247sniper Posted February 7, 2015 Report Share Posted February 7, 2015 Which is best to use with the 80 grain Amax bullet in ballistic programs, G1 or G7? Thanks guys Steve. Link to comment Share on other sites More sharing options...
jay666d Posted February 7, 2015 Report Share Posted February 7, 2015 G7... Link to comment Share on other sites More sharing options...
247sniper Posted February 7, 2015 Author Report Share Posted February 7, 2015 G7... Cheers thanl fella, why would that be best, is it because it's a long boat tail bullet? Cheers Steve Link to comment Share on other sites More sharing options...
jay666d Posted February 7, 2015 Report Share Posted February 7, 2015 That's exactly right... Better for long range stuff. Have a little look at this: http://bulletin.accurateshooter.com/2013/01/g1-vs-g7-ballistic-coefficients-what-you-need-to-know/ Link to comment Share on other sites More sharing options...
dannywayoflife Posted February 7, 2015 Report Share Posted February 7, 2015 G1 is pretty useless for modern bullets. Where ever possible use the g7 Link to comment Share on other sites More sharing options...
gbal Posted February 7, 2015 Report Share Posted February 7, 2015 G1 assumes a bullet shape pretty much like a 22rf bullet......G7 is much closer to modern Boat tail ogive point bullets.G7 has the nice added advantage of being quite stable over diminishing velocity-unlike G1,which is at best averaged-or see Sierra data-gives three velocity bands and the G1s for each...for each bullet.Not too clever,even if your program is so sophisticated. g Link to comment Share on other sites More sharing options...
247sniper Posted February 7, 2015 Author Report Share Posted February 7, 2015 Thanks for your help so far guys, but where will i find out the G7 figures for a said bullet? Cheers Steve. Link to comment Share on other sites More sharing options...
farmer7 Posted February 7, 2015 Report Share Posted February 7, 2015 Thanks for your help so far guys, but where will i find out the G7 figures for a said bullet? Cheers Steve. Bryan Litz gives it a G7 BC of .231. Link to comment Share on other sites More sharing options...
247sniper Posted February 7, 2015 Author Report Share Posted February 7, 2015 Bryan Litz gives it a G7 BC of .231. Thanks for that mate, where did you find that info, was that from his book? Steve Link to comment Share on other sites More sharing options...
farmer7 Posted February 7, 2015 Report Share Posted February 7, 2015 Thanks for that mate, where did you find that info, was that from his book? Steve No, from the Shooter app. Quite a number of the bullets are listed with Litz's own measured BC's. I always use them, (all the bullets I currently use have the Litz BC already loaded) there is quite a difference with some bullets in particular when you compare the same bullets using the Litz G7 BC against the factory G1 BC listed. Link to comment Share on other sites More sharing options...
dannywayoflife Posted February 7, 2015 Report Share Posted February 7, 2015 If you pm me I have a PDF on my iPhone by Litz with a load of gated g7 BC's I can email to you Link to comment Share on other sites More sharing options...
onehole Posted February 9, 2015 Report Share Posted February 9, 2015 If you pm me I have a PDF on my iPhone by Litz with a load of gated g7 BC's I can email to you Any chance you can give me a G7 figure for Hornady105 6mm Amax? thanks,,,,,O Link to comment Share on other sites More sharing options...
247sniper Posted February 9, 2015 Author Report Share Posted February 9, 2015 Any chance you can give me a G7 figure for Hornady105 6mm Amax? thanks,,,,,O Hiya matey, according to Litz's book, the G7 for this bullet is 0.252. Steve. Link to comment Share on other sites More sharing options...
onehole Posted February 10, 2015 Report Share Posted February 10, 2015 Hiya matey, according to Litz's book, the G7 for this bullet is 0.252. Steve. Thank you very much indeed,,,ought to get his book but this is the only "longish range " range bullet I generally use,,,,,can now make some comparisons and may explain some longer range "errors",,,,,regds ,,,,O Link to comment Share on other sites More sharing options...
jcampbellsmith Posted February 10, 2015 Report Share Posted February 10, 2015 One small comment. Looking at Bryan's book there are a range of G7 BC values depending on velocity for each bullet. Regards JCS Link to comment Share on other sites More sharing options...
Cumbrian 1 Posted February 13, 2015 Report Share Posted February 13, 2015 Hi Steve, I believe from reading your previous posts that you use ballistic FTE, if so when you select a bullet, at the top of the page it has "Bullets"Loads"Litz"Other" select Litz and it has the 80amax with its G7 BC and projectile length so you can easily enter the details on the trajectory page for spin & stability. Also the G7 profiles are the most up to date as they are constantly updated I have the 80amax as having a G7 BC of .231 Link to comment Share on other sites More sharing options...
gbal Posted February 13, 2015 Report Share Posted February 13, 2015 "Just out of curiosity" has anyone entered exactly the same data,but for G1 and then G7 BCs,and noted the actual drop differences predicted? I'd imagine quite a bunch of inches less for G7 at 1000 for 308 target...but what would it be,say, in 223 over more typical varmint range 300y? etc... Just curious about the size of the difference-of course,we should use the more accurate G (which might be G1 for flat base) and every inch matters-but how many of them are involved? gbal Link to comment Share on other sites More sharing options...
Roe Posted February 13, 2015 Report Share Posted February 13, 2015 Some math on G1 vs G7 vs Cd. Data included if you want to check it. Bullet Lapua 6,5mm 139gr Scenar as this is an extremely well documented bullet. Published G1 0,578. G7 0,29 used where possible if not Cd (radar data). V0 835 msec at 12˚C changing 0,5 msec pr 1˚C. Rifle zero 100m, 5 cm distance barrel/scope c-c. Sight adjustment 0.1 MRAD or 1cm@100m. Weather 990 hPa, rel air humidity 60%, temp12C . Theoretical trajectory calculated by various programs with the above input, the results is number of clicks. 400m 600m 800m 1000m 1200m Applied Ballistics (G7) 23 45 72 107 153 Shooter (G7) 23 46 74 109 155 Strelok Pro (G7) 23 45 72 106 150 Lapua Ballistics (Cd) 23 44 71 105 nil G1 calculation 23 44 72 105 148 Link to comment Share on other sites More sharing options...
gbal Posted February 14, 2015 Report Share Posted February 14, 2015 Some math on G1 vs G7 vs Cd. Data included if you want to check it. Bullet Lapua 6,5mm 139gr Scenar as this is an extremely well documented bullet. Published G1 0,578. G7 0,29 used where possible if not Cd (radar data). V0 835 msec at 12˚C changing 0,5 msec pr 1˚C. Rifle zero 100m, 5 cm distance barrel/scope c-c. Sight adjustment 0.1 MRAD or 1cm@100m. Weather 990 hPa, rel air humidity 60%, temp12C . Theoretical trajectory calculated by various programs with the above input, the results is number of clicks. 400m 600m 800m 1000m 1200m Applied Ballistics (G7) 23 45 72 107 153 Shooter (G7) 23 46 74 109 155 Strelok Pro (G7) 23 45 72 106 150 Lapua Ballistics (Cd) 23 44 71 105 nil G1 calculation 23 44 72 105 148 Thomas,thank you. Given the likely accuracy of programs (+/- 1 or 2 clicks at best?),it seems the G7 programs are in close agreement.....but so is Cd and G1,with the G7s ,especially at plausible shooting ranges.....hmmmm... Given that Roe's data will have been meticulously collated,what results have others found? In particular,just substituting G1 for G7 BC values with otherwise identical data in the same ballistic engine? Which-if either-was closer to field firing (I appreciate field data-though definitive for the shooter/rifle/load is subject to un-measureable variables,so may differ from predicted) but in general,how do the predictors do when compared esp G1 and G7?Between engine comparisons might emerge from the data too. gbal Link to comment Share on other sites More sharing options...
onehole Posted February 14, 2015 Report Share Posted February 14, 2015 Mmmmmm close isn,t it,,,,,,,,,,,,Think I will stick with what I,m doing ,,,I can pretty much rely on my ups out to 400 its beyond that where conditions have me puzzled sometimes and only a bit of field testing on the day will tell me whats happening and in only one direction I might add and adjust accordingly.These days I have pretty much drawn a line with my 6BR to max out at 600 so yeah only a click maybe two difference in the two two BC measuring models.I adjust a lot more than this out in the field given certain conditions. Another thing ,,,,reading my berger reloading book on G1 and G7 there seems to be another factor involved and to be considered,"Form Factors",,,,? I am going to have to read this again(several times maybe) ,,,,,O Link to comment Share on other sites More sharing options...
.300wm Posted February 14, 2015 Report Share Posted February 14, 2015 Just wondering, does anyone here use the Bulletflight M app? If so, is it just a "skinned" version of Applied Ballistics? I only ask as I do believe it is the US militarys app of choice and have been contemplating downloading it Link to comment Share on other sites More sharing options...
gbal Posted February 14, 2015 Report Share Posted February 14, 2015 Mmmmmm close isn,t it,,,,,,,,,,,,Think I will stick with what I,m doing ,,,I can pretty much rely on my ups out to 400 its beyond that where conditions have me puzzled sometimes and only a bit of field testing on the day will tell me whats happening and in only one direction I might add and adjust accordingly.These days I have pretty much drawn a line with my 6BR to max out at 600 so yeah only a click maybe two difference in the two two BC measuring models.I adjust a lot more than this out in the field given certain conditions. Another thing ,,,,reading my berger reloading book on G1 and G7 there seems to be another factor involved and to be considered,"Form Factors",,,,? I am going to have to read this again(several times maybe) ,,,,,O Fair enough. Delving into i7 isn'r for the faint hearted,and can't be done-as i am trying to even say something about it-while you watch the Rugby! This form factor is a measure of the bullet's drag,compared to a standard.It's easy enough to get the drag idea,and to give the basic formula,but most will have to just take this on trust.But you might find Laurie's description/explanation "The difference between G1 and G7' * 4 June 13 (and Lukas_K follow up,with some data-a good place to begin... Now,what's the score .....0-5...hmmm some ways to go then.....no10 has an interesting Form Factor....17st 13 lb...wouldn't want an 18 stone No10, I suppose.....holy schizzle..... gbal Link to comment Share on other sites More sharing options...
Murph Posted February 20, 2015 Report Share Posted February 20, 2015 Thanks for your help so far guys, but where will i find out the G7 figures for a said bullet? Cheers Steve. If you want to find a g7 value put in g1 value x .517. This hold give you the equivalent g7 value. Handy if you can't find out a value for a bullet. Link to comment Share on other sites More sharing options...
Murph Posted February 20, 2015 Report Share Posted February 20, 2015 If you want to find a g7 value put in g1 value x .517. This hold give you the equivalent g7 value. Handy if you can't find out a value for a bullet. Sorry that should be x.512 - my bad. Link to comment Share on other sites More sharing options...
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