Twist Q

[19818119]

Okay guys,

I'm going to add a .243 Win bbl to my Surgeon build.

I've been told that 1/8 twist, 1/7.5 twist and a 1/7.8 twist is "ideal", only one answer can be accurate.

Going to shoot the DTAC's exclusively, what twist do I want and why?

Cheers,
Rath

 

[Rob01]

Re: Twist Q

All the above will work but make sure they are true twists especially with the 8. Some barrel makers, especially buttoned rifled, will say 8 and it might be a little off like an 8.25 and might give you troubles with the heavier bullets. I use a 7.5 twist and it works great. I would rather be a little over twisted than not have enough twist.

 

[AKA-Spook]

Re: Twist Q

See there? I'd have told him all my 6mm's are 8 twist and shoot Dtac's and 115 Bergers well. Go figure.

 

[Rob01]

Re: Twist Q

True 8 twist barrels will shoot those bullets just fine as you know but if the twist is off they can give problems.

 

[19818119]

Re: Twist Q

Thanks guys,

Is there any downside to a 1:7.5 twist v the 1:8, assuming both are accurate rates of twist?

Rath

 

[Rob01]

Re: Twist Q

Not that I know of unless you plan on shooting much lighter bullets faster then they might come apart with such a fast twist but if it's s designated LR rig and shooting the 115s then go 7.5 twist.

 

[JRWALLSIII]

Re: Twist Q

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">All the above will work but make sure they are true twists especially with the 8. Some barrel makers, especially buttoned rifled, will say 8 and it might be a little off like an 8.25 and might give you troubles with the heavier bullets. I use a 7.5 twist and it works great. I would rather be a little over twisted than not have enough twist. </div></div>

Pefectly stated!!!!!!!!!!

 

[19818119]

Re: Twist Q

THanks guys, very helpful

Rob, I going with a Bartlein 1/7.5, now I have to specify either a 4 or 5R groove as well as either a .236 or .237 bore.

Which and why?

Thanks again.

Rath

 

[19818119]

Re: Twist Q

Yo! Help

 

[Rob01]

Re: Twist Q

Sorry must have missed it. Honestly either groove will work. I have had 4, 5, and 6 groove and all shot well as all have been good barrel makers. It's been said the 5R deforms the bullet less and is easier to clean but they all shoot well and in a well made barrel clean well also.

As for the bore, I have never specified. I would leave it up to the smith. I would want a standard bore and nothing too tight especially with sending the 115s down there. With a 18" .308 a tighter bore might be better to get velocity but I don't think it's needed for a .243/

 

[19818119]

Re: Twist Q

Rob, Thanks.