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9.3x62mm |
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300S&W
Optics God Joined: January/27/2008 Location: Burlington,WV Status: Offline Points: 10592 |
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Posted: March/22/2008 at 05:43 |
Getting ready to have my .25-06 Mauser rebored to 9.3x62. Barrel is now at 26" and will end up at 19"-21". Need to know a proper rate of twist. 8shots,beings your in Africa hopefully this will be right up your alley. Anyones info is APPRECIATED!
til later
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Tip69
Optics Master Extraordinaire Tip Stick Joined: September/27/2005 Location: Nebraska Status: Offline Points: 4155 |
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why so short?
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take em!
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lucytuma
Optics Jedi Knight Joined: November/25/2007 Location: Wisconsin Status: Offline Points: 5389 |
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Great round, 35 whelen on steroids, light kicking, enjoy!
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"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." - Thomas Jefferson
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Tip69
Optics Master Extraordinaire Tip Stick Joined: September/27/2005 Location: Nebraska Status: Offline Points: 4155 |
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Shooting Times's Layne Simpson did a nice article for the March issue on this cartridge. He didn't mention twist rate, but his barrel was 23". I sent him an email, but not sure he'll respond.
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take em!
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300S&W
Optics God Joined: January/27/2008 Location: Burlington,WV Status: Offline Points: 10592 |
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Already have a .25-06 and a .300 with 24" barrels plus a .243 with a 18.5" barrel. The 9.3 from what I've found out is a cartridge that doesn't lose much velocity in a short bbl. One example shows a loss of only 60 to 70 fps when going from a 23.6"bbl down to 20". Plus this isn't a high velocity round anyway. I bought this rifle in the late 80s for just such a project. This bbl is a semi-varmint weight bbl so I figure by shortening it to somewhere around 19"-21" and with the amount of metal taken out by the larger bore it will make this rifle handy in the thick woods,brush,and rhododendron thickets we hunt deer and bear in. But I'm still not sure about twist rate although it seems anywhere from 1-10 to 1-14 is being used with good results. Any new info/suggestions are still APPRECIATED! That's why I'm here!
til later
THANKS Tip69,I'll have to beat feet to the store and look for that mag! Edited by 300S&W - March/22/2008 at 16:08 |
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300S&W
Optics God Joined: January/27/2008 Location: Burlington,WV Status: Offline Points: 10592 |
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Anyone needing to know,it seems that 1-14 twist rate is the norm for most factory rifles(LIKE THERE'S THAT MANY!)and for ALOT of custom rifles.
til later
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8shots
Optics Jedi Knight Lord Of The Flies Joined: March/14/2007 Location: South Africa Status: Offline Points: 6253 |
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The 9,3x62 is a great African cartridge! It is mostly used on bigger game.
300S&W, it seems like a 1;14 or 1;16 is the correct rate for your caliber. When in doubt, go for the tighter twist. So 1;14. Barrel lenth will not effect your spin rate, but velocity will.
If you are mathematically inclined, try this:
You can use the Greenhill Formula to determine optimum twist rate for any bullet and caliber you shoot. Mind you, this is a generic formula, subject to change slightly with velocity, but I've found it to be a good rule of thumb when trying new bullets & loads. You'll need the length of the bullet to start with. Divide the length of the bullet by the caliber. Divide this number into 150. Now, multiply this new number by the caliber again. Example: Hornady #2250 HPBT, 52 grains, .224 caliber, length 0.703": 0.703 divided by .224 = 3.1383 150 divided by 3.1383 = 47.7965 47.7965 multiplied by .224 = 10.706 So, according to the Greenhill formula, the optimum twist rate to stabilize this bullet should be 1 in 10.7 inches Edited by 8shots - March/26/2008 at 10:45 |
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Dogger
Optics Jedi Master Joined: January/02/2007 Location: Ontario, Canada Status: Offline Points: 8903 |
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8shots is right on. I use a factor of 150 up to 1800 fps velocity and 180 if velocity is greater than 1800. Simplified formula is then: 150xDsquared/L or 180xDsquared/L 1 in 10.7 if 1800 or less
1 in 12.8 if greater than 1800
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God save the Empire!
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Big Squeeze
Optics Master Extraordinaire GOOGLE NINJA Joined: August/30/2007 Location: Anaheim, Calif. Status: Offline Points: 3143 |
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300S&W
Optics God Joined: January/27/2008 Location: Burlington,WV Status: Offline Points: 10592 |
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REALLY APPRECIATE ALL the advice and info!! I'm familiar with the formula which works out to a twist of 16.8" but also wanted some hands on experiences,so I'm going with 1-14 unless whoever does the work has an opinion. I actually found twists from 1-10 to 1-16! 1-14 falls one position short of being half way in the list of bullet OALs and twists for the 9.3(.366)cal at velocities under 2800fps.
As far as barrel length goes,I'm comparing handling to my daughters 18.5"bbl Ruger. This med-hvy bbl after being cut and rebored is going to lose ALOT of weight and I think any length from 18.5" to 21" will work. Might just split the difference!
Again THANKS for the help!!
til later
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