Felt Recoil as a function of bullet weight and speed

[mikemyers]

I used to shoot Winchester White Box 45 ACP ammo, 230 gr bullets, muzzle velocity 835 fps, energy: 336 ft. lbs. The recoil was more than I wanted to deal with, so I started reloading. The ammo I made: Hornady 230 gr FMJ-FP (or RN) bullets, 5.2 grs Unique powder, giving 700 fps muzzle velocity. A technician from Speer calculated that this would be 271 ft. lbs. of energy, much less than the 336 from WWB ammo - which is just what I wanted.

(He told me that I can download the equations from "handloads.com" which I will do later tonight, and see if I can do my own calculations.)
​

The bullets I am switching to are Speer 45 cal 185gr .451" TMJ FN, Speer part number 4476, using 7.3 grs powder, for 904 ft.sec muzzle velocity. The Speer technician calculated that at this minimum load, I would have 336 ft. lbs. of energy.

We then had a discussion about this, and he left me with the impression that because of the increase in energy from 271 to 336 ft. lbs, these new 185gr bullets would have more felt recoil than the 230gr bullets I've been reloading. (He also told me much of this depends on the guy I'm using, but it is the same gun for all the ammo, a Les Baer Premiere II.



That didn't make sense to me (maybe I mis-understood??), so I called Hornady. The technician there said that "energy at the muzzle" is not "recoil", and that firing a heavier bullet is likely to give me more felt recoil than with a lighter bullet.

(He also told me that if I switch to Bullseye Powder instead of Unique, it would burn faster, so it's all burnt up before the bullet left the barrel, and that would decrease felt recoil..... that's another question I have, for later.)
​

So, all things considered, using the lightest loads allowable by the reloading books, and ONLY using Unique powder, which of these two scenarios would be correct:

• The 230gr bullet, at 700 ft/sec muzzle velocity would have the most felt recoil?
• The 185gr bullet, at 904 ft/sec muzzle velocity would have the most felt recoil?

........and most importantly, why?

 

[Wreck-n-Crew]

Recoil energy is dependant on bullet weight and velocity.

What you need is to plug your numbers into a recoil energy calculator ( easy way)...http://www.handloads.com/calc/recoil.asp

Sent from my LGLS991 using Tapatalk

 

[AZAndy]

Here's the formula direct from SAAMI.

 

[TheGerman]

And here is an easy to use online calculator:

http://www.handloads.com/calc/recoil.asp

 

[mikemyers]

Thanks, guys. That confirms what the Speer technician told me:

Bullet weight in grains
230
Velocity in fps
700
Powder charge in grains
5.2
Weight of firearm in lbs
2.31
Calculate
Recoil Impulse in (lbs sec)
0.81
Velocity of recoiling firearm (fps)
11.24
Free recoil energy in (ft/lbs)
4.53


Bullet weight in grains
185
Velocity in fps
904
Powder charge in grains
7.3
Weight of firearm in lbs
2.31
Calculate
Recoil Impulse in (lbs sec)
0.87
Velocity of recoiling firearm (fps)
12.15
Free recoil energy in (ft/lbs)
5.29


Apparently, thinking I would get less "felt recoil", I actually got more.

I went to the range today, to fire off 16 rounds to see what the new loads would be like. The noise and feel seemed different with the faster bullets and my impression was that the recoil was less. Unless I'm missing something here, that must have been just "wishful thinking". :-/

 

[45ShooterRFB]

Recoil calks=

185 grain load will have about 13% more recoil!
If you want low recoil and your personal gun will work at 700 FPS with a 185 grain slug, the Remington 185 JHP is a good working slug.
They also make ~155 Grain slugs and the lowest velocity that will function your gun will give you the lowest possible recoil.
However if you want a certain level of Muzzle Energy for self defense, or hunting, then the lightest bullet with the smallest powder charge that will give the velocity you desire will give the least recoil.
My "Light" Self Defense/hunting deer load was the Remington old style 185 Grain JHP with the scalloped jacket in factory +P loads. They give 1140 F/S and 535 Ft-Lbs of ME.
Using the same slug in a .45 "Super" Pressure load to give 1500-1650 FPS in a fully supported chamber, which most .45 ACPs do not have, gives a great hunting and self defense load! That is 1,118 FtLbs of Muzzle Energy, or .44 Magnum levels from a 14 shooter!
I use Para Ordinance P-14 LTD, either stock, or with a long slide and BBL, with or WO a Compensator! The only change from stock is a heavy recoil spring.

 

[mikemyers]

Targets that fight back!

Until I start shooting targets such as this one, I have no need for self defense ammo:

​

 

[mikemyers]

A more serious reply..... based on what you said, should I start looking for more load charts, for using the 185 grain bullets that I already have, with a lower powder load? I wanted to stay with "standard" loads, right from the reloading manuals.

 

[Rule3]

But the velocity (major portion of the equation) is 200 fps MORE with the lighter bullet, If there is data for powder that can be reduced so that the velocity is closer to the heavier bullet you will have less felt recoil.

 

[shootniron]

It might be decision time...do you want less recoil...or...do you want to use "standard" loads from reloading manuals?

Seems to me, that you are missing part of the point of reloading...making your ammo do what YOU want it to do.

Or, at least, that is the major reason that I reload.

 

[hdwhit]

The formula for energy is one-half mass times velocity squared.

In the case of firearms where:

m = weight of the bullet in grains
v = velocity in feet per second​

The formula is:

• velocity times velocity
• times weight of the bullet in grains
• divided by 2
• divided by 7000 (to convert grains into pounds)
• divided by 32.2 (the acceleration of gravity - to adjust weight to mass)

 

[mikemyers]

......Seems to me, that you are missing part of the point of reloading...making your ammo do what YOU want it to do........

Actually, I want both things that you mention, less recoil and standard loads. For the 185 gr bullets I am now using, I have 14 choices listed in the Speer Reloading Manual #14. All I've done so far, is select a powder which I already have, and load it to the minimum listed load. Apparently I can buy some "American Select" powder, and load with 5.5 grains of powder, getting 834 feet/second.

Using the on-line calculator you guys showed me, that gives:
Recoil Impulse in (lbs sec)
0.78
Velocity of recoiling firearm (fps)
10.90
Free recoil energy in (ft/lbs)
4.26

Maybe I made it through pre-school and kindergarten, and maybe even the first grade, but I'm still in grade school. I don't feel comfortable about trying anything new yet.

(Compared to using the off-the-shelf Winchester White Box ammunition, I've already achieved my initial goal - the ammo I am now loading is easy for me to shoot with, and I can get back to improving my group size, which was the objective.)

 

[mikemyers]

The formula for energy is one-half mass times velocity squared.

Thanks....

So, for my new Speer Ammo:

energy =

904 feet per second x 904 feet per second
times 185
divided by 2
divided by 7000
divided by 32.2
​

= 904 x 904 x 185 x 1/2 x 1/7000 x 1/32.2

= 335

That's a good start to understanding things.
Now I need to find out how this relates to the calculated info on handloads.com

 

[Rule3]

Addition to my post #9 above.

If you have a 185 grain bullet and 230 grain bullet, then load them with whatever powder that there is data for, to go the same velocity, which one is going to have more recoil?

You can't compare the two different weight bullets and have one bullet going 200 fps faster. In theory you can get them to have equal recoil by adjusting the velocity

You are using Speer but if you have Hornadys manual they list 5 data points (velocity) for their bullets.

You do the math.

 

[Gtscotty]

One thing to keep in mind is that recoil is not directly related to kinetic energy (.5*m*v^2), but instead is a product of the conservation of momentum (p=m*v), where the momentum of the bullet and gasses are taken into account. As such, if you try to relate calculated recoil to kinetic energy, you will find that velocity will have less of an impact than you expected, and bullet weight will have more.

 

[au_prospector]

double post, sorry!

 

[au_prospector]

Sort of, I love physics questions. Turns out Newton was right. Unfortunately we dont get anything for free when it comes to moving mass.

Bullet mass plus Powder mass (not weight) times acceleration equals Force.
In this case the mass numbers are smaller than the acceleration numbers.

Then you have bullet mass plus powder mass going one direction times acceleration of that mass equals firearm mass times acceleration going the other direction all else being equal. In this case think firearm is more massive so the acceleration is less to equal the same force. This kind of goes with what GtScotty is saying as acceleration ends by the time the bullet exits the barrel and velocity then takes over.

Then you have force (energy/momentum) coming at you, which you feel applied to many factors like below which affects how YOU perceive recoil. So for this part it is all a toss up on individual perception.

How massive is the firearm you are holding.
How are you holding the firearm.
What are the pivot points.
What is your mass?
What are you wearing adding mass to you?
Are you supported? Do you have leverage?
Are you limp wrist resulting in some of the energy bleeding off with muzzle flip?
Joints locked or loose?
It goes on and on, and is why you can say "%$#*! the recoil!" and your buddy fires the same round with his weapon and says "what the heck you complaining about?"

I guess someone will disagree, so fire away!

 

[mikemyers]

Addition to my post #9 above.

If you have a 185 grain bullet and 230 grain bullet, then load them with whatever powder that there is data for, to go the same velocity, which one is going to have more recoil?.....

What I usually do when I make a comparison like that, is to exaggerate. Suppose one bullet weighed 10 grains, and the other weighed 100 pounds.

To me, it's logical that if I used the same amount of powder in this gun, I would get the same recoil from both, all other things being equal.

On the other hand, if I wanted them to exit the gun at the SAME velocity as each other, there would be much more recoil from the heavier bullet.

The heavier the bullet, keeping the speed constant, the more the recoil.

---------------------------------------------

On the other hand, if I had two bullets that weighed the same, and I wanted one to go ten times faster than the other, it's obvious to me that making it go faster will result in more recoil.

---------------------------------------------

Until we had this discussion, I might have known the basics, but the bits and pieces didn't really fit together as they seem to now. I'm maybe more ignorant than most, but to be honest, until now, I never considered the speed of the bullet at all. In retrospect, that's pretty ignorant.

---------------------------------------------

This will make me look even more ignorant, but I would have preferred buying bullets from Hornady, since that's what I'm used to now, and while they did have what i thought I wanted, they didn't include the amount of Unique powder in their listing. The technician from Hornady told me yesterday that this is probably because they didn't have any Unique powder available when they were doing the testing, and that I could have gotten that information had I checked with the people who provide Unique. (I had no second thoughts about using Speer bullets. I bought the latest Speer reloading manual, as my old Speer manual was way out of date.)

I wanted jacketed bullets, not exposed lead.
I "knew" that with a lighter bullet, I'd have less recoil.
I didn't need anything powerful, just something easy to shoot in a 1911.
I gave no thought whatever to the velocity. Ignorance.

.....and once again, there is SO much to be learned in these forums!

 

[mikemyers]

One thing to keep in mind is that recoil is not directly related to kinetic energy (.5*m*v^2), but instead is a product of the conservation of momentum (p=m*v), where the momentum of the bullet and gasses are taken into account. As such, if you try to relate calculated recoil to kinetic energy, you will find that velocity will have less of an impact than you expected, and bullet weight will have more.

I need some time to understand what you just wrote........

 

[mikemyers]

.......Then you have force (energy/momentum) coming at you, which you feel applied to many factors like below which affects how YOU perceive recoil. So for this part it is all a toss up on individual perception........

I was aware of some of those things, but not all. My way of dealing with that is to keep everything the same but for the bullet.

Same gun, same way of holding it, same everything, and try to compare the felt recoil as I shoot.

Using Winchester White Box Ammo, it "feels" to me like there is far more recoil than when I use my own reloads. For target shooting, that allows me to shoot more accurately. Until/unless the targets become dangerous (see above cartoon) all I need is ammo that will punch a hole in the target.

 

[Gtscotty]

Sort of, I love physics questions. Turns out Newton was right. Unfortunately we dont get anything for free when it comes to moving mass.

Bullet mass plus Powder mass (not weight) times acceleration equals Force.
In this case the mass numbers are smaller than the acceleration numbers.

Then you have bullet mass plus powder mass going one direction times acceleration of that mass equals firearm mass times acceleration going the other direction all else being equal. In this case think firearm is more massive so the acceleration is less to equal the same force. This kind of goes with what GtScotty is saying as acceleration ends by the time the bullet exits the barrel and velocity then takes over.

Then you have force (energy/momentum) coming at you, which you feel applied to many factors like below which affects how YOU perceive recoil. So for this part it is all a toss up on individual perception.

How massive is the firearm you are holding.
How are you holding the firearm.
What are the pivot points.
What is your mass?
What are you wearing adding mass to you?
Are you supported? Do you have leverage?
Are you limp wrist resulting in some of the energy bleeding off with muzzle flip?
Joints locked or loose?
It goes on and on, and is why you can say "%$#*! the recoil!" and your buddy fires the same round with his weapon and says "what the heck you complaining about?"

I guess someone will disagree, so fire away!

I suppose it was sloppy of me to use the term weight, all calculations of this type are of course done using mass.

I would say that given the relatively loose mechanical linkage between the gun and shooter (hands, arms and a cushy shoulder pocket), and the millisecond time scale of bullet acceleration, a conservation of momentum calculation is more appropriate for rifle recoil calculation than a sigma F calculation. I would guess that by the time the human body has much impact on the position of the gun, acceleration is complete and you are now trying to stop a rifle with relatively constant velocity. The peak impulse delivered by the rifle to your shoulder would be useful, but I'm sure these online calculators aren't calculating that.

The basic gist of what I was saying though, was that if you try to make sense of the recoil you experience by looking at each round's KE, it is probably not going to line up exactly, especially with widely varying bullet MASS .

 

[au_prospector]

Scotty my man, these things are scientifically measured in a vacuum as you know, and I dont like living in a vacuum. I think between the two of us, we accomplished to say.... Its all relative and you cant compare two different weights errr...masses as if they are alike cause they are not.

 

[Rule3]

Mike,

Do NOT call yourself "ignorant" as you are not. You understand it.

You do not have to be a Physics or math wiz kid to reload these.

Just go with a lighter bullet and a start load and see what you like. They have the online calculators if you really need to mess with numbers.

Use the Speer data, I only suggested Hornady as I like that they have 5 velocities.and use a "real" gun to test.

 

[mikemyers]

Gee, well, right now I know and understand, but two days I certainly was "ignorant" (lacking knowledge or information as to a particular subject or fact). When the technician at Speer explained things, I was fully confused. As I wrote in the original post in this thread "That didn't make sense to me (maybe I mis-understood??), so I called Hornady.

The technician at Hornady pushed me in the right direction, but the discussion in this thread got me to where I understand better - you're correct, I now understand it. Well, let's say more of it.

======================================


That leads to the other question I mentioned in the original post:

"(He also told me that if I switch to Bullseye Powder instead of Unique, it would burn faster, so it's all burnt up before the bullet left the barrel, and that would decrease felt recoil..... that's another question I have, for later.)"


In looking at the Speer book, I see loads that are given for both Unique powder and Bullseye powder. The technician told me that because the Bullseye is a faster burning powder, it will be burnt up before the bullet exits the gun, while the slower burning powder might not be, and therefore I might have more muzzle rise and felt recoil from Unique than from Bullseye.

Knowing what I do now, not only do I see I would use less Bullseye than Unique powder, but the velocity at the muzzle drops from 904 ft/sec (Unique) to 874 ft/sec (Bullseye). What I don't get, is how/why of the 14 powders for which they give loading data, I would select one rather than another.

(I'm also not sure how much of a difference, if any, someone would feel between 850 and 900 ft/sec muzzle velocity.

 

[mikemyers]

.... Its all relative and you cant compare two different weights errr...masses as if they are alike cause they are not.

Suppose Bullet #1 weighs 200 grains, and bullet #2 weighs 400 grains, and everything else remains the same - powder, gun, and so on.

Based on what you just wrote, is it possible to calculate what effect (if any) this would have on "felt recoil", with only that one thing being changed?