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6.5 CM Barrel choice

Started by jozzapozza, January 11, 2022, 04:12:27 AM

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jozzapozza

as a follow up to a previous post . i am also looking to build a 1000+ yrd rifle in 6.5CM . I am looking to go with a tikka t3x action a Bartelin 5r barrel in a MTD ESS chassis.

My questions are what barrel length and twist rate is ideal , im undecided between a 24 and 26 inch and 1 in 7 or 1 in 7.5 twist. i realise that the newer bigger bullets need more twist but will 7 be overkill and spin too fast , or will 7.5 future proof it and be fine for now as well.

VA-XBolt

My newest rifle and two additional barrels are all Kreiger with a 1:7.5 twist, 24" length. Handles the heavier 153.5gr Bergers just fine.

Rob01

I'd go 26" to get free velocity. My match barrels are 28".  If you don't need the shorter length for any reason then go long especially for 1000+ shooting.

For twist all depends on what bullets you plan to use. If using 150+ weights then a 7 or 7.5 would be better to make sure they are stabilized but if staying 147 and below the 8 twist works fine.

autoxforfun

Bob
If everything seems under control......you're just not going fast enough

jozzapozza

Thanks Guys , so going 7 twist will not over do it ? I'm reading some stuff suggesting that if you over twist and get stability over 2 this can be bad ! There's that much stuff to read out there now you don't know what's right .


gman47564

Just my personal opinion.. the 150 class bullets are better suited for say a 6.5 prc or 6.5x284.. the 6.5 creedmoor just lacks a little horsepower to run them effectively.. the 6.5 creedmoor was designed to run the 140 class bullets in a 8 twist and does very well with that weight bullet and shooting to a 1000 yards.. with a 7 twist you get lower velocity and more rpms.. trying to get the velocity up there to where the bullet performs at its best then your spinning it to fast and they like to go poof before they make it to the target.. i personally would stick with a 1and8 twist 26 inch barrel and shoot 140 class bullets.. just my .02 cents worth
Grant

Rob01

Quote from: jozzapozza on January 12, 2022, 07:33:23 AMThanks Guys , so going 7 twist will not over do it ? I'm reading some stuff suggesting that if you over twist and get stability over 2 this can be bad ! There's that much stuff to read out there now you don't know what's right .

Again depends on the bullets you use. I don't see a need for over 147s and run 8 twists on my rifles. Have since 2008 and they run great.

autoxforfun

My best shooting 6.5CM is an 8 twist 30" barrel.  I had tried a 7 twist but it really didn't perform as well as the 8.  I shoot mostly 140g Bergers but I have shot the 147g ELD-M as well with no issues with stability...and they shot very well.
Bob
If everything seems under control......you're just not going fast enough

LeadHammer

I would also run 140 class bullets and a 26" barrel, threaded for a brake. The CM is a bit slow, well not slow exactly but needs all the help it can get. I currently use a 24"
AutoX, what speeds do you get in the 30" barrel?

autoxforfun

Quote from: LeadHammer on January 12, 2022, 04:04:32 PMAutoX, what speeds do you get in the 30" barrel?
I'm getting right at 2830 fps with the Berger 140g Hybrids using RL-16..  
Bob
If everything seems under control......you're just not going fast enough

Rob01

My 28" barrels run 140 ELDs at 2825 with H4350 pretty easy.

I don't think the Creedmoor is slow for a short action case. It's right there with similar cases. Compare it to magnums it is but you have to look apples to apples.

Snaploader

I concur with Rob01,  I run a 28" - 8 twist Xcaliber barrel and get 2825 with 41.8 gr. H4350 and my best 600 yd group on shotmarker is 1.25" using a Savage model 10 receiver in an MDT chassis. i love the Berger 140 Hybrids using Lapua or Starline SRP brass.  I use this combo for monthly club matches at 600 yds and love it.

Mike

boltman13

Quote from: gman47564 on January 12, 2022, 08:10:31 AMJust my personal opinion.. the 150 class bullets are better suited for say a 6.5 prc or 6.5x284.. the 6.5 creedmoor just lacks a little horsepower to run them effectively.. the 6.5 creedmoor was designed to run the 140 class bullets in a 8 twist and does very well with that weight bullet and shooting to a 1000 yards.. with a 7 twist you get lower velocity and more rpms.. trying to get the velocity up there to where the bullet performs at its best then your spinning it to fast and they like to go poof before they make it to the target.. i personally would stick with a 1and8 twist 26 inch barrel and shoot 140 class bullets.. just my .02 cents worth
Gman has it right.  Don't try to make a magnum out of the Creed.  I get outstanding accuracy with the 144 Berger Hybrid in a 31" barrel with a 1:8 twist.  Are you shooting known distance or PRS.  A flatter trajectory helps in PRS and the 150+ bullets are going slow in a Creed way out there even with a better BC.

jozzapozza

Just starting up really . went on a range day and struggled to get to 950 with my 243, so fancied a bigger calibre. Also non toxic legislation in the uk will  make 243 for Deer obsolete. 6.5CM ticks both boxes. want a versatile gun, tho i wont be doing any stalking really . either shooting prone or on a rest from a vehicle.

Rob01

Must be a slow twist .243 barrel. With a faster twist of 8 and faster and 105+ weight bullets you can reach well past 1000 pretty easy.