6ARC barrel twist

[257Roberts]

Would like to shoot 108-110gr bullets in an ARC. Is a 1:8 sufficient?

In my mind, I am thinking 1:7 might be required with the slower speed of the ARC versus say a 6mm Creedmoor where a 1:8 might be okay.

Thoughts or experience?

 

[Idaho-Lefty]

I LIKE, my 1-7.5 Twist, 6 XC barrel as, it "shoots" from, 80 grain to, 108 grain Bullets,..
into, TINY Groups !
1-7 twist, IS probably Necessary for, the 115's but, Sierra 110's "shoot well" with a 1-7.5
IN,.. 6 XC's and 6 Creed's per what, I've read.

 

[David Milisock]

Would like to shoot 108-110gr bullets in an ARC. Is a 1:8 sufficient?

In my mind, I am thinking 1:7 might be required with the slower speed of the ARC versus say a 6mm Creedmoor where a 1:8 might be okay.

Thoughts or experience?

Use the 1 in 7 to be safe, make sure your free bore and head space is properly done.

 

[mikecr]

The cartridge and MV makes no difference to twist requirements of bullets.
What do the bullet makers suggest for twist?

 

[xswanted]

Would like to shoot 108-110gr bullets in an ARC. Is a 1:8 sufficient?

In my mind, I am thinking 1:7 might be required with the slower speed of the ARC versus say a 6mm Creedmoor where a 1:8 might be okay.

Thoughts or experience?

I have two 6x47s one in a 7 and one in a 7.5.

110s Sierras and 112 Barnes shoot well from both.

I shoot 107s from the 7 twist at 3075 with no I’ll effects in the bullet as of yet.


Technically speaking with the 7.5 and 110s I most likely am not achieving the full BC of the 110 but it seems to line up with what it’s “supposed” to.

With the smaller case capacity of the 6mm ARC I don’t believe there is a negative side to having a 7 twist. Like another member said make sure your gun smith sets up you chamber correctly for what bullet or bullets you choose to use.

 

[Henryrifle]

@257Roberts: Are you thinking gasser or bolt gun and for what purpose?

I built a 6mm ARC gas gun last year and shoot Hornady 108 ELD match bullets in it. It has a 21.75" barrel with an 8 twist. Using CFE223 or, my favorite for this cartridge, Leverevolution, I am shooting them at 2700-2720 at below maximum published loads.

I harvested 7 deer with it last year at ranges between 75 and 250 yards and wouldn't hesitate to take the shot as far as 350 yards.

I also shot a 1.8 MOA piece of steel at 1000 yards with the same load. Very accurate at about .75 MOA at 100 yards.

I realize this was more luck than anything else but I took about 11 shots at 18" steel plates at 1300 yards. I hit it 3 times. It might have been 4 but sticking with 3. 30% hit rate at that distance with an AR was much better than I expected.

My conclusion from my experience so far is that 8 twist works for the 108 ELDs.

Henryrifle

 

[David Milisock]

@257Roberts: Are you thinking gasser or bolt gun and for what purpose?

I built a 6mm ARC gas gun last year and shoot Hornady 108 ELD match bullets in it. It has a 21.75" barrel with an 8 twist. Using CFE223 or, my favorite for this cartridge, Leverevolution, I am shooting them at 2700-2720 at below maximum published loads.

I harvested 7 deer with it last year at ranges between 75 and 250 yards and wouldn't hesitate to take the shot as far as 350 yards.

I also shot a 1.8 MOA piece of steel at 1000 yards with the same load. Very accurate at about .75 MOA at 100 yards.

I realize this was more luck than anything else but I took about 11 shots at 18" steel plates at 1300 yards. I hit it 3 times. It might have been 4 but sticking with 3. 30% hit rate at that distance with an AR was much better than I expected.

My conclusion from my experience so far is that 8 twist works for the 108 ELDs.

Henryrifle

What upper, lower and what barrel did you use?

 

[Hohn]

I always err on the side of faster twist. In theory a light varmint 223 should blow up in a 7 twist because it’s turning 370k rpm. In reality it’s fine. Rpm isn’t what fails most bullets, it’s a damaged barrel or defective jacket. So I’d get the fastest twist readily available.

 

[457ciSBC]

This thread is a good read on bullet blowups, I remember when Eric was polling shooters and gathering info for this study.

http://benchrest.com/showthread.php?49336-Berger-bullet-failure-test

 

[SD guy]

Oldy but a goody. Thank you for sharing.

 

[Henryrifle]

@David Milisock I used a Wilson barren blanj and a vltor upper and lower.

 

[David Milisock]

@David Milisock I used a Wilson barren blanj and a vltor upper and lower.

I've been seeing a wide range of results with 6MM ARC builds. So I'm keeping notes on the successful ones. Thanks.

 

[JSH]

I think the 6ARC/PPC/??? Has been a long time coming.
I have a hard time with the fast twist rage and heavy bullets when distances are 350 and under. Go over this that’s a different story.

The “new” cartridges out there are little more than an old one with a fast twist.

I would be all about a 1-10” twist in a 6ARC throated for a 80 grain and under bullet. Though I have found the 6mm varmint bullets in medium to small cases fly OK in faster twist barrels, just not spectacular. My 6BR 1-8” shoots the 105-107’s great, 65 grain Vmax are acceptable but nothing to write home about.

223 fast twist barrels eat varmint bullets. I have been played with a couple of top tier barrels in 223 1-7” twist, they puke most all 50 grain bullets. I have went to the 60 grain Vmax with a lot better results.

 

[Raptor]

I've been seeing a wide range of results with 6MM ARC builds. So I'm keeping notes on the successful ones. Thanks.

David, I built two of them. My first was with a "Shaw" barrel for $230 and it shot great!! I had a shot out Proof RPR 6 Creedmoor barrel in a 1-8 twist and the only thing wrong with it was the throat was bad, no fire cracking. So I had my smith cut it off and make an AR barrel out of it. It is a freaking hammer too!! Both of these guns with there pet loads will shoot 5 shot groups in the .5s and under. The Shaw likes the 87VMAXs and 108ELDs and the Proof liked 87 Bergers.....

 

[David Milisock]

David, I built two of them. My first was with a "Shaw" barrel for $230 and it shot great!! I had a shot out Proof RPR 6 Creedmoor barrel in a 1-8 twist and the only thing wrong with it was the throat was bad, no fire cracking. So I had my smith cut it off and make an AR barrel out of it. It is a freaking hammer too!! Both of these guns with there pet loads will shoot 5 shot groups in the .5s and under. The Shaw likes the 87VMAXs and 108ELDs and the Proof liked 87 Bergers.....

I haven't had the opportunity to really put mine through the paces yet but it has shown the potential to be one of the most accurate rifles I've bought.

Funny I had it put together as a general purpose close quarter and medium game to 600 yard rifles but it prints such great groups with iron sights it's causing me to rethink the optics I want to mount.

 

[Hd98fxdl]

I have just built a 6ARC bolt with a 7 1/2 twist and I’m shooting the 110gr A-Tips

 

[Ray123]

Would like to shoot 108-110gr bullets in an ARC. Is a 1:8 sufficient?

In my mind, I am thinking 1:7 might be required with the slower speed of the ARC versus say a 6mm Creedmoor where a 1:8 might be okay.

Thoughts or experience?

I have a 1-7 that was not accurate with anything, but that was the barrel, not the twist. Bought 2 Proof Research 7.5 twist, accuracy is great out of both..stablizes 105, 108, 110, 112, gr. to 115 gr Dtac.

 

[David Milisock]

I have a 1-7 that was not accurate with anything, but that was the barrel, not the twist. Bought 2 Proof Research 7.5 twist, accuracy is great out of both..stablizes 105, 108, 110, 112, gr. to 115 gr Dtac.

Who manufactured thec1 in 7 twist?