6mm Predator vs 6mm ARC

[stagpanther]

I have both in AR builds and have decided to see if there is any kind of advantage one might have over the other. Both cartridges are necked down from grendel brass--but because the PRC shoulder is knocked back a bit I'm using nickle-plated brass for the predator (so I can tell them apart). Both are using 108 eldm's seated to 2.29 and 8028 XBR for powder. Because the ARC has slightly less H2O capacity I tried to match the loads with a bit less propellant in the ARC. Soon as it stops down-pouring outside I'll try to give them a go.

 

[stagpanther]

Just got back. I would have thought the PRC would have beaten the predator--but I did not take the time to find its "sweet spot" though I did use the case capacity percentage as I used in the predator. My shooting wasn't the greatest for either group--there was almost no wind today though it was foggy/ misty between rain showers.

 

[Shadow9mm]

Very Interesting! Looking at the cartridges visuslly it seems the predator has a bit more taper on the body than the arc does.

Also, did you mix up arc and prc in the 2nd post? Slightly confused.

 

[stagpanther]

The distortion in the pictures is due to the camera--there is no substantive difference in the body taper other than the ARC has a slightly shorter case length to the base of the shoulder AFAIK. It might also have a slightly different shoulder angle (a la Les Bear reissue of 6.5 grendel into 264 LBC) but I haven't measured that. The predator brass is actually nickle-plated brass so I can tell them apart. It's worth noting that the predator brass was new brass sized down (previously unfired) so that it has not fire-formed to the chamber yet--whereas the 6 PRC brass which was also formed from grendel brass was previously fired in the chamber of the rifle. Probably not an entirely fair comparison--among other things I was shooting in misty/foggy conditions and it was hard to get a clear target focus. I thought the difference between the cartridges is so minimal that they should have similar results--but was a bit surprised. The first pic is just 6mm ARC and the second is just 6mm predator.

 

[rickt300]

My 6 Predator is a fine shooter. Running BLC2 with the 58 gr. Vmax and SMP 763 with 100 gr. Speer boatails I get .6 groups often with 5 shots. Haven't moved out to farther range yet but I am taking it deer hunting in a few minutes using the Speer bullet at 2630 fps. I can't prove the ARC has a different shoulder angle than the Predator as I use 6ARC dies to make 6 Predator brass from Grendel cases. Works fine just set the dies to barely bump the shoulder.

 

[stagpanther]

I communicated with Nathan right after Hornady released the ARC--it was a bit of a striking coincidence that it is very similar to the Predator--which Hornady had been making dies for (and I tried to get but was no longer being made IIRC).

 

[tangolima]

Yo Stag. I just bought a 6mm ARC barrel (couldn't resist the black Friday deal). Will see whether I can catch up with you.

-TL

Sent from my SM-N960U using Tapatalk

 

[stagpanther]

Shadow9mm is the one who is deep in the weeds developing loads for it at the moment. I like it, but it's just another "what can we make into a 6mm from the grendel" cartridge to me. If you include 6mm BR and their spinoffs, there's a long dance line of similar cartridges IMO.

 

[Shadow9mm]

Had bad luck with everything i have shot so far. The 75g vmax were over stabilized and inconsistent. Tried all 3 factory ammo options, poor groups. Working up a load with 107g smk. Got one more round of testing to go. Got my fingers crossed.

 

[stagpanther]

Sorry if I already asked this--did you try any of the 105 gr bullets?

 

[Shadow9mm]

I shot all 3 factory varieties from Hornady. 103g eldx, 105g black, 108g eldm., all of which shot pootly. I also worked up loads with 85g nosler partition and 75g vmax. Both had accuracy problems due to, what i believe to be, the bullets being too short and thus over stabilized.

Current workup is with 107g smk.

 

[rickt300]

Seems like you may have a barrel issue. Mine are both twisted 1-8 and so far everything tried has shot well. As for the fast twist affecting those bullets I just can't see 2800 fps overspinning even a 1-7 twist spun 85-87 grain bullet. I admit I was not expecting much from the 58gr. Vmax but it shoots 3 into better than an inch no problem.

 

[Shadow9mm]

Its a 1:7 twist from ballistic advantage. The 75g vmax were going about 2977fps. 85g Partition were going 2795.

All i know is the partition would not group. And the vmax only hsd 1 node that may me sub moa. It was about 0.8, however it had a flier about 1.5in left in the 10 shot group.

Best i can figure the high rpm is exaggerating and imperfections in the bullets. Like an out of balance tire, the faster you go, the more of a problem it becomes.

Looking forward to finish testing with the match bullets

 

[jetinteriorguy]

Not sure if this relates, but I have a stainless 18” heavy profile Ballistic Advantage barrel on my Aero rifle and at first it was a consistent 2MOA shooter no matter what I tried. But the more I shot it the better it got and by the time I’d put around 300 rounds through it I could consistently get 1/2”-3/4” groups. I didn’t employ any special cleaning or break in procedures, just slow aimed fire five rounds at a time and cleaning after every 40-50 rounds depending on how many in a workup.