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Discussion Starter · #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
 

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That extra 32 grains of bullet weight is slowing things down, would be my guess. As for being cleaner I would think different powders being used.
 

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are you using 115 federals
 

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Discussion Starter · #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.
 

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Heavier bullets generally yield less felt recoil...

Some people like it... some people prefer lighter snappier rounds...
 

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Heavier bullets generally yield less felt recoil...
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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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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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.
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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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...
I've always heard that heavier bullets have more inertia and stay in the barrel longer... Muzzle rise moves the point of impact higher. I don't know if that's accurate...


Here's an interesting ultra slow motion close up video of a .45 ACP bullet in a semi-automatic pistol... Looks like the slide and barrel are still moving straight back when the bullet exits the barrel...
 

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I've always heard that heavier bullets have more inertia and stay in the barrel longer... Muzzle rise moves the point of impact higher. I don't know if that's accurate...
I like that explanation because it fits nicely with my hunch that heavier bullets don't (can't) accelerate as fast as light ones!

Chris
 

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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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Discussion Starter · #12 ·
Watching that 45 slow mo video was amazing thank you for posting it.

But it really makes me depressed of how ancient and antiquated our current Weapons handguns or firearms today really are. I might as well be watching video of a Pirate gun being fired or a Musket. I really wish I would be around able to see what technology is around 100 years from now.

I've always heard that heavier bullets have more inertia and stay in the barrel longer... Muzzle rise moves the point of impact higher. I don't know if that's accurate...


Here's an interesting ultra slow motion close up video of a .45 ACP bullet in a semi-automatic pistol... Looks like the slide and barrel are still moving straight back when the bullet exits the barrel...
 

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...But it really makes me depressed of how ancient and antiquated our current Weapons handguns or firearms today really are. I might as well be watching video of a Pirate gun being fired or a Musket. I really wish I would be around able to see what technology is around 100 years from now.
I don't know if firearms will become obsolete, or will change that much.

Remember, the 1911 is 102 years old now, and parts from original issue 1911s fit in today's production guns..well, most of them, anyway. Sure, the 1911 is overly complicated, but it has survived.

That's not to say that improvements haven't occurred, they certainly have. But I think the basics of using combustion to produce gas that pushes a projectile will remain.

Electric ignition of the propellant might be a useful change, that way we wouldn't be dependent on primers!

That is possibly less than 2₵ worth on this topic!

Chris

Chris
 

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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....
yes as newton proved gravity sucks and sucks equaly no mater how heavy you are
 

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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.
 

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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! :)
Cool!:cool: Thanks!
 

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rangerbluedog gets my thanks for providing an actual explanation for why light bullets accelerate faster, and why they feel snappier. I am in your debt!

Chris
 

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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.
 

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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.
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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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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