6mm arc/6.5 grendel/5.56 build?

[JelliedEagle]

I'm building another AR.. I already have another in 5.56, and since 2.23/5.56 uppers are so easy to find, I was thinking about going with a 6.5 grendel/6mm arc, weighing cost of ammo and everyting of course. am wondering what you all have to say about it. gonna pickup from odin works unless someone has other recomendations. I like their work. I mostly am curious about the ballistic differences between 6mm and 6.5 and since i have a press I'm also taking into consideration availability of components. 6.5 grendel seems to be available more than 6mm arc. anyways lemme know what u all think

 

[alamo5000]

I won't go into the ballistics differences. It's been beat to death in the other 200 threads where this was previously asked.

I however do own a pretty nice 6 ARC build. I personally chose that route over the 6.5. That was just personal preference.

6 ARC brass is a pain in the butt to find, but I got on the list for some Starline 6.5 grendel brass and it's been awesome so far. Just get a good stash of that and you will be fine.

If you are not a reloader then I would say maybe 6.5 is a better option because of more factory offerings. If you are a reloader the 6mm is a better option in my opinion. With the 6 ARC you have a much wider array of bullets to pick from. Hornady has load data published from 58 grains all the way to 110 grains.

It all depends on what exactly you are doing and how you want to do what you are doing. The 6.5 won't be a horrible choice or anything like that. No. Not by a mile. It will actually be a great choice depending on what you want to do. When I weighed my options though the ARC came out on top.

 

[JelliedEagle]

I won't go into the ballistics differences. It's been beat to death in the other 200 threads where this was previously asked.

I however do own a pretty nice 6 ARC build. I personally chose that route over the 6.5. That was just personal preference.

6 ARC brass is a pain in the butt to find, but I got on the list for some Starline 6.5 grendel brass and it's been awesome so far. Just get a good stash of that and you will be fine.

If you are not a reloader then I would say maybe 6.5 is a better option because of more factory offerings. If you are a reloader the 6mm is a better option in my opinion. With the 6 ARC you have a much wider array of bullets to pick from. Hornady has load data published from 58 grains all the way to 110 grains.

It all depends on what exactly you are doing and how you want to do what you are doing. The 6.5 won't be a horrible choice or anything like that. No. Not by a mile. It will actually be a great choice depending on what you want to do. When I weighed my options though the ARC came out on top.

what was the use/what you wanted to do with it that made you choose the 6mm arc over the alternative?

 

[Bluedog82]

The main benefit (in my opinion) of 6.5G is the cheap Wolf steel case for about 60cpr. I believe the long range ballistics are better on the 6ARC though, and plan to build one myself.

 

[alamo5000]

what was the use/what you wanted to do with it that made you choose the 6mm arc over the alternative?

For me the idea of longer range precision is the primary goal. I don't hunt that much. Not ruling it out, but the primary goal was to have the ability to hit targets beyond 1,000. The most range I have is 1,400 so that is my far limit.

If you really compare, the 6 ARC has a lot more choices for projectiles. 50 something grains all the way up to 115 is pretty wide. With the Grendel you can still shoot far but typically you are limited on which bullets you can use whereas with the 6ARC you can shoot em all.

Then I got to looking at all my stuff for reloading and I was sitting on 16 pounds of CFE 223 and had the realization that many components are interchangeable with .223. All I really needed was some projectiles and some brass. It gets too big of a hassle when you start managing reloading supplies for a dozen calibers. The 6ARC fit nicely into my overall system. All I really need to do now is buy some bulk packs of the bullets I like and that's it. When you are planning to keep supplies for anywhere between 10,000 and 50,000 rounds per caliber it helps to not complicate things.

Also I did a lot of comparison and depending on what the plan is, 6ARC can be cheaper to shoot in the big picture of things. Again though, with the ARC you can exploit all the new fancy whizbang bullet designs whereas with the Grendel you typically cannot go very far beyond the mid weight range of 6.5 bullets. You will max out around 125 ish weight class, but you leave everything on the heavy end out. Things like the 143 grain bullets are a no go so you are limited in that aspect. The cartridge typically won't push the fatties fast enough to benefit from shooting rhem. With the ARC if I want to shoot a 115 grain DTAC or a 110grain ATIP I can do it. It was built specifically for shooting heavies. It was built for exploiting modern technology bullet designs. With the Grendel maybe I am wrong but I don't think they are trying to redesign a 124grain 6.5 bullet.

Also if you want to just shoot cheap there are plenty of 50ish to 100ish grain weight bullets available for the ARC. Even in the worst ammo drought in history there were tons of cheap 6mm bullets available, assuming you have powder and primers.

There are some other things as well but I can't think of them right now.

 

[LRRPF52]

There are actually more 6.5 projectiles to choose from to shoot in Grendel. I’ve been shooting Grendel since 2009. I have also shot several of my friends’ 6mm ARs. They handle/recoil the same with the same bullet weights (85gr vs 88gr, 90gr vs 90 and 95gr, 100gr vs 100gr, 107gr vs 107gr). I like them both a lot. Both bring far more to the table than .223 Rem/5.56 NATO.

Grendel factory ammo ranges from 85gr-130gr. 6mm ARC factory I think is 75gr-108gr.
You can load most of the heavies in 6.5mm, including 139gr Scenar, 140gr A-MAX/ELD-M, 140gr Berger, 144gr Lapua FMJ, 156gr Oryx, 160gr Hornady RN, but they’re slow. Some guys have developed subsonic loads with 140gr-160gr in Grendel, as well as supers.

6.5 Grendel with the 130gr Nosler RDF will surprise you for LR target work. (.615 G1/.307 G7)
6mm AR is flatter with comparable TGT bullets in a similar BC class, lighter-recoiling. With 6mm, you’re in the mid-.5s for G1, high .26-.29 for G7 BCs in the 105-109grs. With 6.5mm, you’re in the mid .4s to low .5s G1/mid .2’s with 123gr, and mid .5s to low .6s G1/high .2s to low .3s G7 with 130gr.

Grendel impacts on steel are more audible, but not earth-shattering in comparison.
I’ve spotted for years for guys shooting 6mm Dasher and faster 6mms, and they run out of juice on even small plates once you start getting to 700yds in the wind.

6mm 107gr SMK is .547 G1/~.270 G7 IIRC
6mm 109gr Berger LR Hybrid is .288-.291 G7

From right to left...

.308 Win
6mm AR (Grendel necked to 6mm)
6.5 Grendel
6.5x47 Lapua
6mm Creedmoor
6.5 Creedmoor
.260 Remington
6.5x55 Mauser (far left)

Some different things to consider:

If you really like the idea of .308 Winchester but don’t like the feel of the really large frame, bulky/heavy AR-10s, 6.5 Grendel brings about 85% of the common .308 loads’ energies on-target from inside the AR-15 platform, with abut half the recoil. This isn’t re-hashed hype, but actual decades of experience. I’ve owned 6 different AR-10s, probably 10 different Grendels.

If you like the handling of .223 Rem and are looking for a coyote-slayer with no real recoil and hand-load, don’t really care for shooting anything larger than 85-109gr, you will fall in love with the 6mm AR/6mm ARC.

If you’re looking for a large range of bullet weights to be able to shoot and want the option to buy from LGS or big box stores in your area, you might see more Grendel on the shelves depending on your region. It’s been on shelves in my region consistently since 2008.

If you want an 18” rifle that can sling a 75gr at over 3000fps and the raw number at the muzzle means something to you, that’s 6mm ARC/6mm AR territory.

If you want to bite the heels of 6.5 Creedmoor and don’t care how long the rifle is, you can do a 28” Grendel with ELGS and it will surprise you at how fast you can spit 123gr, 130gr, and 140gr TGT bullets.

The main guys I know that shoot 6mm AR do it for either varmint or NRA Hi-Power matches.

Since you have a press, either option will be great for you. Both offer genuine ballistic improvements over the .223 Rem and the numbers aren’t really close when comparing .223 Rem to either.

 

[alamo5000]

There are actually more 6.5 projectiles to choose from to shoot in Grendel. I’ve been shooting Grendel since 2009. I have also shot several of my friends’ 6mm ARs. They handle/recoil the same with the same bullet weights (85gr vs 88gr, 90gr vs 90 and 95gr, 100gr vs 100gr, 107gr vs 107gr). I like them both a lot. Both bring far more to the table than .223 Rem/5.56 NATO.

Grendel factory ammo ranges from 85gr-130gr. 6mm ARC factory I think is 75gr-108gr.
You can load most of the heavies in 6.5mm, including 139gr Scenar, 140gr A-MAX/ELD-M, 140gr Berger, 144gr Lapua FMJ, 156gr Oryx, 160gr Hornady RN, but they’re slow. Some guys have developed subsonic loads with 140gr-160gr in Grendel, as well as supers.

6.5 Grendel with the 130gr Nosler RDF will surprise you for LR target work. (.615 G1/.307 G7)
6mm AR is flatter with comparable TGT bullets in a similar BC class, lighter-recoiling. With 6mm, you’re in the mid-.5s for G1, high .26-.29 for G7 BCs in the 105-109grs. With 6.5mm, you’re in the mid .4s to low .5s G1/mid .2’s with 123gr, and mid .5s to low .6s G1/high .2s to low .3s G7 with 130gr.

What velocities are achieved using heavy bullets in 6.5? By heavy I mean more than the average 124 grain bullet.

Bullets lose that BC factor based on the velocity that is achieved. Sierra actually publishes the BC to velocity comparison for their bullets.

For example the top line of the Sierra 142 grain 6.5 bullet is .626, but if you drop the velocity to say 2000fps the published BC goes down to .581.

 

[LRRPF52]

From a 24” RLGS, you’re looking at 2200-2350fps including the 144gr Lapua FMJBT. RLGS really limits you with port location and earlier unlocking. Stepping up to ELGS allows you to step up a bit.

From a 28” ELGS, 140s will do 2400-2650fps with Power Pro Varmint, which is one of the more mv-producing powders for Grendel.

135gr A-TIP (.321 G7 BC) will do this from 28” ELGS 6.5 Grendel using Power Pro Varmint:

One thing I found shooting all different types of 140gr through my 22” .260 Rem gassers was that I really prefer 130gr and 123gr, with the 130gr VLD being my favorite by far for downrange performance. I get 2800fps with the 130gr VLD from the .260 Rem. If I try to get 2820-2850fps, I start seeing cratering and even worse brass life.

The 28” ELGS Grendel with AR Comp under 123gr will do 2850fps+.

Basically, with some of the new powder developments and going to 28” Grendel ELGS, it kills any residual incentive I might have had to shoot my .260 Rem gasser much anymore. I haven’t made that jump to 28” Grendel since I don’t like long rifles.

I’m the kind of guy that wants .22LR recoil with .50 BMG reach and energy, so I’m always looking for the Goldilocks in the middle somewhere. I have a 22” Grendel that I haven’t shot since 2014, which is a Lilja bull fluted barrel.

I’ve spent the most time shooting 18” Grendel, or really my lightweight 17.6” Lilja build. Now I’ve been more focused on shooting the 12” Grendel.

If you’re looking for max performance though, the long pipes are the way to go. We have thin air up here, so it almost doesn’t matter.