Question on barrel twist rate - 8 vs 12.

[Gwion]

The only real issue in shooting small bullets from a fast twist barrel is that if lightly constructed and pushed fast enough, the centrifugal force imparted may, that's MAY, cause the bullet to come to pieces in flight. For instance, I have some 40gn bullets that the manufacturer warns against pushing faster than 3400fps due to their highly frangible design & construction.

[duncan61]

Great result

[Member-Deleted]

There you go Ikkarus well done i hope the rifle is what your after and hope you enjoy it
Its marvellous how a little bit of know how from people in the know can help
The two weeks longer nothing because you most probably would have regretted it for much longer than that if you had gone ahead
with the original 12'' twist

Best of luck

[Ikkarus]

Thanks guys, I really appreciate the help and I'm glad I decided to ask here. You all seem like an awesome and knowledgable bunch.

[duncan61]

Are you going to try 77gn or 80gn HPBT Sierras.I sure as hell would

[Ikkarus]

Hey duncan61, still got a few flavours of the 55gr stuff that'd I'd already bought and have ordered a few boxes of the 69gr Aussie Outback with the HPBT sierras in em. I'll definitely be keen to try some heavier stuff too and see how it goes in a couple of weeks.

[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.