MK5 HD vs NX8 . . Thoughts?

[ryjack70ss]

Agree. Great read. My takeaway was I should have got my 2.5-10 NXS in mil instead of MOA!


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[bpurtz]

Correction factors:


Rule of thumbs to get close first, and then how to get your actual correction factor for your gun specifically.


Standard base (average gun)=

100- 0
200- .5
300- 1
400- 2
500- 3
600- 4


So what happens when you have a combo that shoots faster than 2800’ish fps or slower than 2,500’ish with a low BC? General rule is “Bad Gun”, “Average Gun”, “Good Gun”.

Average is the standard above.

Bad= Add .5 mils past 300 to the base.

Good= Take .5 mils off the base past 300 from the base.

How I did @grappling_hook 270 combo is to use the corrections. The BC is .4, but the MV is above 2,900’ish. That means is a “good gun”. He gave 480 yards, base is “2.8 mils”, but it’s a “good gun”, so take .5 mils off. The correction is “elevation 2.3 mils”. How well does it work? The actual correction is 2.2 mils at 5K DA. That’s a .1 mil error= 1.7 inches. Having never shot the rifle, didn’t put it into a calculator, and with 5’ish seconds of getting the range/gun info, I would have killed any big game animal on earth.


If it’s a “Bad Gun”. That is low MV, and/or low BC, add .5 mils to the base. Do not let the numbers overwhelm you. This takes less than 30 minutes to have a solid handle on it with paper practice.

Think critically: Who has a higher chance of killing an animal given all else being equal- a person that needs to look at a drop chart for both wind and elevation adding that time to make the shot? Or a person that can do it in their head in less time than it takes to chamber a round?

I guess, I'm going to give a FFP/Mil scope a try - just ordered an ATACR 4-16x42 w/ Mil-R. Not sure which gun I'm putting this on yet, but I'm curious how I determine if I have a "bad, average, or good" gun.

I've got the following:
7mm Rem Mag shooting 195 Berger - 2925 fps, .755 G1
.300 PRC shooting 215 Berger - 2840 fps, .691 G1
.338 Lapua shooting 300 Berger - 2780, .814 G1

Would you classify bad, average, or good for the base?

 

[Formidilosus]

I guess, I'm going to give a FFP/Mil scope a try - just ordered an ATACR 4-16x42 w/ Mil-R. Not sure which gun I'm putting this on yet, but I'm curious how I determine if I have a "bad, average, or good" gun.

I've got the following:
7mm Rem Mag shooting 195 Berger - 2925 fps, .755 G1
.300 PRC shooting 215 Berger - 2840 fps, .691 G1
.338 Lapua shooting 300 Berger - 2780, .814 G1

Would you classify bad, average, or good for the base?

Pull up your data for each and see what you have for 300, 400, 500, and 600 yard drops. That will give you a correction factor to apply.

 

[bpurtz]

Pull up your data for each and see what you have for 300, 400, 500, and 600 yard drops. That will give you a correction factor to apply.

My .300 PRC looks like good gun so deduct .5 mil from the standard base, the quick drop would be:
300 yd - .5 mil (.6 on range card)
400 yd - 1.5 mil (1.3)
500 yd - 2.5 mil (2.1)
600 yd - 3.5 mil (3.0)

Am I calculating correct?

At 600 yards using the quick drop vs calculator that shot wounds a deer - impact is 8.5" high. Does the quick drop not work for some combos?

 

[Formidilosus]

View attachment 652765

My .300 PRC looks like good gun so deduct .5 mil from the standard base, the quick drop would be:
300 yd - .5 mil (.6 on range card)
400 yd - 1.5 mil (1.3)
500 yd - 2.5 mil (2.1)
600 yd - 3.5 mil (3.0)

Am I calculating correct?

At 600 yards using the quick drop vs calculator that shot wounds a deer - impact is 8.5" high. Does the quick drop not work for some combos?

Zero at 100 yards.

 

[bpurtz]

Zero at 100 yards.

.300PRC, 100 yd zero
215 Berger .691 G1
2840 MV
So good gun deduction from base...

300 yd - .5 mil (1. on range card)
400 yd - 1.5 mil (1.7)
500 yd - 2.5 mil (2.5)
600 yd - 3.5 mil (3.4)

Changing the zero to 100 yards fixes the 500 & 600 yard error, but now my 300 yard shot is 5.4" low and my 400 yd is 2.9" low with the quick drop - the 300 and 400 yard error isn't acceptable for me.

 

[Formidilosus]

View attachment 652893

.300PRC, 100 yd zero
215 Berger .691 G1
2840 MV
So good gun deduction from base...

300 yd - .5 mil (1. on range card)
400 yd - 1.5 mil (1.7)
500 yd - 2.5 mil (2.5)
600 yd - 3.5 mil (3.4)

Changing the zero to 100 yards fixes the 500 & 600 yard error, but now my 300 yard shot is 5.4" low and my 400 yd is 2.9" low with the quick drop - the 300 and 400 yard error isn't acceptable for me.

Start the .5 correction at 400 yards. As for being 2.9” off at 400- it’s quick dope. As in rushed.

 

[Grizzle]

Thanks for the great information, I've always shot moa and didn't know any better. Very interesting

 

[philcox]

@Formidilosus I am not understanding I don't think ... here is my 7PRC with 175 LRX @ 2974. So this would be a "Good Gun" and thus .5 off over 300, so ...

100 - Base 0 -> 0
200 - Base .5 -> .5
300 - Base 1 -> 1
400 - Base 2 -> 1.5
500 - Base 3 -> 2.5
600 - Base 4 -> 3.5
700 - Base 5 -> 4.5
800 - Base 6 -> 5.5
900 - Base 7 -> 6.5
1000 - Base 8 -> 7.5

However, when I put this through a BC, I get:
100 - 0
200 - 0.4 (all good, within the .1mil)
300 - 0.9 (all good, within the .1mil)
400 - 1.6 (all good, within the .1mil ... but this is weird because it is .1mil more, not less like the others)
500 - 2.4 (all good, within the .1mil ... back to being .1mil less ... hmm)
600 - 3.2 (now .3mil delta)
700 - 4.1 (now .4mil delta)
800 - 5.1 (still .4mil delta)
900 - 6.2 (.3 mil)
1000 - 7.4 (all good, within the .1mil)

I am confused, so any insight is appreciated. I don't see how I could do this in my head.

(I get similar multiple >.1mil discrepancies with my 6.5 ELDM @ 2835)

 

[Formidilosus]

@Formidilosus I am not understanding I don't think ... here is my 7PRC with 175 LRX @ 2974. So this would be a "Good Gun" and thus .5 off over 300, so ...

100 - Base 0 -> 0
200 - Base .5 -> .5
300 - Base 1 -> 1
400 - Base 2 -> 1.5
500 - Base 3 -> 2.5
600 - Base 4 -> 3.5
700 - Base 5 -> 4.5
800 - Base 6 -> 5.5
900 - Base 7 -> 6.5
1000 - Base 8 -> 7.5

However, when I put this through a BC, I get:
100 - 0
200 - 0.4 (all good, within the .1mil)
300 - 0.9 (all good, within the .1mil)
400 - 1.6 (all good, within the .1mil ... but this is weird because it is .1mil more, not less like the others)
500 - 2.4 (all good, within the .1mil ... back to being .1mil less ... hmm)
600 - 3.2 (now .3mil delta)
700 - 4.1 (now .4mil delta)
800 - 5.1 (still .4mil delta)
900 - 6.2 (.3 mil)
1000 - 7.4 (all good, within the .1mil)

I am confused, so any insight is appreciated. I don't see how I could do this in my head.

(I get similar multiple >.1mil discrepancies with my 6.5 ELDM @ 2835)

As I relayed to you in the PM, quick drop is for “quick” use, generally out to 500 or 600 yards. Some line up much better much farther. That load works to 500, or 550 yards. Starting at 600 yards, take a 1 mil off the base.

 

[philcox]

As I relayed to you in the PM, quick drop is for “quick” use, generally out to 500 or 600 yards. Some line up much better much farther. That load works to 500, or 550 yards. Starting at 600 yards, take a 1 mil off the base.

I likely missed that. Thanks, "learning curve ahead, use caution" ...

 

[ehayes]

Running some numbers for those new to mils like myself. Can someone double check my math.

1 Mil Error in inches equates to
100=3.6 inches
200=7.2 inches
300=10.8 inches
400=14.4 inches
500=18 inches
600=21.6 inches

.1 mil is 1/10th of those numbers

My quick drop delta from actual drop is the following using base numbers above for average gun
100 - 0
200 - 0
300 - .2 = 2 inch error
350 - .1 = 1 inch error
400 - 0
450 - .1 = 1.5 inch error
500 - .1 = 1.8 inch error
550 - .1 = 2 inch error
600 - .1 = 2.1 inch error

In terms of inches, that seems acceptable to me.