Range Report Dope not matching up???

[SDeadeye]

I did some shooting this morning, and came away a little bit puzzled. I am shooting a Rem 700 SPS Tactical, 20" 1/12 barrel. The scope is a 6.5-20x44 Vortex Viper, with 1/4 MOA adjustments. I was shooting my reloads with Hornady 168 gr. HPBT Match and 175 gr. SMK's. I had one target set at 289 yards, and one at 698. Distances were found with the GPS on my phone.

I am using the Shooter ballistic app on my Droid, and have been working on getting it dialed in with my loads since I don't have a chrono to find velocities.

First I shot at the 289 yard target. For the 175 gr. SMK's I plugged 289 yd into Shooter and it said to come up 16 clicks. I dialed up 16 and drilled the target dead center. I kept that setting and shot 7 more and they were all right where they should be.

Then I moved out to the 698 yd target. I put that into Shooter and it spit out +57 clicks, or +14.2 MOA. I dialed that in and hit the ground in front of the target. Long story short, I ended up using 88 clicks, or 22 MOA to put me on the target. Now I'm trying to figure out why there is such a difference.

Load data:
2x Fired Win Brass, neck sized
CCI 200 primers
44.7 gr. RL-15
175 grain Sierra Match King
2.835" COAL

Location:
4300' ASL
60*
Sunny and no wind

This is what I have entered into Shooter for the load:
Bullet Dia: 0.308
Weight: 175gr
Bullet Length: 1.24"
Muzzle Velocity: 2600 fps
MV Variation: 15.0
Powder Temp: 65* F
Drag Model: G7
Zeroed @ 100 Yards


Any Ideas? I used google earth when I got home and double checked my distances and they were within 15 yards of what I found with my phone while I was out there.

 

[Lowlight]

Re: Dope not matching up???

Believe the bullet...

These things (Ballistic calculators) are nothing more than a starting point.

I have an opinion on the dope issue, but I will refrain at this time. Suffice to say, you have to know everything and not just guess in order to insure accuracy. That includes knowing your scope. Alot of the differences don't show until you get past 400 yards to begin with. Anything can be close inside that distance.

FYI with the 175gr , 700 yards is 20 to 22 MOA, 600 is roughly 16MOA, 500 is 11 to 12 MOA etc... handloads will of course vary.

 

[Rob01]

Re: Dope not matching up???

Also you might want to check your scope to make sure it's tracking perfectly.

 

[TimK]

Re: Dope not matching up???

Find the MV to give you 22moa at 700 yards. Now use that MV at your shorter distance and see how close you are.

 

[tlsmith22]

Re: Dope not matching up???

I would guess you are not getting 2600 FPS out of that barrel. Sound like MV is off a little.

 

[McLarenross]

Re: Dope not matching up???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tim K</div><div class="ubbcode-body">Find the MV to give you 22moa at 700 yards. Now use that MV at your shorter distance and see how close you are.

</div></div>

Thats what I did. Also using Droid Shooter. I had to tell the phone my muzzle velocity was 2850 with a 178 A-Max in a 20" 308 when my chrono says 2660. But using that velocity gets the dope right out to at least 800 for my gun. I think Im getting more than 0.10mil per click though. No big deal to me as long as I know my dopes.

 

[TimK]

Re: Dope not matching up???

I had a Leupold MK4 that gave about 35 moa when dialed to 30 moa. I ended up making a board with graduations on it to verify that the tracking was off. I locked the rifle down and twiddled the knobs to see where it moved.

I couldn't handle it not being right, and Leupy ended up replacing it with a new one. It was sold immediately and I switched to NF.

Something to check.

 

[BCP]

Re: Dope not matching up???

Handloads.com ballistic calculator says 22moa come up for 700 yards for a 175smk, .5 BC and 1.5 sight height 2600fps. Your calculator settings are probably buggered somewhere.

 

[SDeadeye]

Re: Dope not matching up???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: McLarenRoss</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tim K</div><div class="ubbcode-body">Find the MV to give you 22moa at 700 yards. Now use that MV at your shorter distance and see how close you are.

</div></div>

Thats what I did. Also using Droid Shooter. I had to tell the phone my muzzle velocity was 2850 with a 178 A-Max in a 20" 308 when my chrono says 2660. But using that velocity gets the dope right out to at least 800 for my gun. I think Im getting more than 0.10mil per click though. No big deal to me as long as I know my dopes. </div></div>

That was my original intention. Right now I've got my MV set at 2525 and it is giving me 4 MOA at 290 yds, which was right on what I was getting when I shot. But then at 700 it is showing 16.7 MOA, or 67 clicks...I was at 22 MOA and 88 clicks.

So I guess my next step is to check my scope adjustments...Should I set up a big target at 100 yards and shoot and shoot as big of a box test as I can fit on there, or would it be better to do it at a longer distance?

 

[Lindy]

Re: Dope not matching up???

Optically Checking Rifle Scopes

 

[SDeadeye]

Re: Dope not matching up???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">Optically Checking Rifle Scopes
</div></div>

Perfect, that will be very helpful.

 

[sniperaviator]

Re: Dope not matching up???

At that range a bullet is dropping 1/2" per yard of so? (check that out). Anyway, off by 20 yards on your distance and you are off by 10" on elevation. So it could be your ranging that is off. I put a target up every 200 yards and don't try and get my rangefinder to range from those long distances. Anyway, we are all haveing trouble getting good dope at distances over 800 yards and I think range is the culprit.

 

[Lowlight]

Re: Dope not matching up???

Sounds like your range is off you made a mistake, the is absolutely no way it was showing 16MOA for 700 yards with a MV even at 2600fps let alone 2525fps

Regardless of what you think a mistake was made, 700 yards starts around 20 MOA and with you MV being low, 22 is right.

An input error nothing more, no magic, 308s are shot to death, the dope is easy enough, and widely available. It sounds like you are misinterpreting the ranges. Because the actual numbers used are in keeping with the rifle used. But the ranges are wrong.

 

[SDeadeye]

Re: Dope not matching up???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Sounds like your range is off you made a mistake, the is absolutely no way it was showing 16MOA for 700 yards with a MV even at 2600fps let alone 2525fps

Regardless of what you think a mistake was made, 700 yards starts around 20 MOA and with you MV being low, 22 is right.

An input error nothing more, no magic, 308s are shot to death, the dope is easy enough, and widely available. It sounds like you are misinterpreting the ranges. Because the actual numbers used are in keeping with the rifle used. But the ranges are wrong. </div></div>

User error is the culprit in this case. Crap in, Crap out... I went out again yesterday to do some more shooting. I set up targets at 400 and 800 yards and made sure to double and triple check my distances. I'm pretty sure the part where I screwed up before was getting the correct temp into the program. I started at 400 and made sure to get 53* in as the correct temp. It gave me +10.9 moa, when I checked the target I was about 1 click low, which could be shooter error most likely. The 800 yd target took +30.2 moa and was right on when I called the wind right. Then we put some steel at 960 yd. I dialed up +33.8 moa according to Shooter and went 16 for 20 on the 18"x22" steel plate. The wind varied between 10 and 15 mph from between 9 and 11 o'clock, and kind of swirled when the treeline jutted out about halfway to the target. I put 2 in the dirt, and 2 into the target stand getting that figured out, and then the rest of them were on the plate.

So, what I ended up with is:

175 gr SMK, 2550 fps, 53*F:

400 yd: +10.9 MOA
800 yd: +30.2 MOA
960 yd: +33.8 MOA

168 gr. Hornady HPBT

400 yd: +7.9 MOA

 

[ReaperDriver]

Re: Dope not matching up???

One thing that hasn't been discussed (unless I missed it) is your source for baro pressure. Are you using sea level pressure and altitude or absolute pressure? I ran into a similar problem with a ballistic calculator on my iphone because I was using SL baro pressure. And I was always getting some error difference from my actual dope.

Finally Lindy turned me onto using absolute pressure (from a kestrel or in my case a Suunto watch) and ever since my dope and my calcs have been MUCH closer together. Again, garbage in/garbage out - but as long as I put the most accurate data in, I was getting very close to actual dope such that I would be fairly comfortable taking a shot at an odd range that I didn't ahve dope for, and the absolute pressure trick was the big turning point for me.

Again, though.... the actual dope is the truth. The iphone gadget is just a starting point.

 

[hula]

Re: Dope not matching up???

Ditto on above. Once your confident with your equipment and ranging keep a good log on your rifle and shooting conditions with a data book. That way you have solid reference.