What is the recommended twist rate for a 6.5 Creedmore?

[BobABQ]

I am pretty sure I am going to have my Remington 700 rebarreled from .308 to either 6mmBR or 6.5 Creedmore. Besides just banging away at steel plates I will use it for the occasional high power silhouette match. I have read that for 6mmBR that a twist rate of 1 in 8 will stabilize 100grain bullets.
If I go with the 6.5 Creedmore I will need to run 140 grain bullets for Rams at 500 meters with is like 550 yards.

So, the question is what twist rate should I go with to stabilize 140 grain bullets?

 

[C-grunt]

It seems 1in8 is the standard

 

[troy fairweather]

Ya 1-8 is standard. My have to do some mag work if going with the 6 br

 

[C-grunt]

Just for reference I'm shooting a 1in8 22 inch barrel 6.5 Creedmoor and my chosen bullet is the 140 ELD-M. It's stable out to a mile.

 

[BobABQ]

Thank you everyone. I need to see if the gunsmith is open during this pandemic and is taking in rifles.

 

[Varminterror]

1:8” in 6.5 Creed or 6BR should be fine with 140/147’s and 105/108’s respectively, but personally, if I were rebarreling with the ability to choose, and intent on hitting HARD at 550 with either - meaning using heavy bullets as an advantage) - I would go 1:7.5” or 1:7”. There’s no penalty for going faster with this weight class of bullets, and a 140 in a 1:8” is JUST slipping over the line for stability at 2650-2700fps. Jumping to 1:7.5” increases the stability factor considerably (1.76 instead of 1.55, with a 1.5 threshold). I’ve shot long with a 1:8” 6.5 too and 1:8” 6mm’s, but given the choice, I ordered 1:7.5” for my 6mm Creed and 6 Dasher. Just a little extra insurance that everything will stay stable downrange. Especially the little 6 BR case - Berger’s calculator shows a 1.38 “marginally stable” for the 105 Hybrid at 2650 in a 1:8” twist. I shoot 105’s at 2850-2900 in a 243LBC (larger case, but shorter seating depth) in 1:8”, and it holds on, but it’s certainly not optimal (1.41 stability factor) - the next barrel on this rifle will definitely be a 1:7”.

That’s not to say a 1:8” is a wrong answer, but a 1:7” or 1:7.5” would definitely be a better answer if you want to run 140+ or 100+ in these respective cartridges.