Holdover\holdunder at different increments

Jack M

The Student
Hey everyone. I got a question for y'all. I'm running a pulsar xq38 lrf on a DD M4A1 .223. I zeroed it in at 50yds and it's a tack driver. At 20yds it shoots 1" low. At 100yds 1.5" high. At 150yds 3" high. At 200tds 4"high. And at 225yds 6"high. The inches are all estimated, yardages are from the built in range finder. So my question is is it normal to have to holdunder with yardage increase? It's been awhile since using glass and can't remember. Also at each yardage I did 3 shot groups and each group the shots were less than 1\2 inch apart.
Thanks
Jack
 

Jack M

The Student
Sorry, but that is totally messed up. You have bullets impacting in a bizarre pattern, first along a linear scale, then curving downward off the line, and skyrocketing upward at 225. Ballistics don't typically work like that where bullets go down and then back up.
Exactly. It's the exact opposite of what it should be.
 

Jack M

The Student
Sorry, but that is totally messed up. You have bullets impacting in a bizarre pattern, first along a linear scale, then curving downward off the line, and skyrocketing upward at 225. Ballistics don't typically work like that where bullets go down and then back up.
Any thoughts on why this is happening?
 

Jack M

The Student
Sorry, but that is totally messed up. You have bullets impacting in a bizarre pattern, first along a linear scale, then curving downward off the line, and skyrocketing upward at 225. Ballistics don't typically work like that where bullets go down and then back up.
I will also video it tonight when it cools down so you can see what going on
 

Chopperdrvr

Deep East Tx
SUS VENATOR CLUB
I don't know if its just me, but you guys don't seem to be saying the same thing. If he is zeroed at 50 yds and 1" low at 20 yds, that is perfectly normal. The bullet starts out lower than the line of sight until it intercepts the line of sight at the zeroed distance and continues to climb until it reaches the apex of the bullets path which in this case seems to be somewhere beyond 225 yds. The bullet didn't go down then back up, it started down and continued to climb. Rather consistently.
 

Brian Shaffer

Hog Hunter
SUS VENATOR CLUB
LoneStarBoars Supporter
Dave, you have to plot it out. He has a different amounts of rise of run that don't follow a normal ballistic curve.

For example,
He gets 1.5" of rise over 50 yards run from 50-100 yards.
He gets 1.5" of rise over 50 yards of run from 100-150 yards....this looks more linear than it should look, but maybe that is a fluke.
He gets 1" of rise over 50 yards of run from 150-200 yards, ...this looks like it is leveling off as you would expect,
but gets 2" of rise over 25 yards of from 200-225 yards. ... so the bullet is now heading up at a previously unprecedented level.

Bullets don't fly like that.
 

Ratdog68

LSB Official Story Teller
LSB TURKEY BUZZARD PRESERVATION SOCIETY
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LoneStarBoars Supporter

Jack M

The Student
Dave, you have to plot it out. He has a different amounts of rise of run that don't follow a normal ballistic curve.

For example,
He gets 1.5" of rise over 50 yards run from 50-100 yards.
He gets 1.5" of rise over 50 yards of run from 100-150 yards....this looks more linear than it should look, but maybe that is a fluke.
He gets 1" of rise over 50 yards of run from 150-200 yards, ...this looks like it is leveling off as you would expect,
but gets 2" of rise over 25 yards of from 200-225 yards. ... so the bullet is now heading up at a previously unprecedented level.

Bullets don't fly like that.
I haven't gotten around to making a video yet to show you guys. Was about to but then walked up on a hog. Will try for tomorrow. Thanks for all the replies.
 

pruhdlr

Cantonment,Fla.
SUS VENATOR CLUB
You have the bullets path which is a arc. Then the sight,scope,thermal,NV,it does not matter,line of sight which is like a laser.
The bullets arc crosses the line of sight twice in it's normal travel to the target if it is somewhat distant.
The ( my) basic thumb rule for a 223/5.56 is - - -> "on at 50 . . on at 150". This is pretty much true in it's simplest form.
Most all my guns,even my large bore guns like 45-70,458Lott,500S&W,etc,are sighted in for " the first" zero at 50yds. Then I run the figures thru the JBM CALCULATIONS (TRAJECTORY) site to fine tune everything.
Been doing this for years. Believe the figures it spits out. And remember - - -> INFO IN <---> INFO OUT. --- pruhdlr
 

J BAR K

Just trying to make a day.
SUS VENATOR CLUB
LoneStarBoars Supporter
Perhaps the Warren Commission should be consulted... they have experience with bullets and unusual trajectories??
 

Jack M

The Student
You have the bullets path which is a arc. Then the sight,scope,thermal,NV,it does not matter,line of sight which is like a laser.
The bullets arc crosses the line of sight twice in it's normal travel to the target if it is somewhat distant.
The ( my) basic thumb rule for a 223/5.56 is - - -> "on at 50 . . on at 150". This is pretty much true in it's simplest form.
Most all my guns,even my large bore guns like 45-70,458Lott,500S&W,etc,are sighted in for " the first" zero at 50yds. Then I run the figures thru the JBM CALCULATIONS (TRAJECTORY) site to fine tune everything.
Been doing this for years. Believe the figures it spits out. And remember - - -> INFO IN <---> INFO OUT. --- pruhdlr
Great info thank you.
 

Chopperdrvr

Deep East Tx
SUS VENATOR CLUB
Dave, you have to plot it out. He has a different amounts of rise of run that don't follow a normal ballistic curve.

For example,
He gets 1.5" of rise over 50 yards run from 50-100 yards.
He gets 1.5" of rise over 50 yards of run from 100-150 yards....this looks more linear than it should look, but maybe that is a fluke.
He gets 1" of rise over 50 yards of run from 150-200 yards, ...this looks like it is leveling off as you would expect,
but gets 2" of rise over 25 yards of from 200-225 yards. ... so the bullet is now heading up at a previously unprecedented level.

Bullets don't fly like that.
You are right, I was just looking at it as a whole trajectory and not paying too much attention to the intermediate impacts were. The height of the optic above the bore will make a big difference in where that second “zero” point would be and I was thinking that his combination just hadn’t reached the apex of the arc yet. I guess that would still make it a pretty flat shooting round.
 

Jack M

The Student
You are right, I was just looking at it as a whole trajectory and not paying too much attention to the intermediate impacts were. The height of the optic above the bore will make a big difference in where that second “zero” point would be and I was thinking that his combination just hadn’t reached the apex of the arc yet. I guess that would still make it a pretty flat shooting round.
I currently only have one zero point and that is at 50yds. Do I need a second zero point for a thermal?
 

Chopperdrvr

Deep East Tx
SUS VENATOR CLUB
I currently only have one zero point and that is at 50yds. Do I need a second zero point for a thermal?
No, but it is helpful to know where your bullets trajectory will cross your point of aim on its way to the earth. This point will be the second point of zero. You should actually see that before 225 yds which has caused this thread to get so involved since your point of impact was still well above the line of sight.
 

Ratdog68

LSB Official Story Teller
LSB TURKEY BUZZARD PRESERVATION SOCIETY
SUS VENATOR CLUB
LoneStarBoars Supporter
This is what is being discussed Jack.

ff8eced66ca6f00d4e74ffc536778835--bullets-zero.jpg
 

Jack M

The Student
No, but it is helpful to know where your bullets trajectory will cross your point of aim on its way to the earth. This point will be the second point of zero. You should actually see that before 225 yds which has caused this thread to get so involved since your point of impact was still well above the line of sight.
Ok I see now what you're saying. Thank you
 

Jack M

The Student
Ok so I finally got around to taking a picture of my issue. The shots in blue are at 50yds and the red at 100yds. Shooting a DD M4A1 in .223 with a 1:8 twist. Ammo is tulammo 75gr HP. Thermal is a pulsar xq38LRF with latest firmware. 20200522_185721.jpg
 
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