Projectile Lengths - The Firearms Forum

JLA · 08-26-2012, 05:12 PM

Purpose of this thread is for the membership here to use for calculating twist rate requirements without having to go buy a box of whatever bullet just to find out it wont work.

Feel free to measure any bullets you use, handgun and rifle alike and post the measurements here. Make sure you list the bullet diameter along with the length measurement.

Here is a handy link to a twist calculator I use quite often and it will fit in with the use of this thread quite nicely.
http://kwk.us/twist.html

JLA · 08-26-2012, 05:53 PM

Here are the ones I have in stock.

200 LSWC Dardas, .452" dia., .652" length
200 Berrys TCFP, .452" dia., .531" length
185 Hornady XTP, .451" dia., .530" length

240 Hornady XTP, .430" dia., .703" length

125 Hornady XTP, .357" dia., .547" length

125 LRN Dardas, .356" dia., .602" length

100 Berrys HBRN (.380 ACP), .356" dia., .485" length
102 Golden Saber (.380 ACP), .355" dia., .473" length

174 Sierra MatchKing, .311", 1.206"

180 gr Winchester FailSafe, .308" dia., 1.303" length
175 Sierra MatchKing, .308" dia., 1.232" length
168 Hornady Amax, .308" dia., 1.278" length
165 Hornady InterBond, .308" dia., 1.312" length
155 Hornady Amax, .308" dia., 1.214" length
110 Sierra Varminter, .308" dia., .803" length

140 Hornady Amax, .264" dia., 1.380" length

105 Hornady Amax, .243" dia., 1.234" length
85 Sierra GameKing, .243" dia., .938" length

69 Sierra MatchKing, .224" dia., .895" length
62 Barnes TSX BT, .224" dia., .939" length
53 Sierra MatchKing, .224" dia., .700" length

I will make it a point to update as I get new projectiles.

steve4102 · 08-26-2012, 08:19 PM

Question.

Isn't the bearing surface of the bullet what dictates how it relates to twist rate and not total length? Basically from base to Ogive instead of base to tip?

JLA · 08-26-2012, 08:37 PM

Not at all. its the total length of the bullet that makes it require a specific RPM, and Bullet RPM is a fuction of velocity and rifling pitch.

Take the 165 Hdy IB I listed above VS the 180 gr Failsafe also listed above. The failsafe requires 13.2 twist (180 gr bullet measuring 1.303" at 2700 fps, which is .30-06 velocity for that weight) and the IB requires 13.4 twist (165 gr bullet measuring 1.312 at 2800 fps, which is also .30-06 velocity for that weight) and the Failsafe has almost twice the bearing surface because it doesnt have a Boat tail. Now slow them both down in reduced loads to 2500 fps and the FS requires 12.7 and the IB requires 12.7, so internal ballistcally speaking they are equals in thier requirements as far as barrel twist is concerned.

THEGUNDOC · 12-27-2012, 08:08 PM

A SLOWER BULLET OF THE SAME LENGTH NEEDS A HIGHER TWIST RATE.. ?

JLA · 12-27-2012, 08:17 PM

yes, because the velocity multiplied by the rifling pitch is what gives you the required RPM. Its why .300AAC blackout barrels are generally 7 or 8 twist.

68c15 · 02-08-2013, 10:24 PM

150 Hornady spire point .277 1.220

130 Hornady SST .277 1.232 boat tail

85 Sierra Game King HP .243 .950

100 Sierra Game King spitzer .243 1.075

105 Speer round nose .243 .960

68c15 · 02-08-2013, 10:37 PM

how do we determine the specific gravity of said projectile? Sierra's website does not list that data

JLA · 02-09-2013, 05:45 AM

copper clad lead core jacketed bullets are 10.9

slofgre · 04-05-2013, 08:46 PM

Anyone by chance have measurements for 0.223 bullets?

JLA · 04-05-2013, 09:09 PM

Just the ones I have listed above.

slofgre · 04-06-2013, 06:54 PM

Thanks, somehow I glossed right over them

rcairflr · 04-06-2013, 07:43 PM

.223 Rem: (.224 diameter)
50 Vmax/Zmax = .770"
55 Vmax = .811
53 Vmax = .828
52 Sierra MK = .714

6,5mm:
123 Lapua Scenar = 1.302"
120 Amax = 1.205
140 Amax = 1.372

08-26-2012, 05:12 PM	#1
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Projectile Lengths Purpose of this thread is for the membership here to use for calculating twist rate requirements without having to go buy a box of whatever bullet just to find out it wont work. Feel free to measure any bullets you use, handgun and rifle alike and post the measurements here. Make sure you list the bullet diameter along with the length measurement. Here is a handy link to a twist calculator I use quite often and it will fit in with the use of this thread quite nicely. http://kwk.us/twist.html __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF! -->

08-26-2012, 05:53 PM	#2
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Re: Projectile Lengths Here are the ones I have in stock. 200 LSWC Dardas, .452" dia., .652" length 200 Berrys TCFP, .452" dia., .531" length 185 Hornady XTP, .451" dia., .530" length 240 Hornady XTP, .430" dia., .703" length 125 Hornady XTP, .357" dia., .547" length 125 LRN Dardas, .356" dia., .602" length 100 Berrys HBRN (.380 ACP), .356" dia., .485" length 102 Golden Saber (.380 ACP), .355" dia., .473" length 174 Sierra MatchKing, .311", 1.206" 180 gr Winchester FailSafe, .308" dia., 1.303" length 175 Sierra MatchKing, .308" dia., 1.232" length 168 Hornady Amax, .308" dia., 1.278" length 165 Hornady InterBond, .308" dia., 1.312" length 155 Hornady Amax, .308" dia., 1.214" length 110 Sierra Varminter, .308" dia., .803" length 140 Hornady Amax, .264" dia., 1.380" length 105 Hornady Amax, .243" dia., 1.234" length 85 Sierra GameKing, .243" dia., .938" length 69 Sierra MatchKing, .224" dia., .895" length 62 Barnes TSX BT, .224" dia., .939" length 53 Sierra MatchKing, .224" dia., .700" length I will make it a point to update as I get new projectiles. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

08-26-2012, 08:19 PM	#3
steve4102 Former Guest Join Date: Jan 2006 Location: Minnesota Contributor Posts: 2,760	Re: Projectile Lengths Question. Isn't the bearing surface of the bullet what dictates how it relates to twist rate and not total length? Basically from base to Ogive instead of base to tip?

08-26-2012, 08:37 PM	#4
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Re: Projectile Lengths Not at all. its the total length of the bullet that makes it require a specific RPM, and Bullet RPM is a fuction of velocity and rifling pitch. Take the 165 Hdy IB I listed above VS the 180 gr Failsafe also listed above. The failsafe requires 13.2 twist (180 gr bullet measuring 1.303" at 2700 fps, which is .30-06 velocity for that weight) and the IB requires 13.4 twist (165 gr bullet measuring 1.312 at 2800 fps, which is also .30-06 velocity for that weight) and the Failsafe has almost twice the bearing surface because it doesnt have a Boat tail. Now slow them both down in reduced loads to 2500 fps and the FS requires 12.7 and the IB requires 12.7, so internal ballistcally speaking they are equals in thier requirements as far as barrel twist is concerned. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

12-27-2012, 08:08 PM	#5
THEGUNDOC Member Join Date: Dec 2012 Location: KENOSHA, WI. Posts: 8	Re: Projectile Lengths A SLOWER BULLET OF THE SAME LENGTH NEEDS A HIGHER TWIST RATE.. ?

12-27-2012, 08:17 PM	#6
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Re: Projectile Lengths yes, because the velocity multiplied by the rifling pitch is what gives you the required RPM. Its why .300AAC blackout barrels are generally 7 or 8 twist. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

02-08-2013, 10:24 PM	#7
68c15 Advanced Senior Member Join Date: Nov 2011 Posts: 2,061	Re: Projectile Lengths 150 Hornady spire point .277 1.220 130 Hornady SST .277 1.232 boat tail 85 Sierra Game King HP .243 .950 100 Sierra Game King spitzer .243 1.075 105 Speer round nose .243 .960 __________________ I'll go defenseless when our leaders do the same

02-08-2013, 10:37 PM	#8
68c15 Advanced Senior Member Join Date: Nov 2011 Posts: 2,061	Re: Projectile Lengths how do we determine the specific gravity of said projectile? Sierra's website does not list that data __________________ I'll go defenseless when our leaders do the same

02-09-2013, 05:45 AM	#9
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Re: Projectile Lengths copper clad lead core jacketed bullets are 10.9 __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

04-05-2013, 08:46 PM	#10
slofgre Member Join Date: Aug 2012 Posts: 6	Re: Projectile Lengths Anyone by chance have measurements for 0.223 bullets?

04-05-2013, 09:09 PM	#11
JLA TFF Moderator/Host Join Date: Feb 2007 Location: Heart Of Texas Contributor Posts: 17,317	Re: Projectile Lengths Just the ones I have listed above. __________________ It takes 43 muscles to frown, 17 to smile, and 3 for proper trigger squeeze. The latest caliber or gear is no substitute for experience and skill. Rifles and cartridges don't make hits -- shooters do. Fact of life: After Monday and Tuesday, even the calendar says WTF!

04-06-2013, 06:54 PM	#12
slofgre Member Join Date: Aug 2012 Posts: 6	Re: Projectile Lengths Thanks, somehow I glossed right over them

04-06-2013, 07:43 PM	#13
rcairflr Advanced Senior Member Join Date: Jul 2011 Location: Wichita, Ks Posts: 1,318	Re: Projectile Lengths .223 Rem: (.224 diameter) 50 Vmax/Zmax = .770" 55 Vmax = .811 53 Vmax = .828 52 Sierra MK = .714 6,5mm: 123 Lapua Scenar = 1.302" 120 Amax = 1.205 140 Amax = 1.372 Last edited by rcairflr; 04-06-2013 at 07:46 PM..