Riddle me this? 115g and 124g groupings

[Markshoots]

I shoot 115g 9mm better than 124g. At 10 yards I can get 2 to 4 inch groups with no bench rest with the 115g but struggle to get a 4 to 6 inch group with 124g.

Here is the interesting part, this happens whether it's my M&P 9 2.0 compact 4", M&P shield 1.0, Taurus g2, and yes even a Glock 17. It does not matter the ammo either. It happens whether I am using cheap steel cased, mid priced range ammo and carry ammo such as Hornady,Barnes, etc.

As an experiment, I loaded 4 magazines each for the M&P and Glock (one with cheap 115g, one with Hornady 115, one with cheap 124g, and one with Hornady 124g). I shot one magazine each at 8 different targets. My son handed each magazine to me so I would not know what I was shooting at each target. Again same result, 115g had better groups than the 124g. My test guns were the M&P 9 and Glock 17 and I used a pistol rest.

I understand point of impact can be different when shooting different weight bullets out of the same pistol. I have not adjusted or zeroed the sights on any of my pistols for the 115g. I performed the "blind" experiment to see if it was just in my head.

I prefer 115g carry ammo anyway, but what is anyone's thoughts on this. My only conclusion is that all of these pistols were factory "zeroed " with 115g ammo.( if that's even a thing)

 

[DrScaryGuy]

something about the barrel not stabilizing the heaver bullet?
twist rate? some small imperfection?
ballistics are all voodoo

 

[RetiredUSNChief]

I shoot 115g 9mm better than 124g. At 10 yards I can get 2 to 4 inch groups with no bench rest with the 115g but struggle to get a 4 to 6 inch group with 124g.

Here is the interesting part, this happens whether it's my M&P 9 2.0 compact 4", M&P shield 1.0, Taurus g2, and yes even a Glock 17. It does not matter the ammo either. It happens whether I am using cheap steel cased, mid priced range ammo and carry ammo such as Hornady,Barnes, etc.

As an experiment, I loaded 4 magazines each for the M&P and Glock (one with cheap 115g, one with Hornady 115, one with cheap 124g, and one with Hornady 124g). I shot one magazine each at 8 different targets. My son handed each magazine to me so I would not know what I was shooting at each target. Again same result, 115g had better groups than the 124g. My test guns were the M&P 9 and Glock 17 and I used a pistol rest.

I understand point of impact can be different when shooting different weight bullets out of the same pistol. I have not adjusted or zeroed the sights on any of my pistols for the 115g. I performed the "blind" experiment to see if it was just in my head.

I prefer 115g carry ammo anyway, but what is anyone's thoughts on this. My only conclusion is that all of these pistols were factory "zeroed " with 115g ammo.( if that's even a thing)

First, eliminate some potential variables by doing bench shooting from a rest.

I'm not saying 124 gr. doesn't shoot differently, but you really need to eliminate as many factors which could affect your accuracy and consistency as possible. And bench shooting from a rest is an excellent way to do that.

Then see how you shoot, maybe at a couple different ranges such as 7 and 10 yards.

 

[wvsig]

At 10 yards I doubt that it is the bullet weight which is making the difference. At 25 yards or more how the gun was zeroed would make a difference but at 10 I don’t think it would.

 

[RetiredUSNChief]

At 10 yards I doubt that it is the bullet weight which is making the difference.

In my experience, the number one suspect for shooting problems is the shooter.

Which is why I believe you need to carefully evaluate how the shooting is being conducted first, THEN move on to other things.

 

[Scsmith42]

Felt recoil from 124 grain is slightly greater than from 115 grain. How tight is your grip? I'd retry the results off of a bench rest, and also using the tightest grip that you can have on the pistol.

 

[wvsig]

OP says his “test” was shot from a rest.

 

[45/70fan]

Not a hundgun but my Ruger PCC 9mm shoots 115 gr bullets much better than 124 gr bullets. I'm thinking it's something with rate of twist.

 

[Markshoots]

Probably is just me or.....maybe my range is over an old Indian burial ground.....or my guns are picky eaters like my kids😄

 

[contender]

I'd get an experienced, seriously good handgunner to shoot a few of the guns and loads. And I'd increase the distance to 25 yds to get a better idea of the true accuracy of each gun & load. If I had to guess,, as to why the OP has issues,, I'd look at his shooting technique.

Lots of variables. But a true evaluation by a top shooter can easily show things to others.

I've had people bring me guns saying "they won't shoot worth a crap," only to wear out a target center at a greater distance than what they had tried. I then have them shoot & watch the way they handle the gun. Almost always,, it's the shooter,, not the gun.

 

[RetiredUSNChief]

Lots of variables. But a true evaluation by a top shooter can easily show things to others.

Awesome idea!

When do we all meet up at Markshoots' for this?

 

[Catfish]

Sounds like you switched up enough variables to leave yourself as the common denominator. Change something about your grip or trigger press technique and see if the result varies?

 

[Pineoak]

115 to 147 jump in recoil is HUGE and I see definite differences in accuracy from newer shooters based on just a few grains difference.

I can see the same for 115 to 124 for the OP