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Posted: 12/21/2017 5:10:34 PM EDT
[Last Edit: purple85gt]
Extremely confused and need this broken down to elementary school level.
I have the following: FN SPR A3 USG 308, 24" barrel (chrome lined). Leupold MK 4 4.5-14x50 w/ mildot reticle. Known distance range from 100y to 600y marked every 100y with IPSC sized steel from 300+ Factory Federal GMM 168gr I have not fired a shot out of this rifle yet as I just got the scope and rings. So looking around 168 FGGM has a drop of ~80 inches at 600y (I know I will have to see what my rifle is). If my scope has 5 mils from the center of the cross hair to the top of the bottom post, and at 500y 5 mils equals 90 inches. Say I want to shoot at the 600y target without dialing all day, If I use the top of the bottom post as a aiming point shouldn't that get a hit? 
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Posted: 12/21/2017 5:34:10 PM EDT
[#1]
First step is, at what distance are you zeroed?
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Posted: 12/21/2017 6:17:33 PM EDT
[#2]
I will zero at 100y
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FL, USA
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Posted: 12/21/2017 9:28:16 PM EDT
[Last Edit: Reorx]
[#3]
Federal 308 GMM 168 grain (168 grain SMK)
Remington XCR compact tactical - 20" / 1:12 twist Chronographed MV = 2,494 (average of 10 shots) - 10 feet in front of the muzzle; ES = 66; SD = 21 Atmospherics: Temp = 80 deg F; Barometric pressure = 29.93" Hg (I am at sea level); humidity ~60% BDC table for 1/2 mil hashes in the reticle >>> Mil = range 0.0 = 100 yards 0.5 = 186 yards 1.0 = 245 yards 1.5 = 297 yards 2.0 = 344 yards 2.5 = 388 yards 3.0 = 429 yards 3.5 = 468 yards 4.0 = 505 yards 4.5 = 539 yards 5.0 = 572 yards 5.5 = 604 yards 6.0 = 634 yards Since you are using using a 24" barrel your MV will likely be higher - probably by about 100 fps. In order to produce an accurate table, you will need some accurate data for MV, temp, Barometer, and bullet information - diameter, weight, BC... and a ballistic calculator... 
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USA
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Posted: 12/22/2017 12:02:48 AM EDT
[#4]
Ballistic AE works pretty well. Own an iPhone?
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Posted: 12/22/2017 8:39:49 AM EDT
[#5]
First stop thinking in inches. Linear measurement just cause confusion and extra conversions that aren't needed. Your using mils so think in mils. Get your data and run it on a ballistic program like JBM which is free online and very accurate. Here is a link. http://jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi
Run it in mils and when you get the data out it will tell you how much you need to hold over. You should have no problem getting to 600 yards in just a hold over from a 100 yard zero. My 20" .308 with a 168 AMAX is only a 2.2 mil hold at 400, 3.3 at 500 and 4.6 at 600. That's at 2650fps. |
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IL, USA
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Posted: 12/24/2017 3:37:14 AM EDT
[#6]
Keep it simple, drop all the math conversions. Yes the post should get you close at 600. I'm at 5.2 with fed gold 168, just adjust for variables to fine tune. You need your velocity to get good data
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CA, USA
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Posted: 12/24/2017 1:00:48 PM EDT
[#7]
Originally Posted By purple85gt:
Extremely confused and need this broken down to elementary school level. I have the following: FN SPR A3 USG 308, 24" barrel (chrome lined). Leupold MK 4 4.5-14x50 w/ mildot reticle. Known distance range from 100y to 600y marked every 100y with IPSC sized steel from 300+ Factory Federal GMM 168gr I have not fired a shot out of this rifle yet as I just got the scope and rings. So looking around 168 FGGM has a drop of ~80 inches at 600y (I know I will have to see what my rifle is). If my scope has 5 mils from the center of the cross hair to the top of the bottom post, and at 500y 5 mils equals 90 inches. Say I want to shoot at the 600y target without dialing all day, If I use the top of the bottom post as a aiming point shouldn't that get a hit? https://i.imgur.com/VBbnXXX.jpg |
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Posted: 12/24/2017 1:03:04 PM EDT
[#8]
Actually talking through PM about setting up a training day in a couple months.
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