338 ARC

[Shoreglide]

I could have sworn I saw somebody making 338ARC barrels with a 1:6.5 Spectre twist but now I can't find it.

Haven’t seen any 6.5 twist, but Mos-tek is doing a 5 twist.

Ready to Ship .338 ARC Barrel 1:5 Twist

Ready to Ship 300 Blackout Upper Receiver 6" 1:5 Twist Tango Profile Ready to Ship. MÔS-TEK INNOVATION. PRECISION. QUALITY.AR15 FIREARMS AND BARRELING.

mos-tek.com

 

[JR1200W3]

I think the 1:5" would be the way to go. My 338 Spectre is a 1:6.5". When the big 300gr Maker solids hit paper they look like they want to start tumbling. There's a crescent shaped side to the bullet holes. I believe they fly straight, but they are on the edge of stable and just the cardboard causes them to start to wobble. They aren't spitzer, boat tail bullets with that type of COG. They're more like a lincoln log. I think they require a little extra twist. If you're shooting conventionally shaped BT spitzer bullets a 1:6.5" will be fine. I definitely wouldn't do an 8".

Now if we could get a CMMG radial delayed barrel extension on those.....

 

[Eric_F]

I might be a weirdo, but I'd love to see somebody make a roller delayed .338ARC with the purpose being to eliminate piston and port pop from the sound signature. The cartridge should be a very good fit, especially since Hornady designed it to have minimal variances between supers and subs, so you may not need more than one angle for the rollers.

The caveat being that I would want it to have an extruded aluminum upper with steel reinforcement inserts on high wear areas. Stamped steel HK53 type guns are way too heavy to be competitive in today's market.

Why do you think roller delay would be better at reducing port pop than gas delay? I haven't heard that e.g. a HK53 or ZF-56 is any quieter than an AR platform.

 

[45-90]

I think the 1:5" would be the way to go. My 338 Spectre is a 1:6.5". When the big 300gr Maker solids hit paper they look like they want to start tumbling. There's a crescent shaped side to the bullet holes. I believe they fly straight, but they are on the edge of stable and just the cardboard causes them to start to wobble. They aren't spitzer, boat tail bullets with that type of COG. They're more like a lincoln log. I think they require a little extra twist. If you're shooting conventionally shaped BT spitzer bullets a 1:6.5" will be fine. I definitely wouldn't do an 8".

Now if we could get a CMMG radial delayed barrel extension on those.....

The 6.5 twist not only stablizes the 300 gr bullets ...it also stablizes the 350 gr bullets.

I have a 6.5 twist 338 Spectre and it shoots 300 gr Maker and slightly longer 300 gr
Berger into tiny groups.
The Maker bullets are twist specific this box is for 6.5 twist 338 Spectre.
I am a fan of the 6.5 twist as I run it in 8.6 Blkout and 338 Spectre, and have scrapped my 3 twist as unworkable.
The 5 twist may be ok for subs but it still spins bullets in super unnecessarily fast.

The 338 ARC & Spectre are smaller capacities helping them out in the sub category for velocity consistency.

Hornady runs the 8 twist and their 307 gr bullets rather blunt. But if the 307 gr works exceptionally well and fairly cheap plus available in factory loading.
I wouldn't hesitate to get the 8 twist, as it will be better for light supers...and cast lead bullets like the 300 blackout.

Here is the 300 Berger and 350 Maker. Note the bullet box is 338 Spectre 6.5 twist, both easily stablize in the 6.5 twist.
The 338 ARC and 338 Spectre are very similar as pictured with the longest bullet being a 350 gr Maker.
The 350 gr Maker modified to bore rider has no trouble stabilizing as shown here in the 6.5 twist 338 Spectre.
The 6.5 twist 165 gr Maker Super is made for supers to 2100 fps and 6.5 twist specifically so they don't come apart.

I don't plan on hunting with any of them, so it's up to the individual to decide. I just test and shoot them for fun.

 

[JR1200W3]

From my experience, I think a 1:5" may be necessary for non-spitzer, solid subs that have a more forward COG. And I say this from a perspective of experience at 7000ft asl. Someone at sea level would benefit even greater from a faster twist.

 

[PBWalsh]

The 6.5 twist not only stablizes the 300 gr bullets ...it also stablizes the 350 gr bullets.

I have a 6.5 twist 338 Spectre and it shoots 300 gr Maker and slightly longer 300 gr
Berger into tiny groups.
The Maker bullets are twist specific this box is for 6.5 twist 338 Spectre.
I am a fan of the 6.5 twist as I run it in 8.6 Blkout and 338 Spectre, and have scrapped my 3 twist as unworkable.
The 5 twist may be ok for subs but it still spins bullets in super unnecessarily fast.

The 338 ARC & Spectre are smaller capacities helping them out in the sub category for velocity consistency.

Hornady runs the 8 twist and their 307 gr bullets rather blunt. But if the 307 gr works exceptionally well and fairly cheap plus available in factory loading.
I wouldn't hesitate to get the 8 twist, as it will be better for light supers...and cast lead bullets like the 300 blackout.

Here is the 300 Berger and 350 Maker. Note the bullet box is 338 Spectre 6.5 twist, both easily stablize in the 6.5 twist.
The 338 ARC and 338 Spectre are very similar as pictured with the longest bullet being a 350 gr Maker.
The 350 gr Maker modified to bore rider has no trouble stabilizing as shown here in the 6.5 twist 338 Spectre.
The 6.5 twist 165 gr Maker Super is made for supers to 2100 fps and 6.5 twist specifically so they don't come apart.

I don't plan on hunting with any of them, so it's up to the individual to decide. I just test and shoot them for fun.

Do the 350gr Makers actually fit in a magazine (STANAG or ICAR pattern)?

 

[45-90]

From my experience, I think a 1:5" may be necessary for non-spitzer, solid subs that have a more forward COG. And I say this from a perspective of experience at 7000ft asl. Someone at sea level would benefit even greater from a faster twist.

I shoot these at 1200 to 1500 feet evevation with no problem with the longer match bullets or the solid copper, with the 6.5 twist. I could shoot em at sea level or 10,000 feet, but I ain't gonna climb a mountain, about 60 miles away, or the ocean about the same distance, and a couple of hundred feet in elevation is easy, the shooting range is at 240 ft.

No actual need at all for a 5 twist, or the 3 twist, unless you want one of those twists, then get one...but it's not necessary to stablize any bullet from 160 gr Barnes to 350 Maker which even stabilizes at 800 fps at 1200 ft elevation.

 

[JR1200W3]

I shoot these at 1200 to 1500 feet evevation with no problem with the longer match bullets or the solid copper, with the 6.5 twist. I could shoot em at sea level or 10,000 feet, but I ain't gonna climb a mountain, about 60 miles away, or the ocean about the same distance, and a couple of hundred feet in elevation is easy, the shooting range is at 240 ft.

No actual need at all for a 5 twist, or the 3 twist, unless you want one of those twists, then get one...but it's not necessary to stablize any bullet from 160 gr Barnes to 350 Maker which even stabilizes at 800 fps at 1200 ft elevation.

Totally disagree. You're experience is a data point of one. My experience has been different. Regardless of how much you're going to post, it's not going to change what I've seen.

You don't need to try to be the definitive voice and stifle others. Say your piece and be done. Let others decide for themselves.

 

[45-90]

Totally disagree. You're experience is a data point of one. My experience has been different. Regardless of how much you're going to post, it's not going to change what I've seen.

You don't need to try to be the definitive voice and stifle others. Say your piece and be done. Let others decide for themselves.

No strife, when I say "get a 3 twist or 5 twist if you want one"....but it's not needed.

You are welcome to your opinion, as is anyone.
Hornaday has an opinion too.. with lots of test data, and deep pockets to develope the 338 ARC ....they chose the 8 twist for the 338 ARC.
It will most likely stablize most any reasonable bullet from 160 gr to 300 grs...or maybe just their 307 gr.
I haven't tested it yet....but the majority of barrel makers are following suit with 8 twist as standard for the 338 ARC...including Faxon who touts the 3 twist for the 8.6 and Hornady engineers called it "ridiculous". And I tend to agree after owning the 3 twist.....but that doesn’t mean you shouldn't own a 3 twist, 5 twist, etc, or even promote it for your purpose, if it's a good fit for your personal shooting endeavors.

I have lots of data on 3 twist and 6.5 twist...not just one or limited to one caliber.

The 6.5 twist has really worked well for me in 2 calibers, being very versatile and more accurate and consistent.
Some of that do to the poor Faxon quality, especially of their first barrels...lots of complaints, and bullet blow-ups destroyed muzzle devices and chronographs...lots of warnings put down in these pages.

No strife, get whatever twist you like for whatever caliber you like. No one cares what you decide.
Freedom of lots of choices is good...and so is freedom to experiment, & express opinions.
But manufacturers also "sell"...to get you to "buy.".. their products over the next manufacturers, as better, newly designed, the future, etc.and most everyone buys into the propaganda, a few work almost as stated, but many do not.
So get what you want, report on it...see if it's up to your expectations.

 

[45-90]

Do the 350gr Makers actually fit in a magazine (STANAG or ICAR pattern)?

This has all been discussed in other pages...
The 350 gr Maker is alot of bullet for the 338 Spectre and 338 ARC.

I have used cut out mags to get it to work but velocity was low in the 850 fps area, needed a different powder but it's a compressed load...but about 900 fps would seem the velocity limit with out further development, and experimentation.

I guy wanted a .416/ 338 Spectre developed, and was not concerned about AR 15 mag length as it was for a bolt gun.

So after machining bullets to 402 gr complete with holllow point. I fit it into a 338 Spectre case to decide how much powder space was needed to get it to 1100 fps. This was achieved with bore riders.

So I used the same concept on the 338 Spectre and machined different bullets. Then went to the 350 gr Maker to modify it to gain more powder space, and had 2 solutions, one being the long bore rider.
Easy to make in a precision lathe with collets.
But it was single load in an AR 15 but work great in a bolt gun.
That's alot of bullet, but its accurate and consistent to run right to the edge of subsonic/ supersonic flight, another .5 gr runs 1047 fps in the AR 15 single load these.