Betcha Leornard or Sheldon would know the answer...

[kamikaze1a]

Something I just started to wonder about;

If you are reloading the same weight cast and jacketed/plated bullets for one pistol, you must have noticed how much the velocity could be affected by substituting one for the other. And that you will probably need to adjust the charge weight to maintain your desired velocity.

e.g. Loading a 180gr cast lead for practice and 180gr plated bullets for match, USPSA major.

I believe we would all agree that loading a different powder with a given velocity will often change the perceived or felt recoil but is the perceived recoil affected when you change the charge weight to compensate for a different bullet while maintaining the same velocity?

i.e. Loading 40 major with 180gr bullet, my target velocity would be 917+ fps and with my pistol/powder/bullets combo I need about 1/2gr more powder to make major with a plated vs a cast lead bullet. Will the perceived recoil remain the same because the velocity is the same or Is the varying powder charge and the quantity of burning gas a bigger factor? Or is it all about velocity when the bullet leaves the muzzle? Or is the 1/2gr difference too small to be felt? I know that I could "feel" a 1/2gr lighter or heavier powder charge if the bullet did not change as that would 1/2gr would be almost a hundred fps difference.

I have not noticed a difference in recoil when I maintain the velocity but changed the powder charge weight to compensate for lead or plated but then again I have not tested for that or even tried to determine if there is a difference. I guess I could load a mag with alternating plated then cast and the difference would be more apparent. Or is there no difference?

Anyone looked into this?

Edited October 10, 2014 by kamikaze1a

[superdude]

Yes, someone has looked into this. I don't have .40 S&W data, but I do have .45 ACP data.

Here is data for a 230 grain bullet in a .45 ACP loaded with Winchester 231 at 165 power factor (717.4 fps). The "recoil" is measured two ways: 1) Ransom Rest movement. 2) Mathematically calculated recoil force based on the charge weight required to make 717.4 fps in a 2.5 lb gun. The number are calculated via linear regression.

Plated bullet;

Charge weight required = 5.27 gr

Ransom Rest movement = 61.1mm

Calculated recoil force = 4.39 ft lb

Cast bullet;

Charge weight required = 4.71 gr

Ransom Rest movement = 59.3mm

Calculated recoil force = 4.29 ft lb

The cast bullet required 0.56 gr less gunpowder, produced 1.8mm less Ransom Rest movement and 0.1 ft lb less calculated recoil force for the same velocity as the plated bullet.

It's not much of a difference, but the cast bullet did produce less recoil. Whether a person can feel that much of a difference is another issue.

Edited October 10, 2014 by superdude

[Hi-Power Jack]

Great info ... thanks for sharing .... :bow:

[kamikaze1a]

Perfect! Exactly the info I was looking for. The results should be similar for 40 too. By his figures, it looks like his load test also indicate about 1/2gr more for plated than cast. For your info, with my loads, Hi-Tek coated bullets took about .2 or so more powder than cast lead with conventional wax lube to maintain the velocity.

I had been loading my cast bullets for practice and matches rounds for years but a while back, after a stage where the smoke was an issue, I started loading plated for matches. Just the other day I started to wonder if the difference in powder charge was enough to "feel". I had never noticed and never really checked that out.

Being that the POI is similar, I am once again secure with loading a practice load with a different load for matches.

Thanks and good shooting to you!

[Vlad]

It is quite simple really. The more powder you are burning the more recoil. There is a qualitative aspect of how you perceive it, but in raw numbers if you burn more powder there is more energy in the system and that energy has to go somewhere. Also keep in mind that there are at least 2 major components to recoil, the first being the bullet pushing back against the gun as it moves down the barrel, and the second being the rocket engine that is the barrel as it shoots out excess gas after the bullet left. More powder means more of the second.

[razorfish]

So is it safe to say that due to the fact that a coated bullet requires less powder than an identical weighted FMJ bullet that it has less recoil or less felt recoil?

At this point I have several pistols that have never had anything down the barrel but coated bullets beyond the FMJ's used by the factory for testing. I've always presumed that I should get more life out of the barrels and it seems reasonable that recoil would be less if I'm using less powder for a given bullet weight.

Hmm... lower cost, less recoil and longer barrel life.

[Vlad]

So is it safe to say that due to the fact that a coated bullet requires less powder than an identical weighted FMJ bullet that it has less recoil or less felt recoil?

That's what makes sense to me, but remember this is "sum of all forces" kinda thing, not necessarily how it feels to you.

[superdude]

So is it safe to say that due to the fact that a coated bullet requires less powder than an identical weighted FMJ bullet that it has less recoil or less felt recoil?

The differences in recoil between the different bullet types at the same velocity, even requiring different charge weights for the same velocity, is rather small. Let's put this in perspective.

I noted a difference in recoil of 0.1 ft lb above in my first reply. How does this number compare to the difference in recoil that one would experience in a 10-shot string of the same bullet with the same powder charge? Here is an example, and I'll use my data with a 230 grain HI-TECH coated bullet (in honor of razorfish) loaded with 5.0 grains of Winchester 231. That 10-shot string averaged 747.9 fps. The high velocity was 764 fps and the low was 731 fps, for a spread of 33 fps (s.d. 11.35). If I plug the actual velocities into the mathematical formula for calculating recoil, I get a recoil force for the high velocity of 4.86 ft lb. The recoil force for the low velocity is 4.49 ft lb. That's a difference of 0.37 ft lb. So, I get a larger difference in recoil of a 10-shot string than I get on average between the different bullet types (cast compared to plated in the first example).

Here's another variable. Bullet weight. The prior examples have all used a bullet of 230 grains. We know that not every bullet in the box weighs exactly the same. Here again I'll use data from the 230 grain HI-TECH coated bullets. The average weight of 10 bullets was 231.8 grains. The heaviest bullet was 233.0 grains and the lightest was 230.8 grains. That's a difference of 2.2 grains. If I assume they made the same velocity, say 750 fps, the heavy bullet produces 4.81 ft lb recoil, and the light bullet 4.73 ft lb recoil. That's a difference of 0.08 ft lb.

IF the heavy bullet was the fastest (764 fps) it would produce 4.97 ft lb recoil, and IF the light bullet was the slowest (731 fps) it would produce 4.52 ft lb recoil. That's a difference of 0.45 ft lb.

Same thing with Ransom Rest movement. I noted above an average 1.8mm difference in RR movement between the cast and plated bullets. The spread difference in RR movement of the 10-shot string with the coated bullets was 6mm.

Have any of you fired a string of rounds of the same load and thought you felt a difference in recoil between some of the shots? I have, or at least I thought I did. It was a small difference, but it was enough to notice.

These numbers indicate that you can get a greater difference in recoil in a 10-shot string than you can for the average recoil of different bullet types at the same velocity. Is the recoil of different bullet types enough to notice? Maybe, maybe not.

[Vlad]

I'm really curious what formulas you are using and if they account for the "rocket effect"

[superdude]

The formula I use is like the one at the link below. Yes, they take the gunpowder charge weight into account, so, more charge weight for the same velocity means more recoil force as per the conservation of mass.

http://kwk.us/recoil.html

I use the 4000 fps as the constant. There is no consensus on what value should be used for the constants (people differ in their opinions), but since they are constants the output values will change but not their relative relationships (i.e. more will always be more).

[Vlad]

Ok, so here is what I'm saying, that average and guessing on powder/gas velocity seem odd to me. They are going to vary wildly from powder to powder, and how much gas each powder generates. Then you have comps, and barrel lengths and all the other stuff. That high gas volume powder is going to eject a lot more gas and create more recoil in a simple barrel but all that gas would make a comp work a lot better if it existed. A small gas volume fast powder might have a lot less gas shooting out the muzzle. That page also writes "It seems reasonable to me the propellant's velocity will be related to the bullet's" but I'm not sure that makes sense, I think it depends on barrel volume and load pressures.

[SilverBolt]

I just tested some new .40-major loads this weekend. I loaded 180gr X-Treme plated and 180gr MG jacketed with the same 4.8gr of N320. The ten round average showed the plated bullets to be 45fps (average) faster at the same charge weight. This was out of a 6" 2011.

[superdude]

Ok, so here is what I'm saying, that average and guessing on powder/gas velocity seem odd to me. They are going to vary wildly from powder to powder, and how much gas each powder generates. Then you have comps, and barrel lengths and all the other stuff. That high gas volume powder is going to eject a lot more gas and create more recoil in a simple barrel but all that gas would make a comp work a lot better if it existed. A small gas volume fast powder might have a lot less gas shooting out the muzzle. That page also writes "It seems reasonable to me the propellant's velocity will be related to the bullet's" but I'm not sure that makes sense, I think it depends on barrel volume and load pressures.

What's your point? You don't like the constants used in the formula, or you don't like mathematical models, or what? The absolute value kicked out by any formula does not matter. The utility of using a mathematical model in this case is to understand whether a bullet type, or gunpowder (or whatever), produces more or less recoil than another. It's the relative value that matters (is one higher or lower than the other), not the absolute value (that it's 4.35 by one formula or 5.85 by another formula).

Adding a compensator changes how the gun reacts. With no compensator more gas for the same velocity increases muzzle rise, but the compensator means that more gas for the same velocity decreases muzzle rise. But it does not change the recoil force. It only redirects the force.

[Vlad]

My point is that it may be more complicated then that formula accounts for.

You seem angry about something but I'm not sure what, so I'll try again. I think the TYPE of powder you use makes a difference. Subjectively we all "know" that faster burning powders are "softer". Of course, this comes into the qualitative not quantitative aspects of recoil. Personally I think that this a much more complex problem then we give it credit for.

For example, think of all the work a comp does, more obviously so in a rifle. All that work is done with waste gases, mostly after the gases stopped acting on the bullet and the bullet has stopped acting on the gun. If those gases can have all that effect on the gun when directed in one direction, think of all the effect they have as part of the total felt recoil when they are acting as a rocket engine, adding to the total recoil instead of subtracting.

What I'm curious to see if anyone has tried is building a rig that test the powders component of recoil, in the absence of a bullet. It is harder then it sounds because shooting blanks does not build up the same pressure in expending space as the barrel does while the bullet moves forward to say nothing of incomplete burns and what not. To my mind ALL the recoil in a gun caused by the powder acting on a piston, because all the energy in the system comes from the burning of the powder.

[superdude]

I'm not angry about anything. It simply wasn't clear from what you wrote what your point was.

It might be more complicated than a formula can account for. The only way to know is to test it, as you suggest.

The formula(s) I pointed out can address simple questions. More complex questions might require more complex formulas/testing.