ASSRA Forum - diameter/weight/length formula?

ASSRA Forum › General › Reloading the Single Shot Rifle › diameter/weight/length formula?

(Moderator Group: Moderator)

‹ Previous Topic | Next Topic ›

Page Index Toggle

Pages: [1] 2

Hot Topic (More than 10 Replies)

diameter/weight/length formula? (Read 6671 times)

broken_arrow Full Member Offline Posts: 202 Location: Lancaster County Joined: Aug 12^th, 2008	diameter/weight/length formula? Dec 18^th, 2013 at 10:52am	Print Post
	Hi all, Does anyone know of a mathematical formula for the following theoretical situation.... Can you determine the length of an unknown lead bullet if you have the diameter and the weight of said bullet? Thanks, Dave

	ASSRA #10186 (10-25-2021) Every Mighty Oak Was Once A Little Nut That Held Its Ground
	IP Logged

gunlaker Frequent Elocutionist Online Posts: 2271 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: diameter/weight/length formula? Reply #1 - Dec 18^th, 2013 at 11:16am	Print Post
	It'll depend a lot on the nose profile of the bullet. Chris.


	IP Logged

Chickenthief Junior Member Offline Posts: 81 Location: Here Joined: Aug 5^th, 2013	Re: diameter/weight/length formula? Reply #2 - Dec 18^th, 2013 at 11:30am	Print Post
	WAG is the best without a lot more info! Number and size of GG's Nose shape and length Then youre pretty much there. But then again alloy is an issue. Lead = 11,34gram/cc~2843,2grain/cui Antimony = 6,7gram/cc~1680grain/cui Tin = 7,3gram/cc~1830grain/cui For a true wadcutter you can come pretty close: Weight gives you volume Diameter gives you area of a slice of bullet And that leads you to length Volume = radius x radius x PI x length Length = volume /(radius squared x 3.1415) For lead: example 148grain .357" caliber Volume = 148/2843,2 = 0.052 cui Length = 0.052/(0.1875 squared x 3.1415) = 0.052/0.1 = 0.52inch


	IP Logged

frnkeore Frequent Elocutionist Offline Posts: 7268 Location: Central Point, OR 97502 Joined: Jun 16^th, 2010	Re: diameter/weight/length formula? Reply #3 - Dec 18^th, 2013 at 1:35pm	Print Post
	This is a good example of the difference between two bullets of almost the same length. If the 320366 was cast of linotype and the PJ cast of 30/1, there would be even more difference in weight.

	ASSRA Member #696, ISSA Member #339
	YIM AIM IP Logged

joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: diameter/weight/length formula? Reply #4 - Dec 18^th, 2013 at 3:39pm	Print Post
	Yes. GREENHILL FORMULA WORKBOOK.xls" will estimate bullet length from weight and caliber. PM me your email address and I'll send it. broken_arrow wrote on Dec 18^th, 2013 at 10:52am: Hi all, Does anyone know of a mathematical formula for the following theoretical situation.... Can you determine the length of an unknown lead bullet if you have the diameter and the weight of said bullet? Thanks, Dave


	IP Logged

Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3877 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: diameter/weight/length formula? Reply #5 - Dec 18^th, 2013 at 4:31pm	Print Post
	For just an estimate, probably not a bad idea. Greenhill's formula was for a given bullet shape that likely would be right-much heavier than other bullets - due to nose shape and grooves - but that's a great place to start.

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
	WWW IP Logged

SSShooter Frequent Elocutionist Offline Posts: 2917 Location: Southern NJ Joined: Aug 1^st, 2010	Re: diameter/weight/length formula? Reply #6 - Dec 18^th, 2013 at 9:51pm	Print Post
	gunlaker wrote on Dec 18^th, 2013 at 11:16am: It'll depend a lot on the nose profile of the bullet. Chris. Indeed. My 38cal Brooks mould casts a 340gr 'Money' bullet and the PJ mould casts a 368gr bullet. Both are 1.423" in length.

	Glenn - 2x CPA 44 1/2 w/22LR (Shilen ratchet-rifled & Bartlein 5R rifled), 38-40RH & 38-55WCF (Bartlein 5R rifled) & 40-65WCF (GrnMtn 'X') barrels
	GTalk IP Logged

joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: diameter/weight/length formula? Reply #7 - Dec 19^th, 2013 at 1:30am	Print Post
	Or, the same without Excel: Bullet length ~ bullet weight/Factor Bullet weight ~ bullet length * Factor DIAMETER FACTOR 0.257 122 0.286 151 0.308 175 0.323 192 0.357 235 0.375 259 0.410 310 0.429 339 0.457 385 The precise relationship depends on bullet shape, number and volume of grease grooves and alloy composition. Close-to-exact relationships can be found using other, more involved arithmetic that is seldom worth the effort..


	IP Logged

joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: diameter/weight/length formula? Reply #8 - Dec 19^th, 2013 at 8:16am	Print Post
	I doubt both weights-both look too low, and the difference doesn't seem correct. Does anyone have similar bullets to check weight? frnkeore wrote on Dec 18^th, 2013 at 1:35pm: This is a good example of the difference between two bullets of almost the same length. If the 320366 was cast of linotype and the PJ cast of 30/1, there would be even more difference in weight.


	IP Logged

broken_arrow Full Member Offline Posts: 202 Location: Lancaster County Joined: Aug 12^th, 2008	Re: diameter/weight/length formula? Reply #9 - Dec 19^th, 2013 at 8:53am	Print Post
	Thanks guys, Your responses have me a lot closer than my WAG were getting me. And the simple formula that Joe posted will get me close enough for starters. Thanks again, Dave

	ASSRA #10186 (10-25-2021) Every Mighty Oak Was Once A Little Nut That Held Its Ground
	IP Logged

frnkeore Frequent Elocutionist Offline Posts: 7268 Location: Central Point, OR 97502 Joined: Jun 16^th, 2010	Re: diameter/weight/length formula? Reply #10 - Dec 19^th, 2013 at 1:02pm	Print Post
	joeb33050 wrote on Dec 19^th, 2013 at 8:16am: I doubt both weights-both look too low, and the difference doesn't seem correct. Does anyone have similar bullets to check weight? frnkeore wrote on Dec 18^th, 2013 at 1:35pm: This is a good example of the difference between two bullets of almost the same length. If the 320366 was cast of linotype and the PJ cast of 30/1, there would be even more difference in weight. Joe, I also own the bullet molds and the bullets. Frank

	ASSRA Member #696, ISSA Member #339
	YIM AIM IP Logged

joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: diameter/weight/length formula? Reply #11 - Dec 19^th, 2013 at 2:26pm	Print Post
	frnkeore wrote on Dec 19^th, 2013 at 1:02pm: joeb33050 wrote on Dec 19^th, 2013 at 8:16am: I doubt both weights-both look too low, and the difference doesn't seem correct. Does anyone have similar bullets to check weight? frnkeore wrote on Dec 18^th, 2013 at 1:35pm: This is a good example of the difference between two bullets of almost the same length. If the 320366 was cast of linotype and the PJ cast of 30/1, there would be even more difference in weight. Joe, I also own the bullet molds and the bullets. Frank Frank; Would you tell us about sample weights of the two bullets?


	IP Logged

gunlaker Frequent Elocutionist Online Posts: 2271 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: diameter/weight/length formula? Reply #12 - Dec 19^th, 2013 at 7:03pm	Print Post
	I haven't looked at how those factors were generated, but obviously with a reference bullet of. Particular shape. The "money" bullets are a relatively slender tangential ogive with a small hemispherical tip. I imagine that they'll always come out a bit longer than the formula predicts. But that's ok, it's still likely useful. The only way to get a really accurate answer is to calculate the volume by integration. For reference, I just weighed a Buffalo Arms 324gr "money bullet" in 20:1 alloy. It is 1.322" long and the formula predicts 1.251". Still probably good enough for whatever you want it for Chris.


	IP Logged

Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3877 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: diameter/weight/length formula? Reply #13 - Dec 19^th, 2013 at 7:15pm	Print Post
	gunlaker wrote on Dec 19^th, 2013 at 7:03pm: I haven't looked at how those factors were generated, but obviously with a reference bullet of. Particular shape. The "money" bullets are a relatively slender tangential ogive with a small hemispherical tip. I imagine that they'll always come out a bit longer than the formula predicts. But that's ok, it's still likely useful. For reference, I just weighed a Buffalo Arms 324gr "money bullet" in 20:1 alloy. It is 1.322" long and the formula predicts 1.251". Still The only way to get a really accurate answer is to calculate the volume by integration. probably good enough for whatever you want it for Chris. Just a few keystrokes when drawn in 3d cad!

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
	WWW IP Logged

gunlaker Frequent Elocutionist Online Posts: 2271 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: diameter/weight/length formula? Reply #14 - Dec 19^th, 2013 at 7:57pm	Print Post
	Cat_Whisperer wrote on Dec 19^th, 2013 at 7:15pm: Just a few keystrokes when drawn in 3d cad! Indeed!


	IP Logged

Page Index Toggle

Pages: [1] 2

‹ Previous Topic | Next Topic ›

« Board Index ‹ Board Top

Top

ASSRA Forum » Powered by YaBB 2.6.12!
YaBB Forum Software © 2000-2024. All Rights Reserved.

Valid XHTML

Valid CSS

Powered by Perl

Source Forge

Page completed in 0.7888 seconds.