9mm shifted point of impact

[tack]

My 9mm 1911 surprised me at the range last week. I shot several mags and then changed ammunition from one major brand to another. The point of impact dropped by at least 3.5 inches at 15 yards. I shot enough to make sure it was a consistent drop.

Here is some background information. This 9mm was never very accurate compared to my 45. I’ve improved the fit at both the barrel bushing and the barrel-to-slide lock up, so both ends are good. The gun has target sights and I wondered if they were out of adjustment, but it took 6-8 clicks to get back on target. The pistol feeds and extracts reliably. I was wondering if the barrel diameter might be a bit tight.

Has that happened to you? Please offer me your ideas as to what is going on here.

Thanks in advance,
Tack

 

[Sapper771]

In my limited experience, I have found that some factory ammunition will print differently than others. I have seen variances of up to 6" between certain ammunitions, but that is not very common.

Where I see this the most is when I am doing load development for my reloads. I tweak the rounds that I am making to see which combination (bullet + powder + primer + case + length + crimp) will shoot POA in my particular pistol. That's the good thing about reloading. It gives you the ability to "tailor make" your ammo for a particular firearm. Sometimes, minor tweaking is all that is required to bring a load that is shooting 2" high, down to POA.

Was the bullet weight the same between the two types of 9mm you shot ?

Did one load feel hotter/weaker than the other ?

Were the bullet designs similar (RN , FP , FMJ , HP , TC) ?

Hopefully, the issue that you are experiencing is just minor.

 

[killchain]

Could the recoil be different too?

I have to adjust for lighter loads because the "anticipated recoil" will make me shoot low.

 

[Shipwreck]

In my Beretta 92FS - I can shoot 115gr FMJ all day long and it hits where I want. But 115gr JHP hits 2 inches low.

Different weights can and will hit in different spots on some guns. That's another reason why you should test your carry ammo. Not just to see that it feeds 100%, but for accuracy

 

[tack]

Both brands were 115 gr FMJ. I did not shoot them mixed in the same magazine. I assume the felt recoil would be different.

 

[1SOW]

point of impact dropped by at least 3.5 inches at 15 yards.[/QUOTE

That's a pretty 'major' drop at only 15 yds, even with a fairly big load change. Consider that a 9mm only drops about 8" at 100 yds. Yours would drop 23".

I'd look at the gun again. What gun and what ammo??

 

[Magnumite]

It could be that much of a difference at 15 yards if there is an extreme difference in bullet weight and velocity. If it is consistant to the ammo, then it is the ammo. You could start changing springs, etc, to compensate, but I'd just adjust for that ammo.
I even have a small notebook with sight adjustments for different ammo in specific pistols to keep me competitive.

"I have to adjust for lighter loads because the "anticipated recoil" will make me shoot low." BAll and dummy method should help in this matter. It is advisable to adjust shooting technique here, not the sights.