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Posted: 5/22/2010 9:30:52 AM EDT
| I looked on a ballistics calculator and it said for the bullet I am shooting to sight it in for 300 meters or 328 yards I could sight it in at 19 yards and the arc of the bullet at 19 yards would align and hit roughly the same area than at 300 meters. So If I sight it in at 19 yards it will hit the same at 300 meters due to the arc of the bullet. I am using a EoTech sight. Would this work? |
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Quoted:
I looked on a ballistics calculator and it said for the bullet I am shooting to sight it in for 300 meters or 328 yards I could sight it in at 19 yards and the arc of the bullet at 19 yards would align and hit roughly the same area than at 300 meters. So If I sight it in at 19 yards it will hit the same at 300 meters due to the arc of the bullet. I am using a EoTech sight. Would this work? What round and barrel are you using? |
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I do not mean to question you but how do you know? Do you use the same ammo, another ballistics calculator? (However I did question the Norma Ballistic calc I used because I made up my own bullet for 2 different loads and they did come to the exact same trajectory...)
I believe you more I just want to make sure and thanks for the help!!! |
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Great.... Hey in you opinion what would be the best 5.56 round for both close quarters and 300 meter shooting between these 2.
77gr Sierra OTM or 60gr Nosler Partition. or is there a better bullet. I looked on the forums under the self defense ammo but I still cant decide. I want a round that will cause a lot of damage (example 1 shot 1 kill) but still go through barriers like car doors, glass, wood etc... And since you know what you are talking about I would rather get your opinion than guess myself. |
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Ballistics tables and graphs are great, but don't they require chronographing on any given rifle? The 3240 fps I keep seeing is from a 20" test barrel. Couldn't there be a LOT of variability from barrel to barrel?...enough to throw off a ballistics graph that assumes 3200 FPS?
Also, how big is the effect of ballistics coefficient? That's a number that also seems to fluctuate a lot from mfgr to mfgr. |
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Quoted:
Ballistics tables and graphs are great, but don't they require chronographing on any given rifle? The 3240 fps I keep seeing is from a 20" test barrel. Couldn't there be a LOT of variability from barrel to barrel?...enough to throw off a ballistics graph that assumes 3200 FPS? Also, how big is the effect of ballistics coefficient? That's a number that also seems to fluctuate a lot from mfgr to mfgr. If you don't like the data that I posted, don't use it. Better yet, post some of your own first hand data that you think does a better job of anwering the OP's question. |
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Quoted:
Great.... Hey in you opinion what would be the best 5.56 round for both close quarters and 300 meter shooting between these 2. 77gr Sierra OTM or 60gr Nosler Partition. or is there a better bullet. I looked on the forums under the self defense ammo but I still cant decide. I want a round that will cause a lot of damage (example 1 shot 1 kill) but still go through barriers like car doors, glass, wood etc... And since you know what you are talking about I would rather get your opinion than guess myself. There is no single bullet that will do all those things well and certainly no bullet can guarantee a "1 shot, 1 kill." For use when intermediate barriers are not to be expected, either Hornady's 75 grain 5.56 TAP or something loaded with Nosler's 77 grain BTHP have demonstrated to have the best terminal ballistic properties in testing. If intermediate barriers are expected, the bonded soft-points recommended by Dr. Roberts, such as the Speer 64 grain Gold Dot or Federal 62 grain TBBC load have shown the best results in testing. |
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Quoted:
I do not mean to question you but how do you know? Do you use the same ammo, another ballistics calculator? (However I did question the Norma Ballistic calc I used because I made up my own bullet for 2 different loads and they did come to the exact same trajectory...) I believe you more I just want to make sure and thanks for the help!!! I'm betting you didn't use the proper height over bore value. Most calculators use 1.5" which is fine for a bolt gun, however for an AR-15 the 'standard' value is 2.6". |
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Quoted:
Ballistics tables and graphs are great, but don't they require chronographing on any given rifle? The 3240 fps I keep seeing is from a 20" test barrel. Couldn't there be a LOT of variability from barrel to barrel?...enough to throw off a ballistics graph that assumes 3200 FPS? Chronoing your rifle with your load in your shooting environment is best. Barring that using data on the commerical load you're looking to buy in the same length barrel. Many of us here have posted out Chronograph data on a variety of ammo and barrel lengths. I'd note my data looks very similar to Molon's Also, how big is the effect of ballistics coefficient? That's a number that also seems to fluctuate a lot from mfgr to mfgr. It's VERY important, especially for distance shooting. Different bullets have different BCs (and adding a cannalure can effect the BC - so a 77gr SMK with cannalure can have a different BC from the 77gr SMK sold commercially w/o one). BCs can also change due to velocity (Sierra is very good about posting this data) but for most people using the BC based on the Muzzle Velocity is good enough). Also notethe BC can be different for different ballistics models. Some models work better than others for a specific bullet type. So make sure the BC you are using matches the ballistic modle your software uses (some programs allow you to select the model you want to use. Check out the online JBM Ballistics calculator to see this option next to the BC entry window - it defaults to the 'G1' model). |
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