twist 'n shout

[jefats]

I've seen/heard/read shooters inquire as to which rate of twist to get when building/buying a 6BR. Seems like the popular answer is the slower twist for the lighter bullets and faster twist for the heavies. This may have had some validity back when bullets weren't made as good as those offered today. The days of jackets and cores separating due to high rates of spin are long gone. So, wouldn't it make sense now to just get the fastest barrel twist possible and then you're covered no matter which bullet you select?

 

[cmillard]

those days are not over! why go with too much twist anyhow? that just builds pressure and i believe it can have a negative effect on accuracy

 

[soldierofchrist]

Also if you do Varmint shooting, a 1 in 8" twist will not have the barrel life nor the velocity of the slower twist barrels. And usually if you have a rifle with the faster twist it will be throated for the longer bullets, requiring the lighter weight bullets to jump further which is usually detrimental to accuracy. The 1 in 8" is great for 80 grainers and up, The 1 in 14" is go for 55-70 grainers. I like the 1 in 12" because I do a lot of varminting and it lets me shoot 55 grainers to 80 well. I use my 1 in 8" to shoot 87 grain bullets up to 105's and it reaches out further but has more drop.

 

[jefats]

)

----------------------------------------------------------------------------------------

-------


to jefats,

- I have a couple 14-tw that will shoot 66's real tight at 100/200.
- I have a 12-tw that will shoot 87's tight to +500y.
- I have several 8-tw that will shoot the 66, the 87, and ever bullet from 55's to 115's very well, without the magnitude of negative effects.

I think you make my point.



Happy Shooting
Donovan Moran
[/quote]

 

[260Remshtr]

As a competitive shooter, the big "thing" talked about much and trashed back and forth is barrel twist. I hear it on the range, I hear it on this site and others. IMHO, there exists such a thing as too much twist, which adversely affects accuracy by putting too much spin on the bullet (overstabilization). The same is also true the other way, too little twist and bullets never stabilize. What I can recommend is that before purchasing a barrel, call barrel makers like Obermeyer, Brux, Bartlein etc. and talk to them about their recommended twists for the velocity and bullet that you wish to shoot. These guys know what they are talking about and can tell you exactly what they feel is the appropriate twist rate. That is what I have done and I can honestly say that I have never been let down by their suggestions. In all three cases of the barrel makers that I called they suggested slower twists than what I had expected.

 

[cmillard]

from what i have read on this site, the short range benchrest crowd shoots with a twist that will barely stabalize the intended bullet that they will shoot. now, on the other hand, the long range shooter will go that extra little bit and take a little more spin. but, i think that going too far--as in the 6.5" twist being absolutely necessary for the 90 grain .224 bullets is hogwash. just aske Laurie Holland (sorry i threw your name out there). a friend of mine--old high power shooter--has a medesha built space gun with a 6.5" twist. now, no matter what he does, it only shoots about 1 MOA. too much twist? bad barrel? it's hard to say. proof is in the pudding

 

[6BRinNZ]

jefats - The thing I have learnt is the throat can be as much a key area for versatility as the twist...versatility is I guess where you are coming from? Should you build a versatile rig with compromises or one specialised for the job?

For outright accuracy a slower twist will be less inclined to highlight bullet inconsistencies. Plenty of examples and or applications to contradict this but the principle stands.....choose the slowest twist to suit your needs.

Personally I have gone the 1-8 fits all track with the throat dimensions being the dictator for what bullet size I shoot. I have found a good compromise with the 95 Berger VLD. It shoots awesome in my rifle throated for 75 v-maxes, and will get me to 1k at a pinch.

 

[Frankr]

I've seen/heard/read shooters inquire as to which rate of twist to get when building/buying a 6BR. Seems like the popular answer is the slower twist for the lighter bullets and faster twist for the heavies. This may have had some validity back when bullets weren't made as good as those offered today. The days of jackets and cores separating due to high rates of spin are long gone. So, wouldn't it make sense now to just get the fastest barrel twist possible and then you're covered no matter which bullet you select?

NO!
look its not a big secreat im a die hard 6BR 14 twist guy..
The main question is what do you want to do with the rifle.?
you want to shoot varmits and targets to 300yrds as accurately as you can , go with the 14 twist you will love it
any of the 65-70gr bullets can be pushed fast enough to be very flat shooting and hard hitting to be a great varmit round and the accuracry is hard to beat. I would tell you shooting the 65 to 70 gr bullets to 750 yrds its a tough combo to beat.. you dont need anymore bullet for that. I would also say if we were to shoot groups at 600yrds in very still condintions the 14 twist will post some impressive groups at 600 yrds.. once the wind picks up the heaver bullets will proubly win out, but does that mean they are more accurate or was it just the shooter was out shot at that range.

the 1-8 twist i have no experience with but its obvious to see the benefit of the high BC beyond 600 yrds,and the fast twist helps stabilize the bullet when the velocity falls off the twist keeps the bullet stable.
I have seen some great groups with 80-115 gr bullets out of the 8 twist. so im uncertain of it accuracry with the light bullets. But im building a 6 dasher and im going with the 8 twist.

Read this link.

http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm

 

[soldierofchrist]

to cmillard,

How much more pressure are you talking ?
Take a 14-tw and a 8-tw and shoot the exact same load with say a 65gr bullet.

And how much of a negative effect to accuracy are you talking ?
(from the same scenario)

----------------------------------------------------------------------------------------

to soldierofchrist,

How much barrel life will a 8-tw give up to your 12-tw ?
And at how much velocity lose ?

----------------------------------------------------------------------------------------


to jefats,

- I have a couple 14-tw that will shoot 66's real tight at 100/200.
- I have a 12-tw that will shoot 87's tight to +500y.
- I have several 8-tw that will shoot the 66, the 87, and ever bullet from 55's to 115's very well, without the magnitude of negative effects.

Happy Shooting
Donovan Moran

I get about 250 fps difference between my 1 in 12" twist and my 1 in 8" twist. My 1 in 12" is a Hart barrel and my 1 in 8" is a Kreiger. Now granted I usually run less pressure out of my 1 in 8" because it has a longer throat to seat the 105's and my rifle with the slower twist has almost no leade whatsoever because I shoot nothing but short Varmint bullets out of it. As far as barrel wear I couldn't make a direct comparison as I have had different barrel manufactures on both rifles. General consensus though even with my 223's I had a 1 in 8" twist and a 1 in 12" Varmint Rock River Arms, and the slower twist outlasted in the accuracy department for another 2000 rounds. that could be because of the increased bearing surface of the longer and heavier bullets though. For me velocity wins out to about 400 yards then after that BC takes over. So for most of my Varmint hunting I use the slower twist and if its a calm day for wind i can even stretch it out to 600 yards. On the windier days or for ranges past 400 the faster twist allows me to shoot the 105's which even though they drop more, they beat the wind a lot better.

 

[jhord]

Something you may need to consider is barrel torque, depending what you are using the rifle for. I play around shooting local 100yd bench matches with my 8-twist 6BR and lighter bullets, (usually Berger 80 match varmints) and the gun really wants to move around in the bags. If I were to build a dedicated short range 6BR I would definitely go with a slower twist just because of that. In fact I have been thinking about it.