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Greenhill Graph (Read 23315 times)

SSShooter Frequent Elocutionist Offline Posts: 2942 Location: Southern NJ Joined: Aug 1^st, 2010	Re: Greenhill Graph Reply #15 - Dec 20^th, 2014 at 2:58pm	Print Post
	Was suggesting that for the mods. Think they are the only ones who have that privilege.

	Glenn - Stevens 044 1/2, Bartlein SS 5R barrel in 22LR
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JDA Participating Member Offline Posts: 37 Joined: Dec 23^rd, 2007	Re: Greenhill Graph Reply #16 - Dec 20^th, 2014 at 4:18pm	Print Post
	I don't know..would this help? (You need to *Login* or *Register* to view media files and links)


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LRF Oldtimer Offline Posts: 706 Location: MN Joined: May 8^th, 2010	Re: Greenhill Graph Reply #17 - Dec 20^th, 2014 at 4:30pm	Print Post
	Here is 25 and 28 caliber (You need to *Login* or *Register* to view media files and links)


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Sendaro Oldtimer Offline When the sight is on SEND IT! Posts: 588 Location: Saratoga Springs NY Joined: Nov 21^st, 2010	Re: Greenhill Graph Reply #18 - Dec 20^th, 2014 at 10:03pm	Print Post
	Thank you for posting the 25 cal. info. Sendaro


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George Babits Frequent Elocutionist Offline Posts: 1144 Joined: Sep 27^th, 2012	Re: Greenhill Graph Reply #19 - Dec 22^nd, 2014 at 9:36am	Print Post
	Thanks for all the work and different charts based on caliber. One question I have is the "bullet length." Is that in inches or calibers? As I recall, the original Greenhill formula used length in calibers, but many later programs use inches. Thanks, George


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LRF Oldtimer Offline Posts: 706 Location: MN Joined: May 8^th, 2010	Re: Greenhill Graph Reply #20 - Dec 22^nd, 2014 at 5:34pm	Print Post
	Inches


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George Babits Frequent Elocutionist Offline Posts: 1144 Joined: Sep 27^th, 2012	Re: Greenhill Graph Reply #21 - Dec 22^nd, 2014 at 5:40pm	Print Post
	Thanks, I thought they were but wanted to be sure. George


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beltfed Frequent Elocutionist Offline Posts: 1821 Location: Central Wi Joined: Dec 20^th, 2007	Re: Greenhill Graph Reply #22 - Dec 23^rd, 2014 at 10:16pm	Print Post
	The basic greenhill formula uses a constant of "150" in the equation. It might be good enough to calculate twist needed for say 200yds or a bit farther. But it will not work for long range. For example, I KNOW that a 1.55" long bullet will NOT be stabile out to more than a few hundred yards from a 16 twist barrel. In fact, we have seen that a 1.37" long lyman snover bullet may do well at 600yds, decently at 800, fair at 900, but will not be stabile at 1k out of a 16 twist barrel. One needs to plug in a constant of "125" or so to do the calculations for getting an idea of twist needed for long range stability at BPCR velocities. beltfed/arnie


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SgtDog0311 Senior Forum Member Offline Posts: 391 Joined: Mar 19^th, 2014	Re: Greenhill Graph Reply #23 - Jan 9^th, 2015 at 12:42pm	Print Post
	Am I wrong in thinking the bullet weight is relative?

	Best Regards, John
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John Boy Ex Member	Re: Greenhill Graph Reply #24 - Jan 9^th, 2015 at 3:45pm	Print Post
	Quote: I would be willing to share the Excel file calculator if someone could tell me how to share on the forum. LRF, if you posted the Excel lines of code in a post, then folks could open their Excel program, copy the code lines and do their calculations. Unfortunately, Excel files re not allowed to be posted (Unless a Moderator adds "xls" file extensions ) to the Attachment provision. Currently only these file extensions are allowed ... Quote: Allowed file types: txt doc docx psd pdf bmp jpe jpg jpeg gif png swf zip rar tar You could also zip the Excel file and then add the zip file as an attachement in your post
	« Last Edit: Jan 9^th, 2015 at 3:51pm by »

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LRF Oldtimer Offline Posts: 706 Location: MN Joined: May 8^th, 2010	Re: Greenhill Graph Reply #25 - Jan 9^th, 2015 at 4:44pm	Print Post
	Beltfed, You wrote: "For example, I KNOW that a 1.55" long bullet will NOT be stabile" What caliber?


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LRF Oldtimer Offline Posts: 706 Location: MN Joined: May 8^th, 2010	Re: Greenhill Graph Reply #26 - Jan 9^th, 2015 at 5:01pm	Print Post
	Beltfed, Guessing that you were talking 40 cal. here are the calculations for a constant of 150 and then 125. Twist BL 40 cal 11 @150 @125 12 1.734 13 1.601 14 1.784 1.486 15 1.665 1.387 16 1.561 1.301 17 1.469 1.224 18 1.387 1.156 19 1.314 20 1.248 21 1.189 22 1.135


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John Boy Ex Member	Re: Greenhill Graph Reply #27 - Jan 9^th, 2015 at 9:40pm	Print Post
	The multiplier 150 for fps slower than 2800 is used for smokeless reloads The multiplier 125 for fps slower than 2800 is used for black powder reload Source: Old Scout, 25 years as a gunsmith and gun crank personified ... now deceased


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bohemianway Oldtimer Offline Posts: 706 Location: Andover, MN Joined: Apr 16^th, 2004	Re: Greenhill Graph Reply #28 - Jan 9^th, 2015 at 10:00pm	Print Post
	Here is a velocity adjusted formula that matches my 32-40 experience ( (You need to *Login* or *Register* to view media files and links)). JPEG is table for 32.


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bohemianway Oldtimer Offline Posts: 706 Location: Andover, MN Joined: Apr 16^th, 2004	Re: Greenhill Graph Reply #29 - Jan 9^th, 2015 at 10:15pm	Print Post
	Attempt at supplying a zip file where you can download. Cross your fingers. If it works I could provide another that plots the graphs.

	(You need to *Login* or *Register* to view media files and links) ( 5 KB \| Downloads )
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