New Upper: 6mm ARC or 6.5 Grendel?

[Legionnaire]

I'm starting the quest for a new upper. I have an AR that doesn't get shot much as I'm mostly a bolt-action guy. I'm thinking a new varmint-barreled upper in 6mm or 6.5mm might pique my interest more and give me options for some informal competition. I'd like a 20-inch, or maybe even a 24-inch barrel. This would be primarily a target gun, but might get some use hunting varmints--probably not deer or hogs, but I wouldn't rule that out.

For those of you who have made this jump, which cartridge do you prefer? I've read a bunch and know the comparative strengths and weaknesses of the two cartridges. I'm a handloader, so the fact that there are more factory ammo options for the Grendel isn't a significant factor. I'm interested in knowing what cartridge you settled on and why you picked it. I'll add a poll for the heck of it, but am more interested in your comments.

I don't want to build an upper, so who makes one you'd recommend? I'm in no rush on this, so in stock / not in stock isn't crucial, either. Just charting a course at this point.

ETA: Any thoughts on the Aero Precision / Ballistic Advantage uppers available through Brownell's?

 

[gotboostvr]

I don't have either cartridge, yet.

I think for a pure target rifle, with a nice long barrel 6ARC wins.

For just varmints, 6ARC is more than enough oomph, and should be sufficient for deer/hogs.

If deer/hogs were more of a primary requirement rather than a secondary "maybe I'll use it for that too" I'd suggest the 6.5G. Or if you wanted to run it in a shorter pistol barrel as the larger calibers tend to be a little more efficient in shorter barrels.

But for your stated purposes, I think the 6ARC is the winner.

 

[jak67429]

I am currently moving from 6.5 to 6 in my prairie dog gun. reason is lack of 6.5 varmint bullets. Almost all of the 6.5 are heavy target bullets.

 

[jr_watkins]

My next AR will be chambered in 6 ARC. With the state of things though, it may be another year. I think either 6 ARC or 6.5 Grendel are great cartridges.

 

[Skylerbone]

Mine is only in regards to the Aero uppers complete which I have had excellent luck with in other calibers. While accurate, I would not give the go-ahead for competition ready accuracy. Just my opinion, they could still ring steel, but not gonna circumcise a gnat unless you get real lucky. Maybe Rainier makes a complete upper???

Won’t comment on the rest as I’ve not made the move past 5.56/.223 Wylde.

 

[Legionnaire]

Maybe Rainier makes a complete upper???

Thanks for the feedback and the thought. I don't see 6mm ARC or 6.5 Grendel on Rainier's site.

 

[Walkalong]

Check White Oak Armament and see if they do a 6 ARC upper

 

[Legionnaire]

Check White Oak Armament and see if they do a 6 ARC upper

Nope. .223/5.56, 6.8 SPC, .20 Prac, .22 Nosler.

 

[Skylerbone]

May be difficult to find a complete one with a top notch barrel.

 

[kmw1954]

I am still arguing with myself as to whether to switch to a 6mm BR or the 6mm ARC in a bolt gun for short target range.

 

[BigBlue 94]

I built a Grendel before owning a 5.56 AR. That was about 10 years ago. 24" stainless HBAR Satern barrel, FF forend, A2 stock.

I have no real interest in a 6 ARC. I have a 243 and a 6mm rem bolt gun. Dont need another 6mm, and im not interested in adding another non-oddball caliber to my collection.

The thing about the Grendel, as mentioned, is only a small selection of bullets. Its pretty much pick 107gr or 123gr and go from there. 140 is a bit heavy. And it seems most companies making 6.5 bullets are focusing on 140 gr and up.

6mm has a huge range of bullets from 70gr and up.

 

[Legionnaire]

May be difficult to find a complete one with a top notch barrel.

May be. I might consider a less-than-premier option to get into the game and swap out the barrel at some point. Although the capabilities are not unrelated, I'm more interested in ringing steel than punching small groups; that is, more interested in PRS-type than Benchrest-type competition.

 

[Walkalong]

I am still arguing with myself as to whether to switch to a 6mm BR or the 6mm ARC in a bolt gun for short target range.

Short range bolt gun? 6 BR, no question.

 

[Legionnaire]

I've no interest in 6mm ARC in a bolt gun. I like my .243 Win, .243 Ackley, and 6 GT. My purpose is to generate a bit more personal interest in the AR platform. I'm not interested in getting rid of the AR, just want to make it more interesting for me to shoot. Leaning toward the 6mm ARC over the 6.5 Grendel at the moment.

 

[AJC1]

I picked 6 arc because if you plan on shooting in cross course competion I think that would be the better choice. If it's just a fun gun and no competition I would get a 300bo. It's not really a great round but I could load for it soooo cheap.

 

[kmw1954]

A customer of ours at the range hunts yotes. He carries an AR 6ARC and a 223 bolt gun. on the AR he has an IR scope on it. He shows up this time of year and tapes hand warmers to his targets. Fun to watch. He is happy with his 6ARC. He doesn't reload so is stuck with factory loads.

Lastly from the data I can find were I can compare the 6br and the 6ARC head to head with the same bullets and same powders both loaded for bolt guns I see very little difference in velocities.

 

[Legionnaire]

I see several have voted 6.5 Grendel. Care to make the case?

 

[Skylerbone]

I know of one forum member who’s built many ARs using high quality barrels and parts and I believe he just finished a father/son pair in 6.8 SPC and 243 LBC. Might be willing to point you in the right direction for a no-hassle precision build. I wouldn’t forgo the Aero for the price and performance but if you really wanna do it right...

I think that same Kansan also had some experience with Aero’s rails he might lend, if he’s not too busy terrorizing varmints.

 

[horsemen61]

I'm starting the quest for a new upper. I have an AR that doesn't get shot much as I'm mostly a bolt-action guy. I'm thinking a new varmint-barreled upper in 6mm or 6.5mm might pique my interest more and give me options for some informal competition. I'd like a 20-inch, or maybe even a 24-inch barrel. This would be primarily a target gun, but might get some use hunting varmints--probably not deer or hogs, but I wouldn't rule that out.

For those of you who have made this jump, which cartridge do you prefer? I've read a bunch and know the comparative strengths and weaknesses of the two cartridges. I'm a handloader, so the fact that there are more factory ammo options for the Grendel isn't a significant factor. I'm interested in knowing what cartridge you settled on and why you picked it. I'll add a poll for the heck of it, but am more interested in your comments.

I don't want to build an upper, so who makes one you'd recommend? I'm in no rush on this, so in stock / not in stock isn't crucial, either. Just charting a course at this point.

ETA: Any thoughts on the Aero Precision / Ballistic Advantage uppers available through Brownell's?

So I have both the 6.5 Grendel was a PSA KIT BUILD just to see if I liked the cartridge (I’m a 6.5 Nut so of course I did) 18 inch upper it has a Vortex 4-12x40 diamond back tactical on it it’s ok nothing wrong with it for sure I bought a CZ 527 because I liked it so much the cartridge that is



6MM ARC I went and did a full build just to see if I could make an accurate AR 15 I bought a 24 inch bull barrel 1~7 twist Shilen barrel 24 inches which came with a headspaced bolt NiB BCG it has a bushnell forge
5-25x56 on it I got on clearance for $200 from midway a while back it’s very very accurate


So if I were you with your parameters I would get the 6 arc it can run the same bullets as your 6GT if you want it can go lighter down to like 58 grains for varmints or a 90 grain ELD X FOR a deer I think Hornady did their homework on this one I think it’s a winner I can highly say it’s worth recommending I think you will enjoy it

 

[jmorris]

My purpose is to generate a bit more personal interest in the AR platform. I'm not interested in getting rid of the AR, just want to make it more interesting for me to shoot.

Then just get what you feel like, can always add the next flavor later.

I have lots of stuff I don’t use much but I could shoot most any caliber because of a well rounded stock of components. So variety isn’t always bad, in an “all eggs in one basket” way.

I have some very accurate 6mm paper punchers but I don’t need them for up to coyote sized varmints, the .224 caliber rounds do that just fine.

I do have a 6.5 Grendel that’s been pretty accurate but I haven’t used it on hogs yet, I don’t think SMK’s are a very good hunting bullet but it’s not too shabby on paper…and I have lots of other stuff that’s been working well for pest elimination.

 

[rayatphonix]

I have both the 6.5 Grendel and a close cousin to the 6mm ARC, the 6mm AR Turbo. Varmint hunting favors the 6mm due to a greater selection of bullets. You seem to already have a supply of 6mm bullets and I’d take advantage of that.

I would say hunting larger game favors the Grendel, but many a deer has fallen to 6mm cartridges so I’m not sure that’s a valid argument these days.

 

[BigBlue 94]

I know of one forum member who’s built many ARs using high quality barrels and parts and I believe he just finished a father/son pair in 6.8 SPC and 243 LBC. Might be willing to point you in the right direction for a no-hassle precision build. I wouldn’t forgo the Aero for the price and performance but if you really wanna do it right...

I think that same Kansan also had some experience with Aero’s rails he might lend, if he’s not too busy terrorizing varmints.

243 LBC? Or 264 LBC, which is nearly identical to 6.5G?

My 24" grendel barrel is actually a 264 LBC. 20" one im building is a Grendel barrel with type II bolt.

I didnt vote because I have no experience with 6ARC

 

[Skylerbone]

243 LBC? Or 264 LBC, which is nearly identical to 6.5G?

My 24" grendel barrel is actually a 264 LBC. 20" one im building is a Grendel barrel with type II bolt.

I didnt vote because I have no experience with 6ARC

https://www.thehighroad.org/index.p...t-parts-did-you-choose-and-why.736364/page-21 post #519

 

[Varminterror]

I know of one forum member who’s built many ARs using high quality barrels and parts and I believe he just finished a father/son pair in 6.8 SPC and 243 LBC.

243 LBC? Or 264 LBC, which is nearly identical to 6.5G?

243LBC - a straight 6 Grendel. I ordered an extra 243LBC barrel in the early days of the 6 ARC speculation, before reamers were available - it’ll be converted to 6 ARC when the barrel burns out, just to facilitate easier logistics.

@Legionnaire - I voted 6 ARC over 6.5 Grendel, for the simple fact it has a better ratio of bullet weight to case capacity, and is capable of using bullets which maximize the ballistic efficiency of the caliber.

6.5 Grendel is a close second to the ARC in terms of performance in the AR platform, but if I’m picking one, it’s an ARC.

Here’s a 20” 6.5 Grendel I did several years ago (actually a 264LBC marked barrel, from Black Hole Weaponry, using a Type I bolt), absolutely wonderful rifle. Sub-MOA, smooth, capable, and doesn’t look too bad for an AR.



A few weeks ago, I finally put together a spare parts build I had laying around - I ordered an extra barrel and changed my mind last year, so it sat in a box on the shelf. For all intents, this one might as well be a 6 ARC, even though it is actually a 243LBC - and it’ll be an ARC soon enough when this barrel burns out. A little longer case and shoulder, forcing me into shorter ogive bullets but offering a bit more powder capacity… but basically an ARC on steroids (or rather, about an ARC bolt gun equivalent, but at gas gun pressures - and this also uses a Type I bolt). It also needs a weight kit to move the balance point forward where it should be for my purposes - 4lbs or so of M-lok weights coming soon. Smooth, fast, flatter shooting, better balance (extra weight and length), albeit a bit cliche in aesthetic and a bit bulkier and longer than the Grendel rifle above. Absolutely love the Geissele Mk18 handguard, even if it does cause some headaches for AGB selection.



243LBC, 6.5 Grendel necked down to 6mm, without pushing back or shortening the case, such is the ARC.

 

[LoonWulf]

I voted 6 ARC over 6.5 Grendel, for the simple fact it has a better ratio of bullet weight to case capacity, and is capable of using bullets which maximize the ballistic efficiency of the caliber.

+1

I really LIKE the Grendel, but IMO the 6.5s want another 10grs of capacity, and preferably 15.