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Range Report Where am I going wrong? ***Pics*** added as bribe

sakerfalcon

Private
Full Member
Minuteman
Sep 10, 2007
11
0
40
Louisville, Ky
I go to knobcreek today with my "newer" (right at 200 rnds) 700 .308. It is the only LR rifle I own. I am shooting HSM 175 grn SMK at 2600fps, per snipercentral's webpage. I dont own a chrono to verify this info so I just trust the manufacturer.

The rifle is factory 700 SPS 26" BBL. Scope NIKON MONARCH 4-16 MILDOT SF. 20 MOA EGW base.

BRIBE

Before I went to the range I printed out three range situations with all known data off of JBM calculations. The only variable was that I changed the BC. They were .475, .496, .505 respectively. Here is the data I put into all three as constants.

60 deg temp
29.92 pressure
humidity 60%
10mph crosswind
G1 drag function
1.25" sight height
460 ft elevation (approx guestimation)

So I double check my sights are tracking. Did a box test (first time I had done this for this setup) and it passed. Then shoot another box at 100 just for the heck of it.

BRIBE

I START MOVING TO LONGER RANGE TARGETS

Things get interesting. The come ups on the JBM calc is high by quite a bit. Hmmm...

I knew I made sure to put select 1/4" clicks on the JBM calculator page (the scope says 1/4" clicks). The only thing I did before I went to the range was to divide the clicks by 4 to get the "MOA" (in my words, "MINUTE OF CLICK") adjustment. I know that MOA equals 1.047 and my scope is 1/4". MOA is MOA, 1/4" is 1/4". Ive learned from you all not to confuse the two especially at long range.

I checked before I went that this "MOC" idea is correct with the amount of clicks. It is. Look below to see what I did.

JBM SAYS:
300yrds = 21.8 clicks / divided by 4 = 5.4 MOC

So I turn it to 5.5 MOC and miss high. I double check my math. Yup, 5.5 MOC is 22 clicks from zero.

BRIBE

It was this way for everything out to 500.

200, 300, 400, 500 was high. If I could have gone further I am positive it would have been high for longer range too.

Look below at what JBM wanted compared to real life shooting:
For 200 JBM wants 9.4 clicks
For 300 it wants 21.8 clicks
For 400 it wants 36.1 clicks
For 500 it wants 52.4 clicks

Here is what real life wants (focus on the clicks and compare to above)

200yds was .75 MOC (3 clicks)
300yds was 4 MOC (16 clicks)
400yds was 5 MOC (20 clicks)
500yds was 11.25 MOC (45 clicks)

WHY THE DIFFERENCE?

BRIBE

I have even gone back to the JBM website and tried to redo it allover again and to no avail. Even a guy at the range had the book "DEAD ON" and his drop charts in that book were even high. I've checked everything I can imagine...

I am to the point that I think the velocity must be higher...but THAT much higher?

Is my math Jacked?

I even did JBM 6 times just now AGAIN before sending this post to make sure I am not crazy. I changed a lot of temperature/ pressure/ humidity settings and it never made that much of a difference. Kept the drag function at G1 and BC at .496.

Help guys...

IN THE BEGGINING
 
Re: Where am I going wrong? ***Pics*** added as bribe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sakerfalcon</div><div class="ubbcode-body">I go to knobcreek today with my "newer" (right at 200 rnds) 700 .308. It is the only LR rifle I own. I am shooting HSM 175 grn SMK at 2600fps, per snipercentral's webpage. I dont own a chrono to verify this info so I just trust the manufacturer.

The rifle is factory 700 SPS 26" BBL. Scope NIKON MONARCH 4-16 MILDOT SF. 20 MOA EGW base.

BRIBE

Before I went to the range I printed out three range situations with all known data off of JBM calculations. The only variable was that I changed the BC. They were .475, .496, .505 respectively. Here is the data I put into all three as constants.

60 deg temp
29.92 pressure
humidity 60%
10mph crosswind
G1 drag function
1.25" sight height
460 ft elevation (approx guestimation)

So I double check my sights are tracking. Did a box test (first time I had done this for this setup) and it passed. Then shoot another box at 100 just for the heck of it.

BRIBE

I START MOVING TO LONGER RANGE TARGETS

Things get interesting. The come ups on the JBM calc is high by quite a bit. Hmmm...

I knew I made sure to put select 1/4" clicks on the JBM calculator page (the scope says 1/4" clicks). The only thing I did before I went to the range was to divide the clicks by 4 to get the "MOA" (in my words, "MINUTE OF CLICK") adjustment. I know that MOA equals 1.047 and my scope is 1/4". MOA is MOA, 1/4" is 1/4". Ive learned from you all not to confuse the two especially at long range.

I checked before I went that this "MOC" idea is correct with the amount of clicks. It is. Look below to see what I did.

JBM SAYS:
300yrds = 21.8 clicks / divided by 4 = 5.4 MOC

So I turn it to 5.5 MOC and miss high. I double check my math. Yup, 5.5 MOC is 22 clicks from zero.

BRIBE

It was this way for everything out to 500.

200, 300, 400, 500 was high. If I could have gone further I am positive it would have been high for longer range too.

Look below at what JBM wanted compared to real life shooting:
For 200 JBM wants 9.4 clicks
For 300 it wants 21.8 clicks
For 400 it wants 36.1 clicks
For 500 it wants 52.4 clicks

Here is what real life wants (focus on the clicks and compare to above)

200yds was .75 MOC (3 clicks)
300yds was 4 MOC (16 clicks)
400yds was 5 MOC (20 clicks)
500yds was 11.25 MOC (45 clicks)

WHY THE DIFFERENCE?

BRIBE

I have even gone back to the JBM website and tried to redo it allover again and to no avail. Even a guy at the range had the book "DEAD ON" and his drop charts in that book were even high. I've checked everything I can imagine...

I am to the point that I think the velocity must be higher...but THAT much higher?

Is my math Jacked?

I even did JBM 6 times just now AGAIN before sending this post to make sure I am not crazy. I changed a lot of temperature/ pressure/ humidity settings and it never made that much of a difference. Kept the drag function at G1 and BC at .496.

Help guys...

IN THE BEGGINING </div></div>

MOC=NOGO
 
Re: Where am I going wrong? ***Pics*** added as bribe

Why? I dont question anyones authority...just cant figure out why JBM calc is not working. (Even if I drop the whole MOC idea, and just count clicks it does the same thing as the MOC idea and it is still high.

The MOC idea isn't no go from what I can tell, it is the JBM giving me wrong info or I am just truly messed up. Could it be that I dont need to tell JBM that I need 1/4" clicks and need something else?

Profile updated...
 
Re: Where am I going wrong? ***Pics*** added as bribe

Are you sure your sight height is 1.25" that seams a little low??? just asking
 
Re: Where am I going wrong? ***Pics*** added as bribe

Your right it is low. That made some difference. Went back and recalc'd it.

200yds is now 8.3 clicks instead of 9.4
300yds is now 20.2 clicks instead of 21.8
400yds is now 34.2 clicks instead of 36.2
500yds is now 50 clicks instead of 52.4

however this still doesnt get me close to what I was shooting in reality.

example: 500 yds I was only having to give 45 clicks. Thats a 7 click spread (and by my math 8.75" difference, therefore making me overshoot my target)

Also, just in case anyone is hung up on my use of the "MOC" thing. I only named it that because I dont want to call it MOA when the clicks are truly 1/4" clicks (BOX TEST at exactly 100 yrds/ 40 clicks up gave 10" change not 10.5" change)

I made this term up because on my scope there are 12 numbers that correspond to 4 clicks which each click is 1/4".

So kinda like MOA, instead of counting 45 clicks to shoot 500yds. I know that 11.25 on the scope is 45 clicks. Thats all "MOC" means.

[color:#FF0000][/color]UPDATE

I started messing around with the velocity in JBM. Still nothing consistent. I could input velocities that were high enough to match oh say my real 500yd zero...but the 400 yd Jbm calcwould be high by 10" in real life. Strange. I wonder if the drag function is wrong...
 
Re: Where am I going wrong? ***Pics*** added as bribe

It is getting late so i may have missed it in your post but just to clarify you are zeroing at 100yds right? thats what your JBM data is set for?
 
Re: Where am I going wrong? ***Pics*** added as bribe

Crosshairs, I'm not going to give you a hard time because your brain is working and you are fitting elevation adjustments to what makes sense to you. That and I just wrote a run-on sentence. But, you are re-inventing the wheel. It is all MOA or Mils.

Once you grasp MOA and how it relates to the turret, it will click (pun) for you.
 
Re: Where am I going wrong? ***Pics*** added as bribe

I guess the reason im asking this is, im assuming your zero'd at 100yds, and assuming so makes your field data of only .75 "MOC" at 200yds seems nearly imposible, you would have to have a velocity of about 3340 fps for this to be true. According to Sierra Infinity anyways.



 
Re: Where am I going wrong? ***Pics*** added as bribe

I think it definately has something to do with your 100yd. zero.Shoot 4-5 shots at 100 yds and take an average.Also,when you shot your 100 yard zero,did you shoot it in the same position as all the other shots?Different shooting positions can cause different points of impact.That is why you should alway's zero your gun in your normal position.
 
Re: Where am I going wrong? ***Pics*** added as bribe

You say you ran a box test .... how many MOA up and down did you run this with?

As a side note, you'd be better off to just forget about "clicks".

Run your charts in MOA.
You already dial your scope in MOA.
You should work in MOA.

If your chart says to dial 6 MOA, you dial until you knob says 6 MOA. It doesn't matter how many clicks it took to get there.
 
Re: Where am I going wrong? ***Pics*** added as bribe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Crosshairs308</div><div class="ubbcode-body">example: 500 yds I was only having to give 45 clicks. Thats a 7 click spread (and by my math 8.75" difference, therefore making me overshoot my target)</div></div>

Thats about par for the course in ballistics calculators. I'm using "Point-Blank" because it was free and I wasn't planning on relying on the data it gave me...just using it as a ballpark figure when I was out shooting to get my "real-life" come-ups. Being off by 8.75" at 500 yds is closer than "Point-Blank" got me at that range. I was off by about 18" or so, but what matters is the first group was all on the paper. I was able to adjust 3.5 MOA to be hitting center mass and get my "real-life" data. I did this out to 600 yds and the further I got, the worse the computer generated ballistic data was off.
 
Re: Where am I going wrong? ***Pics*** added as bribe

Crosshair,

Too many "clicks".

Please speak only in MOA or Mils. Pick one and stick with it.

Beyond your sight height value which appears low, you should determine if your scope adjustment is true MOA or SMOA/IPHY. That is going to have a bearing, especially at longer range.

JBM ballistic calculator will give you values that are fairly close, however bullet BC is NOT a constant value. Also most published BC's are G1 values, while I have had closer values using G7 values. Also, how accurate your Density/Altitude information is going to effect the calculated versus actual values.

I reiterate: Please speak in MOA or Mils.
 
Re: Where am I going wrong? ***Pics*** added as bribe

Newbs count clicks, trust the knobs on your scope, JBM is to get you close, shooting in the real world is what counts.
 
Re: Where am I going wrong? ***Pics*** added as bribe

JBM is to get you on the target, if you enter all the correct data with the Velocity. There is still going to be field work to figure the exact data.
 
Re: Where am I going wrong? ***Pics*** added as bribe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Crosshairs308</div><div class="ubbcode-body">Here is what real life wants (focus on the clicks and compare to above)

200yds was .75 MOC (3 clicks)----(3 more)
300yds was 4 MOC (16 clicks)-----(13 more)
400yds was 5 MOC (20 clicks)-----(4 more)
500yds was 11.25 MOC (45 clicks)-(25 more)

WHY THE DIFFERENCE?
</div></div>

It should have taken::
200 yards shb 2.05 MoA or 8 clicks
300 yards shb 4.75 MoA or 11 more clicks than 200 yards
400 yards shb 7.95 MoA or 13 more clicks than 300 yards
500 yards shb 11.6 MoA or 14 more clicks than 400 yards

See the nice slow progression 8->11->13->14, the next one ALWAYS being more than the previous; this is a sign that the ballistics data is not lying to you. Your data is neigther smooth or monotonic. This suggests errors in A) reading the scope turrets, B) errors in distance to target, or C) dramatically changing conditions.
 
Re: Where am I going wrong? ***Pics*** added as bribe

What is your velocity? I can enter in Sierra Infinity 6 software. It is normally pretty accurate.
 
Re: Where am I going wrong? ***Pics*** added as bribe

Also did the ammunation you purchase stated the Velocity? Did they tell the test length of the barrel? If the test barrel was 24" you could gain 50 to 75 fps.
 
Re: Where am I going wrong? ***Pics*** added as bribe

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Beyond your sight height value which appears low, you should determine if your scope adjustment is true MOA or SMOA/IPHY. That is going to have a bearing, especially at longer range.</div></div>

Come on guys, Read the Fabulous Question! Answered before even asked! The OP has a scope that's IPHY, and said so.

He also doesn't want to confuse anyone who can read by calling his IPHY "MOA" when it's 4.whatever percent off true MOA. He ran a box test and described the results.

Anyway, similar results here with JBM, but strangely the opposite direction. A nice 2600 fps .308 load with Noslers, altitude consistent between Google Earth and a map and the roadside signs on elevation on wither side of the shooting site, temp, humidity, sight height and pressure and everything I can think of good, and it called for 11.5 MOA (1.047 or whatever) at 500 yards and the impacts were exactly 2 MOA low. No amount of reasonable fudging on BC or velocity or anything else could bring the calcs in line with the results--except METERS. So, the error is twice the difference between IPHY and MOA.

The distance calculated at yards both with Google Earth and the optical rangefinding function on the reticle. Reticle verified at a measured 100 yards, too. Even counted my MOAs back down to 100 to make sure I didn't get lost.

Nice 3-shot group, BTW. 1 inch of vertical with 9 inches horizontal in a variable 10 mph wind fishtailing from 12:00 to 10:30. All calls good, too.

I'm trusting Google Earth on distances because every rifle range I've scoped out with it measured within 1 yard--whether meters or yard.
 
Re: Where am I going wrong? ***Pics*** added as bribe

On a side note, how do you measure your sight height? Up to the middle of the eye piece?
 
Re: Where am I going wrong? ***Pics*** added as bribe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Beyond your sight height value which appears low, you should determine if your scope adjustment is true MOA or SMOA/IPHY. That is going to have a bearing, especially at longer range.</div></div>

Come on guys, Read the Fabulous Question! Answered before even asked! The OP has a scope that's IPHY, and said so.

He also doesn't want to confuse anyone who can read by calling his IPHY "MOA" when it's 4.whatever percent off true MOA. He ran a box test and described the results.

</div></div>

Grump,

I re-read the OP and I didn't see anything in there that stated he VERIFIED that his scope was IPHY. He did state the turrets were marked 1/4" but nothing to verfy it. 4.7% begins to make a difference at long range. Pardon me if I missed it.

Nevertheless, I suggest the OP use MOA or Mils, then shoot and acquire real dope.
 
Re: Where am I going wrong? ***Pics*** added as bribe

On 4/26/09, the OP followed up with:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I dont want to call it MOA when the clicks are truly 1/4" clicks (BOX TEST at exactly 100 yrds/ 40 clicks up gave 10" change not 10.5" change)</div></div>

I'm satisfied even if not one else is.
 
Re: Where am I going wrong? ***Pics*** added as bribe

<span style="text-decoration: underline">Bribe</span> = No naked chicks
mad.gif
 
Re: Where am I going wrong? ***Pics*** added as br

Crosshairs 308
I have not been to Knob Creek in several years but unless they have made drastic changes, there is only 300 yards of flat ground. The 400 and 500? Yard shots would be severely up-hill.
I cannot tell you what the angle is but I can guarantee your POI would be high if shooting actual yardage.
 
Re: Where am I going wrong? ***Pics*** added as br

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AQC440</div><div class="ubbcode-body">Crosshairs 308
I have not been to Knob Creek in several years but unless they have made drastic changes, there is only 300 yards of flat ground. The 400 and 500? Yard shots would be severely up-hill.
I cannot tell you what the angle is but I can guarantee your POI would be high if shooting actual yardage. </div></div>
I got just about 350 flat ground, X'ing the corner's last trip I made.
 
Re: Where am I going wrong? ***Pics*** added as br

Now I feel stupid. I just looked at dates. This was over with in april and somehow it came back up to the top......