I'm pondering a new rifle in 22 Creedmoor...
I want to use 75 gr - 80 gr bullets.
What twist do I need 1-7" or 1-8" ?
What feebore do I want on the reamer?
All help and info appreciated!
Bob
I run a 7.5" Bartlein on my 22 Creed. Works well with Berger 80.5 and 85.5 bullets. A lot of guys like the 88 ELD but it doesn't appear to be very stable in an 8 twist, according to Berger's calculator.
The 88s shoot 3150 in my 22xc into teeny groups in an 8 twist. The 22 CM will go even faster than that. Terminal spin for 8 twist is 3500.
I hate to sound dumb but could you explain what you mean by this? Are you saying that if I go with a twist faster than 8, I may lose jackets? I don't understand...
I assumed that was what he was getting at, but I'm a little confused as to why a heavier bullet would lose a jacket before a lighter bullet...I believe he’s stating that at 3500fps an 88 ELD will shed its jacket due to too high of RPMs
That’s around 315k RPM which is quite high for a big bullet.
I’ve ran the 75 Berger from an 8 twist rifle just over 3500 and not lost jackets.
I’ve read 88 ELDs are more susceptible to this.
Evan has a thread on here regarding a 22 Br and jackets coming off due to velocity. It’s a good read.
I assumed that was what he was getting at, but I'm a little confused as to why a heavier bullet would lose a jacket before a lighter bullet...
Do you have a link to the thread you mentioned?
At 22CM speeds, 8T w/88 ELD-M’s does fine.A lot of guys like the 88 ELD but it doesn't appear to be very stable in an 8 twist, according to Berger's calculator.
It’s the jacket, not the weight that matters. At 3200 fps and 7T the rpm is approximately 330,000 rpm and some bullets just come apart. In general you need to keep bullets under 300,000 rpm. Some will tolerate more, some need less. An 8T will give you approximately 288000 rpm.I assumed that was what he was getting at, but I'm a little confused as to why a heavier bullet would lose a jacket before a lighter bullet...
1-8 at 2700’ and up works great for me with 75-88 gr Eldms … 22-250 AI but basically twin to 22 CM. I d say .060-.080 FB for 80 s down and if you really want to run heavies you ll need .150 or so FB.