fast/slow powders on felt recoil A question to those who might know: If I were to load a cartridge with say a 158 gr. .357 dia.bullet with a fast burning powder like Bullseye to produce 1000 fps, would the felt recoil be the same as , less than, or greater than that same cartridge loaded with a slow burning powder like 2400? Same bullet @ the same velocity, Same recoil? Thanks in advance, dang __________________ I shoot, therefore I am.

March 22, 2017, 03:45 PM	#3
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,808	Recoil is calculated with mathematical equations with the following factors. Weight of projectile Weight of firearm Weight of powder charge Velocity of the projectile The rate of burn isn't a factor. If you can find a powder (or cartridge case) that will achieve the same speed with less powder you will have less recoil. In some cases there enough difference to be noticeable. If a 308 and 30-06 are loaded to shoot 150 gr bullets at 2850 fps, the 30-06 will need more powder to achieve that speed and will recoil more. Some case designs are more efficient. I think you could very easily see the same speed with 357 Sig and 357 mag and notice a difference in recoil. Recoil speed is also a factor not always understood. You could load the 357 mag with 158 gr bullets and 125 gr bullets and mathematically have exactly the same recoil. But the heavier bullet with the slower speeds means recoil is spread out over a few milliseconds longer time. The actual recoil may be exactly the same, but most people would find the 158 gr load more comfortable. __________________ "If you're still doing things the same way you were doing them 10 years ago, you're doing it wrong" Winston Churchill

March 22, 2017, 05:48 PM	#6
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,833	After getting lost in a couple of discussions about recoil energy and how to calculate it, I have decided that it is essentially a waste of time. Finding the numbers might be useful as a comparison, for some folks, but what matters to me more is what I FEEL, and that involves a LOT of factors, both objective and subjective. You might notice a difference in recoil from a slower powder, you might not. Loaded to the same speed, the slower powder will use more powder, and produce more muzzle blast. And that might make the recoil seem like more than a faster powder which at that same speed might seem more like a "pop" than a "blast". Or you might not. Calculate all you want, two different people can have two different opinions about the "feel" no matter what the numbers say. Personally this issue never comes up for me, as I don't load fast powders up to the velocities I load slower powders to get. Nor do I down load slower powders, to me that's just a waste (the exception being if a certain gun shows a clear preference for a certain powder). In other words, I don't use Bullseye when I want 1200fps nor do I use 2400 when I only want 850fps. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

March 22, 2017, 06:54 PM	#7
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	Even if there was a tiny bit of acceleration difference, which is what people always think would lessen the "punch" of the recoil, if your slow powder charge is 10 _ 20% heavier, the total impulse, or recoil energy, will be increased. Some. May not be all of the proper terminology, but the basics are that combined powder and bullet charge factored with velocity determines the actual recoil energy, and that the acceleration of the charge up the bore can't possibly make a noticeable difference. What the individual feels is obviously an individual experience. When that round goes off, perceived recoil will be affected by the noise, flash, size and shape of the gun, any of these may make a bigger perceived difference than other factors. When I run a series of pistol rounds upward, I notice increases in noise and flash and that makes it feel like the recoil itself has increased. But, for example, if I push the charge up two grains on a 158 grain bullet, raising the velocity 150 or so fps, that's really almost insignificant as far as actual recoil energy. __________________ None.

March 22, 2017, 09:29 PM	#9
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	The standard calculation is limited. The assumption about what velocity the gas is accelerated to after the bullet clears the muzzle is usually fixed. SAAMI uses approximations that are multiples of muzzle velocity. But a moment's thought will reveal that the higher the muzzle pressure is, the greater the actual gas velocity will be. It will change with powder quantity and barrel length. This determines "rocket effect" or "after-effect" (meaning after the bullet has got out). It's also the reason a muzzle brake works with a heavy load: it lets the gas pressure release in a direction that is not forward, and thus the recoil portion due to rocket effect is reduced. But when you shoot mild, low pressure loads, the brake doesn't make much apparent difference. Another factor not considered is that muzzle velocity as measured includes some acceleration of the bullet by muzzle blast for a short distance after it clears the muzzle. Harold Vaughn measured a .270 Winchester picking up 84 fps out of about 2800 fps from muzzle blast. About 3%. I looked at a continuous Doppler radar readout of a 40 S&W fired from a 4" barrel, and it gained about 35 fps out of 1050 fps after clearing the muzzle, so it happens with pistols, too. That part of the bullet's momentum should be discounted in the recoil calculation, but it isn't. And it's another factor that changes with muzzle pressure. Felt recoil is a whole other animal. Jeff Cooper taught pulling a rifle hard into the shoulder to minimize this, and it works. It causes a portion of the body mass to be tied to the rifle firmly enough that the recoil is accelerating that body mass as well as the rifle mass. Despite the equal and opposite momentum, accelerating that larger total mass reduces the recoil velocity of the rifle, and since recoil energy is proportional to the square of velocity, it reduces the recoil energy as the inverse of the square of that velocity difference. You still feel it just fine, but the energy determines much of what the smack to the body feels like. If you don't believe it, fire a rifle held hard into the shoulder, then again with a little gap to the shoulder. A sixteenth of an inch is enough. Caution: don't try this with a hard recoiling magnum. Another factor in felt recoil is psychological. A lot of people feel the old 1911 in .45 Auto kicks like a mule. Well, fire a dozen full power rounds of 44 Magnum, then pick up the 1911 and tell me it still feels like it recoils hard. It won't. What most people are really experiencing is a startle response to the muzzle disturbance in conjunction with the noise and suddenness of the event. 1911 equal and opposite momentum is transferred to the wrist first by direct recoil, then by the slide slamming into the frame, and then even more as the slide is pushed forward by the recoil spring. It doesn't stop jumping up until the slide locks the barrel up, at which point it transfers its momentum from the recoil spring pushing the slide forward back into the frame, which actually helps move the sights back down on the target. But how high the sights jump altogether still gives the impression of a lot of recoil when it isn't anything special. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

March 22, 2017, 03:01 PM	#2
NoSecondBest Senior Member Join Date: December 7, 2009 Location: Western New York Posts: 2,736	You wouldn't notice any difference. The time difference in the burn is too minute for you to notice anything. I've shot .357mag for fifty years and I've used, and use, just about every powder that's been available. After several hundred thousand rounds I haven't noticed anything different.....when they're loaded to the same velocity.

March 22, 2017, 04:31 PM	#4
Reloadron Senior Member Join Date: June 8, 2016 Location: Cleveland, Ohio Suburbs Posts: 1,750	If you want to read about FREE RECOIL ENERGY here is a link to the SAAMI Data and formula. Hatcher's notebook also covers it pretty well. There is the actual calculated FRE (Free Recoil Energy) and there is also "felt recoil" the latter being how the free recoil energy feels to each individual shooter. A Google of free recoil energy calculator will bring up several online calculators. What is interesting is with the same data put into several of these calculators you can often get different results. There are also several Excel Spreadsheet examples out there to be had. The data from Hatcher's Notebook is pretty good stuff. Ron

March 23, 2017, 04:19 AM	#10
Nosler guy Member Join Date: June 6, 2015 Location: Oregon Posts: 82	I notice a substantial difference in felt recoil between h1000 and retumbo, same bullet, same rifle and similar velocities. Retumbo wins the mares leg competition every time. Sent from my SM-N920V using Tapatalk

March 23, 2017, 08:57 AM	#11
ZenShot Junior Member Join Date: March 2, 2017 Posts: 10	Bullseye feels harsher to me than Universal. The harshness with Bullseye is more like a vibration pulse than a "push" type of feel with Universal.

March 23, 2017, 09:04 AM	#12
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	In the really early years,people who grew up shooting the .38 calibers thought that .45 hurt. Years later, the .357, .44, and such hurt. Then along came the contender came out with rifle cartridges, then the casull and larger, recoil has reached new levels Nd the .45 is thought to be modest at best. __________________ None.

March 23, 2017, 09:53 AM	#13
Nick_C_S Senior Member Join Date: March 21, 2013 Location: Idaho Posts: 5,523	Great read Unclenick. Thanks. __________________ Gun control laws benefit only criminals and politicians - but then, I repeat myself. Life Member, National Rifle Association

March 23, 2017, 03:04 PM	#14
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	Where you will notice a difference is when you go to extremes. A powder too fast vs a powder too slow.