115gr vs 147gr in 9mm

[Eric86]

How much higher will 147 grain shoot than 115 grain bullets out of a 4.25in barrel at 10 yards?

 

[averycustom]

At that range POI is negligible.

Regards,

Mark

 

[Eric86]

I was hoping it would be a couple inches. I took my m&p out and shot it for the first time and it seemed to be shooting about 3 or 4 inhes low with 115 grain ammo and was hoping 147 grain would bring it up. I guess I'll have to buy some adjustable sights.

 

[Indy_Guy_77]

I was hoping it would be a couple inches. I took my m&p out and shot it for the first time and it seemed to be shooting about 3 or 4 inhes low with 115 grain ammo and was hoping 147 grain would bring it up. I guess I'll have to buy some adjustable sights.

Why not just compensate with your sight picture?

 

[Mango]

I've found that with the M&P's you really have to drive the dot.

 

[Sling10mm]

Is the thought that the heavier/slower pill will impact higher because it is in the barrel longer and hence affected by the recoil more?

Thanks, Sling

 

[in625shooter]

both my M&P's have pretty much the same POI with 115 and 124's I would suggest letting another person (experienced person) shoot it and see where they are at.

If the sights need changed I would suggest maybe a different hight front sight unless adj sights are something you really want.

 

[gunman41mag]

I was hoping it would be a couple inches. I took my m&p out and shot it for the first time and it seemed to be shooting about 3 or 4 inhes low with 115 grain ammo and was hoping 147 grain would bring it up. I guess I'll have to buy some adjustable sights.

Are you sure you're not jerking the trigger

 

[ZbornacSVT]

I would wager the 115s will shoot flatter than the heavier 147s at distance, but I agree that at 10 I doubt you'd notice...

 

[Exodus]

Wouldn't a heavier projectile shoot lower? Sorry as I am pretty ignorant on ballistics. But like stated at 10 hers it would be negligible IMO.

 

[HandK]

There are two different sights set ups from different factory's Glock's are pumpkin on the post! Meaning that you put the round center circle on top of the front sight and your impact point will be in the center of the ring!

The other is Point of aim! this is where you put the exact center of the target on top of the front sight and the POI will be the where you are pointing!

Both of those are with the front sights properly aligned with the back sight's!

Hope this helps!

 

[in625shooter]

Wouldn't a heavier projectile shoot lower? Sorry as I am pretty ignorant on ballistics. But like stated at 10 hers it would be negligible IMO.

In theroy yes but in reality the lighter the projectile the lower the impact.

 

[Eric86]

I can't 100% say that I'm not jerking the trigger but when I shoot every round low I believe it's more with the sight picture. When I pull the trigger very slowly it does not change poi.

 

[Indy_Guy_77]

Typically:

heavier bullets impact higher because of the ever-so-slightly longer dwell time in the barrel allowing the recoil to ever-so-slightly affect bullet travel.

the 115 grainers exit a tiny bit more quickly than the 147 grainers, thereby "outracing" the recoil.

Note* This is how I've heard it explained. Always willing to learn better if it's incorrect!!

-J-

 

[Indy_Guy_77]

I would wager the 115s will shoot flatter than the heavier 147s at distance, but I agree that at 10 I doubt you'd notice...

Both bullets are falling at the same rate.

 

[cosermann]

FWIW, I haven't noticed any significant difference in POI using mid to full-size handguns. Can't speak for the subcompacts.

As Indy_Guy mentioned, this phenomenon is explained by barrel transit time and the change in barrel position that occurs from recoil during that time. (It's NOT a velocity issue. Otherwise, we'd expect the lighter bullet to hit higher.) So, since a heavier bullet is in the barrel a longer time, the recoil impulse has more time to raise the barrel, thus contributing to the sometimes higher POI observed with heavier bullets (under certain conditions).

That said, the effect is most pronounced with handguns that are very light, and have grips that allow the gun to roll back in the hand more during recoil (both factors that promote barrel flip). So, the classic example of this is the airweight revolver.

I suspect small semi-autos are a little different bird due to the different grip design of many. That would tend to reduce the effect I would think.

Try out a box of the different bullet weight and let us know what you find.

YMMV.

 

[ZbornacSVT]

Both bullets are falling at the same rate.

I understand that, but a bullet travelling faster would be further away from the shooter when it hits the same drop, no?

 

[cosermann]

I understand that, but a bullet travelling faster would be further away from the shooter when it hits the same drop, no?

All other factors constant, yes.

However, that's not the case in reality. Changing things like velocity and bullet weight affect recoil, which affects where the gun is pointing when the bullet exits the barrel, which affects the POI. Over typical defensive handgun distances, this change in barrel alignment has far more impact on POI than the change in velocity.

 

[netsecurity]

I've never noticed any change, but I'll do some tests, since I carry 147gr for defense and shoot 115's. Maybe you are just not holding on to the grip tight enough, and the recoil is having its way, or maybe your powder is hotter on the 147's.

 

[Aaron1776]

Are you sure you're not jerking the trigger

I can't 100% say that I'm not jerking the trigger but when I shoot every round low I believe it's more with the sight picture. When I pull the trigger very slowly it does not change poi.

Are you 110% sure? The M&P has a really crappy trigger. I had to ligthen mine because I couldn't stand it.
Have another competent shooter (besides yourself) shoot the gun and see where it is landing.

Also, lighten the trigger anyway. You'll be happier with the result.