Thread: 338 ARC - An Early Guess At Reloading Data

Originally Posted by NCGNSMITH

The 165 ECX go well out of my 8.6 blackout
Get good mushroom out of them
I am running a 1-1” twist 18” barrel
Rem ti long action
And getting pretty easy 2350 fps
Accurate 1680 powder fed mag primer
Have found that moly coating allows
Me to drive them harder with less fouling
Or pressure

Yeah the biggest thing is expansion, sounds like your driving them fast enough, gunna be fun testing these over summer.

Hey, ncgsmith, where did you get those 338 ecx projectiles? I can’t see them anywhere .

They are just called Ecx they not actually a hornady projectile
Extreme cutting eXpanding by memory what they were called
I think they were made in nth island
Will see if I can track details down

Was given a few hundred by a customer he tried them out in a
338x39 that Robbie Tiffen built back in the day on a brno 601
Wasn’t happy with the results he was getting in a 1-11”
So went back to cast

Originally Posted by NCGNSMITH

They are just called Ecx they not actually a hornady projectile
Extreme cutting eXpanding by memory what they were called
I think they were made in nth island
Will see if I can track details down

Was given a few hundred by a customer he tried them out in a
338x39 that Robbie Tiffen built back in the day on a brno 601
Wasn’t happy with the results he was getting in a 1-11”
So went back to cast

CHeers you had me stumped for a bit.

I have some 161 cutting edge to try at some point…. Loaded some peregrines 275 gr in the 338 br tonight to test tomorrow.

Bit of quiet sat arvo so I grabbed some 7.62x39 & 6mm ARC brass to see how chopping and forming would go.

7.62 was a bit of a fail as I over chopped and then the shoulder forming doesnt look quite right, might have to revisit when I get some more brass, had only 1 case lol

6mm ARC brass I chopped back to 34 & 35mm expecting it to shorten as the larger cal neck formed....yeah nah should just chopped off at 33mm. Annealed and bumped up to 30 cal with my 308W FLS die re annealed and then sized up with the 338 ARC dies

Cases turned out perfect with 12 thou neck thickness V 13 thou and plenty of neck tension with the 161gr OEP .



338/6mm ARC on the left

Testing of the peregrine on target last weekend from 50 to 200m.
Validation in the field this week:


Dropped a big hind at 110m, nice big expansion through the heart from a 3/4 back shot.

Quick range session today with the Howa Mini, a case full of 2205 pushed the 161gr Outer Edge along at 2386fps, Hornady 175gr HPBT Black went 2180fps. Despite the small case capacity and given enough barrel length pretty happy with the SUpersomic performance, 175gr HPBT just wanted to stack at 50m, 3 shot group went 4mm and a 10 shot group went about 1 MOA.

More testing tmw with pics

10 Shot group with 175gr Hornady Black ammo, 3 shot group went 4mm so I went the whole hog and put 10 down at 50m, Barrel was warmish, shame you cant but this projectile yet, top speed was 2180fps which isnt too shabby for a 0.385 BC projectile

Will be fine tuning this load as it was virgin brass

So in my arc the , the 175 factory are going at 2130.
I shot some 161 cutting edge with from 22.5to 24 gr of 1680 and I start to hit a pressure point at 24 gr with just under 2000fps . This is into an 18” barrel with 1 in 7” twist. Back to the drawing board with a faster powder.
And it is funny that the 175 gr have a bc of 0.385 and the 307 gr have a bc of 0.375. Almost the same bc but with so much weight difference.

Bit slow with the Cutting edge Friwi, whats your coal ? Ive found N110 is giving slightly more speed than 2205 but I'm going to work the shit out of these 2 powders as I have 8lbs on hand and it would be good to use them up. I have some Power Pro 300 MP which I already know will add at least 100fps over what I'm getting. Is 2500fps possible with a 161gr projectile from the 338 ARC ? LOL more than likely ....

I have some n110 , but not that much and honestly I would love to be able to put my hand on some more. If you have some spare I could buy I d like to get in touch via pm.
I ll try a few rounds with it to see where it goes, also little gun is going to be another candidate.
I am only experimenting at supersonic speed in the long barrel to see what is achievable and to provide a bit of info to the community.
More likely the barrel will be cut down in a month time and the rifle exclusively used for sub work.

So Friday's target with both 2205 and Vihtavuori N110 in a back to back test.

Not only did N110 give marginally better speed but it also showed a consistency in accuracy that I was looking for.

Had an opportunity Friday night to blood the 338 on some pigs but I had already grabbed the 6mm ARC as the light was dimming which got the job done

First shot of the day with a cold clean barrel was with the 307gr Subsonics, 2nd and 3rd shot are overlapping. Speed of the Subsonics was only 1006fps and it really sounded like a 22lr, 22 inch barrel knocked about 44fps from what 16inch rifles are getting.

Done good news from Hornady, for those of us who were hoping for it.

https://www.hornady.com/bullets/rifl...07-gr-sub-x#!/



Hmm... Not sure why I'm getting two copies of the screenshot after removing one, but nevermind