115gr vs 147gr

[superdude]

No one waits for the slide. The slide is done cycling before a fast split time. Never seen someones trigger finger outrun a pistol.

Really? OK, well, google "waiting on the slide 147 9mm". If your splits are in .20s+ you likey won't notice. Below that, well, give it a try and see.

How slow is the slide when shooting 147s?

A 45 ACP 1911 shooting light loads with 185 grain bullets and a 12 lb recoil spring has a total cycle time of about .060 (60 milliseconds) or less.

http://www.shootingtimes.com/gunsmithing/recoil-spring-rate-affects-timing/

[Garmil]

No one waits for the slide. The slide is done cycling before a fast split time. Never seen someones trigger finger outrun a pistol.

Really? OK, well, google "waiting on the slide 147 9mm". If your splits are in .20s+ you likey won't notice. Below that, well, give it a try and see.

What people perceive is happening and what actually happens are two different things. You would need single digit hundredths of a second splits to even come close to waiting. And to get close to that fast you're not waiting for anything just pulling as fast as you can.

[kneelingatlas]

I'm convinced the "waiting" feeling is the time it takes to get the front sight back on target due to slide weight, spring choice and firing pin stop angle.

[R.Elliott]

You're not waiting on the slide, you're waiting on the recoil. The slide cycles long before the muzzle returns out of recoil.

Heavier bullets = longer recoil event. Softer feel.

Lighter bullets = shorter recoil event. Snappier feel.

It's all about preference. I prefer 147s because I feel that the less vent recoil impulse let's me track the sights better, but it's subjective. On the clock the split times are mostly regulated by how fast I can get the sights back on target. Up close wh~ I don't have to aim split times are identical, regulated by how fast it can reset and pull the trigger. I cannot pull the trigger faster than the gun can cycle. So though technically slower to recoil, 157s seem to afford faster visual perception. At least for my eyes.

[R.Elliott]

You're not waiting on the slide, you're waiting on the recoil. The slide cycles long before the muzzle returns out of recoil.

Heavier bullets = longer recoil event. Softer feel.

Lighter bullets = shorter recoil event. Snappier feel.

It's all about preference. I prefer 147s because I feel that the less vent recoil impulse let's me track the sights better, but it's subjective. On the clock the split times are mostly regulated by how fast I can get the sights back on target. Up close wh~ I don't have to aim split times are identical, regulated by how fast it can reset and pull the trigger. I cannot pull the trigger faster than the gun can cycle. So though technically slower to recoil, 157s seem to afford faster visual perception. At least for my eyes.

[StraightSh00ter]

My take on this (I try not to get technical forums, but since I didn't start it...):

The difference in felt recoil is due to the different charge used for the each bullet. Using the same power factor, the lighter bullet has more kinetic energy, and therefore required more energy to accelerate it. It might actually be rocket science, but we call can grasp that concept that igniting a bigger amount of an explosive is going to have more of a felt reaction.

As far as hitting power: The momentum of the 2 bullets is the same. If you're looking at equations, 'mv' is exactly the same for any 2 bullets with the same power factor (power factor is basically the same thing as momentum - mass x velocity). The only place you will see a difference is in energy equations, where the velocity term is squared (which is substantial).

For a 'real world' example, I recently tried 2 different loads - same 115gr bullet, but changing powder charge and OAL to maintain power factor. The round with less powder felt a tiny bit softer - go figure.

I read somewhere that 'stopping power is a term we all use and understand, yet something we can't measure'. I'm having a tough time understanding why a heavier bullet with the same power factor as a lighter bullet would have more knock down power. Stopping power takes entry/exit holes and bodily injury into account, which doesn't apply to knocking down steel. And I think the picture we get in our heads ignores the velocity component of the equation.

Here's a different kind of example: an impact wrench. Impact wrenches (like mechanics use to take wheels off a car) can have a ton of torque (mine is rated at 1150 ft-lb - the equivalent of 1150lbs of force working on a 12" wrench - that's huge!). They operate using a small mass traveling at high velocity which impacts an anvil to do the work. So its clear that a light object traveling with high velocity can impart a huge force on an object. And yet you hardly feel anything happening while you're holding the tool, because the reaction is so quick. Imagine the 12" wrench is actually a 12" steel popper, and it's so rusty that it takes 1100lbs of force on its head to make it move. That little 2lb anvil in the impact wrench can do just as good of a job moving the popper as any 1100lb object pushing on it's head.

Many of us know the equation: Force = mass x acceleration (F=ma). That's one equation, but its actually derived from a different equation: Force = the change in (mass x velocity) over time, or F=d(mv)dt. It's the same equation, just written differently. It says that the heavier and lighter bullet will hit with the same force if fired into a fixed steel plate which stops all forward motion. If the bullet rebounds 90deg to the side, or 180deg backwards, it still had to come to a complete momentary stop thus imparting 100% of the force.

I am relatively new to shooting. If you tell me that a heavier bullet with the same power factor as a lighter bullet will do a better job of knocking down steel, I'll believe it, but not understand it. But it would be important to know if that's based on exactly the same shot, hitting the same point, and with the exact same power factor. Still, maybe it does and I'm just missing something.

[phecksel]

Many of us know the equation: Force = mass x acceleration (F=ma). That's one equation, but its actually derived from a different equation: Force = the change in (mass x velocity) over time, or F=d(mv)dt. It's the same equation, just written differently. It says that the heavier and lighter bullet will hit with the same force if fired into a fixed steel plate which stops all forward motion. If the bullet rebounds 90deg to the side, or 180deg backwards, it still had to come to a complete momentary stop thus imparting 100% of the force.

There is the ole 1/2 MV^2 thingy

Since 147 grain run slower, and velocity is squared....

Personally, in my very limited experience, I've done 119, done 147, and like the 125 best.

Edited December 7, 2015 by phecksel

[peterthefish]

There is the ole 1/2 MV^2 thingy

Since 147 grain run slower, and velocity is squared....

Once you figure out how to conserve kinetic energy in an inelastic collision let me know.

Shoot plates enough and you'll notice it's the 230 GR sub-minor slugs that tend to bounce back in once piece - you know, the ones with the lowest 1/2 MV^2 thingy?

That's because the extra energy lighter projectiles carry tends to go towards deforming / splattering them.

[StraightSh00ter]

There is the ole 1/2 MV^2 thingy

Since 147 grain run slower, and velocity is squared....

Once you figure out how to conserve kinetic energy in an inelastic collision let me know.

Shoot plates enough and you'll notice it's the 230 GR sub-minor slugs that tend to bounce back in once piece - you know, the ones with the lowest 1/2 MV^2 thingy?

That's because the extra energy lighter projectiles carry tends to go towards deforming / splattering them.

Yeah without knowing what happens after the bullet hits the plate, you can't use the energy equation. I referenced it for the reaction in the slide though.

If heavier, slower bullets are better, the breakup could be the part of the equation I'm missing. I would love to test this theory! I need to find a club, and wait for a nice summer day

[Miranda]

overall it is not hard.

the best you will get is approximate

you can assume the max energy transferred is the amount of energy in the moving bullet.

it is possible to transfer more and that is rare.

if the bullet stops or shatters on the steel most of the energy is transferred.

where things get fun is in estimating how far the bullet or big pieces went after it hit

if the bullet did not effectively stop on the steel.

At that point you have to consider what direction the energy went.

deflecting a heavy bullet takes more energy than deflecting a light bullet.

miranda

[StraightSh00ter]

you can assume the max energy transferred is the amount of energy in the moving bullet.

it is possible to transfer more and that is rare.

The first part is correct, and the lighter bullet with higher velocity has more energy. The second part is incorrect, since energy can neither be created or destroyed (the bullet can only transfer the energy it has).

deflecting a heavy bullet takes more energy than deflecting a light bullet.

That is not a good assumption. If I throw a 147gr bullet at a popper, and you load and shoot a 115gr bullet at a popper, which bullet will take more energy to deflect?

[peterthefish]

you can assume the max energy transferred is the amount of energy in the moving bullet.

it is possible to transfer more and that is rare.

The first part is correct, and the lighter bullet with higher velocity has more energy. The second part is incorrect, since energy can neither be created or destroyed (the bullet can only transfer the energy it has).

deflecting a heavy bullet takes more energy than deflecting a light bullet.

That is not a good assumption. If I throw a 147gr bullet at a popper, and you load and shoot a 115gr bullet at a popper, which bullet will take more energy to deflect?

Probably just easier to say that nearly everything Miranda wrote is incorrect and reflects a failure to grasp even HS level physics.

Of course, lack of knowledge on a subject doesn't stop folks from posting.

[Miranda]

yall are a riot.

k...

If you can live with being wrong, so can I

hohohohohohohohohoho

miranda

[JLeeCZ]

147s are just cool.

[savagemann]

147s are just cool.

OK, I'm sold.

[GOF]

Why not just put up some USPSA targets at 12 to 15 yards.... load 147s to PF.... load 115s to PF... and run double taps as fast as you can...

See what the timer & targets tell you. They don't lie... and they don't really care about Quantum Physics and that MV/2V/thingy. They just do the time and record the holes. Just like they do in a real match!

As for knocking down steel poppers... the 147s will be more positive.... but if the 115s don't you can always call the MD to bring out a chrono and a calibration load. Lotsa luck with that at a club match

[Miranda]

GOF,

the math involved agrees with you.

miranda

[Nathanb]

As Jack pointed out, higher level shooters generally don't run 147s because then they run into the situation where they are "waiting for the gun" meaning they are waiting on the slide to cycle before they can get off their next shot.

Wait a sec...I know I've read/heard Sevigny, Vogel, and Stoeger all shoot 147's in matches. Am I wrong?

When I took a class wih Vogel I asked what his load was. 147 grain 9mm over titegroup loaded to 135 power factor

[LeviSS]

As Jack pointed out, higher level shooters generally don't run 147s because then they run into the situation where they are "waiting for the gun" meaning they are waiting on the slide to cycle before they can get off their next shot.

Wait a sec...I know I've read/heard Sevigny, Vogel, and Stoeger all shoot 147's in matches. Am I wrong?

When I took a class wih Vogel I asked what his load was. 147 grain 9mm over titegroup loaded to 135 power factor

That's what I thought. He says he shoots 147's in the Panteao videos...because they feel softer.

There's a section in Robin Taylors book about Glocks, where Sevigny talks about why he prefers the 147's.

I know Stoegers says he shoots 124's in practice and 147's in matches. He said he does it that way because of cost in one of his podcasts.

So who are these "top shooters" shooting 124's and 135's?

[phecksel]

Oh, the physics experts

kinetic energy doesn't care how it stops It's still kinetic energy, until it stops

bullet hitting a steel plate is in no way an inelastic collision.

Besides, slower bullets take longer and add time to your score

[busdriver02]

bullet hitting a steel plate is in no way an inelastic collision.

It is definitely a partially inelastic collision.

[peterthefish]

bullet hitting a steel plate is in no way an inelastic collision.

It is definitely a partially inelastic collision.

Don't you know that if you mock people as "physics experts" you don't need to actually have any understanding of physics?

You can just state something, like a bullet hitting a steel plate isn't an inelastic collision, and it's true?

I mean, no one has ever seen a bullet deform while bouncing off a plate, right? So clearly KE and momentum are conserved. Not like any of the KE goes towards the non-existent deformation of the bullet hitting the plate.

/where's the bang head on desk emoticon?

[Hi-Power Jack]

WOW!!! And all this time, I thought that it was all an individual preference, based on

perceived observation. :bow:

[RippinSVT]

I shoot both, both in minor Bianchi Cup loads. I like the 115's in my 6" Metallic 1911 (9mm) because it cycles especially soft with the added slide mass. In my comp'd Bianchi Open gun (38SC), I like the 147's because it is less "blasty" from the comp when I'm shooting barricades and it recoils insanely soft, almost like an airsoft gun. It also puts 6 shots into .68" at 50 yards.

[Garmil]

I shoot both, both in minor Bianchi Cup loads. I like the 115's in my 6" Metallic 1911 (9mm) because it cycles especially soft with the added slide mass. In my comp'd Bianchi Open gun (38SC), I like the 147's because it is less "blasty" from the comp when I'm shooting barricades and it recoils insanely soft, almost like an airsoft gun. It also puts 6 shots into .68" at 50 yards.

Mind sharing your 147 load?