30 cal/10 twist...shortest bullet ??

M

mike in co

Guest
this is an odd question, but i shoot in an odd match.

in a 10 twist 30 cal bbl, what is the shortest bullet that will work (stabilize) for 100 yds ?? est velocity around 3000-3300 fps

not a true benchrest nor a 600/1000 yd question, but it is club level hunter benchrest.

thanks
mike in co
 
1.707", Roughly

Bullet Length = (180x.308x.308) / T

constant of 180 for 2,800fps or faster.
constant of 150 for 1,500 to 2,800fps.

Personally, I think 150 grain+ bullets will work in a 10 twist. The above is just a portion of the Greenhill Formula.


T = Twist Rate Required
D = Bullet Diameter
R = Bullet Length / Diameter
L = Bullet Length

Use the Constant of 150 for velocities between 1500 to 2800 fps
Use the Constant of 180 for velocities of 2800 fps and faster

T = (150 x D) / R
L = (150 x D x D) / T
 
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isnt greenhill based on soft lead bullets ??

i know they shoot 155s in 13/14/15 twist

thanks
help...
mike

ps the berger 210 vld is only 1.47"
 
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mike in co said:
isnt greenhill based on soft lead bullets ??

i know they shoot 155s in 13/14/15 twist

thanks
help...
mike

ps the berger 210 vld is only 1.47"
Click to expand...
I'm not sure if it's based on Lead Tip's or not. I know it doesn’t make since that it would take a 1.7" projectile. I still believe 150's plus will shoot in a 1-10. What are they, .8" to 1.0" or so long?

I know there's no mathematical formula to tell you what your barrel will like/dislike. For 100 yard club BR with a 1-10, I'd be looking at a flat base 150 grain. That’s JMHO, YMMV.
 
sticking with known 30 cal and std twists f being greenhills factor

factor on a 10 t sie 150 mk ,f is 117
with a 12 t 140
with a 168 in a 12 twist f is 160

155 palma in a 14 t,f is 167

a 175 with a 10 t , f is 134

yes this is backwards math....but nothing is near 180.

how fast are you guys shooting 118/112 30 cal in 18/17 twist and how long are they ?
 
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I think ya's all are missing the point......ANYTHING under about 210gr will fer shure stabilize in a 10" twist. It's LONGER bullets which lose stability and try to tip over.

Any bullet shorter than one you've already used will work. YES 180's, YES 155's and YES 110gr, 112gr, 118gr stuff. The only thing that you'll find to be marginal is 240's........

al
 
oft dis'd member...
thanks i knew how to go to the top of weight/length...but was unsure of going short....
just a brain phart
thanks

mike in co
 
1:10 in a 308

Tim North at Broughton told me John Widden was shooting a 1:10 in his Palma gun. He won the National Long Range Chamionship and is on the US Palma Team. You figure.....
Rustystud
 
Not about stability, but ....

Mike,
The shortest 30 bullet I've ever shot was the Speer "plinker" 100 gr bullet in a 1903A3 with 2 groove barrel. With reduced loads the plinker bullet shot with normal accuracy, so they were certainly stablized by the 1/10 twist.

However, with max loads, they would come apart in the air. Over a plowed corn field, you could see the fragments hitting all over the place, a few yards in front of the muzzle! At 2500 fps they were OK, but >3000 fps they never made it to the target.

Regards, Ron
 
Mike,

300 WM 10 twist, I load, carry and hunt small game and varmints with the Speer 110g spire point. Very accurate in my rifle, even with long jump to lands. I load it to 1800-2000 fps for slow loads, and 3600 fps for faster, flatter loads. I usually always carry the slow and fast 110s with me in the field. These loads are a joy to shoot.

longshooter
 
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