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question about bullet length to twist ratio (Read 36662 times)

oughtsix Global Moderator ASSRA Board Member Offline Posts: 1361 Location: Columbus Joined: May 31^st, 2009	question about bullet length to twist ratio Dec 1^st, 2011 at 4:35pm	Print Post
	If I were to order a bullet mould for a 32-30 Rem, is there a ratio for bullet length to barrel twist rate that is optimum? I have a .314 diameter barrel with a 1:24 twist. I have hunted the vastness of the 'net and can't find a production mould out there. (I have a loaner in the works) I will breech seat most of the time, but occasionally load up a few for plinking. Any help is appreciated. oughtsix

	Life Member ASSRA, OGCA & TSGC I'm all in favor of keeping dangerous weapons out the hands of fools. Let's start with typewriters........ Frank Lloyd Wright
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JLouis Frequent Elocutionist Offline Posts: 10625 Joined: Apr 8^th, 2009	Re: question about bullet length to twist ratio Reply #1 - Dec 1^st, 2011 at 4:45pm	Print Post
	Oughtsix send me a PM with your e-mail address and I will send you a copy of Don Millers Twist Rate Rule. It is the most accurate means I have found for cast bullets and I have had great success with its use. J.Louis

	" It Is Better To Now Have Been A Has Been Than A Never Was Or A Wanna Be "
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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 12324 Location: Why, out West of course Joined: May 29^th, 2006	Re: question about bullet length to twist ratio Reply #2 - Dec 1^st, 2011 at 5:18pm	Print Post
	Heres the one I use. (You need to *Login* or *Register* to view media files and links) It'll get you in the ballpark. Fun to play with if nothing else. Joe.

	A blind squirrel runs into a tree every once in a while.
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frnkeore Frequent Elocutionist Offline Posts: 7641 Location: Central Point, OR 97502 Joined: Jun 16^th, 2010	Re: question about bullet length to twist ratio Reply #3 - Dec 1^st, 2011 at 5:52pm	Print Post
	As a direct answer to your question........... I would get a 3118 mold and have the base band opened to .317, it will cast right at .3155 and should shoot as well as anything in your 24 twist, BSed. For loading data, I would add 1.0 gr to 32/20 starting loads. Frank

	ASSRA Member #696, ISSA Member #339
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JLouis Frequent Elocutionist Offline Posts: 10625 Joined: Apr 8^th, 2009	Re: question about bullet length to twist ratio Reply #4 - Dec 1^st, 2011 at 6:34pm	Print Post
	Oughtsix run as fast as you can away from Westerner's program! I entered the data for the Hoch .322-205 @ 1.070 in length and it came up with a 12.8 twist. If that is close I'll be walking over to a friend's house in Pa. tonight and I live in Ca. J.Louis

	" It Is Better To Now Have Been A Has Been Than A Never Was Or A Wanna Be "
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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 12324 Location: Why, out West of course Joined: May 29^th, 2006	Re: question about bullet length to twist ratio Reply #5 - Dec 1^st, 2011 at 9:45pm	Print Post
	JLouis wrote on Dec 1^st, 2011 at 6:34pm: Oughtsix run as fast as you can away from Westerner's program! I entered the data for the Hoch .322-205 @ 1.070 in length and it came up with a 12.8 twist. If that is close I'll be walking over to a friend's house in Pa. tonight and I live in Ca. J.Louis I came up with 12.9 Whats wrong with it John? Why will you be walking from CA to PA? I dont understand? Joe

	A blind squirrel runs into a tree every once in a while.
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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 12324 Location: Why, out West of course Joined: May 29^th, 2006	Re: question about bullet length to twist ratio Reply #6 - Dec 1^st, 2011 at 11:10pm	Print Post
	oughtsix wrote on Dec 1^st, 2011 at 4:35pm: If I were to order a bullet mould for a 32-30 Rem, is there a ratio for bullet length to barrel twist rate that is optimum? I have a .314 diameter barrel with a 1:24 twist. I have hunted the vastness of the 'net and can't find a production mould out there. (I have a loaner in the works) I will breech seat most of the time, but occasionally load up a few for plinking. Any help is appreciated. oughtsix Using the calculator from the link I provided, I got a length of .559 for a .314 bullet at 1400 FPS. I think is in line with Frnkeore's post. Joe.

	A blind squirrel runs into a tree every once in a while.
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John Boy Ex Member	Re: question about bullet length to twist ratio Reply #7 - Dec 1^st, 2011 at 11:57pm	Print Post
	Powley Bullet Stability Calculator ... Oughtsix, if you want the calculator, send me a PM with your email address and I'll send the Excel program

	(You need to *Login* or *Register* to view media files and links) ( 15 KB \| Downloads )
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: question about bullet length to twist ratio Reply #8 - Dec 2^nd, 2011 at 3:16am	Print Post
	The Greenhill formula gives a maximum bullet length for a .314" barrel and 24" twist of .616". My estimator says that that bullet would weigh ~ 112 grains. joe b.


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Fred Boulton Oldtimer Offline Posts: 801 Joined: Jan 6^th, 2007	Re: question about bullet length to twist ratio Reply #9 - Dec 2^nd, 2011 at 6:13am	Print Post
	All these formulae are approximate. The twist stablises the bullet through gyroscopic forces resisting the aerodynamic effects which impart lift to the nose and try to tip the bullet over backwards: a complex way of saying that the nose shape and position of centre of gravity are important. Non of the formulae give a stable result for a muzzle loading Enfield with its 78" twist, but the hollow base is another shape factor. Fred


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screwloosetc Ex Member	Re: question about bullet length to twist ratio Reply #10 - Dec 2^nd, 2011 at 10:52am	Print Post
	oughtsix as a sugestion for a source of bullet weight and design you mught want to consider paper patching 30cal up to the 314 bore. There are a ton of light weight 30 cal. molds out there in various designs. The lube grooves in the bullets don't affect the patch as you would suspect. you can also run the higher velocities the slow twist and light bullets require. Tom


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38_Cal Frequent Elocutionist Offline Posts: 2255 Location: Montezuma, Iowa Joined: Apr 27^th, 2005	Re: question about bullet length to twist ratio Reply #11 - Dec 2^nd, 2011 at 1:26pm	Print Post
	Something like the Lyman 3118 (311008) at a nominal 115 gr. might just cast the right diameter for this barrel...if not, it's not a big deal to open up the base band by .003" or so. David

	David Kaiser Montezuma, IA
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John Boy Ex Member	Re: question about bullet length to twist ratio Reply #12 - Dec 2^nd, 2011 at 2:02pm	Print Post
	Quote: I have hunted the vastness of the 'net and can't find a production mould out there. (You need to *Login* or *Register* to view media files and links) oughtsix - take your pick. For the 311 molds, you can 'beagle' it and use 7 parts pure lead and 3 parts Lyman #2 to make it work with your groove of 314 and also gain the extra weight. The 7:3 alloy shoots well with both black powder and smokeless reloads. My choice would be the 311-100-2R. Though this is a round nose, Cartridges of the World has the Lyman 311316, now obsolete, FN bullet listed @ 111gr Lyman 311316 - 112g (GC) (You need to *Login* or *Register* to view media files and links)
	« Last Edit: Dec 2^nd, 2011 at 2:08pm by »

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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 12324 Location: Why, out West of course Joined: May 29^th, 2006	Re: question about bullet length to twist ratio Reply #13 - Dec 2^nd, 2011 at 11:14pm	Print Post
	westerner wrote on Dec 1^st, 2011 at 9:45pm: JLouis wrote on Dec 1^st, 2011 at 6:34pm: Oughtsix run as fast as you can away from Westerner's program! I entered the data for the Hoch .322-205 @ 1.070 in length and it came up with a 12.8 twist. If that is close I'll be walking over to a friend's house in Pa. tonight and I live in Ca. J.Louis I came up with 12.9 Whats wrong with it John? Why will you be walking from CA to PA? I dont understand? Joe

	A blind squirrel runs into a tree every once in a while.
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: question about bullet length to twist ratio Reply #14 - Dec 3^rd, 2011 at 4:21am	Print Post
	I've never found a case where Greenhill fails. Please tell us the caliber and bullet length and description in the 78" twist Enfield. Thanks; joe b. Fred Boulton wrote on Dec 2^nd, 2011 at 6:13am: All these formulae are approximate. The twist stablises the bullet through gyroscopic forces resisting the aerodynamic effects which impart lift to the nose and try to tip the bullet over backwards: a complex way of saying that the nose shape and position of centre of gravity are important. Non of the formulae give a stable result for a muzzle loading Enfield with its 78" twist, but the hollow base is another shape factor. Fred


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