Bullet drop/rise question

Neutron · Jul 29, 2019

I zeroed my .22 cal at 50 yrs and when I moved to 100 yrs the bullet drop was about 6 to 8 inches which I think is normal. I did the same thing with my AR 9 and the bullets were higher on the target by several inchez. Does this seem normal? I would think they would drop a little, not rise.

danb · Jul 29, 2019

9mm from a 16" barrel could be going 1400 fps depending on the load.

http://www.ballisticsbytheinch.com/9luger.html

CCI, 22lr, 1200 ish from a 16" barrel.

but this all depends very much on load. A 147 gr 9mm is not breaking the sound barrier even in a 16" barrel, so figure 1000 ish fps. Whereas 22lr CCI stingers are going 1400 fps...

THier · Jul 30, 2019

danb said:
9mm from a 16" barrel could be going 1400 fps depending on the load.

http://www.ballisticsbytheinch.com/9luger.html

CCI, 22lr, 1200 ish from a 16" barrel.

but this all depends very much on load. A 147 gr 9mm is not breaking the sound barrier even in a 16" barrel, so figure 1000 ish fps. Whereas 22lr CCI stingers are going 1400 fps...

What he is trying to say,, "normal" :lol2:

erwos · Jul 30, 2019

NeutronBlu said:
I zeroed my .22 cal at 50 yrs and when I moved to 100 yrs the bullet drop was about 6 to 8 inches which I think is normal. I did the same thing with my AR 9 and the bullets were higher on the target by several inchez. Does this seem normal? I would think they would drop a little, not rise.

No, that's not normal. Your bullets should have 6-8 inches of drop. The only way you end up higher is if you have a 10-12yd zero with your 9mm. Something is going wrong with either your optic, your zero, or your shooting.

smokey · Jul 30, 2019

NeutronBlu said:
I zeroed my .22 cal at 50 yrs and when I moved to 100 yrs the bullet drop was about 6 to 8 inches which I think is normal. I did the same thing with my AR 9 and the bullets were higher on the target by several inchez. Does this seem normal? I would think they would drop a little, not rise.

The big factor is the height over bore. If your .22 has something traditional, like a 1.5" height over bore, then that drop should make sense. It's what I see on my marlin 795 moving from 50 to 100. Now with your ar, you're typically looking at something like a 2.7" height over bore. In that case, you're lobbing the bullet up at a greater angle to intercept the line of site at 50 yards, which could account for the different impact at 100.

smokey · Jul 30, 2019

Drop at 100 from my 795 with wolf subsonics

danb · Jul 30, 2019

erwos said:
No, that's not normal. Your bullets should have 6-8 inches of drop. The only way you end up higher is if you have a 10-12yd zero with your 9mm. Something is going wrong with either your optic, your zero, or your shooting.

There can be as much as a 400 fps difference between 22lr and 9mm loads from a 16" barrel.

The bullet drop @100 yds for 22lr going 1150, sighted in at 50 yds, will be 6 in.

The bullet drop @100 yds for 9mm going 1350fps, sighted in at 50 yds, will be 4 in.

(and as smokey0118 mentions in #5, these results are for 1.5" over bore. This will matter too.)

If the actual bullet drop of 22lr per the OP was 6-8 in, its going slower than 1150. Blazer 9mm 115 gr FMJ target loads (what I often shoot in my 9mm AR also sighted in at 50 yds ) drops about 4 in.

"plausible"

erwos · Jul 30, 2019

danb said:
If the actual bullet drop of 22lr per the OP was 6-8 in, its going slower than 1150. Blazer 9mm 115 gr FMJ target loads (what I often shoot in my 9mm AR also sighted in at 50 yds ) drops about 4 in.

"plausible"

I concur that that is plausible behavior, albeit we don't know the bullet weights or velocities he's shooting with, which means 6-8 inches is also not implausible. Problem is, the OP also said the bullets were winding up "higher" on the target at 100yds. If he simply meant not dropping as much as 6-8 inches, sure, there's no problem. If he meant that he zeroed at 50 and the impacts were at like an inch or two higher than the bullseye of the target, something is going wrong. You're latching onto my numbers; his problem is essentially trajectory behavior that should be physically impossible.

danb · Jul 30, 2019

erwos said:
I concur that that is plausible behavior, albeit we don't know the bullet weights or velocities he's shooting with, which means 6-8 inches is also not implausible. Problem is, the OP also said the bullets were winding up "higher" on the target at 100yds. If he simply meant not dropping as much as 6-8 inches, sure, there's no problem. If he meant that he zeroed at 50 and the impacts were at like an inch or two higher than the bullseye of the target, something is going wrong. You're latching onto my numbers; his problem is essentially trajectory behavior that should be physically impossible.

Well, yeah, I interpreted "higher on the target by several inchez" as higher than 22lr. You are correct, I did first rule out interpretations that violate the laws of physics.

smokey · Jul 30, 2019

yeah, even a 2.7 height makes it tricky to figure out why it's landing higher at 100 with 50 or 25.

erwos · Jul 30, 2019

danb said:
Well, yeah, I interpreted "higher on the target by several inchez" as higher than 22lr. You are correct, I did first rule out interpretations that violate the laws of physics.

I've been on gun forums long enough to know that small things like the laws of physics are no barrier to a motivated shooter.

danb · Jul 30, 2019

erwos said:
I've been on gun forums long enough to know that small things like the laws of physics are no barrier to a motivated shooter.

Maybe I should have said chupacabra.

Neutron · Jul 30, 2019

erwos said:
I concur that that is plausible behavior, albeit we don't know the bullet weights or velocities he's shooting with, which means 6-8 inches is also not implausible. Problem is, the OP also said the bullets were winding up "higher" on the target at 100yds. If he simply meant not dropping as much as 6-8 inches, sure, there's no problem. If he meant that he zeroed at 50 and the impacts were at like an inch or two higher than the bullseye of the target, something is going wrong. You're latching onto my numbers; his problem is essentially trajectory behavior that should be physically impossible.

No, the 9mms bullets were higher on the 100 yd target than they were on the 50 yd target meaning they "rose" a few inches instead of drop a few inches as expected. They were 124g copper plated over 3.9g of bullseye. I'm going to go back to the range and repeat this test to see if it repeats. The.22 cal bullets behaved as expected.

lazarus · Jul 30, 2019

Really extra high sight height?

smokey · Jul 30, 2019

lazarus said:
Really extra high sight height?

Looks like the sight is mounted about 8 inches over the bore. :innocent0

danb · Jul 31, 2019

erwos said:
I've been on gun forums long enough to know that small things like the laws of physics are no barrier to a motivated shooter.

I take it back...

NeutronBlu said:
No, the 9mms bullets were higher on the 100 yd target than they were on the 50 yd target meaning they "rose" a few inches instead of drop a few inches as expected. They were 124g copper plated over 3.9g of bullseye. I'm going to go back to the range and repeat this test to see if it repeats. The.22 cal bullets behaved as expected.

This is only possible if your bullets were in excess of about 2200fps. That is 7.62x39 velocity. No way. Unless your scope is loose. Or your scope height is 8", lol.

Try this:

http://www.shooterscalculator.com/b...bf;Vel[x+y]~ft/s&lbl=&submitst=+Create+Chart+

Biggfoot44 · Jul 31, 2019

OP , What is the sight on the 9mm carbine ?How is it mounted ?

To be " couple of inches " above aiming point @ 100yds , wouldn't need to be 8in above , 6-ish should get above POA .

Spitballing here ;

IF the sight in use on the PCC is a Red Dot, with a generous sized dot ( 4moa or larger ) , then there could be discrepancies in the actual aiming point . ie Was the group centered in the exact center of the dot ? Or more at the top or bottom edge ? Likewise when shooting at 100yd, is the dot equally hanging over the aiming point on all sides, or aiming with top edge or bottom edge for 6' o'clock , or a figure 8 sight picture ?

Mini14tac · Jul 31, 2019

OP, do some research on Point Blank Ranging. It might help you understand that the projectile crosses the line of sight twice on an arc. If your round is hitting dead on at 50 and high at 100 then 50 is where the round is crossing the line if sight first and it is crossing the line of sight somewhere past 100 at the second point. As mentioned above that sight height above the axis of the bore affects where the initial point where the crosses the line of sight first. The round is dropping as soon as it leaves the bore. Bullet rise is just an effect of bore angle in relation to the line of sight. Hope this helps.

erwos · Jul 31, 2019

Mini14tac said:
OP, do some research on Point Blank Ranging. It might help you understand that the projectile crosses the line of sight twice on an arc. If your round is hitting dead on at 50 and high at 100 then 50 is where the round is crossing the line if sight first and it is crossing the line of sight somewhere past 100 at the second point. As mentioned above that sight height above the axis of the bore affects where the initial point where the crosses the line of sight first. The round is dropping as soon as it leaves the bore. Bullet rise is just an effect of bore angle in relation to the line of sight. Hope this helps.

For this to be true with 9mm, you need like a 10yd zero, not the 50yd zero that the OP says they have.

Blacksmith101 · Jul 31, 2019

Mini14tac said:
OP, do some research on Point Blank Ranging. It might help you understand that the projectile crosses the line of sight twice on an arc. If your round is hitting dead on at 50 and high at 100 then 50 is where the round is crossing the line if sight first and it is crossing the line of sight somewhere past 100 at the second point. As mentioned above that sight height above the axis of the bore affects where the initial point where the crosses the line of sight first. The round is dropping as soon as it leaves the bore. Bullet rise is just an effect of bore angle in relation to the line of sight. Hope this helps.

This diagram illustrates what he is saying:
https://cdn.britannica.com/30/178630-050-D12B8390.jpg

Calculate the mid range height and place a target at the mid range distance and the impact point should be that much higher than the zero if your zero is intersecting the descending arc of the bullet path however if the mid range impact is lower than the zero you are intersecting the rising arc of the bullet path. Either will be a "zero" at 50 yards but the down range results will be different.

Bullet drop/rise question

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