MkII G Project (or, how accurate can I get this thing!?)

[shanejohnson2002]

Shane
I made this up for Wolf Match. I have shot it with all others, (SK Standard, Eley Tenex) and for tactical hold over, it is dead on. Copy it and laminate it and keep it with the gun...


http://i.imgur.com/dEMPJ.jpg

Thanks, but with my rifle, it won't be valid at anything but 12x. I don't have an FFP scope on this rifle so the reticle stays fixed across all zoom ranges. Besides, the method worked just fine....can't ask for more than that.

[russ10x]

You can do it, but the math does not make it practical..yes, stay with your system. But if you get a 10x, here ya go! You can pass it on..

[shanejohnson2002]

I did keep it...i have a fixed 20x on my fv that this would work very well fur. Thanks!

[russ10x]

remember to double your hold over.....this is for 10 X. I found that out the hard way!

[shanejohnson2002]

The mils on the 20x are still true mils (3.6"@100y)...this should still work. The reticle is just bigger to compensate for the power level.

[russ10x]

What make is the 20x..if it is a SWFA, it's not. the only way to do it is to make 2" dots on a target, 10 of them, connect them with a line vertically on a 100 yard target and see if they fit in. The Sniper's Hide sells targets that has this feature. My SWFA was doubled....

[shanejohnson2002]

I'm fairly certain it is a true mil. I have the MilRad version, and when I set up a mildot confidence target, the diamonds were dead-on 3.6". There are hash marks at .5 mils.

According to their site, even the standard 20x mil-dots are true mils:

http://www.opticstalk.com/uploads/6137/ss20X42Subsbig.jpg

And the Mil-Rad version:

http://www.opticstalk.com/uploads/298/20XReticle.jpg

I could be wrong though... in fact it happens more than I'd like to admit.

Also, what program did you use to get the drop on that mil-dot? It's pretty clean-looking.

[russ10x]

Actually no program...it is a page out of John Plaster's book "The Ultimate Sniper". You can do the same thing on JB, and when you get the solutions in MILs or MOA, make it out on a Word format by inserting a MILDOT reticle and adding the drops.

[russ10x]

http://www.ultimatesniper.com/Shooting_Articles/Calculating-Mil-Dot-Reticle-Holdovers.PDF

[shanejohnson2002]

I have to say, I was inspired. I created a come-up chart using MSPaint. I made a mil-dot reticle (with exactly .36" between dots) and started crunching numbers. Mine lines up almost exactly with yours, except my 75y is a bit lower. I used a .132BC / 1066 MV for Lapua Midas+...I don't have a chrony so I used the published data. I then repeated the process for 2 more zeroes @ 100 and 150 yards. Then I made a sidebar with the drift for full-value wind. On the backside of the card is a drift chart with clicks to zero it out.

The math is fairly complicated but it works out easily enough and seems to be accurate based on comparisons to other peoples' published dopes.

I'm going to the range again on Friday to work on my Mk. II FV some more (I need to spend some time tuning it now that I have a good torque wrench) and I'll see how close this dope is then.

If anyone would like a blank copy and some instructions, message me and I'll do my best to explain.

The Mil-Dot reticle:
http://i33.photobucket.com/albums/d70/shanejohnson2002/DataCardLapuaMilDot_zps88ce5adc.png

The drift chart:
http://i33.photobucket.com/albums/d70/shanejohnson2002/DataCardDriftChartLapua_zps59496263.png

NOTE: This chart is for Lapua Midas+. It should be reasonably close for Eley, Wolf, SK, etc....basically any 40gr pill with a similar BC and MV. It's also using data from an 80 degree day with moderate-high humidity, which is the most common condition where I live.

[russ10x]

Be very careful how much you torque the action. Many a blog warns about too much torque. Pay out the money and get this ingenious torque wrench:
http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/wrenches/general-wrenches/multi-preset-torque-drivers-prod32490.aspx

I keep it in my drag bag for full bore comps. along with assorted torque heads. Posts on places like Rimfire.com say may 27 inch pounds at the most. Some say, (if you have a wood stock) torque till you hear the wood crackle. I think that is too much. There is no easy way to pillar bed this thing, and humidity does play a role...
Your chart is great! My BC was .135 and my MV was 1050. Like you, not chony'd. Let me know how you make out.

[shanejohnson2002]

Actually I bought a Seekonk torque wrench with a 100 in/lb dial and a memory needle...from what I understand, they're fairly near the top of the heap for torque measuring tools.

I was worried about the torque too, but I've taken the action out and put it back in with no problems, and with the washers and bottom metal distributing the load I'm not as worried as before. Worst-case scenario, I get a Boyds varmint stock and send it to Dan Killough to be bedded.

I will report (with pictures this time, I promise!) on the success / abject failure of my scope chart this Friday. I also get to try out my new metal targets...the Champion self-resetting diamond pop-ups. Only $10 at wally world!

[russ10x]

This was off JBM Calculations, simple trajectory....
I guessed your altitude and temp...






Trajectory (Simplified)


Input Data


Ballistic Coefficient:
0.132 G1
Caliber:
0.220 in


Bullet Weight:
40.0 gr







Muzzle Velocity:
1066.0 ft/s







Sight Height:
1.80 in
Line Of Sight Angle:
0.0 deg


Cant Angle:
0.0 deg







Wind Speed:
5.0 mph
Target Speed:
3.0 mph





Temperature:
50.0 °F
Pressure:
29.53 in Hg


Humidity:
50 %
Altitude:
700.0 ft





Std. Atmosphere at Altitude:
No
Pressure is Corrected:
Yes


Zero at Max. Point Blank Range:
No
Target Relative Drops:
Yes


Column 1 Units:
1.00 MOA
Column 2 Units:
1.00 mil


Round Output to Whole Numbers:
No




Output Data


Elevation:
10.644 MOA
Windage:
0.000 MOA





Atmospheric Density:
0.07471 lb/ft³
Speed of Sound:
1106.7 ft/s





Maximum PBR:
132 yd
Maximum PBR Zero:
112 yd


Range of Maximum Height:
62 yd
Energy at Maximum PBR:
68.7 ft•lbs





Sectional Density:
0.118 lb/in²






Calculated Table


Range
Drop
Drop
Windage
Windage
Velocity
Mach
Energy
Time
Lead
Lead


(yd)
(MOA)
(mil)
(MOA)
(mil)
(ft/s)
(none)
(ft•lbs)
(s)
(MOA)
(mil)


30
0.4
0.1
0.7
0.2
1009.7
0.912
90.5
0.087
14.6
4.2


40
0.2
0.1
0.9
0.3
993.6
0.898
87.7
0.117
14.7
4.3


50
-0.6
-0.2
1.1
0.3
978.5
0.884
85.0
0.147
14.8
4.3


60
-1.7
-0.5
1.3
0.4
964.2
0.871
82.6
0.178
15.0
4.4


70
-2.9
-0.9
1.5
0.4
950.8
0.859
80.3
0.209
15.1
4.4


80
-4.4
-1.3
1.7
0.5
937.9
0.847
78.1
0.241
15.2
4.4


90
-5.9
-1.7
1.9
0.5
925.7
0.836
76.1
0.273
15.3
4.5


100
-7.5
-2.2
2.1
0.6
914.0
0.826
74.2
0.306
15.4
4.5


110
-9.2
-2.7
2.3
0.7
902.7
0.816
72.4
0.339
15.5
4.5


120
-10.9
-3.2
2.4
0.7
891.9
0.806
70.6
0.372
15.7
4.6


130
-12.7
-3.7
2.6
0.8
881.4
0.796
69.0
0.406
15.8
4.6


140
-14.5
-4.2
2.8
0.8
871.2
0.787
67.4
0.441
15.9
4.6


150
-16.4
-4.8
3.0
0.9
861.4
0.778
65.9
0.475
16.0
4.6


160
-18.4
-5.3
3.1
0.9
851.8
0.770
64.4
0.510
16.1
4.7


170
-20.3
-5.9
3.3
1.0
842.5
0.761
63.0
0.546
16.2
4.7


180
-22.3
-6.5
3.5
1.0
833.5
0.753
61.7
0.581
16.3
4.7


190
-24.4
-7.1
3.7
1.1
824.6
0.745
60.4
0.618
16.4
4.8


200
-26.5
-7.7
3.8
1.1
816.0
0.737
59.1
0.654
16.5
4.8







30/10/13 10:32, JBM (http://www.jbmballistics.com/)/jbmtraj_simp-5.1.cgi (http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi)

[russ10x]

Great torque wrench. I bought mine for bare bones reasons! Looking forward to your results. I too would love to find a good smith, but I just paid out big bucks to have my Rem 700 re-barreled in 6.5 Creedmoor!

[shanejohnson2002]

Without crunching the numbers, it looks like the JBM chart falls close to the reticle chart. Now I'm really getting stoked to try it out...I got two of the diamond targets, I may get 2 more and set them at 25 yard intervals starting at 75. They're 7.5" tall by 2.75" wide, so it should be a test of both the rifle and the accuracy of the chart.

Also, Friday is looking better and better. Forecast says no clouds and negligible wind. The range is deep in a woodline so it's pretty well wind-free unless it's gusting over 5mph.

[shanejohnson2002]

Getting busy with the come-up charts! Here's one for an SWFA MILRAD scope. The click values at the bottom changed because these use 1/10 mil clicks (.36" @ 100y) instead of the usual 1/4 MOA clicks (.25" @ 100y).

The MILRAD chart:
http://i33.photobucket.com/albums/d70/shanejohnson2002/MilradHoldoverChartLapuaMidas_zpse2a3cecc.png

Another noteworthy discovery: the SWFA SS scope has more than enough vertical travel to get the 150y zero. I'm not using any angled base either. I'm sure if I did, it would be even easier, but it works with a flat base. These are *fantastic* scopes!

I also mentioned a "full-value" wind for these charts....for me, that means 10mph. It makes the calculations ridiculously easy that way. So the charts are showing a constant 10mph wind from 3 o'clock. If it's 8 mph, just go 80% of the way to the mark for the range to your target....5mph go halfway. Ad infinitum. From the left? Just flip the chart the other way. From any other angle? Use the "clock rule" to determine how much to divide it by.

Clock rule: http://www.cybersniper.com/windus.htm

[shanejohnson2002]

Last post for the night!

I decided to create a "Zero Checker" target to use on Friday to verify my zeros before I actually engage the longer-range targets. The idea is simple: Each box represents the POI at 50y for a zero at the given ranges. When aiming at the 50y box, the rounds should hit dead center in each box for the ranges given; up or down means I need to revise my charts, and left or right means the scope is canted the opposite direction.

The target:
http://i33.photobucket.com/albums/d70/shanejohnson2002/Lapua50yZeroTest_zpsd2fdbc30.png (http://s33.photobucket.com/user/shanejohnson2002/media/Lapua50yZeroTest_zpsd2fdbc30.png.html)

[justinp61]

Shane. Are going to shoot that using hold overs with the mil dots?

[shanejohnson2002]

No. The plan is to zero it at 50, then shoot 5 shots at the 50y zero. Then I'll re-zero the scope to 100 yards and shoot 5 more shots. If the match is correct, it'll land in the 100 yard box while I'm still aiming at the 50.

Basically, it's the reverse of using hold-overs; instead of moving the scope so the groups land in the same place at 50, I'm holding the rifle on the 50y target at all 3 zero settings and letting the POI change. The target is more to verify that my click values are correct for my zero ranges than it is to verify my holdovers.

However, the POI should still line up with the holdovers marked on my chart. In other words, if I'm aiming at the 50y box on my 100y zero setting, the POI should be ~2.2 mils high.

[justinp61]

However, the POI should still line up with the holdovers marked on my chart. In other words, if I'm aiming at the 50y box on my 100y zero setting, the POI should be ~1.9 mils high.

That's what I was thinking. If you hold 1.9 mils over the 50 yard target the cross hair should be on the 100 yard target. This mil stuff is new to me, so I'm picking up a bunch of info here.