6 Gren/ARC with light bullets
- Thread starter bodhisafa
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I do that with a 223 or Valkyrie.
6 ARC gets fed 95-110gr.
They all feed and eject correctly.
Edit: if you really want to shoot that light a grain from 6 ARC/Grendel, then have a talk with your barrel maker & let them know. It may need a little bigger gas port.
If it runs on normal loads with heavy bullets, it should run on normal loads with light bullets. Lighter bullets means more powder in the case.
Light bullets = faster powder, less port pressure. Also more speed = less dwell time.
Unlike 223 many 6ARC barrels come std with RL + gas & I’ve yet to see a complaint that an ARC was over gassed.
Many threads on here about under gassed issues with the ARC.
Might not be an issue with STD length gas or cheaper barrels that tend to be over gassed by defualt?
Not saying it won’t work, but barrel maker should be made aware of intent.
The ARC will work, but It’s not ideal. Why take a hit on case capacity by using a cartridge purposefully designed to run long heavies. If that is what I was after I’d go 6 x 6.8 or 6 Grendel before ARC.
Edit: Your going to be reloading anyway. Show me a factory Varmit load in the 60-75gr tange for the ARC.
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Being to short? With Light bullets.
2.185ish for 87 Vmax & shorter with lighter.
That’s why I’d lean towards a 6x6.8
Most of the 6 arc feeding issue threads i just looked up were with heavy bullets and long gas systems, making me wonder about running a rilfe+ gas system in one. 6 arc is going to be using something like Varget, RL15, 4166 with light bullets or heavy bullets.
If a 6 arc will run on heavy bullets, its going to run on light bullets also, because if its getting enough to gas to run with one, its going to be getting enough to gas to run with the other.
I think you missed an important point 357Max made. The powders used for light vs. heavy bullets are going to have completely different pressure curves and burn rates. The powders used in lighter bullet loads will typically be faster and will possibly be completely burnt with pressure dissipating by the time the bullet passes the gas port.
I don't know about completely burnt... but definitely lower port pressure.
I have a 6arc with a Proof Stainless Rifle +1 i run 58 and 87 gr vmax with cfe and lever and have had absolutely no problems with it. Has killed quite a few coyotes already too.
@BiggBeans - That’s good to hear. Are you suppressed? Lever is gassy. Several complaints on here were for the proof 18” RL + 1” leaning undergassed.
Example of dwell time. 224 valk 18” RL +1”with 60gr Vmax + hot load of XBR 8208 = 3230fps. Runs with gas wide open,but it’s on the edge.
Compare to 88gr + Lever @2730. Runs with adj block in middle.
Quick math & might have screwed it up? +500fps for 60 Vmax to cover the 3” past the port = 2 milliseconds less dwell time vs. the 88gr. Not insignificant with regards to gas system function.
Example of dwell time. 224 valk 18” RL +1”with 60gr Vmax + hot load of XBR 8208 = 3230fps. Runs with gas wide open,but it’s on the edge.
Compare to 88gr + Lever @2730. Runs with adj block in middle.
Quick math & might have screwed it up? +500fps for 60 Vmax to cover the 3” past the port = 2 milliseconds less dwell time vs. the 88gr. Not insignificant with regards to gas system function.
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No, I got what he said and don't agree. Many of powders are going to be the same powders. RL15, Varget, H335, LVR 60g-105g. I seriously doubt there are many barrels sitting on shelves ported to where they are only going to run on 105s and sta-bal. As in the Valkyrie example above, IT runs with light bullets and 8208, and LVR and heavy bullets. That is a pretty wide operating window. It will likely have its gas wide open for heavy bullets and 8208, and half closed LVR and light bullets like with heavy bullets.
That's backwards. Half closed with Lever and heavies. Wide open with light & XBR.
It needs more gas for lighter bullets. In the Valkyrie example, there’s 15% lessl time to transfer gas on the Vmax load vs. the 88 Eld.
The Valk runs just barely with a hot loaded 60 Vmax & gas wide open. This is with a low mass carrier + std VLTOR A5 buffer/spring. With a 69gr RMR loaded with XBR to 2875 it's a single shot. Have to change out spring to reduced power + light buffer to get it to run.
For the ARC, factory loads are 103, 105, 108, and 109. What do you think they ported the barrels for? Haveing extended gas systems does have advantages, but a wide forgiving tune window is not one of them.
No, not backwards I don't think you read it correctly. It needs more gas with XBR because XBR is on the fast end of what will work. Its the powder burn rate and port pressure more so than the bullet weight. As your example with the 69RMR helps demonstrates. At the very least that example is backwards to what you are saying about the ARC only running with heavy bullets. It should run better with heavier slower bullets and 8208 right? More dwell time, but you're pouring less of a faster burning powder down it so less port pressure.
Not the Valkyrie, your Valkyrie. My Valkyrie runs just fine with a 60g bullets and light load of Varget. In fact it uses the same gas setting as the same charge of Varget under a 70 RDF.
Not the Valkyrie, your Valkyrie. My Valkyrie runs just fine with a 60g bullets and light load of Varget. In fact it uses the same gas setting as the same charge of Varget under a 70 RDF.
I have tried a great many powders in the 87-115gr range in the 6mm ARC and had no problems with even book minimum loads locking a bolt back. When I ventured into the 55-65gr range I started finding those problems. Not always, not every gun, especially if you run a can, but the light weight end of the spectrum appears to give the gas system (the rifles I've tested with I believe are all Rifle +1, except for a couple shorties) less oompf.
I'd say 10 for that grain weight.
You've provided almost no info on intended purpose. Assuming varmint application??
What barrel length, muzzle break, suppressor, barrel profile.
Based on the limited info I'd just buy this and build it. Should come ported correctly out of the gate, but I'd still recommend an adjustable gas block.
I have one of their Polygonal 6.8 SPC2 barrels & it shoots well.
https://truesportingarmsllc.com/product/ar15-243lbc-1x10-20-std-r-5-8-m/
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I've run some 85gr SGKs in my Odinworks 21" w/+2 gas. I run everything suppressed, and was using LVR, both of which should help with cycling. Velocities topped out around 3,000 fps, but rifle seemed to like the ~2,940 fps area
I would lean more toward cfe223 for light bullets. I loaded up some 65 vmax with a light charge of 8208 and slight jam to blow the shoulder forward in some of my brass. 2959fps 28.5 grains Starline grendel brass.
The 6mm ARC with light bullets is unimpressive in an AR, IMO. I have two 6mm ARCs .
I'd just use a 5.56 if I were gonna shoot 55 to 70 gr bullets.
The 6mm ARC shines with heavy bullets 7 to 7.5 twist barrels. Go watch the video "60 coyotes down," with the 6mm ARC, shooting factory 108 gr eldm. He drops coyotes out to 700 yds instantly. Shooting on the run 2 & 300 yds. Killing all 4 called in, none escape, with a 6mm ARC AR & 108 eldm factory loads, a display of marksmanship and coyote killing power ... even the wife downs a few coyotes. The 108 gr eldm or Berger 108 gr are extremely accurate and consistent for an AR, putting 5 shots in the .4" is common, some even less with both of the 18" SS Proof barrels, and Leverevolution. The Proof SS barrels have been impressive the first 5 shots went into .5" out of the new barrel, while the Ballistic Advantage 3 shot MOA guarantee barrel shot over 2.0" closer to 2.5" for 5 shots side by side with the same match ammo on the same day. It would "sometimes" shoot 3 shots close to MOA, but never 5, not even close.
So I went home and ordered another Proof Research 6mm ARC barrel to replace the BA barrel, which was slightly more accurate than the first, with everything else but the barrel exactly the same. Now I have two accurate 6 mm ARC ARs.
I'd just use a 5.56 if I were gonna shoot 55 to 70 gr bullets.
The 6mm ARC shines with heavy bullets 7 to 7.5 twist barrels. Go watch the video "60 coyotes down," with the 6mm ARC, shooting factory 108 gr eldm. He drops coyotes out to 700 yds instantly. Shooting on the run 2 & 300 yds. Killing all 4 called in, none escape, with a 6mm ARC AR & 108 eldm factory loads, a display of marksmanship and coyote killing power ... even the wife downs a few coyotes. The 108 gr eldm or Berger 108 gr are extremely accurate and consistent for an AR, putting 5 shots in the .4" is common, some even less with both of the 18" SS Proof barrels, and Leverevolution. The Proof SS barrels have been impressive the first 5 shots went into .5" out of the new barrel, while the Ballistic Advantage 3 shot MOA guarantee barrel shot over 2.0" closer to 2.5" for 5 shots side by side with the same match ammo on the same day. It would "sometimes" shoot 3 shots close to MOA, but never 5, not even close.
So I went home and ordered another Proof Research 6mm ARC barrel to replace the BA barrel, which was slightly more accurate than the first, with everything else but the barrel exactly the same. Now I have two accurate 6 mm ARC ARs.
^^This
I'm running a 26" 6ARC shooting 110 A-Tips @ 2725fps and I'm regularly amazed at how far I can shoot consistently with it. In every way it feels like a 5.56mm, yet I'm able to hit IPSC steel not only at the limit of what I can do with a 5.56mm, but I've now taken it to 1168 yards without an issue. So it feels like a typical AR-15, yet shoots like a mild 6.5 Creed.
I'm running a 26" 6ARC shooting 110 A-Tips @ 2725fps and I'm regularly amazed at how far I can shoot consistently with it. In every way it feels like a 5.56mm, yet I'm able to hit IPSC steel not only at the limit of what I can do with a 5.56mm, but I've now taken it to 1168 yards without an issue. So it feels like a typical AR-15, yet shoots like a mild 6.5 Creed.
So far the Berger 108’s are near 2700 fps. I usually shoot heavies in any caliber. That’s my go to.
I ran across A2230 and some 58 VMAX locally and just figured I’d play with them so see what kind of velocity and accuracy I could put together.
I ran across A2230 and some 58 VMAX locally and just figured I’d play with them so see what kind of velocity and accuracy I could put together.
