R.G
Can you perhaps list me your bullets for the .30BR as well as what their lengths are?
I also have a 1:16 twist barrel coming my way and would like to order bullets from you.
I don't seem to find the lengths on your web page.
Thanks
Frans
Frans, sorry for the tardy reply. The BIB thirty caliber bullets and the respective length/weight options,all lengths are J4 raw jacket length actual bullet length may be different): .925" = 112 Gr.,7 ogive only); 1.00" = 118;125 Gr.,either 7 or, 10 ogive); 1.080" = 127;134 Gr.,either 7 or, 10 ogive); 1.150" = 136Gr.;155.5 Gr.,TEN ogive only); 1.300" = 187 Gr.,Ten ogive only). All BIB bullets are custom [hand] made-to-order.
Ogre6br
Charter Member
Registered: 2/19/05
Posts: 167 Yesterday
R.G.
Et all
Would a 1:10 twist cause to much jacket stress on the match bullets at 3000 fps or higher??
I have a spare 1:10 twist barrel that I'm thinking of getting made into a 30 BR.
Thanks
alter
P
__________________
Doze a greenie.
This is a very good question. Empirical evidence suggests that the centrifugal forces imparted by faster twist barrels and high,er) velocities may "cause" bullet failure. I could relate a good many instances of this, but will keep it short, offering only one model as an example: People using the BIB thirty caliber 187 Gr. FB, combined with twist rates of 1:11" or SLOWER, have never reported a bullet failure - at any pressure/velocity! Conversely, as soon as someone runs the 187s through a 1:10" or faster twist, at MVs in excess of 3100 FPS, it's kiss 'em good bye - at about a 30% failure rate.
,Note: For the BIB 187, at sea level & STD. conditions, 1:12.5" is "ideal", providing Sg of 1.5. People using the 12" & slower twist rates have reported MVs of up to 3400 FPS AND excellent results.)
Henry Childs informs me that with regard to the centrifugal force issue, I am "burying my head in the sand",my wording - Henry is much kinder than THAT!), that this force is relatively small and can be dismissed as a cause of bullet failure. . . but certainly, it contributes to failures. My best guess is that, with many,most?) models, we are skating so close to the edge that the centrifugal force is very likely the proverbial final straw on the camels back! I will confess to having a very difficult time ignoring repeatable empirical evidence which supports this notion; we're seeing the same thing with the new 6mms.
But back to YOUR specific example - I doubt if you can hurt good BR quality bullets using a 1:10" twist barrel and a BR capacity chambering. Via such a fast twist, I would expect BR quality bullets to outperform the mass produced variety to a more readily observable degree than would be noticeable via, say, a 1:17 or 1:18" twist - this is because of the relative jacket[wall] run-out; the BR quality jackets will make for a smaller center-of-gravity offset, thus less radial dispersion. R.G.