55 vs 62 grain POI Difference

**ShadeRabbit** · March 2nd, 2023, 11:11 AM

Went out shooting yesterday morning. Shot some 55 grain American Eagle 5.56. Then I shot some 62 grain PMC. 1:9 twist barrel. The 62 grain was hitting 4-5 inches higher than the 55 grain at 100 yards. No windage difference. Figured it had something to do with the barrel/gun, so I started shooting both types through a different gun with 1:8 twist. Same thing happened.

Is this normal/common? Anyone else have something similar happen?

I'm not a 5.56/.223 expert, and I'd expect some deviation based on the bullet weight, and even different companies. But 4-5 inch POI difference seems excessive to me. One thing I did notice was the 55 grain American Eagle cases were tarnished more than I'd like. Not green or anything, but fairly scuzzy looking. I'm wondering if it was "going bad." Every single one went bang without a problem though.

**Aggies Coach** · March 2nd, 2023, 04:09 PM

Originally Posted by ShadeRabbit

Went out shooting yesterday morning. Shot some 55 grain American Eagle 5.56. Then I shot some 62 grain PMC. 1:9 twist barrel. The 62 grain was hitting 4-5 inches higher than the 55 grain at 100 yards. No windage difference. Figured it had something to do with the barrel/gun, so I started shooting both types through a different gun with 1:8 twist. Same thing happened.

Is this normal/common? Anyone else have something similar happen?

I'm not a 5.56/.223 expert, and I'd expect some deviation based on the bullet weight, and even different companies. But 4-5 inch POI difference seems excessive to me. One thing I did notice was the 55 grain American Eagle cases were tarnished more than I'd like. Not green or anything, but fairly scuzzy looking. I'm wondering if it was "going bad." Every single one went bang without a problem though.

Happens to me all the time. I only shoot 62 grain out of my 1:8. And only 55 grain out of 1:9. I have my magazines color coded so I know which is which.

**Delkal** · March 2nd, 2023, 06:38 PM

Heavier bullets shooting higher is normal at closer ranges for rifle and pistol. The heavier / slower bullet stays in the barrel longer so recoil starts to have an effect.

Then there is barrel harmonics where the barrel is ringing like a bell and whipping around. Thats why when your reloading a few grains difference in powder charge can make a difference in accuracy. But I don't think harmonics in two different rifles is the reason here.

**Brick** · March 2nd, 2023, 06:46 PM

Generally a faster bullet will shoot lower than a slower bullet, same caliber same gun. The slower bullet is just a tiny fraction of a second further into the recoil cycle than the lighter.

**West Chester** · March 2nd, 2023, 11:05 PM

Did you chrono the rounds? Different BCs, grain weights and powder charges. Any change in any of the specs will change the POI.

**ShadeRabbit** · March 3rd, 2023, 12:19 AM

Originally Posted by West Chester

Did you chrono the rounds? Different BCs, grain weights and powder charges. Any change in any of the specs will change the POI.

No, I don't have a chronograph

I knew there would be differences between brands and grains, I was just surprised that in this particular instance it was that much of a difference at only 100 yards. I'm a bigger AK guy (because the ammo was much cheaper until recently and I'm a cheap bastard, and there's just something sexy about cheap laminate wood), and there is very little difference, in my experience, between 122, 123, and 124 grain (the main AK flavors).

I've had a few ARs for a while, I just don't shoot them as much because my wallet cringes every time I watch brass fly out. And I was mostly shooting 55 grain, because my wallet would cringe harder with the 62 grain. I don't own nor have I ever even fired a single round of 69 or 77 grain (shocking LOL).