Tequila Shooter Posted January 14, 2023 Share Posted January 14, 2023 Ok, I’m just getting into long range BPCR shooting and realized I have what is probably a question with a simple answer that I just haven’t figured out. I understand that at 100 yards each MOA of elevation is equal to about 1 inch and 2 inches at 200 yards, etc. Looking at the picture below, if at 100 yards the elevation is say 50 (just a random number), is there a way of knowing what it would be at 200 yards or at 300. Link to comment Share on other sites More sharing options...
Guest Posted January 14, 2023 Share Posted January 14, 2023 This might help. A pdf document is also attached. (Photo 01 - Soule Sight) A Soule type rear sight is adjusted in the following ways: WINDAGE: Adjustments are made by turning the windage knob on the base of the rear sight. It is built on a left-hand thread therefore; clockwise turns move the sight body to the left. Counterclockwise turns move the sight body to the right. The windage knob features large and small index marks on the right side. Rotating the assembly from one large mark to the next results in 1/2 minute if angle adjustment. Moving from a large mark to the nearest small index mark provides 1/4 minute of angle adjustment. One entire revolution of the windage knob equals 2 1/2 minutes of angle. ELEVATION Adjustments are made by turning the elevation knob on the top of the rear sight. Before making ANY vertical adjustments of the rear sight, be sure to loosen the sight disks 1/2 turn. Failure to do so will result in damage to the sight. The rear sight ladder or staff is indexed in increments of 5 minutes of angle. The elevator is indexed in increments of 1 minute of angle. Note how the smaller index marks on the elevator do not align themselves with any index mark on the staff at this point. In the example the elevator is set to the “25” index mark (see photo "figure A)". To move the elevator up one minute of angle (to “26”), turn the elevation knob clockwise until the first small index mark on the elevator aligns with the “30” index mark on the staff (see photo "figure B)". To continue an additional minute of angle (to “27”), turn the elevation knob until the second small index mark on the elevator aligns with the “35” index mark on the staff (see photo "figure C)". To continue in increments of one minute of angle, continue the adjustment procedure as explained, always aligning the next index mark on the elevator with the very next index mark on the staff. When a full five minute cycle of angle has been finished the first line on the elevator will align with the next 5 minute mark on the staff. (In this example, the “30” index mark.) What are minutes of angle? The term "minute-of-angle" (MOA) is used regularly by target shooters at the range, but is probably understood, thoroughly, by few. Defined loosely, one MOA = 1" at 100 yards; so, if you shot your rifle 5 times into a 100-yard target and every shot went into a one-inch circle you had drawn on the paper, then your rifle could be said to shoot 1 MOA. Likewise, if every shot goes into a two-inch circle at 200 yards, then you're shooting 1 MOA. A 10-inch group at 500 yards would be 2 MOA. Is 1 MOA actually 1" at 100 yards? It is actually 1.047197580733 inches at 100 yards. Apparently, it is just a coincidence that 1 MOA happens to be REALLY close to 1" at 100 yards. It is, however, quite convenient. The advantage in using a sight calibrated in minutes if angle is simple. It makes absolutely no difference what firearm the sight is mounted on; it can be easily and repeatedly adjusted no matter what caliber you are shooting. If you are hitting 2” low at 100 yards you will move you sight 2 MOA up and you’ll be at point of aim. The other advantage of MOA is in further distances. If you know your ballistics for your chosen round, you can be pretty accurate in setting you sights for longer distances. For example, if you are sighted in at 100 yards and want to shoot at 500 yards, here is what you can do. Look at your ballistic chart. At 100 yards, note the height above the sight plane that the bullet is for a 500 yard impact. If it’s 45 inches, move your sight up 45 MOA and you’ll be in the ballpark. Vernier sights.pdf Link to comment Share on other sites More sharing options...
Uriah, SASS # 53822 Posted January 14, 2023 Share Posted January 14, 2023 100yd zero 200 13.75 moa 300 29.0 moa 400. 45.75 moa 500 63.5 moa 600 82.5 moa 45-70 1160 fps 537 gr bullet, .357 BC Uriah Link to comment Share on other sites More sharing options...
Griff Posted January 14, 2023 Share Posted January 14, 2023 That's where your knowledge of exterior ballistics comes in. A ballistics program is your friend. If the program tells you that you should have 37 inches of drop between 200 & 300 (for example), it's a simple mathematical calculation to determine how many moa's that is. Link to comment Share on other sites More sharing options...
Wyatt Earp SASS#1628L Posted January 14, 2023 Share Posted January 14, 2023 How to read a vernier scale. http://tmtpages.com/vernier.htm Link to comment Share on other sites More sharing options...
Three Foot Johnson Posted January 14, 2023 Share Posted January 14, 2023 You really have to go shoot it and see. I set up a 4' x 4' portable target every fifty yards from 100 to 500 yards, shot a hundred rounds, and wrote the settings in a notebook. 535 grain Postell, 65 grains volume Swiss 1.5, .030" wad, CCI-200 primers. Lee Shaver Deluxe long range Soule, bubble level front globe. 100 - 21 150 - 27 200 - 34 250 - 41 300 - 47 350 - 56 400 - 66 450 - 73 500 - 83 Pretty close to what Uriah posted - 62 points between 100 and 500, compared to his 63.5. Link to comment Share on other sites More sharing options...
Hoss Posted January 14, 2023 Share Posted January 14, 2023 Key is finding your “zero”. I use a 100 yd target got my zero. This will vary from rifle to rifle, and load to load. for example, with my standard loads sharps 100 yd zero is 25 hiwall it’s 15 then you add MOA for there. A ballistics calculator (I like Bullet drop but there are lots of them available) will give you the answer at each distance increment. It won’t be 100% as wind and other atmospheric influences will make a slight difference, but not much. also, 1 MOA is 1”/hundred yards with a 30” barrel. If your barrel is longer or shorter it will make a difference Link to comment Share on other sites More sharing options...
Tequila Shooter Posted January 14, 2023 Author Share Posted January 14, 2023 @Hoss, @Three Foot Johnson, @Griff, @Uriah, SASS # 53822, @Hedley Lamarr, SASS #14478 Life, thanks guys, I’m starting to see a trend, at least enough that I can get close enough so I can zero in. Link to comment Share on other sites More sharing options...
Buckshot Sheridan Posted January 15, 2023 Share Posted January 15, 2023 Who made the sight you are using? Most are scaled correctly to be approximately 1MOA per point if using a 30-32” barrel. Others have a scale that doesn’t correspond to anything useful. Link to comment Share on other sites More sharing options...
Clyde Henry #7046 Posted January 15, 2023 Share Posted January 15, 2023 For a quick and dirty rule of thumb, with my 45-70 loaded with about 60 grains of 1 1/2 Swiss BP and a 500 grain bullet and a 30 inch barrel, I figure about 15 mins of elevation per 100 yards out to about 600 yards. Then I use about 17 to 19 mins elevation up for 700 to 900 yards and then go up 20 mins from the 900 setting to get out to 1000 yards. All of these numbers can be affected by temperature, humidity, ground elevation and wind. If I don't hit the target, the bullet will at least dig dirt near the target and I can adjust my sights to move to the bullet onto the target. At the longer distances, spin drift and rifle cant (as in holding it leaning to one side or the other) will skew bullet's flight and move bullet impact some distance from where you think it should go. Your job, as a rifleman, is to figure this out for your rifle and how it will preform at the target range and and given weather conditions. Link to comment Share on other sites More sharing options...
Tequila Shooter Posted January 15, 2023 Author Share Posted January 15, 2023 3 hours ago, Buckshot Sheridan said: Who made the sight you are using? Most are scaled correctly to be approximately 1MOA per point if using a 30-32” barrel. Others have a scale that doesn’t correspond to anything useful. MVA Link to comment Share on other sites More sharing options...
Buckshot Sheridan Posted January 16, 2023 Share Posted January 16, 2023 With MVA it will be fine. The problems show up with the Italian copies. Link to comment Share on other sites More sharing options...
Johnny Knight Posted January 16, 2023 Share Posted January 16, 2023 Does anyone have some rough numbers for 38-55? Starting to get to know a Winchester 1885 High Wall, 28" bbl, loading 46 gn Grafs 2F pushing a 245 gn .379 Ballard RNFP? Thanks in advance! Johnny Link to comment Share on other sites More sharing options...
Uriah, SASS # 53822 Posted January 16, 2023 Share Posted January 16, 2023 Johnny, 100yd zero 200 13 moa 300 27 moa 400. 43 moa 500 60 moa 600 80 moa 38-50 Rem-Hepburn 1200 fps 363 gr bullet, .357 BC That should get you close. 1-2 moa off, for the shorter range. Higher fps for your load. Uriah Link to comment Share on other sites More sharing options...
Johnny Knight Posted January 16, 2023 Share Posted January 16, 2023 Thanks Uriah. I got the new sights mounted the other day, but it appears I'll need to drift the front sight just a bit to center it up on the rear markings. More rounds down range in the near future.... Johnny Link to comment Share on other sites More sharing options...
Wallaby Damned Posted January 18, 2023 Share Posted January 18, 2023 Rounds down range is really the only sure bet. Every rifle and every load is different. Once you know both, you’ll be hard to beat. Link to comment Share on other sites More sharing options...
Uriah, SASS # 53822 Posted January 18, 2023 Share Posted January 18, 2023 Johnny and others, I like to set up my rifles, so they shoot 1-3 moa RIGHT with the rear side and front sight at zero settings (100-200 yds) With a right hand twist barrel, the spin drift will be to the right. I like to set up my rifles for a mechanical zero at every given range based on the spin drift. And go from there with my wind drift. With my rifle shooting to the right, I only have two dial in the LEFT spin drift for the mechanical zero. In my estimation, a rifle, shooting to the left at 100 yards, is the worst situation, for mechanical zero at long range. I have a front side that is adjustable for the wind. I have it set to 3 moa RIGHT, 200 yds, with both sights set at zero. That way, I never cross the zero mark with my front sight. It takes a lot less thinking out of it. Uriah Link to comment Share on other sites More sharing options...
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