Weight, Velocity, and Recoil?

[Stafford]

Three types of factory ammo:

115 grain, 1145 velocity, PF of 131

135 grain, 970 velocity, PF of 130

147 grain, 920 velocity, PF of 135

 

Given this info, which should have the lightest recoil? I currently shoot the 115 grain, but will probably try out the others. 

[4n2t0]

147...

 

But which feeds better, shoots better and is faster for you?

Edited June 13, 2023 by 4n2t0

[zzt]

Actual recoil doesn't matter.  Felt recoil does, and only you can determine that.  Many shooters prefer the 147gr load, because it 'feels' softer.  It actually has more recoil, but the pulse is spread out over a longer time.  I prefer the 115.  The felt recoil impulse is sharper, but the sights are back on more quickly.

[4n2t0]

25 minutes ago, zzt said:

Many shooters prefer the 147gr load, because it 'feels' softer.  It actually has more recoil, but the pulse is spread out over a longer time. 

 

Really? So if the PF and powder used is the same there will be more recoil with a 147gr when compared to a 124gr? So what's happening here zzt?

 

Here's my TG load to make 130 PF w/ 124gr (I even undercut the actual charge weight trying to give the 124gr an advantage):

 

Now the 147gr (I use the exact same charge weigh to give the 147gr a disadvantage):

Edited June 13, 2023 by 4n2t0

[xrayfk05]

What do you mean with the 147 has more recoil?

At 125 PF a 124 grain bullet has 280 ftl/lbs of energy and a 147 grain only 236 ft/lbs, thus less recoil.

This is exactly why heavier bullets have less recoil at the same PF, it does not caclulate energy just weight * velocity.

 

There are several pro's en cons to each, try them yourself and stick to whatever works.

Chasing after flattest/softest/whatever is waste of time and energy, especially with 9mm.

 

With Production optic you may even prefer heavier bullets because the slide velocity is slower, you don't  loose sight of the dot as much.

Edited June 13, 2023 by xrayfk05

[Alaskapopo]

5 minutes ago, xrayfk05 said:

What do you mean with the 147 has more recoil?

At 125 PF a 124 grain bullet has 280 ftl/lbs of energy and a 147 grain only 236 ft/lbs, thus less recoil.

This is exactly why heavier bullets have less recoil at the same PF, it does not caclulate energy just weight * velocity.

 

There are several pro's en cons to each, try them yourself and stick to whatever works.

Chasing after flattest/softest/whatever is waste of time and energy, especially with 9mm.

 

With Production optic you may even prefer heavier bullets because the slide velocity is slower, you don't  loose sight of the dot as much.

Muzzle energy has absolutely nothing to do with recoil at all.  

[travail]

Agree with others. Try them all and see what feels best for you. The math for power factor doesn’t always translate into what feels best for you as a shooter or with your gun. 

[zzt]

22 minutes ago, 4n2t0 said:

 

Really? So if the PF and powder used is the same there will be more recoil with a 147 when compared to a 124?

 

Winchester formula for recoil

E=(Bw x Mv + 4000 Pw) squared / 64.348 x Gw

Bw = biullet weight or weight of the ejecta

Mv = muzzle velocity in fps

4000 is the velocity of propagation of sound in the propellent gasses (Hodgdon uses 4700)

Pw = powder weight in pounds

64.348 is twice the acceleration of gravity

Gw = gun weight in pounds

 

[4n2t0]

2 minutes ago, zzt said:

 

Winchester formula for recoil

E=(Bw x Mv + 4000 Pw) squared / 64.348 x Gw

Bw = biullet weight or weight of the ejecta

Mv = muzzle velocity in fps

4000 is the velocity of propagation of sound in the propellent gasses (Hodgdon uses 4700)

Pw = powder weight in pounds

64.348 is twice the acceleration of gravity

Gw = gun weight in pounds

 

 

Great. So how does it work out?

[zzt]

5 minutes ago, 4n2t0 said:

 

Great. So how does it work out?

 

Since the weight of the powder is part of the formula, the OP did not provide sufficient info to calculate.

[4n2t0]

2 minutes ago, zzt said:

 

Since the weight of the powder is part of the formula, the OP did not provide sufficient info to calculate.

 

Use my examples from above. Both PF's are 129.95.

Edited June 13, 2023 by 4n2t0

[zzt]

6 minutes ago, 4n2t0 said:

 

Use my examples from above. Both PF's are 129.95.

 

How?  You made up the powder charge.

[4n2t0]

17 minutes ago, zzt said:

 

How?  You made up the powder charge.

 

Huh? Maybe I'm confused (I probably am). Why does the math care about my charge weight since I gave the advantage to the 124gr? It would take more powder for the 124gr bullet to make PF and less for the 147gr bullet. I can't replicate a perfect equivalent in PF but if it helps it takes approximately 4.1gr of TG for the 124gr and 3.6gr for the 147gr.

Edited June 13, 2023 by 4n2t0

[zzt]

Take the OP's original data.  115 @ 1145fps and 147 @920fps.  I used your gestimate of 4.1 and 3.6gr respectively.

 

115*1145+2.343=131677 (top line of formula before squaring)

147*920+2.057=135242

 

Even before squaring, the 147 has a larger number and will have more actual recoil.

 

I'm not sure what you are driving at.  Powder weight is important, because it is part of the formula. 

 

132 PF loads for 115, 124 and 147gr bullets are all going to equal 132000 for Bw*Mv.  So the difference in actual recoil will be determined by the powder used and the charge weight.  Is it possible for the 147gr load to generate less actual recoil than the 115?  Yes, depending on powder used.

 

[4n2t0]

19 minutes ago, zzt said:

Take the OP's original data.  115 @ 1145fps and 147 @920fps.  I used your gestimate of 4.1 and 3.6gr respectively.

 

115*1145+2.343=131677 (top line of formula before squaring)

147*920+2.057=135242

 

Even before squaring, the 147 has a larger number and will have more actual recoil.

 

I'm not sure what you are driving at.  Powder weight is important, because it is part of the formula. 

 

132 PF loads for 115, 124 and 147gr bullets are all going to equal 132000 for Bw*Mv.  So the difference in actual recoil will be determined by the powder used and the charge weight.  Is it possible for the 147gr load to generate less actual recoil than the 115?  Yes, depending on powder used.

 

 

Not 115gr zzt, 124gr. Of course those number worked in your favour. The 115gr would take even more powder than the 4.1gr you used (I presume you already knew that). Also, they're not such a guesstimate, it's pretty close. 4.1gr for 124gr and 3.6gr for 147gr. I have a chrono. I've tested many rounds. Those numbers are pretty sound for my bullet with TG in the same gun on the same day.

 

I'm not driving at anything. Please do the math with the numbers I provided you because it's all too complicated for my small brain.

 

Remember, you replied to this:

 

Really? So if the PF and powder used is the same there will be more recoil with a 147gr when compared to a 124gr? 

 

Edited June 13, 2023 by 4n2t0

[Guy Neill]

Since calculating recoil energy starts with a momentum balance to determine the gun velocity - as I recall, equal power factor will equal recoil energy. Power factor is a momentum value, but with odd units.  The powder gases are part of the ejecta and play a part in the momentum.

 

Once the gun velocity is known, putting it in the kinetic energy formula gives the recoil energy.

 

As stated above, many like the heavier, slower bullets for spreading the recoil energy over a longer period of time. Also, as stated, many prefer the sharper (quicker) recoil energy of a lighter, faster bullet.

 

Even though the actual recoil energy is the same.

[4n2t0]

So, recoil energy is exactly the same when two projectiles of differing weights are loaded with the same powder, to the same PF (the heavier bullet always needing less powder), and fired in the same gun?

 

Oh boy, now I'm really confused because zzt stated that the heavier projectile would produce more recoil.

 

I'm just trying to learn and get what I thought to be true (apparently misinformation regarding recoil) straightened out.

Edited June 13, 2023 by 4n2t0

[zzt]

2 hours ago, 4n2t0 said:

Remember, you replied to this:

 

Really? So if the PF and powder used is the same there will be more recoil with a 147gr when compared to a 124gr? 

 

That is not what I replied to.  Using the data you subsequently added to your second post (124@1048 and 147@884, nominal).  If you equalize the PF for both you have BW*Mv of 129952 for each.  Add 2.343 Pw for the 124 = 129954.34 before squaring.  129952 + 2.057 for the 147 =129954.06.   The 124 load will have minutely more actual recoil in this scenario, assuming your 'pretty close' gestimates of 4.1 and 3.6 are accurate. 

 

              

[Joe4d]

8 minutes ago, 4n2t0 said:

So, recoil energy is exactly the same when two projectiles of differing weights are loaded with different charges (the heavier bullet always needing less powder), at the same PF, with the same powder, and fired in the same gun?

 

Oh boy, now I'm really confused because zzt stated that the heavier projectile would produce more recoil.

 

I'm just trying to learn and get what I thought to be true (apparently misinformation regarding recoil) straightened out.

umm no,, because powder weight AND get this another wrench in gears,, powder burn rate, and barrel length also affect perceived recoil.

 

[zzt]

9 minutes ago, 4n2t0 said:

Oh boy, now I'm really confused because zzt stated that the heavier projectile would produce more recoil.

 

You are confused because you made an incorrect assumption.  If you reread my original post it is clear I was referring to the OP's factory data.  His 147 factory load will have more actual recoil than the 115 or 135 loads.  You confabulated that into something else.

[4n2t0]

2 hours ago, zzt said:

 

You are confused because you made an incorrect assumption.  If you reread my original post it is clear I was referring to the OP's factory data.  His 147 factory load will have more actual recoil than the 115 or 135 loads.  You confabulated that into something else.

 

But you replied directly to me when I ask you a question. Remember? Same PF, same powder? Then you posted a formula which I'm still trying to figure out how it answers my question. Also, if you were talking about the OPs load how could you make that determination? I thought you needed the powder charge weights? Which weren't provided. That's what you said. Besides, this hardly sounds like you're talking about the OP's data:

 

"Many shooters prefer the 147gr load, because it 'feels' softer.  It actually has more recoil, but the pulse is spread out over a longer time."

 

I guess "many shooters" is a substitute for OP's data with unknown charge weights?

 

You are the one squirming here, not me...

Edited June 13, 2023 by 4n2t0
Spelling, punctuation and additional clarification.

[Guy Neill]

Yes - if the powder charge weights vary, it will vary the recoil energy.

[Guy Neill]

Leet's look at your numbers;

 

Gun weight - not given, but assuming 36 ounces.

Powder weight - unknown - using zero

bullet weight - 115gr

bullet velocity - 1145 fps

recoil energy = 2.46 ft-lbs

 

Similarly, 

 

124gr recoil = 2.04 ft-lbs

147gr recoil = 2.58 ft-lbs

 

[4n2t0]

16 minutes ago, Guy Neill said:

Leet's look at your numbers;

 

Gun weight - not given, but assuming 36 ounces.

Powder weight - unknown - using zero

bullet weight - 115gr

bullet velocity - 1145 fps

recoil energy = 2.46 ft-lbs

 

Similarly, 

 

124gr recoil = 2.04 ft-lbs

147gr recoil = 2.58 ft-lbs

 

 

All my numbers are in post 4 and I provided the charge weights, 4.1gr for 124gr, 3.6gr 147gr.

 

[Guy Neill]

sorry, I was using post one values.