Barrel twist advice

[JuddL]

When I build mine next year, it will be a 1:9". That is plenty for up to 230s. Which I wouldn't shoot any heavier than a 230 in a .300WM personally.

In all reality, a 1:10" is adequate for a 230 in most situations. That is what I shot in my 1:10" .300RUM.

^^^ that's the right answer but the current trend is to over twist everything.

 

[Taylorbok]

^^^ that's the right answer but the current trend is to over twist everything.

It doesn't hurt to over twist.... if the bullet stays together.

250 A-tips call for 1:8.5 but I blew up one or two in a 9 twist pushing them about 3k

 

[Petey308]

It doesn't hurt to over twist.... if the bullet stays together.

250 A-tips call for 1:8.5 but I blew up one or two in a 9 twist pushing them about 3k

Part of the problem there is they require that fast of a twist to get fully stabilized and thus full BC potential, but longer barrels and fast twist, along with thin jackets (such as the A-tip being only .024-.022" thick) produce higher amounts of friction, and thus heat, and those thinner jackets transfer that heat to the cores to the point they start melting and then come apart in flight.

So then you have that fun problem regarding twist rate and stability too. That's when the 1:9 tends to be better than a 1:8

Obviously monos don't have this issue.

 

[RockyMtnMT]

Marginally stable bullets can fly quite accurately but the probability of poor on game performance will go up with marginal stability.

 

[WildRose]

Marginally stable bullets can fly quite accurately but the probability of poor on game performance will go up with marginal stability.

The problem I've noticed is that even if they group well at 100yds, the wheels tend to start coming off quickly out at around 400-500yds

 

[jasent]

I went 1:8 28" with mine. I won't be going slower on the next barrel. I'm currently shooting badlands 205gr sbd2's and this rifle loves em. They leave the barrel at 2960 and still super sonic at a mile.

 

[Barbourcreek]

8.5 will be ideal for the slower velocity and higher bc bullet. Stability factor will be very good.

 

[Jester560]

I think I will go 1-8 twist so I can shoot most anything available.

Thanks all!

 

[FEENIX]

I think I will go 1-8 twist so I can shoot most anything available.

Thanks all!

There you go, done! Have fun with it.

 

[WildRose]

I think I will go 1-8 twist so I can shoot most anything available.

Thanks all!

Smart Move. A decade ago a 9 tw was "all you'll ever need" for 7mm and 1:8 for 6.5's. Five years from now at the rate we keep coming up with new, "heaviest in it's class bullets" we'll be looking at, at least a half turn or full turn faster just to keep up.

 

[Taylorbok]

The problem I've noticed is that even if they group well at 100yds, the wheels tend to start coming off quickly out at around 400-500yds

I'm shooting A-tips that are "marginally stable" and they shoot great out to 2000 yards. Haven't had the chance to stretch them passed that yet.

 

[WildRose]

I'm shooting A-tips that are "marginally stable" and they shoot great out to 2000 yards. Haven't had the chance to stretch them passed that yet.

You're luckier then than I've been with them.

 

[sable tireur]

I went 1:8 28" with mine. I won't be going slower on the next barrel. I'm currently shooting badlands 205gr sbd2's and this rifle loves em. They leave the barrel at 2960 and still super sonic at a mile. View attachment 401709

I started testing the Badlands 195 SBD2 a while back because they advertised the 1:10" twist rate. I thought this was great for all the guys and gals shooting the standard .300 Win. Mag. with the 1:10" barrels. Yes, they are 'stable' and the performance is excellent but they lose BC so the longer range calculations suffer. I'm not criticizing Badlands, just pointing out the semantics taking place in these discussions.

I still shoot them in my original 1:10" barrel but I've switched over to their 205 SBD2 in a 1:8" twist barrel for anything beyond 5-600 yards. Both work but my drop/drift with the 205's are improved. I won't be shooting any cup and core bullets so there is no worry there.

Enjoy!