For the 8mm guys

[RockyMtnMT]

We put two new 8mm bullets on the site today. One for a 10" twist and one for a 9" twist.

Just want you guys to feel the love.

Steve

 

[mgood]

Thank you. That 221 gr might be interesting to try. gun)

 

[Varberger757]

That's what I would call good news to Easter. Both would perfectly fit the 8x68S, 8 RM and several powerful wildcats in .323 / 8 mmS. Twist for both should be 1: 9 due to better stabilization IMHO.

 

[RockyMtnMT]

That's what I would call good news to Easter. Both would perfectly fit the 8x68S, 8 RM and several powerful wildcats in .323 / 8 mmS. Twist for both should be 1: 9 due to better stabilization IMHO.

Yes. The good thing is you really can not over spin these bullets. The recommended twist for the 221g at sea level is on our web site as 10". It is technically 9.75". The 10" twist would give a stability factor of 1.48, very close to the target of 1.5sg. Most people are not at sea level so we felt that this bullet would work as designed in the 10" twist very well. Also I don't think any of the low altitude guys will notice a lack of spin.

My partner Brian is all fired up about these 8mm. He is ready to build his next rifle in 8mm. The 8mm guys on LRH got him going.

Thanks for looking.

Steve

 

[mgood]

Yes. The good thing is you really can not over spin these bullets. The recommended twist for the 221g at sea level is on our web site as 10". It is technically 9.75". The 10" twist would give a stability factor of 1.48, very close to the target of 1.5sg. Most people are not at sea level so we felt that this bullet would work as designed in the 10" twist very well. Also I don't think any of the low altitude guys will notice a lack of spin.

My partner Brian is all fired up about these 8mm. He is ready to build his next rifle in 8mm. The 8mm guys on LRH got him going.

Thanks for looking.

So . . . how much does the stability factor go up with altitude? I'm not planning to hunt anywhere near sea level any time soon. I could be anywhere from 3000 to 10K+ though. I could get away with a little heavier bullet with my 10-twist 8mm Rem Mag? (Or with my 10-twist 25-06 Rem?)
I guess what I'm wondering is when a bullet manufacturer says you need x-twist rate to stabilize this bullet, they're giving numbers for sea level, I presume. How do I translate that to a different altitude?

 

[RockyMtnMT]

So . . . how much does the stability factor go up with altitude? I'm not planning to hunt anywhere near sea level any time soon. I could be anywhere from 3000 to 10K+ though. I could get away with a little heavier bullet with my 10-twist 8mm Rem Mag? (Or with my 10-twist 25-06 Rem?)
I guess what I'm wondering is when a bullet manufacturer says you need x-twist rate to stabilize this bullet, they're giving numbers for sea level, I presume. How do I translate that to a different altitude?

JBM Calculations has a twist rate calculator as well as Berger. They are easy to use, just plug in the pertinent values. Try this with your equipment a where you will be using it.

Steve

 

[mgood]

JBM Calculations has a twist rate calculator as well as Berger. They are easy to use, just plug in the pertinent values. Try this with your equipment a where you will be using it.

Ah, I figured there was an online calculator somewhere. In fact, I've seen the one at JBM but never tried it. I use their trajectory-drift calculator and have it bookmarked. Thanks.

 

[sambo3006]

I may have to give the 221 gr a try in my 25.5 " Rock Creek barreled 8mm mag. I would think 3000 fps would be a realistic velocity. They would shoot quite a bit flatter than the 200 gr Partitions I'm flinging now.

 

[RockyMtnMT]

I may have to give the 221 gr a try in my 25.5 " Rock Creek barreled 8mm mag. I would think 3000 fps would be a realistic velocity. They would shoot quite a bit flatter than the 200 gr Partitions I'm flinging now.

Checking load data I think you are correct. Should run great for you.

Steve