Range Report What is the G5 BC for the Sierra 175 SMK (.308)?
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Re: What is the G5 BC for the Sierra 175 SMK (.308)?
G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.
G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.</div></div>
The G1 is for flat based bullets. G7 is better for the 175 SMK but is mostly for the VLD's. G5 is more appropriate for boattails.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.</div></div>
The G1 is for flat based bullets. G7 is better for the 175 SMK but is mostly for the VLD's. G5 is more appropriate for boattails.
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Leaddog</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.</div></div>
The G1 is for flat based bullets. G7 is better for the 175 SMK but is mostly for the VLD's. G5 is more appropriate for boattails. </div></div>
OK, my memory is fubar.
G7 is for long boat tail bullets with long ogive
G5 is for short boat tail bullets with short ogive
G7 is more appropriate for low drag and very low drag bullets.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Leaddog</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">G5 is for flat base bullets, the 175 SMK has a definate boat tail and thus, G5 is not an appropriate drag model.
Drag models are matched to the shape of the bullet, and different shapes want you to use different drag models.</div></div>
The G1 is for flat based bullets. G7 is better for the 175 SMK but is mostly for the VLD's. G5 is more appropriate for boattails. </div></div>
OK, my memory is fubar.
G7 is for long boat tail bullets with long ogive
G5 is for short boat tail bullets with short ogive
G7 is more appropriate for low drag and very low drag bullets.
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
I think I recall Brian Litz saying in another thread that G5 was most appropriate for SMKs. But I also have yet to find the actual G5 number for them.
I think I recall Brian Litz saying in another thread that G5 was most appropriate for SMKs. But I also have yet to find the actual G5 number for them.
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
The G5 BC for the Sierra .308 175 gr MK BTHP is .319. I ran the calculations twice to confirm. The G5 coefficient drag model was developed for boat tail bullets. The G6 coefficient drag model was developed for flat based bullets.
The G7 BC for the Sierra .308 175 gr MK BTHP is .253. You really won’t go wrong using the G7 coefficient drag model calculations. Actually you’ll be splitting hairs between the results of the G5 or G7, but using the G1 BC IMHO is a total waist of time.
Hope it helps.
The G5 BC for the Sierra .308 175 gr MK BTHP is .319. I ran the calculations twice to confirm. The G5 coefficient drag model was developed for boat tail bullets. The G6 coefficient drag model was developed for flat based bullets.
The G7 BC for the Sierra .308 175 gr MK BTHP is .253. You really won’t go wrong using the G7 coefficient drag model calculations. Actually you’ll be splitting hairs between the results of the G5 or G7, but using the G1 BC IMHO is a total waist of time.
Hope it helps.
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeff in TX</div><div class="ubbcode-body">The G5 BC for the Sierra .308 175 gr MK BTHP is .319. I ran the calculations twice to confirm. The G5 coefficient drag model was developed for boat tail bullets. The G6 coefficient drag model was developed for flat based bullets.
The G7 BC for the Sierra .308 175 gr MK BTHP is .253. You really won’t go wrong using the G7 coefficient drag model calculations. Actually you’ll be splitting hairs between the results of the G5 or G7, but using the G1 BC IMHO is a total waist of time.
Hope it helps.
</div></div>
Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeff in TX</div><div class="ubbcode-body">The G5 BC for the Sierra .308 175 gr MK BTHP is .319. I ran the calculations twice to confirm. The G5 coefficient drag model was developed for boat tail bullets. The G6 coefficient drag model was developed for flat based bullets.
The G7 BC for the Sierra .308 175 gr MK BTHP is .253. You really won’t go wrong using the G7 coefficient drag model calculations. Actually you’ll be splitting hairs between the results of the G5 or G7, but using the G1 BC IMHO is a total waist of time.
Hope it helps.
</div></div>
Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different?
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
[/quote] Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different? [/quote]
Nope and good catch. Bryan's BC's are actual measured G7 BC's. I didn't have that info available so I had to convert the published G1 to G5 & G7.
Using Bryan's G7 BC .243 your new G5 BC would convert to .306
Hope it helps,
[/quote] Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different? [/quote]
Nope and good catch. Bryan's BC's are actual measured G7 BC's. I didn't have that info available so I had to convert the published G1 to G5 & G7.
Using Bryan's G7 BC .243 your new G5 BC would convert to .306
Hope it helps,
Re: What is the G5 BC for the Sierra 175 SMK (.308)?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeff in TX</div><div class="ubbcode-body">[/quote] Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different? </div></div>
Nope and good catch. Bryan's BC's are actual measured G7 BC's. I didn't have that info available so I had to convert the published G1 to G5 & G7.
Using Bryan's G7 BC .243 your new G5 BC would convert to .306
Hope it helps, [/quote]
Thanks! I may run some numbers tonight using that G5 and see how it matches my actual dope. I've been curious to try the G5 #s, so that might be interesting.....
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeff in TX</div><div class="ubbcode-body">[/quote] Jeff, Thanks for the G5 number. But I thought Mr Litz posted the G7 BC for the 175SMK at .243. Is your .<span style="font-weight: bold"><span style="font-style: italic">253 </span></span>a typo or something different? </div></div>
Nope and good catch. Bryan's BC's are actual measured G7 BC's. I didn't have that info available so I had to convert the published G1 to G5 & G7.
Using Bryan's G7 BC .243 your new G5 BC would convert to .306
Hope it helps, [/quote]
Thanks! I may run some numbers tonight using that G5 and see how it matches my actual dope. I've been curious to try the G5 #s, so that might be interesting.....
