Optimal 6mm twist

[FLguy55]

Alright kids. Gonna grab a 6mm gt barrel and I’m back and forth between 7 and 7.5 twist. So many arguments on both sides of this one and not a ton of feedback out there, especially for 6gt in particular. On one hand you’ve got GAP who created the thing and barrels tons of bartleins, and they’re 7.5. Pretty much everyone else is offering 7 twist, including for other 6mm chamberings. Proof does offer a 7.5 option. Berger stability calculator indicates a 7.5 will stabilize basically everything including 115s, at least at my average temps and elevation here in Florida. This is for a prs rifle and will probably be running 105 and 109 Berger hybrids which could mean 3050 fps. I don’t want to over twist them but need them stable out to say 1300 yards which isn’t uncommon in matches.

Hit me with your thoughts, especially those of you that are pretty deep in to a GT barrel.

 

[Supersubes]

It’s .5” of twist. Meaningless. Eenie meenie miney mo should help you with the decision.

 

[FisherT&C]

Slowest twist required will result in less projectile failure, like jacket separation.

 

[Supersubes]

Slowest twist required will result in less projectile failure, like jacket separation.

No way a 6GT hurts the jacket of a 105-115 match bullet.

 

[Andrew07]

I shoot 6 creed with a Bartlein 7.5 twist 105 hybrid going 3150 and it shoots lights out

 

[Threadcutter308]

I shoot 6 creed with a Bartlein 7.5 twist 105 hybrid going 3150 and it shoots lights out

Samesies, only difference is 6 x 47 Lapua/3,000 FPS. Lights out too. Best caliber/loading I have ever had.

 

[spife7980]

Get the 7, it’s not gonna hurt and you aren’t going to overtwist anything intended to be shot at distance.

 

[Rob01]

I run 7.7 twist on my 6mm. Either of those will work. I would go 7.5.

 

[MarshallDodge]

I'm running a 7.5 twist Hawk Hill in my 6X47 and I know it will stabilize a 115 RDF@2800 FPS, 2600' elevation, out to 1200 yards. I am a little curious to see how it will do with an 87 V-max if I ever go to shoot prairie poodles.

 

[WolfThorn]

I went with a Bartlein 7.5 twist for my 6gt build and plan on shooting 105s.

 

[McMillan]

I'm in the 7.5 or 8 twist camp. I run 105 to 110 range and dont go 115s. I won't go a 7 twist because my Smith has had to many 7 twist barrels that wouldn't shoot well

 

[swampbuck]

I believe GAP uses 7.2 for what it's worth

 

[FisherT&C]

No way a 6GT hurts the jacket of a 105-115 match bullet.

Ok

 

[NiteQwill]

I have both... 7 and 7.5 for 6GT. Flip a coin.

Bartlein and Hawk Hill. Both barrels shoot better than me with 109 Berger hybrids.

 

[FLguy55]

FYI - Talked to Josh at PVA, who's been running 6MMs of all varieties for years, and he recommends 1:7 across the board without any concerns. So, that's the direction. I'll have no concerns about running Sierra 110s now, even if I end up in a match in the cold some day.

 

[cjs88]

Could got the route of a Bartlein LHGT 7.5-7 twist.

 

[_Windrider_]

Could got the route of a Bartlein LHGT 7.5-7 twist.

Bingo. I just ordered a 7.75-7 LHGT at 22”.

 

[cjs88]

I have a 8.5-7.5 on order for my 6.5.

 

[RTH1800]

I would contact @Frank Green and let him know exactly what bullet and cartridge you will be shooting. Then get a gain twist Bartlien on order. Possibly one of the new special steel barrels.

 

[cjs88]

I would contact @Frank Green and let him know exactly what bullet and cartridge you will be shooting. Then get a gain twist Bartlien on order. Possibly one of the new special steel barrels.

Is the special steel for a longer barrel life worth the $200ish extra + the charge for GT? I guess if he is a match competitor but as a recreational shooter I just went with SS.

 

[RTH1800]

Not sure but extremely cool for sure.

 

[FLguy55]

Is the special steel for a longer barrel life worth the $200ish extra + the charge for GT? I guess if he is a match competitor but as a recreational shooter I just went with SS.

If their quotes for how much it gives you actually hold up, could be. Especially if you're gonna push the GT over 3000. I'd think the new steel could be a huge bang for the buck for the 6mm CM shooters. I've heard the new steel may be less impacted by long strings of fire where heats builds also. I know somebody who's got one, but on a bench gun, but it's a custom 6mm cartridge that pushes faster than a 6mm CM so time will tell.

 

[Cardboard Assassin]

Is the special steel for a longer barrel life worth the $200ish extra + the charge for GT? I guess if he is a match competitor but as a recreational shooter I just went with SS.

For ~double the barrel life (which is what they are saying) then ~$200 is surely worth it for the new 400MODBB barrel?

 

[Cardboard Assassin]

If their quotes for how much it gives you actually hold up, could be. Especially if you're gonna push the GT over 3000. I'd think the new steel could be a huge bang for the buck for the 6mm CM shooters. I've heard the new steel may be less impacted by long strings of fire where heats builds also. I know somebody who's got one, but on a bench gun, but it's a custom 6mm cartridge that pushes faster than a 6mm CM so time will tell.

I'm thinking of a 400MODBB and am curious to know that it shoots as well as the 416R equivalent (cant see why it wouldn't).

If it does then thats the way I will be going, apart for an extra ~$200 up front there are no downsides.

 

[FLguy55]

I'm thinking of a 400MODBB and am curious to know that it shoots as well as the 416R equivalent (cant see why it wouldn't).

If it does then thats the way I will be going, apart for an extra ~$200 up front there are no downsides.

My buddy's shoots just as lights out as any other Bartlein SS barrel, of which he has several. He loves it.

 

[Cardboard Assassin]

My buddy's shoots just as lights out as any other Bartlein SS barrel, of which he has several. He loves it.

No other quantifiable differences either? Same effort / process to clean etc?

If there are no downsides (bar price), and it dont seem like it, take my money!

Anyone know what color this new material is (black / stainless etc)?

 

[_Windrider_]

No other quantifiable differences either? Same effort / process to clean etc?

If there are no downsides (bar price), and it dont seem like it, take my money!

Anyone know what color this new material is (black / stainless etc)?

I’m guessing it’s whatever color cerakote you can get

 

[Cardboard Assassin]

I’m guessing it’s whatever color cerakote you can get

Indeed, but what is the natural uncerakoted color of the material?

Can you get cerakote in a matte stainless finish?

 

[_Windrider_]

Indeed, but what is the natural uncerakoted color of the material?

Can you get cerakote in a matte stainless finish?

It’s still a 400SS, so I’m guessing it will be like any other SS barrel as far as color or the raw SS look

 

[Cardboard Assassin]

It’s still a 400SS, so I’m guessing it will be like any other SS barrel as far as color or the raw SS look

I just found a vendor offering prefits in the new material and you are correct, it does look like regular stainless (and they do offer cerakote).

 

[_Windrider_]

Bingo. I just ordered a 7.75-7 LHGT at 22”.

Edit to add. I panicked, i called back and made it a 24”.

 

[Cardboard Assassin]

Edit to add. I panicked, i called back and made it a 24”.

I'm still trying to figure all this out for my first build but based on everything Ive read you probably made the right call going with the longer option.

 

[cjs88]

Edit to add. I panicked, i called back and made it a 24”.

Why not just get the normal 26" blank then decide on length later?

 

[Cardboard Assassin]

Why not just get the normal 26" blank then decide on length later?

26" does seem to be the most common length for sure. I've been looking at 6BR and 6BRA and its not uncommon for them to be longer still.

 

[_Windrider_]

Why not just get the normal 26" blank then decide on length later?

Because by the time it gets to me from bartlein it will be chambered and threaded.

 

[cjs88]

Because by the time it gets to me from bartlein it will be chambered and threaded.

Ah, fair enough. I will probably change my delivery address to go to Stewart Rifles since Matt will be doing the work for me. Would be cool if Manners stock and barrel order are finished at the same time then ship it all to him from the factory.