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Glennster
May 28, 2007, 11:53 AM
I got a great load for the old .308 bolt rifle. I put it thru the Chronograph, then I entered all the proper info ( BC, FPS, bullet weight, ect.. ) to figure the bullet drop from 100 to 1,000 yards.
Once I had all that, I figured it wouldn't be too hard to work my way out to 1,000 yards, BUT, I couldn't get hits at 700 ! ! ! ! ! This range has 24'' steel plates set out every 100 yards.
It was a fairly calm day, so wind was not too big an issue. Maybe I'm not adjusting the scope properly.
If the computer says the drop from 600 to 700 yards is 63'', and I have a 1/4 moa scope, wouldn't about 35 clicks up get me on the steel?

scouter27
May 28, 2007, 01:06 PM
whats your projected velocity at 600 and 700? if the bullets pass the sound barrier in there it can throw off your impact

Trapper L
May 28, 2007, 01:09 PM
I ran the Hornaday 168 HPBT loaded at 2700'ps thru my program and get a 156" drop from a 100 yd zero. All other values were zero. Doesn't sound like you are near enough clicks.

Slamfire
May 28, 2007, 02:17 PM
You might need to get a 20 MOA sight base. OEM scope rings and bases are set up so scope bore is parallel with the rifle bore. Which means that half of your elevation is used up just zeroing your rifle at close range. You should be close to running out of elevation at 600 yards.

700 yards is a long way with a 168. I have shot 168's at 1000 yards, and between 600 yards and 1000 yards, the bullets go subsonic and start tumbling. Maybe that is what happened to you.

Go get some 175 Sierra Matchkings, they don't tumble at extreme range.

Jseime
May 28, 2007, 02:22 PM
The drop is 63 inches from 600 to 700 yards right.

1/4 [email protected]/click

1 MOA @400 yards/click

1.5 MOA @ 600 yards/click

63"/1.5"= 42 Clicks

Anyone who knows more than I about math help me out. I think I've got it.

Trapper L
May 28, 2007, 04:02 PM
If the rate of trajectory was linear, you'd be on, but it's not. How about posting the data that you have and we can all get on the same page. Bullet, bullet weight, speed, etc.

Glennster
May 28, 2007, 04:31 PM
Jseime,
I was figuring 1 3/4'' per click because I was going from 600 to 700 yards, that was part of my problem ( I think???? ). I think you're right, I should have been using
1 1/2'' per click to go from 600 to 700 yards.

Trapper L,
I'll gather my data and post it a bit later. Here's part of the info, 168 grain Berger VLD (BC = .495 ), @ 2650 FPS. I use 43.5 grains of BL-C2.
We're having some people over and my wife's on me to go to the store : - (

I sure appreciate the input!!!!!!!!!

L Puckett
May 28, 2007, 07:30 PM
Glennster,

First, always calculate your dope from your Zero, not from the last target, as you can build in error. Another help is don't count clicks, use your turret numbers (whole numbers, not hash marks). Counting clicks will drive you crazy, work in MOA and use the clicks for the fraction of MOA.

There are a lot of variables (mainly, temp, humidity, pressure) but using "Standard Atmosphere". For 600 yrds your drop should be 15.43 MOA (15 1/2), basically 15 whole numbers on the turret and 2-1/4 clicks. For 700 yrds it should be 19.89 (20.0) again, 20 whole numbers.

The Berger your using, at that speed should get you past 1100 yrds while super sonic. Remember this is using standard atmosphere, temperature, altitude, etc.

LP

joshua
May 28, 2007, 07:54 PM
L. Puckett has the info and then some. My original post just asked what your zero is.

Jseime
May 28, 2007, 08:17 PM
I was figuring 1 3/4'' per click because I was going from 600 to 700 yards, that was part of my problem ( I think???? ). I think you're right, I should have been using
1 1/2'' per click to go from 600 to 700 yards.

If the drop is 63" between 600 and 700 yards you want the bullet to arrive 63" high at 600 yards to land on the target at 700 thats why I figured 1.5 MOA. Good luck and good shootin.

Glennster
May 28, 2007, 08:43 PM
My Zero was 100 yards.
Here's what the balistics program showed my drop to be with the load I have.

100 = 0
200 = 4''
300 = 14''
400 = 33''
500 = 60''
600 = 97''
700 = 146''
800 = 209''
900 = 288''
1,000 = 386''

I was counting clicks, and you're right, it was driving me crazy. I also noticed (as I look back at my notes), that I was looking at my .223 info, so, mixing my .223 chart with my .308 chart insured that I would be ALL SCREWED UP !
Here's what I wanted to come away with when I was done shooting today. I wanted to be able to dial the scope to hit at anything from 100 to 1,000 yards, in 100 yard increments.
So I need to convert these drop in inches into drop in MOA?????

rockstar.esq
May 28, 2007, 09:14 PM
So I'm at a bit of a loss as to what's going on here. My .308 Winchester load is a 168grain Sierra Matchking HPBT with a muzzle velocity of 2650fps or thereabouts. The 700 dope required (from a 100 yd zero) comes to 21.1 MOA . I've shot at this distance and the actual dope came to 23 MOA so I'm pretty sure that my math closely matches the real world. If you were hitting stuff at 600 yards, there's something like 5 MOA of difference between them. One MOA at 700yds is a bit over 7 inches so you'd be looking at right about one yard low (5 x 7 = 35") if you were shooting at 700 with a 600 dope dialed in. My scope's maximum elevation is only about 93 MOA and that's with a 30mm tube! Either somebody's got their math wrong or I'm misunderstanding something.

Jimro
May 28, 2007, 09:20 PM
100 = 0
200 = 4'' 2 MOA
300 = 14'' 4.6 MOA
400 = 33'' 8.25 MOA
500 = 60'' 12 MOA
600 = 97'' 16.2 MOA
700 = 146'' 20.8 MOA
800 = 209'' 26.1 MOA
900 = 288'' 32 MOA
1,000 = 386'' 38.6 MOA

Someone check my math?

Jimro

IdahoG36
May 28, 2007, 09:38 PM
.50 BMG!! That will get you there.:D

Powderman
May 28, 2007, 09:43 PM
Couple of questions:

First, are you shooting on level ground? If not, did you calculate the cosine angle, to determine what dope to dial in?

Second, are you reading the wind at that distance correctly? And, even more importantly, are you adding the proper windage? Remember, while your elevation and range dope can easily be dialed in, windage is a whole nother story. A rough calculation factor to use is to double your windage measurement per increment of range.

Example: If your bullet drifts .30 inches @100 yards per mph of wind, then it will drift:

.60 @ 200 yards
1.20 @ 300
2.40 @ 400
4.80 @ 500
9.60 @ 600
19.20 @ 700

per minute of adjustment.

Thus, if you are looking at a 10 mph full value crosswind, and the bullet at 500 yards is said to drift 5 minutes at that range per mile per hour of wind, then your initial calculation should be:

5 minutes/mph x 10 mph = 50 inches of drift @ 500 yards.

From your dope, you already know that each minute of windage will move the strike of the bullet 4.80 inches at 500 yards.

50 divided by 4.80 = 10.41.
Thus, add 10.5 minutes windage in the appropriate direction, and favor the target. Hope that helps!

mikikanazawa
May 29, 2007, 01:41 AM
At this range, what role would mirage play?

Glennster
May 29, 2007, 04:56 AM
Powderman,
I was shooting from a bench, the range does run very slightly uphill as you go up in yardage.

Rockstar.esq,
I had a 20 MOA tapered base put on this rifle when I had it built, I've got plenty of elevation to go 700 yards. I think I've got enough to go 1,000, with the help of you guys that is.......

Gbro
May 29, 2007, 06:02 AM
I set up on a clean 200yd frame covered with freezer paper. its marked so i can easily see the rise as i dial the scope up. (easy to see if it runs out of adj).
Its much easier to work close with bullet rise and see the results, than watch for dirt at 600+ yards.

L Puckett
May 29, 2007, 06:32 PM
Glennster,

You might notice I quoted some MOA's that are slightly less than Jimro's. That may be my mistake, as I ran the dope for the Berger 168 grn VLD which has a BC of .512. If I use the Berger Match BT at .495 Jimro's numbers match. Again using STD ATM.

Remember, software (range cards) are like reloading guides.......they are a guide. Log your dope in all conditions and you can then dial it and dump it.

Print a little range card for your ranges to 1000, have your wife listen as you recite them, if you miss a number it is 25 pushups per miss. She'll love it and you'll learn REAL fast.

Sorry if I may have misled you,

LP

mswestfall
May 29, 2007, 07:51 PM
Can I go to the range and just watch you guys? Please?

Excellent post. I"m gonna print this when I get home.

I'm off to the CMP South Store on Thursday...

Glennster
May 29, 2007, 07:58 PM
LP,
You've been a ton of help.

Jimro,
I really appreciate you taking the time to put some numbers together for me.

THANK YOU, to all for the input. You guys make this a great site for rookies like me that really need sound advise.


Again, THANK YOU ! ! ! !

Jseime
May 29, 2007, 10:09 PM
Rookie!?

Heck you're scoring hits on a 600 yard target, I havent even thought about attempting that yet. Keep at er and youll get it dialed i think 700-800 will be the source of another great thread.

rockstar.esq
May 29, 2007, 10:38 PM
Well Jimro and I are within a few tenths of MOA at 700yds so if you've got that elevation dialed in, you should be close enough that your elevation won't be a problem. Angle of Cosine is WAY less of a big deal than it's made out to be. The effect it has is to REDUCE the actual dope required to equal effect whether the angle be uphill OR downhill. At 10 degrees (pretty steep) you're looking at 98% of the straight line distance to your target as the effective distance which is what you'd use to set your dope. So if that were the case the 700 yard target would actually require 689 yards of dope (essentially the same). Wind as another poster mentioned earlier is a huge factor. 700 yards is just shy of 40% of a mile, mirage makes the target wiggle pretty badly. Wind has blown me the better part of 2 MOA (15mph approx crosswind) at that distance. Really the key is to be patient and watch the wind blowing stuff around. When you spot a calm spell make the most of it. This is why few long range shooters will dial windage on their scope. It's quicker to adjust your hold when needed. When there's 5mph "lulls" I'll sometimes dial in enough windage to hold for the 5mph and just hold less for the gusts. Try as I might, reading the wind ends up being a S.W.A.G. more often than not.

T. O'Heir
May 30, 2007, 01:54 AM
"...wouldn't about 35 clicks up get me on the steel?..." Thirty-five clicks should move the POI 8.75", based on your 1/4" clicks. Your ballistics program is telling you 49" between 600 and 700.
Try working up a load with 175 grain Matchkings. 168's work best out to about 600 yards. And don't put too much faith in ballistics programs.
"...what role would mirage play?..." Mirage is a heat thing. It can make the target disappear entirely. Or make it appear like you're shooting through water. However, once you've learned how to read it, you can tell what the wind is like down range.

jrothWA
May 30, 2007, 07:52 AM
with a target marked with the impacts from 100 yds.
Remember if you move 1/4 inch @ 100, you'll move 1/2 inch @200, etc.
Hope this helps.

30Cal
May 30, 2007, 10:40 AM
Just another thing to watch out for. You may be getting some shift in windage as you pile on the elevation clicks.

Ty

Dirty_Harry
May 30, 2007, 10:44 AM
:eek:So many mathematical charts

Mute
May 30, 2007, 11:25 AM
How are you getting 35 clicks? 1/4" per click would equal 15 clicks. According to the chart you printed, the drop between 600 and 700 yards is 49" or 46 MOA. If you have a true 1/4 MOA turret that's 11.5 clicks.

Jseime
May 30, 2007, 01:40 PM
If you have a true 1/4 MOA turret that's 11.5 clicks

1/4 inch at 100 yards works out to be 1 inch at 400 yards and 1.5 inches at 600 yards.

Mute
May 30, 2007, 05:10 PM
A MOA is actually equal to 1.047" at 100 yards, but we're splitting hairs now. The original poster needs to know what measurements his turret actually uses, 1/4" per click or 1/4 MOA per click, because at extended distances, the disparity between the two is enough to cause a miss.

Scorch
May 31, 2007, 02:03 PM
at extended distances, the disparity between the two is enough to cause a miss
1" at 100 yds or 1.04" at 100 yds?

The difference:
.04" at 100 yds = .4" at 1,000 yds.

At 1,000 yds (to take an extreme position), that is less than 1/2" difference between 1/4 MOA clicks and 1/4" clicks on the scope turret adjustments. Hardly enough to cause a miss.

Find a good trajectory table (I use the one at www.eskimo.com) that gives you drop in MOA, and then sight in the rifle at various ranges to verify (since most bullet makers use the old G1 comparator for BC).

Like they said above, don't compound the problem by adjusting your sights from the previous range settings, go back to a BSZ setting until you get the rifle sighted in. Keep notes, so you know how many clicks of elevation you need at each range. Then you can go back and work on adjustments between different ranges. It's confusing at first, but it will become second nature the more you play with it.

Mute
May 31, 2007, 02:42 PM
At 1,000 yds (to take an extreme position), that is less than 1/2" difference between 1/4 MOA clicks and 1/4" clicks on the scope turret adjustments. Hardly enough to cause a miss.

If you know you're dealing with MOA or inches that's fine, but let's do an example. Let's say at 1000 yards, the drop in inches for FGMM 175 gr. is 380. Divide that by 10 and you've 38. Now if you do 38 clicks that are 1" each click that's 380 inches, but if you do 38 1MOA clicks that's 398 inches. That's an 18 inch differences in point of impact. Definitely enough to cause a miss.

Scorch
May 31, 2007, 04:57 PM
Now if you do 38 clicks that are 1" each click that's 380 inches, but if you do 38 1MOA clicks that's 398 inches.
OK, but most scopes have 1/4" or 1/4 MOA adjustments. Presumably you would know what your scope adjustments are to begin with, which is why I said then sight in the rifle at various ranges to verify If you just pick MOA to begin with and stop switching back and forth between inches and MOA, it's a lot less confusing.
Whether you would miss or not depends a lot on the size of the target. If you are shooting match at 1,000 yds, you are shooting at a 8'X8' target, and 18" low would still be in the black (60" black). If you are in combat, 18" low is still a hit. If you are shooting ground squirrels, you would miss.

Mute
May 31, 2007, 05:05 PM
Correct. Like I said, one needs to know which measurement one's scope uses, inches or MOA. If you assume it's one and it's the other, than you have to do a great deal more homework to get the correct dope for your rifle. 18" change in impact may still give you a hit, but it's going to be less than idea and is enough to miss outright depending on the situation.