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A5BLASTER Wrote:That's cool but I'm still going to test and see if normal gas lengths will work. If I do get one it will be a 12 inch.
I believe it was Lantac who tested a 11.5 n 12 ARC barrels and they went with a carbine gas systems. Imo this tells me that short barrels dont need the longer than normal gas lengths but with longer barrels the gas system needs to be bumped up one. 14.5 rifle and 18 rifle +1 and I thought with the 22-24 they used a Rifle +2(not a 100% on that)
Im wanting a 18 upper but a 12.5-13.5 upper with my SBRd lower would be sweet too!
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am4966 Wrote:I believe it was Lantac who tested a 11.5 n 12 ARC barrels and they went with a carbine gas systems. Imo this tells me that short barrels dont need the longer than normal gas lengths but with longer barrels the gas system needs to be bumped up one. 14.5 rifle and 18 rifle +1 and I thought with the 22-24 they used a Rifle +2(not a 100% on that)
Im wanting a 18 upper but a 12.5-13.5 upper with my SBRd lower would be sweet too!
If I get one that's where it will live on my sbr'd six8 setup with modifiyed mags I'm useing now.
Personally after looking at all the 20, 22 and 24 inch data I could find. A long barreled 6mm ARC just isn't worth the squeese for me. For what I do with my rifles the small I'm problem in drop and drift isn't worth the extra price over my CZ grendel.
But a 12 inch slinging some 80 to 90 grain copper are bonded bullets would be a fun time next to my 12 inch grendel doing the same thing.
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CMMG now has 6mm ARC rifles, uppers, barrels & BCGs...
https://cmmginc.com/shop/?orderby=price-...er=6mm-arc
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Too lazy to ready 13 pages of replies, does anyone know how the predicted 1:7" or 1:7.5" twist will fare with 6mm varmint bullets weight 65-85gr? This could be the ultimate AR coyote cartridge!
Thanks, Dinny
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Given the reduced velocity potential compared to a .243 Winchester, I suspect the faster twist will be just fine with the varmint bullets.
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Dinny Wrote:Too lazy to ready 13 pages of replies, does anyone know how the predicted 1:7" or 1:7.5" twist will fare with 6mm varmint bullets weight 65-85gr? This could be the ultimate AR coyote cartridge!
Thanks, Dinny
Some of the barrels are 1/7-1/7.5 so Im sure you wouldnt have a problem. Since your pill isnt going to go 3k FPS or if it does it wouldnt be by much
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A5BLASTER Wrote:What I'm wondering is this. Might the headspace of this 6mm ARC be close enough to fire factory ammo in a 6mmar chambered barrel?
Basicly fireforming it to the 6mmar chamber.
A5,
Did you ever get a response to this?
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06-12-2020, 03:56 PM
(This post was last modified: 06-13-2020, 02:32 AM by Harpoon1.)
Dinny Wrote:Too lazy to ready 13 pages of replies, does anyone know how the predicted 1:7" or 1:7.5" twist will fare with 6mm varmint bullets weight 65-85gr? This could be the ultimate AR coyote cartridge!
Thanks, Dinny
Nosler has load data for the 6 Creedmoor with a 1/7.5 twist shooting 5 different 55 grn bullets over 4000 FPS, 2 different 70 grn pills over 3600 FPS and an 85 grn over 3300 FPS. Doubt youll have a problem with the 6mm ARC and 1/7-7.5 twist rate. IMO.
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The heaviest longest 6 mm bullet I checked on the Berger stability factor web site was a 115 grain hunting bullet at 0 degrees and sea level. The 1.75 twist had marginal to poor stability with the 115 grain bullet but 1.7 was better. I checked a 65 grain target bullet under the same parameters With 1.7 & 1.75 twist and both were gtg.
https://bergerbullets.com/twist-rate-calculator/
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VASCAR2 Wrote:The heaviest longest 6 mm bullet I checked on the Berger stability factor web site was a 115 grain hunting bullet at 0 degrees and sea level.
https://bergerbullets.com/twist-rate-calculator/
I thought of making a snarky remark like "Well don't keep yer bullets in the freezer dag-nab it! Keep them in your pocket so they'll stay warm!"
That seemed awfuliy silly, so I think I'll keep that comment to myself.
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Since the cartridge seems to have been designed for use with a 108gr bullet, im not really shocked that the twist rate isnt fast enough for a 115. The majority bullets for deer sized game will be in the 85-100gr range as it is. Given the mixed bag of results I have seen of tests done with the Berger hunting bullets I have no desire to even think of using them, especially in a lower velocity cartridge.
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2 years ago whren they started this the 108gr was the heaviest 6mm bullet Hornady made and the 119gr A-Tip is their heaviest and longest now. Hornady is not going to design a cartridge around someone elses bullet like Berger or the DTac. Those bullets are also long and I doubt the shape and design would work well in an AR15.
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what is the difference in performance between my grendel and the 6mm arc??
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One can shoot 100gr 6mm bullets at 2700 FPS and one can shoot 100gr 6.5mm bullets at 2700 FPS. I would think the 6mm would be better suited for longer range applications.
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jonny rotton Wrote:what is the difference in performance between my grendel and the 6mm arc??
Not sure if you meant 6mm Grendel which if I remember correctly it was advertised in ARPs website as the 6mm Predator which could sling the 105s at 2900fps.
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what is the performance difference between the 6.5 grendel and the 6mm arc??? why would i want to trade my grendel in on a arc???
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jonny rotton Wrote:what is the performance difference between the 6.5 grendel and the 6mm arc??? why would i want to trade my grendel in on a arc???
2750 fps with a B.C. of .536
https://www.midsouthshooterssupply.com/i...-20-rounds
I think most here are not going to trade their Grendel for a ARC but add another tool to the tool kit.
The appeal of the ARC for me is that it will be easier to get hits at longer range and bullets mostly cost less.
Why would you want a 6mm ARC? Why wouldn't you?
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Lemonaid Wrote:2750 fps with a B.C. of .536 https://www.midsouthshooterssupply.com/i...-20-rounds
I think most here are not going to trade their Grendel for a ARC but add another tool to the tool kit.
The appeal of the ARC for me is that it will be easier to get hits at longer range and bullets mostly cost less.
Why would you want a 6mm ARC? Why wouldn't you?
I'm always looking to add to my tool box! Like Lemonaid said cheaper bullets, better BC, faster, what's not to like?
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Thanks folks for all the info posted here. It has led me to many of the discussions on the 6mm ARC. I have ordered from both ODIN and Brownells. One complete upper at 21" and a barrel at 16". I've never considered having more than enough tools a problem, well until I moved interstate. 6mm ARC looks like a keeper.
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We will definitely be waiting on your reports! Im going to be in but waiting on a couple details.
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