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Heavy Bullets Shoot Softer

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115 124 165 180 bullet heavy light recoil weight
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26K views 31 replies 16 participants last post by  Yankee.Samurai  
I
#1 · (Edited)
As a new first time shooter I put 200 rounds of 9mm through my G17 Gen 4 Version 2 at the range everyone like the FDE color. But what really struck me was how different and snappier more muzzle flash 115gr rounds have over 147gr rounds. I was able to get back on target right away. And Thanks to the improvements of the new Gen 4 Version 2 no brass to the face and less recoil or muzzle rise thanks to the included factory beaver tail earlier versions of the FDE Gen 4 dont have the extra attachment point to affix the beaver tail.

I ll post pics later.

http://i42.photobucket.com/albums/e336/MikeL1/gun003_zps7d886cea.jpg
 
I
#4 ·
using 115 federal and remington

when I used 147gr Gold Dot and Lawman WOW. Something about TMJ total metal jacket that prvents the exposed lead base of the bullet from vaporizing ala less smoke. Also Higher quality powder again less smoke and flash. Im not buying 115gr again If I can avoid it.

And at $15.00 from Cabela's free shipping no tax I can't complain bought 5 boxes of Hornaday 147gr 50 rounds Critical defense and 4 boxes Winchester PDX 147gr don't bother logging on to search Cabela's messed up an order of mine some time again now a glitch in their ordering system keeps me in a constant ordering loop of ANY 147gr 9mm they get in automatically.
 
#6 ·
__jb said:
Heavier bullets generally yield less felt recoil...
Click to expand...
I remember the first time I experienced that... I bought some Federal HST Tactical 147 +P JHP and I was expecting .40 cal performance, or at least "heavy duty" 9mm recoil. First shot, I thought it was a "squib" it was was so soft shooting.

It seemed counter-intuitive to me at the time, but since getting into reloading it makes perfect sense.... Heavier bullets are bigger bullets and bigger bullets leave less room for powder. Heavy bullet loads usually have a smaller powder charge due to head space challenges caused by the larger bullets. So, larger bullet and lighter powder load equals less recoil.

Another counter-intuitive fact with heavier bullets is that they shoot "high" compared to lighter bullets. A 147gr 9mm WWB will shoot @ 6" higher at 15 yards than a 115gr 9mm WWB. That seems backwards to me, but it's true. It must be inertia, but it sure puzzles me...
 
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G
#7 ·
Another reason it does this is that a heavier bullet takes a smaller powder charge.
Look at a 147 grain and 115 grain reload data from Winchester.
115 GR. / Hodgdon HS-6 / 6.7 / 1171 / 26,700 CUP / 7.0 / 1234 / 29,400 CUP
147 GR. / Hodgdon HS-6 / 4.3 / 773 / 20,200 CUP / 5.0 / 885 / 27,900 CUP

About a 50% increase in powder used at low and high end for the 22% lighter bullet.

This was hard for me to understand when I started reloading my 45ACP. The heavier 230 bullets take less powder than a 200 grain.
My initial thought was it would take more to move a heavier object but that's not the case in reloading.
230 grain shoots softer than the 200.
 
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#8 ·
GT4point6 said:
Another reason it does this is that a heavier bullet takes a smaller powder charge.

Look at a 147 grain and 115 grain reload data from Winchester.
115 GR. / Hodgdon HS-6 / 6.7 / 1171 / 26,700 CUP / 7.0 / 1234 / 29,400 CUP
147 GR. / Hodgdon HS-6 / 4.3 / 773 / 20,200 CUP / 5.0 / 885 / 27,900 CUP

About a 50% increase in powder used at low and high end for the 22% lighter bullet.

This was hard for me to understand when I started reloading my 45ACP. The heavier 230 bullets take less powder than a 200 grain. My initial thought was it would take more to move a heavier object but that's not the case in reloading.
230 grain shoots softer than the 200.
Click to expand...
If we ignore the powder charge matter for a minute and just look at the bullet weight and velocity, we can use the USPSA method for determining "Power Factor" (PF).

((Bullet weight in grains) * (velocity in feet per second)) / 1,000 = PF

Comparing PF between two loads gives you a simple basis for comparison of the recoil that the load will produce.

For your sample loads:

(115 * 1,171)/1,000 = 134.6 PF
(115 * 1,234)/1,000 = 141.9 PF

(147 * 773)/1,000 = 113.6 PF
(147 * 885)/1,000 = 130.1 PF

Power Factor is important in USPSA because targets are scored slightly differently, based on the PF of the ammo used by the shooter: below a PF of 160, the load is called "minor", above that is called "major". Because (I guess) it's more difficult to shoot a higher PF, more points are awarded for Major than Minor in B, C, and D zone hits.

There's one more point I want to raise here, and that is acceleration of the bullet. I wish I was a physicist at times, so that I would really understand and be able to explain my hunch, which is that heavier bullets cannot accelerate as fast as light bullets (given a reasonable range energy values produced by the powder), and the slower acceleration yields less "snap" in the recoil.

One more thing, GT4point6: I really appreciate your analytical approach to this topic. Well done.

Chris
 
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#11 ·
Newton's 3rd law of gravity? I initially "figured" that a heavier bullet would be more affected by gravity and therefore hit lower... Wrong! Hell, what do I know?

Pass the Tylenol....
 
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#14 ·
EdF702 said:
Newton's 3rd law of gravity? I initially "figured" that a heavier bullet would be more affected by gravity and therefore hit lower... Wrong! Hell, what do I know?

Pass the Tylenol....
Click to expand...
yes as newton proved gravity sucks and sucks equaly no mater how heavy you are
 
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#15 · (Edited)
Since I'm a nerd, I had to play around with the equations. Newton's 2nd law: Force = mass X acceleration. Moving things around algebraically, we get: acceleration = Force / mass.
Another useful equation is for pressure: Pressure = Force / Area. Moving stuff around again, we get Force = Pressure X Area. If we plug this equation for Force into the first equation, we have a new equation that states: acceleration = (Pressure X Area) / mass.

acceleration in this case is the initial acceleration of the projectile. We know also from Newton that "every action has an equal and opposite reaction." So the acceleration imposed on the projectile will also be opposed by the mass of the firearm, and your hands/arms/shoulders. I'm looking at this from a 30,000 ft view, so all this is not "exact", but simplified enough that I can make calculations anyways... :)

I converted all the units to metric because it's simpler for me to work in metric units. Using Winchester's published reload data that GT4point6 provided, I calculated the instantaneous acceleration resulting from the peak published pressure.

acceleration = (Pressure X Area) / mass:
For the 115 grain projectile, with a peak pressure of 29,400 cup, the acceleration equals 19.27 meters/second^2
For the 147 grain projectile, with a peak pressure of 27,900 cup, the acceleration equals 14.23 meters/second^2

I love it when theory and the "real world" agree.
Now I'm gonna have to do this for 124 grain projectiles. That's what I shoot! :)

<edit> Just found the source, and it has data for 125 grain bullets: 6.8 grains of HS-6, 1,169 ft/sec; 27,100 cup.
Using the above equation the 125 grain bullet has an acceleration of 16.22 meters/second^2
How about that - it's right between the other two....

BTW, keep in mind I am making a huge simplification by implying that instantaneous bullet acceleration is directly proportional to greater felt recoil.
 
#16 ·
rangerbluedog said:
Since I'm a nerd, I had to play around with the equations. Newton's 2nd law: Force = mass X acceleration. Moving things around algebraically, we get: acceleration = Force / mass.
Another useful equation is for pressure: Pressure = Force / Area. Moving stuff around again, we get Force = Pressure X Area. If we plug this equation for Force into the first equation, we have a new equation that states: acceleration = (Pressure X Area) / mass.

acceleration in this case is the initial acceleration of the projectile. We know also from Newton that "every action has an equal and opposite reaction." So the acceleration imposed on the projectile will also be opposed by the mass of the firearm, and your hands/arms/shoulders. I'm looking at this from a 30,000 ft view, so all this is not "exact", but simplified enough that I can make calculations anyways... :)

I converted all the units to metric because it's simpler for me to work in metric units. Using Winchester's published reload data that GT4point6 provided, I calculated the instantaneous acceleration resulting from the peak published pressure.

acceleration = (Pressure X Area) / mass:
For the 115 grain projectile, with a peak pressure of 29,400 cup, the acceleration equals 19.27 gram-meters/second^2
For the 147 grain projectile, with a peak pressure of 27,900 cup, the acceleration equals 14.23 gram-meters/second^2

I love it when theory and the "real world" agree.
NOTE: all the above is theoretical, and is nowhere near exact...
Now I'm gonna have to do this for 124 grain projectiles. That's what I shoot! :)
Click to expand...
Cool!:cool: Thanks!
 
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J
#18 ·
My 2 cents worth. Yes it takes longer for a heavier bullet to exit the barrel than a lighter bullet. (slower so stays longer in the barrel) The energy of the heavier bullet is also less because energy is related to the square of the velocity but directly related to mass. So the 147s I have shot in my G17s "feel" like they have less of a recoil than higher velocity 115s likely because the energy they do have is expended over a longer period of time. The pressure curve might also be flatter. Federal agencies are switching to the slower 147s so I assume they feel that although they have less energy they have better stopping power. New bullet designs will apparently open up at lower velocities. However, many sporting goods stores I have talked to will not stock 147 gr 9mm. Why? Because apparently many guns will not work well with these loads. The typical comment from them is "Glocks will handle anything." But the government would not go this rout unless they have tested them well with their issued carry pistols, but apparently many guns don't like them. They are also over the maximum bullet weights specified in the NATO specs that most guns are designed to. I have not experienced them shooting high in my Glocks however I have heard this from LE when switching to Gen4s. So in my experience they do seem to shoot "softer" than lighter 9mm loads. Just my thoughts.
 
#19 ·
Jim,

That's a LOT more than 2 cents' worth, thanks for passing that along. The more explanations I read from people like you who do understand the physics, the better I understand the matter. I now have read enough from you and rangerbluedog to convince myself of a new "rule of thumb": buy ammo with the heaviest bullets you can get, at least for handguns.

Good work!

Chris
 
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#20 ·
Does anybody else think we should "stick" this thread, and maybe move it over to Glock Tech / Warranty?

There's enough good information here on bullet weight and recoil that I think we will re-use the thread quite a lot, but it may be my own enthusiasm getting away with me again. If you think this thread is worth "sticking", please speak up.

Chris
 
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#21 ·
cohland said:
Does anybody else think we should "stick" this thread, and maybe move it over to Glock Tech / Warranty?

There's enough good information here on bullet weight and recoil that I think we will re-use the thread quite a lot, but it may be my own enthusiasm getting away with me again. If you think this thread is worth "sticking", please speak up.

Chris
Click to expand...
plus 1
 
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#23 ·
I got carried away and renamed the thread so that it would be noticed. We got so much real information and data on this thread, on a topic that comes up pretty frequently, that I wanted to make sure that members understood what was being discussed..that was the reason for changing the name of the thread.

Chris
 
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#24 ·
Interesting data in this thread... Nice work rangerbluedog and JimFS

Interesting that some of the federal agencies are going to 147gr 9mm ammo... I hadn't heard that... I wonder which ones?

There are several trends of thought on the heavier bullet softer shooting equation in the competition world... Everyone seems to agree that the heavier bullets are softer and have a less felt recoil, but... some people like the snappier feeling of lighter bullets... some people say that the heavier bullets slow down the slide so much that their transition and split time are affected... Not sure about that... Some of the fastest USPSA Production shooters use heavy bullets and they don't seem to have any split issues with them.
 
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#25 ·
All is extremely true BUT like all things on physics there is a point of diminishing returns. Case in point the .40 S&W round 180gr vs. 165 gr. Here is where things start to flip. The 165 ends up with more muzzle energy than the 180, and it keeps it throughout its spectrum both in velocity and muzzle energy. I know thinking would go with "bigger is better" but not always. This also happens in the .223 world as well. Ain't science fun?
 
#27 ·
I'm a "salt and pepper on my steak then grill it" kind of person when it comes to most things. The explanations provided un-selfishly by the members was fantastic. Am I correct in saying we usually accept what should be the obvious ie; 165gr HST is higher velocity than 180gr HST? We've all seen the water jugs explode with more violence when the lighter grain bullet impacts yet some of us carry the larger heavier grain bullet for more surface area to be damaged.

Before exposing myself to various ammunition in my journey to secure what I feel will best protect my family; those around me and finally myself, I never understood what was meant by "snappy or pushing back" recoil. Too bad this past Sunday I shot 170gr, 180gr and 165gr produced by different manufacturers. I'm not able to narrow down which is the culprit for my right hand to be a bit sore still today. lol Maybe it was the 12 gauge shotgun also?

Thanks again for the information.
John
 
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#29 ·
Well, I have to agree. I shot my G42 for the first time today, and I was running the SIG Elite 100 grain .380 ACP rounds through it. Oddly enough, it did shoot those "softer" than the 95 and 88 grainers I had too. Did not matter the bullet profile either. Strange. :confused:
 
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#31 ·
It does seem logical that a lighter bullet would produce less recoil, I was under the same impression for years. To convince yourself otherwise, all you need to do is buy two boxes of bullets in the same caliber with very different weights, and burn them up at the range. You'll feel the difference in your hand.

A couple of examples: in .40 S&W get 165 and 180. In 9mm, get 115 and 147.

Chris
 
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