Hornady seemed to keep this pretty quiet. I’ll be interested to find out more as people get experience with it.
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338 ARC
- Thread starter Parham4020
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Hornady seemed to keep this pretty quiet. I’ll be interested to find out more as people get experience with it.
I was wondering when someone would post about this. Interesting difference from 8.6BLK in that it fits in a small frame AR and mag length, and can be seen as a better case capacity fit for subs.
Seems like a great option for silent critter thumper in a small frame AR15.
@Ledzep
How do pressures compare to a subsonic .300BO?
Curious if suppressors rated for subsonic .300BO will be able to handle this cartridge (i.e. Octane 45HD).
How do pressures compare to a subsonic .300BO?
Curious if suppressors rated for subsonic .300BO will be able to handle this cartridge (i.e. Octane 45HD).
I'm waiting to see what all the hornady haters will say because its always fun to see people spaz out. When I saw the podcast title at first I thought it was going to be some type of short action magnum for AR10's. When I saw it was just a subsonic primary AR15 round with more kinetic energy I was a little disappointed but I look forward to seeing how it does against Pigs.
I can see a smaller market for this. If you essentially want an 8.6 Blackout in a small frame AR, I think this will be the ticket.
I still think that there are better options if you are in the small frame AR market for hunting, but this one will probably be king of the subsonic performers for a little while.
I haven't watched the video yet, so know nothing at this point about magazine/bolt compatibility.
I still think that there are better options if you are in the small frame AR market for hunting, but this one will probably be king of the subsonic performers for a little while.
I haven't watched the video yet, so know nothing at this point about magazine/bolt compatibility.
Definitely a niche cartridge, though a pretty fun looking one...
Looks a LOT like the 338 Spectre but guessing it will have better support.
For subs, pistol cans should be fine. We've run several 9mm cans on 1/2-28 threaded test barrels @7".
Hornady is first and foremost a bullet company. As they say in the podcast intros "We Make Bullets".
That said they have been designing cartridges with advanced/modern features for quite a while now. I watched the podcast quoted above (#150) and it goes into great detail as to the when, why and what for they developed this cartridge. They actually started this in 2017 and shelved it until new technologies came about that made it possible to build what they wanted. Two loads available: a supersonic 175gr HP and a 307gr subsonic round plastic nose. No gas adjustments needed. Sub 307gr will work fine with 9mm/45ACP pistol suppressors.
Posting here without watching the detailed podcast above is just farting at the Moon. That said, you can watch the cliff notes by watching the first 3-minutes of their New Releases for 2025 post. Great for attention deficit people
. It wont answer all questions like podcast #150 but it will give you an idea of the what and why.
Here's the link to the cliff notes:
That said they have been designing cartridges with advanced/modern features for quite a while now. I watched the podcast quoted above (#150) and it goes into great detail as to the when, why and what for they developed this cartridge. They actually started this in 2017 and shelved it until new technologies came about that made it possible to build what they wanted. Two loads available: a supersonic 175gr HP and a 307gr subsonic round plastic nose. No gas adjustments needed. Sub 307gr will work fine with 9mm/45ACP pistol suppressors.
Posting here without watching the detailed podcast above is just farting at the Moon. That said, you can watch the cliff notes by watching the first 3-minutes of their New Releases for 2025 post. Great for attention deficit people
. It wont answer all questions like podcast #150 but it will give you an idea of the what and why.Here's the link to the cliff notes:
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Seems like a better mouse trap compared to the 8.6 blackout with its ridiculous twist, especially if you are already invested in the arc game.
Really happy to see this. 8.6 BLK supers don’t really do anything special, and 8.6 BLK sub capability has long been possible in small frames with cartridges like 338 Spectre.
The only problem was lack of support for the small frame 338 subs. Hopefully that is fixed with this.
I realize this will always be a fairly niche cartridge, but I think it is a great addition to Hornady’s lineup.
Looking keenly towards discreet ballistics for them to load 280gr expanding solids in this new caliber.
The only problem was lack of support for the small frame 338 subs. Hopefully that is fixed with this.
I realize this will always be a fairly niche cartridge, but I think it is a great addition to Hornady’s lineup.
Looking keenly towards discreet ballistics for them to load 280gr expanding solids in this new caliber.
Quite niche. But it’s exactly what I want. My can is 36 cal and I want a thumper subsonic cartridge for shorter range hunting. Just (hopefully) need to swap a barrel, gas tube, and probably a buffer.
And maybe reloading components will be plentiful
And maybe reloading components will be plentiful
And a bolt.Quite niche. But it’s exactly what I want. My can is 36 cal and I want a thumper subsonic cartridge for shorter range hunting. Just (hopefully) need to swap a barrel, gas tube, and probably a buffer.
And maybe reloading components will be plentiful
Damn. And a bolt.
Funny how in this hobby, you never get to say “oh, man, that’s cheaper than I thought it would be”
Hornady is first and foremost a bullet company. As they say in the podcast intros "We Make Bullets".
That said they have been designing cartridges with advanced/modern features for quite a while now. I watched the podcast quoted above (#150) and it goes into great detail as to the when, why and what for they developed this cartridge. They actually started this in 2017 and shelved it until new technologies came about that made it possible to build what they wanted. Two loads available: a supersonic 175gr HP and a 307gr subsonic round plastic nose. No gas adjustments needed. Sub 307gr will work fine with 9mm/45ACP pistol suppressors.
Posting here without watching the detailed podcast above is just farting at the Moon. That said, you can watch the cliff notes by watching the first 3-minutes of their New Releases for 2025 post. Great for attention deficit people
Here's the link to the cliff notes:
Footnotes!
It’s 53 minutes!!!
I think it could be a great hog thumper! I guess I just like the idea of a slinging a heavy weight in an AR platform if a mad minute situation arises. Defiantely not gonna reach out but that's what the 22 ARC is for. You will need an ARC bolt and everything I am hearing says Grendel mags are the way to avoid headaches. I have Duramag steel units for the incoming 22 ARC. The hard question for me... 16.1" barrel or 10.5" barrel?
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Hmmmmm......what about a 175 gr projectile out of a 338 Lapua Improved...maybe 4000 fps?
Looks like a better mouse trap for what I'd use it for than the 8.6. It's usable in an AR-15, doesn't have a corkscrew speed twist that limits you to only the most expensive bullets. I'm sure the super load is going to be slow, I'd be surprised if it breaks 2k, but the sub load might merit a barrel to give it a try on woods deer.
Hornady specs the supers at 2075FPS and the subs at 1050FPS.
Looks like I'm not the only one that wondered why anyone would want to use a large frame to shoot subs. I've never quite understood the 8.6Blackout thing.
Yeah, because we need to only gain 30 lbs. KE more over a 220 sub .300BLK after spending a few thousand dollars on new brass, dies, .338 Sub-X bullets, and a new barrel with a special twist rate & bolt... This is getting a bit on the retarded side.
Did everyone lose their boner for the 8.6 BLK already, despite it being a retarded idea to begin with? Then again, do we really expect anything more from Kevin? He always has to do something similar, but different, just to say "I did this..."
I mean, they'll probably sell a ton of these, but the sad reality is, it's nothing special, and if you want to shoot that size case, you might as well just buy some Hornady Sub-X ammo for your 7.62x39...It will cycle in an AK with a can on it just fine. At the functional distances you can shoot subsonic ammo to, there will be almost zero advantage to this or the 8.6 BLK over a .300 BLK... And the .300 BLK will actually have less drop and drift (lighter bullet, less RPM twist rate).
Did everyone lose their boner for the 8.6 BLK already, despite it being a retarded idea to begin with? Then again, do we really expect anything more from Kevin? He always has to do something similar, but different, just to say "I did this..."
I mean, they'll probably sell a ton of these, but the sad reality is, it's nothing special, and if you want to shoot that size case, you might as well just buy some Hornady Sub-X ammo for your 7.62x39...It will cycle in an AK with a can on it just fine. At the functional distances you can shoot subsonic ammo to, there will be almost zero advantage to this or the 8.6 BLK over a .300 BLK... And the .300 BLK will actually have less drop and drift (lighter bullet, less RPM twist rate).
That’s not how gravity works.
For those doing subsonic hunting, this might make sense. Looking at the Discreet Ballistics expanding copper solid bullets, the .338 version gets you an additional ~100gr for more momentum and penetration, while still offering very nice expanded petals to effectively increase the meplat and crush more tissue. But I’m not sure of the difference in the expanded diameters between their .30 and .338 offerings.
Yeah, because we need to only gain 30 lbs. KE more over a 220 sub .300BLK after spending a few thousand dollars on new brass, dies, .338 Sub-X bullets, and a new barrel with a special twist rate & bolt... This is getting a bit on the retarded side.
Did everyone lose their boner for the 8.6 BLK already, despite it being a retarded idea to begin with? Then again, do we really expect anything more from Kevin? He always has to do something similar, but different, just to say "I did this..."
I mean, they'll probably sell a ton of these, but the sad reality is, it's nothing special, and if you want to shoot that size case, you might as well just buy some Hornady Sub-X ammo for your 7.62x39...It will cycle in an AK with a can on it just fine. At the functional distances you can shoot subsonic ammo to, there will be almost zero advantage to this or the 8.6 BLK over a .300 BLK... And the .300 BLK will actually have less drop and drift (lighter bullet, less RPM twist rate).
Hornady appears to be developing a Grendel based ecosystem that's main advantage is market availability. I can see the appeal even if I think there's better options in different platforms.
It does address the problems with 8.6 Blackout, too fast twist with the 3 twist.
Too much capacity for subs, but one can work with it with different powders.
I changed my 8.6 blk the 3 twist to 6.5 twist, and eliminated those problems. No problems with lead core jacketed bullets.
With 6.5 twist runs 350 gr Maker subs 1050 fps to 1673fps without bullet blow up.
Lol, not even close on supers, comparing the 338 ARC, the 8.6 is way better.
The 160 gr 338 Barnes in the 8.6 reached 2800 fps,
200 gr Speer 2550 fps, cheap and accurate.
300 gr SMK or Bergers to just under 2000 fps.
Don't forget the 450 Bushmaster...get the 16 twist barrel only...AR 15 16" barrel over 3000 ft /lbs of energy with supers change to 500 gr subs no change in gas system, way more power than 338 ARC. Shoots cast lead, pistol bullets, and any .458" bullet resized in a cheap Lee sizing die.
Mags work great, and one of the best dual cartridges subs and supers available.
Next is the 510 Whisper, if ya want to put 2000 ft/lbs on target at 1000 yds with a muzzle velocity of 1100 fps, with lathe turned 1002 gr bullets. It only loses 180 fps between muzzle and 1000 yds, and one could actually hit targets at 1000 yds without specialized equipment. Just rifle and scope.
A 500 gr resized .458 bullet for the 450 bushmaster.
A 750 Atip 510 Whisper vs 350 gr Maker 8.6 blk.
With a 510 Whisper, maybe you want to pierce some AR 500 armor, or just blow shit up.
The 338 ARC would be a good subsonic round...not much of a super round.
Last but not least ...A serious flaw with the 338 ARC . I necked up a 6mm ARC to 338 ...It will not fit 300 gr Bergers or the 285 or 300 ge Atip in the magazine of an AR 15. ...or any other if desirable readily available long match bullets in 338.
It appears you'll be stuck with short 338 bullets made specifically by Hornady for the 338 ARC.
For that reason alone its a no go, for me.
Unless its way shorter than the 6mm ARC.
Want an AR 15 338 sub gun...Check the 338 Spectre for sub 338s they were shooting 300 gr SMK & Bergers I believe.
Definately, Check it out before buying this what appears to be a very limited Round...do some research.
Too much capacity for subs, but one can work with it with different powders.
I changed my 8.6 blk the 3 twist to 6.5 twist, and eliminated those problems. No problems with lead core jacketed bullets.
With 6.5 twist runs 350 gr Maker subs 1050 fps to 1673fps without bullet blow up.
Lol, not even close on supers, comparing the 338 ARC, the 8.6 is way better.
The 160 gr 338 Barnes in the 8.6 reached 2800 fps,
200 gr Speer 2550 fps, cheap and accurate.
300 gr SMK or Bergers to just under 2000 fps.
Don't forget the 450 Bushmaster...get the 16 twist barrel only...AR 15 16" barrel over 3000 ft /lbs of energy with supers change to 500 gr subs no change in gas system, way more power than 338 ARC. Shoots cast lead, pistol bullets, and any .458" bullet resized in a cheap Lee sizing die.
Mags work great, and one of the best dual cartridges subs and supers available.
Next is the 510 Whisper, if ya want to put 2000 ft/lbs on target at 1000 yds with a muzzle velocity of 1100 fps, with lathe turned 1002 gr bullets. It only loses 180 fps between muzzle and 1000 yds, and one could actually hit targets at 1000 yds without specialized equipment. Just rifle and scope.
A 500 gr resized .458 bullet for the 450 bushmaster.
A 750 Atip 510 Whisper vs 350 gr Maker 8.6 blk.
With a 510 Whisper, maybe you want to pierce some AR 500 armor, or just blow shit up.
The 338 ARC would be a good subsonic round...not much of a super round.
Last but not least ...A serious flaw with the 338 ARC . I necked up a 6mm ARC to 338 ...It will not fit 300 gr Bergers or the 285 or 300 ge Atip in the magazine of an AR 15. ...or any other if desirable readily available long match bullets in 338.
It appears you'll be stuck with short 338 bullets made specifically by Hornady for the 338 ARC.
For that reason alone its a no go, for me.
Unless its way shorter than the 6mm ARC.
Want an AR 15 338 sub gun...Check the 338 Spectre for sub 338s they were shooting 300 gr SMK & Bergers I believe.
Definately, Check it out before buying this what appears to be a very limited Round...do some research.
Attachments
I never let my needs get in the way of my wants so yeah, I'm in.
Well that's interesting, I watched a couple of the videos last night and heard them say that the .338 supers would be a little slower than 300 supers, but didn't catch a velocity.
My real subsonic hunting setups for this year are a cut and threaded 77/44 and a Henry X with 305gr cast hps and 300gr xtp respectively. I don't really think the .338 ARC will serve my needs any better than those, but it might make an interesting short upper for my SBR if there are bullet options available. The did mention that the 307gr sub-x is a further development and improvement over the earlier 190gr, so I'll be interested to see how it actually performs.
The 510 Whisper does seem neat. But the 338 ARC does not appear to merely be necked up. From the pictures, until we get actual measurements, it seems to be a good bit shorter.
Also, Discreet Ballistics says they may be trying to put their 280gr expanding solid in 338 ARC.
Picture for size reference. I’m on my phone, otherwise I’d paste them together, to scale.
EDIT: measuring the image, it appears the 338 ARC case is ~1.06” long. Or, ~0.43” shorter than the 6 ARC case.
Double EDIT: It appears Hornady may have messed with the aspect ratio of their image. KAK is saying 1.293”, or only 0.197” shorter than 6 ARC.
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They changed the video URL - found it and replaced it. Should work now.Footnotes!
It’s 53 minutes!!!
Ya, I'm still waiting to see what the case looks like. Their photo of the loaded round looks like the aspect ratio is off. I'd like to see a diagram. If I'm sure about anything, I'm sure it's not just a necked up 6 ARC. I already have a 338 Spectre. I have to imagine it's pretty close in length, neck and body to that just based on the restrictions of an AR mag.
Scanning the specs I immediately thought of the 45-70 in a trap door rifle. 300g at 1300-1900fps. A 500+gr could be a sub no problem. A very different mouse trap to launch something quite similar. Carry on, old man musings here.
Twist rate 1:8? That seems slow for bullets that long. I think for really heavy/ long .300 BO bullets you need a 1:5. I'm using 1:6.5 in 338 now
Getting an upper as soon as they are available.
Snip from the video I posted above:
Snip from the video I posted above:
I’ll let the general population test it, manufacturers tweak it, then I’ll give in.Getting an upper as soon as they are available.
Snip from the video I posted above:
View attachment 8526224
Agree. Hilarious that the 8.6 stuff seems fast as hell and this seems slow as hell.
I’m used to thinking in 30 cal twists, so I don’t know where 1:8 sits in a .338 scale. Larger diameter means it’ll spin faster at 1:8 than a smaller diameter at 1:8? Like truck tires.
Idk.. I’m that smooth brainer everyone talks about.
338 Spectre is a SPC bolt face. 1.252 case length. With something like a .275" long neck. Below are loaded with a 300gr Maker at 2.3". 1050fps with 9 GR of Lil Gun in a 12" barrel.
As far as comparison to 300 BO, most people probably shoot 200gr bullets. All things being equal the 338 subs are going to add energy commensurate with the additional bullet weight. Sure you could try to stuff a 245gr EOL in a BO but you could also try to stuff a 350gr SMK in a Spectre. Realistically the comparison from BO, to Spectre, to 375 Raptor is 200gr, 300gr, and 400gr.
I just hope they did something to that 307gr SUBX bullet bc if it's a standard SUBX the expansion is anemic compared to Maker REX.
As far as comparison to 300 BO, most people probably shoot 200gr bullets. All things being equal the 338 subs are going to add energy commensurate with the additional bullet weight. Sure you could try to stuff a 245gr EOL in a BO but you could also try to stuff a 350gr SMK in a Spectre. Realistically the comparison from BO, to Spectre, to 375 Raptor is 200gr, 300gr, and 400gr.
I just hope they did something to that 307gr SUBX bullet bc if it's a standard SUBX the expansion is anemic compared to Maker REX.
Hornady should really look into making a SUB-CX line. I wonder if adding a section of lead in the base like a Partition with a copper jacket and sectioned nose like the REX would help keep the length down on heavy copper expanding subs. Or if it would throw the balance and stability off in the bullet?
Thousands of dollars? More like $700.
500pcs of new Spectre brass is $230. A die set is $70. A barrel and bolt is $385. $685 total.
And you could save half the brass cost by forming it from pistol brass if you want. Realistically the component costs between these and 300BO is more like a 15 - 20% increase.
You forgot the ridiculous cost of .338 projectiles…
But overall, it still doesn’t make it any less retarded and basically useless and more expensive compared to a .300 BLK with 220 subs. There’s an old saying that more people need to understand these days… “Just because you can, doesn’t mean you should.”
I didn't. They are just consumables that don't figure into the cost of tooling up imo. But if you want to figure that in because I can see where people do think it's a cost worth comparing then it's real easy.
30cal 200gr Makers cost exactly the same as 338cal 300gr Makers.
Sure, you can buy all sorts of cheaper 30 cal bullets for plinking that aren't appropriate for even thinking about subsonic hunting but plinking isn't what the Spectre, ARC, or Raptor are for. If you want to give the blackout credit for plinking with cheaper supersonic style bullets over these other cartridges then that's your win.
I'm calling it 9x39 American and you can't convince me otherwise 
That being said, this is interesting news for the AK crowd too, since like the 6Arc and 22Arc both will run in an AK platform and provide something more available in the US.
I can see the utility for Hunting purposes. it hits a sweet spot between raw mass and ballistic efficiency that allows it to carry energy farther than its larger-bore counterparts.
That being said, this is interesting news for the AK crowd too, since like the 6Arc and 22Arc both will run in an AK platform and provide something more available in the US.
I can see the utility for Hunting purposes. it hits a sweet spot between raw mass and ballistic efficiency that allows it to carry energy farther than its larger-bore counterparts.
For a guy that doesn’t have an AK, doesn’t have a 300BO (anymore), has a 36cal can, already has a couple ARs that’s Lego pieces can be swapped, this will be a good offer. As long as components are available and the round gets support. 
So I took the time to make a die and present the case with the known facts on the 338 ARC.
Trimmed a case 1.283" or .010" short to be an advantage to the 300 gr Berger which is on the edge of the ogive at. 3375"... so crimp it slightly.
This makes the 338 ARC useful for most subs 300 gr, beside Hornady low BC 307 gr of .375 g1, and low BC 175 gr super, which is .385 g1 with a sectional density of .219 poor for penetration, on a 338 lead bullet.
The 1-8 twist is good to go for the long 300 gr Berger according to the twist calculator.
The 350 Maker leaves no room for powder.
Yeah! The 338 ARC is a fairly useful sub gun.
But the 300 Blk is better with supers, cause it can run at much higher pressures, and the 250 gr Atip ain't much behind the 300 grs for practical use in subs, and will over take the poor BC of the Hornady 307 gr at .375 vs 878 for the 300 Blk. Even the 338 300 gr Atip is behind the 250 a bit in BC.
The 338 ARC can not match the power of the 8.6 Blk as it can easily take the 350 gr Maker, for heavier subs and smoke it in supers IF ya get the 6.5 Twist barrel, close to 338 Federal performance.
Forget the supers, it would be a fairly good subsonic gun. But the cost of components is higher for general use, compared to a small increase in sub energy.
The 450 bushmaster brings a lot more energy with 16 twist and 500 to 570 gr bullets, plus good short range supers, but probably less accuracy in the straight wall case.
You decide if this 338 ARC is for you, this is what I've gleaned from early research on this new cartridge.
Trimmed a case 1.283" or .010" short to be an advantage to the 300 gr Berger which is on the edge of the ogive at. 3375"... so crimp it slightly.
This makes the 338 ARC useful for most subs 300 gr, beside Hornady low BC 307 gr of .375 g1, and low BC 175 gr super, which is .385 g1 with a sectional density of .219 poor for penetration, on a 338 lead bullet.
The 1-8 twist is good to go for the long 300 gr Berger according to the twist calculator.
The 350 Maker leaves no room for powder.
Yeah! The 338 ARC is a fairly useful sub gun.
But the 300 Blk is better with supers, cause it can run at much higher pressures, and the 250 gr Atip ain't much behind the 300 grs for practical use in subs, and will over take the poor BC of the Hornady 307 gr at .375 vs 878 for the 300 Blk. Even the 338 300 gr Atip is behind the 250 a bit in BC.
The 338 ARC can not match the power of the 8.6 Blk as it can easily take the 350 gr Maker, for heavier subs and smoke it in supers IF ya get the 6.5 Twist barrel, close to 338 Federal performance.
Forget the supers, it would be a fairly good subsonic gun. But the cost of components is higher for general use, compared to a small increase in sub energy.
The 450 bushmaster brings a lot more energy with 16 twist and 500 to 570 gr bullets, plus good short range supers, but probably less accuracy in the straight wall case.
You decide if this 338 ARC is for you, this is what I've gleaned from early research on this new cartridge.
