Question on barrel twist rate - 8 vs 12.

[duncan61]

I experimented with Target shooting at the Coolilup range and went down with my .222 to become world champion and it did not make 400m.Which is why I ended up with the 7mm Rem Mag.Sierra make a.284 dia. (7mm) 197 gr. HPBT MatchKing.But my biggest pill is 175gn in my Sendero.Perhaps others could tune me in with what chamber can launch a .284 dia. (7mm) 197 gr. HPBT

[Gwion]

It will come down to twist rate for stabilisation, Duncan.

I found this Berger stabilisation calculator the other day:
http://www.bergerbullets.com/twist-rate-calculator/

[duncan61]

Hey thanks for that 7mm.168gn HPBT Matchkings are perfect for my 1;9.25 twist and 26 inch barrel.I jagged it on the first go.I wondered why they grouped so good when I made them years ago.My only hope to get any better would be to Rechamber to 7mm STW the gunsmith will do the chamber better than the mass produced rifle maker which lends its self to better grouping at distance

[bladeracer]

I experimented with Target shooting at the Coolilup range and went down with my .222 to become world champion and it did not make 400m.Which is why I ended up with the 7mm Rem Mag.Sierra make a.284 dia. (7mm) 197 gr. HPBT MatchKing.But my biggest pill is 175gn in my Sendero.Perhaps others could tune me in with what chamber can launch a .284 dia. (7mm) 197 gr. HPBT

Nothing to do with the chamber, it's all down to the twist rate. Sierra spec is 7.5" twist or faster. The Sendero should be 9.25".
You can get even heavier .284" bullets - up to 208gn.

[Oldbloke]

Just got off the phone to the GS now and they were happy to swap it for a 1in8 twist. 2 more weeks waiting but I think I'll be happier with it in the long run. Thanks again all for your help and advice!

Wise move.