Powder speed effect on recoil?

J

JimGnitecki

Member
Joined
Mar 28, 2010
Messages
1,258
Does the burn speed of smokeless powder affect firearm recoil in any predictable way?

For example, does a slower burning powder generate a bit less recoil because it takes longer to burn? If so, how MUCH can the burn rate affect recoil?

I am asking because I was surprised at how strong the recoil was on a Federal factory 45-70 load with just a 300g bullet rated at 1850 fps muzzle velocity, that actually generated 1950 to just over 2000 fps muzzle velocities in my single shot 45-70 rifle. I plan to handload 405g at 1300 fps or so, and the pure mathematcis says that the power factor, which I thought is USUALLY a decent predictor of recoil, will be only about 15% lower.

I shot 45-70 out of a similar single shot rifle back about 2 decades ago, using a 45-70 handload with a 405g bullet, and never experienced enough recoil to comment on it.

In addition, at leats one blackpowder shooter has said that the recoil from a blackpowder load is more like a "longer push" rather than the more typical smokeless "spike".

Can different powder actually affect recoil a lot?

Jim G
 
Supposedly....slower burning powder equals more of a (slower) shove into the shoulder whereas a faster powder means more of a sharper jab. Concerning smokeless powder anyway

My dad (and others) told me that many years ago and he still stands by it. I haven't personally noticed a difference but he swears he does but he admits it's a slight difference.

We are talking a miniscule amount of time for powder burn between the 2 burn rates.

Powder amount (charge) definitely plays a role. As does bullet weight and weight of the gun concerning objective recoil.

Felt recoil is such a subjective thing, though. Same load in 2 different rifles can feel very different to eachother
 
Burn rate has very little direct "feelable" effect on recoil. Recoil is all about how fast the stuff exits the barrel. Your right the PF is a decent first order approximation but PF negated the recoil caused by the propellent gases. SAAMI had a good formula for estimating the contribution the propellant makes to recoil.

https://saami.org/wp-content/uploads/2022/11/Gun-Recoil-Formulae-2018-07-9.pdf
 
mcb said:
Burn rate has very little direct "feelable" effect on recoil. Recoil is all about how fast the stuff exits the barrel. Your right the PF is a decent first order approximation but PF negated the recoil caused by the propellent gases. SAAMI had a good formula for estimating the contribution the propellant makes to recoil.

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

Wow, that SAAMI formula is a little heavy, even for a detail guy like me! But thank-you, I downloaded the pdf to my computer! :)

Still more interested though in a non-math answer. I will also be trying 500g+ bullets in that 45-70, so ANY powder effect on recoil is going to interest me.

I HAVE ordered a recoil pad that I can wear when shooting that rifle.

Jim G
 
My only experience with this subject was when I was reloading a lot of 44 Magnums. I used many of the powders listed for the Magnum and I could tell a load of Bullseye from a load of 2400. Equivalent level/velocity loads the Bullseye was a sharp "snap" recoil and the 2400 was a slower "push".
 
https://shooterscalculator.com/recoil-calculator.php

This calculator will do the math for you but it assumes everything is a rifle (Vpg = 1.75Ve) from the SAAMI formula. It also calculate free recoil energy which is probably the best number for comparing recoil especially across different rifle weights.

ETA: There are lots or recoil calculators out there that utilize the SAAMI formula or very similar formulas.
 
Last edited:
IMO you have to try it and see. Some people prefer a small amount of fast powder combined with a heavy bullet for the lightest "felt recoil" compared to a slower powder with the same bullet. Even though the velocity and power factor may be identical, the way your gun tracks and recovers from recoil can be different. This is primarily in handguns.

IMO in the .45-70, your shoulder will not likely be able to tell a statiscially measurable difference between a faster powder pushing a 500gr bullet at 1,400 fps and a slower powder pushing a 500gr bullet at 1,400 fps. It's going to suck either way :D
 
I can't honestly say there is a difference. A different powder can sometimes produce a different sound - and certainly a different fireball - which can significantly affect the "felt" experience, but honestly, the actual difference in burn rate between a "slow" powder and a "fast" one is undetectable to human senses. I have real doubt that we would feel the difference in recoil, if any. As @fxvr5 points out, the total volume of ejecta does affect felt recoil, so I also must assume that any differences caused by burning speed would be overwhelmed by the increased volume required from a slower powder in order to produce similar velocity to a faster one.
 
Thanks, guys! That calculator that mcb linked to gives some VERY interesting results, in the GRAPH that is included at that webpage, down a few inches from the calculator. The entry in that GRAPH for 45-70 recoil energy is MUCH higher than what the graph seems to calculate when I feed in the stats for the Federal round I fired yesterday and 2 handloads I am planning to try.

So . . . apparently I am truly a wimp now compared to 2 decades ago, because the recoil energy they show in the graph for 45-70 is over 26 ft lb, where all 3 of the laods I calculated were around the same ft lb: 16. Wow.

Jim G
 
I used the calculator mcb linked to to see how much difference it predicts in recoil, at Cowboy Action load levels solely due to a lower or higher number of grains of powder:

I assumed a typical Cowboy Action load:
405g bullet
1300 fps
10.5 lb rifle (the weight of my Pedersoli Sharps Hunter model)
25g or 35g of powder (I have seen various powders showing low and high values like this for 405g bullet in the 1300 fps range)

The results:

25g 35g Difference
Recoil impulse 2.89 3.11 0.22 = +7.6%
Recoil velocity 8.86 9.54 0.68 = +7.1%
Recoil energy 12.82 14.86 2.04 = +15.9% !!!

Looks like powder WEIGHT makes a pretty big difference.

So, a "more efficient" powder rewards the shooter with lower recoil on top of lower cost. :)

Jim G
 
JimGnitecki said:
So . . . apparently I am truly a wimp now compared to 2 decades ago, because the recoil energy they show in the graph for 45-70 is over 26 ft lb, where all 3 of the laods I calculated were around the same ft lb: 16. Wow.
Click to expand...

Watch it, I resemble that remark….
My 45-70 Henry with factory loads leaves my shoulder a bit bruised, where did all the muscle go? Usually the Adrenalin when a deer goes by offsets the perceptible kick.

I’ve used the online recoil calculator for 9mm when testing 147gr bullets with Titegroup and N320 to a 132 PF. The powder weight was within .2 gr, but the felt recoil, for me, was sharper with Titegroup.
 
lordpaxman said:
Watch it, I resemble that remark….
My 45-70 Henry with factory loads leaves my shoulder a bit bruised, where did all the muscle go? Usually the Adrenalin when a deer goes by offsets the perceptible kick.

I’ve used the online recoil calculator for 9mm when testing 147gr bullets with Titegroup and N320 to a 132 PF. The powder weight was within .2 gr, but the felt recoil, for me, was sharper with Titegroup.
Click to expand...

Interesting, because TiteGroup IS a faster burning powder than VV N320.

Also interesting that the SAAMI formula does not mention powder burn rate. Although perhaps quantifying the difference in terms of efefct on recoil might simply be too complex to handle in a formula like that, and perhaps small enough that SAAMI ignored it.

Jim G
 
Not sure exactly if it's weight of the powder or not, but there sure can be a difference!

Lil Gun powder had MORE recoil & blast than 700x while pushing the same bullet out the same barrel at the same speed. (LCR firing .32 magnum) Same day same chronograph.

In fact the Lil Gun powder starting load I...started with had more recoil & blast while driving the bullet slower.
 
Yeah ... it's called Newton's Third Law of Motion ...
...For every action there is an Equal and Opposite reaction .

But to put it simply ... the more gunpowder (weight) in a load the more recoil will be felt , bullet weight and velocity being the same of course ... It really is Rocket Science !

The weight of the gun powder does make a difference in recoil !
Gary
 
I can tell the difference in 9mm pistols. (always same gun) Titegroup is noticeably snappier than the same bullets loaded to the same velocity with HS-6 or Longshot. I’ve become a recoil snob actually and prefer the slower powders.

I believe it becomes more noticeable if you shoot one load for a long time, like a year, and then switch to the opposite end of the burn rate chart.
 
There are two parts of recoil velosity and energy. You play mostly with the velosity of recoil if you change the speed of the powder only. Realistically though if one uses a slower powder one also uses more of it effecting your total ejecta. In higher recoil senerios I would like less recoil velosity. The velosity is tempered by a heavier rifle.
 
When I was shooting a lot of Trap in the 1970s, there was a powder fad.
The idea was that a slow burning powder would accelerate the shot more gradually and "spread out" the recoil.
That was the American theory.
The European theory was that a fast powder would "get it over with" quicker.
I think the fad faded and people got back to picking loads for patterns and economy.

As far as the OP, the Answer to BPCR at any substantial range is all the powder you can get in under a heavy bullet, demonstrated in 1879 and not challenged since. Some BPCR metallic silhouette shooters keep a lighter load for the 200 meter chickens but I thought it was more trouble than it was worth.
 
Jim Watson said:
When I was shooting a lot of Trap in the 1970s, there was a powder fad.
The idea was that a slow burning powder would accelerate the shot more gradually and "spread out" the recoil.
That was the American theory.
The European theory was that a fast powder would "get it over with" quicker.
I think the fad faded and people got back to picking loads for patterns and economy.

As far as the OP, the Answer to BPCR at any substantial range is all the powder you can get in under a heavy bullet, demonstrated in 1879 and not challenged since. Some BPCR metallic silhouette shooters keep a lighter load for the 200 meter chickens but I thought it was more trouble than it was worth.
Click to expand...

Given the trip down the barrel of even a long shotgun barrel is over in roughly 3 milli-seconds (even shorter time for rifle and pistols) it is fairly arguable the that human body and mind does not have the temporal resolution to feel the differences within that short of an event assuming the total recoil impulse is roughly the same.
 
AJC1 said:
There are two parts of recoil velosity and energy. You play mostly with the velosity of recoil if you change the speed of the powder only. Realistically though if one uses a slower powder one also uses more of it effecting your total ejecta. In higher recoil senerios I would like less recoil velosity. The velosity is tempered by a heavier rifle.
Click to expand...

I get what you are saying. Energy is defined as 1/2 x mass x velocity squared, so velocity is important for THREE reasons here:

1. It gets SQUARED in the equation, versus mass which is NOT squared

2. A higher velocity recoil means a shorter, but sharper, impact to the shooter

3. It makes sense that a higher velocity recoil will "hurt more" than a lower velocity recoil, even if 1/2mVxV is the same for both. Just look at the way handgun and rifle cartridges both show that loads with higher VELOCITY versus mass generate much larger temporary wound cavities. This is why a 357 Mag or 357 SIG is so much more effective in stopping an assailant even high on drugs than a 9mm. Same bullet diameter but much higher velocity. with a much larger temporary wound cavity that overwhelms the assailant's motor control.

Jim G
 
mcb said:
Given the trip down the barrel of even a long shotgun barrel is over in roughly 3 milli-seconds (even shorter time for rifle and pistols) it is fairly arguable the that human body and mind does not have the temporal resolution to feel the differences within that short of an event assuming the total recoil impulse is roughly the same.
Click to expand...

I respectfully have to disagree. In my 357 vs 9mm example above. the bullets from the 357 and the 9mm are only inside the body for about .0009 of a second for the 357 and .0013 of a second for the 9mm (because it has less velocity to scrub off via destroying the target's flesh to come to a stop). But, which one would you rather be hit with?

Apparently, it makes a difference. Felons hit with a 9mm sometimes continue to fight for a few seconds. Felons hit with a 357 cease ALL activity RIGHT NOW.

Jim G
 
You must log in or register to reply here.

Similar threads

M
  • Locked
Confusion about powder burning rates vs recoil
Replies
15
Views
3K
brickeyee
B
R
  • Locked
Recoil Approximation
Replies
3
Views
383
R Merrell
R
D
Effects of fast vs. slow burning powder on recoil
Replies
8
Views
467
mcb
mcb
B
  • Locked
Faster loads without the pain !? (SW 500)
Replies
7
Views
683
RippinSVT
R
D
  • Locked
does burn rate of powder effect felt recoil?
Replies
11
Views
3K
wally
wally
Back
Top