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Post by benerwin93 on Feb 11, 2017 11:56:06 GMT -8
Toying with my profile settings, can't find the drag function of my ammo online. Shooting federal 223 55 grain fmj. Any other stats would be appreciated if you 100% know them!
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tomvb
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Post by tomvb on Feb 11, 2017 14:31:31 GMT -8
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Post by benerwin93 on Feb 11, 2017 14:59:02 GMT -8
No chance of me making sense of that
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Post by benerwin93 on Feb 11, 2017 15:51:30 GMT -8
No chance of me making sense of that
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tomvb
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Post by tomvb on Feb 11, 2017 15:53:32 GMT -8
If I've read the info correctly, your standard 55 gr fmjbt is going to be a G7.
Tom
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bunnyblaster
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Competitive target shooting & hunting for about 25 years, mostly vermin hunting.
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Post by bunnyblaster on Mar 2, 2017 10:05:29 GMT -8
If I've read the info correctly, your standard 55 gr fmjbt is going to be a G7. Tom Whats the part number on the box so I get the exact round...I love a quest!
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tomvb
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Post by tomvb on Mar 2, 2017 12:04:23 GMT -8
BTFOOM 😜
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bunnyblaster
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Competitive target shooting & hunting for about 25 years, mostly vermin hunting.
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Post by bunnyblaster on Mar 8, 2017 0:26:41 GMT -8
Lol, ya divil, I went and looked up fedral BTFOOM !! I feel like a right dope now
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oldspook
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Post by oldspook on Mar 15, 2017 8:49:39 GMT -8
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testament
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Post by testament on Mar 18, 2017 9:41:07 GMT -8
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oldspook
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Post by oldspook on Mar 18, 2017 14:22:44 GMT -8
NVM
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oldspook
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Post by oldspook on Mar 18, 2017 14:34:16 GMT -8
If I've read the info correctly, your standard 55 gr fmjbt is going to be a G7. Tom One would think that but I've just been mulling it over. If the vendor gives a BC and does not specify the drag model, I'm betting they will be using G1. I've never seen a ballistics calculator that defaulted to anything but G1. Even Chairgun defaults to G1. The vast majority of shooters are clueless about drag models. If they use a ballistics program, they are generally clueless about how to use it so they settle for the defaults. The first thing they figure out they might want to change is the muzzle velocity. Then they read a bit more and decide they need to do the BC. A little more reading and they figure out that sight height matters. Finally after all of that they start to think about that thing called drag model. I'll bet nine of ten never actually bother to change it from G1. So if I was a vendor I'd specify my BC relative to the G1 model and if I was feeling really nice I'd also specify the BC relative to G7. There is a big difference between a G1 BC and a G7 BC. www.jbmballistics.com/cgi-bin/jbmgf-5.1.cgi
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testament
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Post by testament on Mar 18, 2017 15:39:43 GMT -8
G1 and G7 are two different methods of calculating Ballistics. G1 is the old system for measuring BC and is suitable for flat based bullets, but many bullet manufacturers use this coefficient for boat tail bullets as well.
Basically you can use g1 and if while using g1 and its not really specific or accuracy is not performing just change to G7 if accuracy substantially increases then your obviously shooting boat tails. whether your bullet is boat tail or not your pretty safe if starting with G1 Coefficent unless you know specifically your shooting boat tail. Start with the G1 coefficient since most manufacture's just load cheap old flat based bullets for there mass production rounds cheaper end cost.
Federal obviously just defaults to g1 for all there calculations based on there BC calculator.
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oldspook
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Post by oldspook on Mar 18, 2017 16:09:46 GMT -8
G1 and G7 are two different methods of calculating Ballistics. G1 is the old system for measuring BC and is suitable for flat based bullets, but many bullet manufacturers use this coefficient for boat tail bullets as well. Basically you can use g1 and if while using g1 and its not really specific or accuracy is not performing just change to G7 if accuracy substantially increases then your obviously shooting boat tails. whether your bullet is boat tail or not your pretty safe if starting with G1 Coefficent unless you know specifically your shooting boat tail. Start with the G1 coefficient since most manufacture's just load cheap old flat based bullets for there mass production rounds cheaper end cost. Federal obviously just defaults to g1 for all there calculations based on there BC calculator. G1 and G7 are two of several different drag models. The calculations are the same only the drag coefficients change. In the interest of not being misunderstood, the drag model specifies drag coefficients for different velocity ranges, usually in the form of an equation or a graph. The BC in conjunction with the drag coefficient specified by the specific drag model are used to calculate drop, time of flight and velocity loss from point to point along the trajectory. That is why a BC which is good for the G1 drag model won't work as well with one of the other models. The shooter should use G1 UNLESS the vendor specifies a different drag model for the reasons I mentioned above. In the case of the data on the federal web site, it is reasonable to assume the BCs specified there are G1 UNLESS they specify otherwise BECAUSE their calculator defaults to G1.
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testament
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Post by testament on Mar 19, 2017 8:58:43 GMT -8
thanks for saying basically the same thing lol. to keep it simple since most people are really only shooting at a range under 250 yards at night, for that fact even during the day hunts too. The difference is negligible between g1 and g7, so you shouldn't really sweat it. you only see the benefit of a very accurate G1 or G7 DC for long range shooting 800+ yards when you really want as much specific and accurate data as you can. simple answer G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets. Ok lets get back on topic what is the drag coefficient for a .223 55gr FMJ Answer: the drag function for .223 55gr FMJ is 0.269 G1 and 0.129 G7 For those who want a simple converter from G1 to any coefficient www.jbmballistics.com/cgi-bin/jbmgf-5.1.cgi
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oldspook
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Post by oldspook on Mar 19, 2017 14:51:37 GMT -8
NVM
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oldspook
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Post by oldspook on Mar 19, 2017 14:56:02 GMT -8
I could have said exactly the same thing, lol. Or maybe you just didn't read the post immediately above this post of yours.
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oldspook
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Post by oldspook on Mar 19, 2017 15:07:58 GMT -8
thanks for saying basically the same thing lol. to keep it simple since most people are really only shooting at a range under 250 yards at night, for that fact even during the day hunts too. The difference is negligible between g1 and g7, so you shouldn't really sweat it. you only see the benefit of a very accurate G1 or G7 DC for long range shooting 800+ yards when you really want as much specific and accurate data as you can. simple answer G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets. Ok lets get back on topic what is the drag coefficient for a .223 55gr FMJ Answer: the drag function for .223 55gr FMJ is 0.269 G1 and 0.129 G7 For those who want a simple converter from G1 to any coefficient www.jbmballistics.com/cgi-bin/jbmgf-5.1.cgiWe do not know what most people are doing, really. Neither do we know what people intend to do in the future, really. There are a lot of different uses for this optic. Crossbow shooters, airgun hunters, long range varmiters, ... lots of different users and applications. So I don't think we can make that generalization. While the difference between G1 and G7 are small, they are not "negligible". In some applications they might not matter, in other applications they will matter greatly. Some shooters are shooting half minute targets not pie plates at 150 yards. A 5mm Sheridan shooting a pellet at 650 fps and zeroed at 24 yards when calculated on the G1 drag model will be more than a MOA lower than it calculates to on the G7 drag model, at 50 yards. So the difference between the G1 and G7 drag models at 50 yards is the difference between a crippled squirrel and a dead squirrel. A .270 Winchester shooting a 130 spire point Corelokt bullet (.408 G1 BC) at 2850 fps zeroed at 100 yards will show 39.05" of drop at 450 yards using the G1 drag model but the same bullet using the G1 BC calculated using the G7 drag model will show 31.86" of drop. I don't think 7.2" of drop (1.6 MOA of drop) is something that can be ignored... The bottom line is if the vendor gives you a G1 drag model for a bullet with a boat tail you had BETTER use G1 for your calculations or you are going to miss or worse than that cripple something. Unless a user intends to work up his own form factor and compute his own BC based upon one or another drag model he should always go with what the vendor tells him. In the absence of a specified drag model it is safest for that person to assume the vendor is specifying a G1 BC EVEN IF the bullet he is using is a boat tail. This is because G1 has been the standard drag model for a hundred and twenty years or so. If the vendor did not specify a drag model then the vendor used G1. If the shooter uses G7 with a G1 BC it will cause him problems unless he is shooting pie plates at a hundred and fifty yards. I linked JBM's BC conversion calculator (that you just relinked) previously in the thread apparently you missed that when you read the thread.
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testament
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Post by testament on Mar 19, 2017 16:30:34 GMT -8
back to my original answer posted use the federal site for there ammo www.federalpremium.com/ballistics_calculator/G1 coefficient 0.269 not trying to start nothing spook lol just answer a simple question for a fellow shooter/hunter. Peace out move along nothing to see here!!!
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Post by superhik on Mar 26, 2020 15:32:10 GMT -8
hello - I need some help here as well...
Can somebody tell me what DC should I use with Wolf Gold 223 55 grain ammo? I was going to try 0.129 G7, but wanted to check...
Please let me know.
Thanks
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