If you wanted to get two rifles in different cartridges, a precision bolt gun and a 16" AR15 pattern gun designed for defensive use, but didn't want to buy bullets in different calibers for reloading, which ecosystem would you buy into?

6mm Creed/6 ARC or 6.5mm Creed/6.5 Grendel?

General thoughts? I'm leaving the "use" of the guns open to interpretation, but think more along the lines of "fun/shits 'n giggles/defensive" than "competition to win all the games".

Primary consideration is lower recoil and reloading component ovrerlap, not barrel life.

I’m on the “lite” version of this…

I have a .243 bolt action and 6x45 AR.

I can load up to 100gr bullets in the 6x45 but will likely just stick to 70-85gr and heavier for the .243

Your definition of ecosystem is different than any version I've used. It's a stretch.

There's is no overlap in cases between the options. I suspect powder type could be the same for both options, but that's a question for those who reload.

The 6mm options will push the same bullet well -- say, in the 105-109 grain ballpark. From my initial evaluations of 6CM factory ammo, I found great accuracy with:
- Hornady ELD 108
- Hornady HPBT 105
- Berger 105 OTM
- Berger 109 LR Hybrid
BCs are respectable for all of these bullets. MV is very good with 6CM, and should be acceptably fast with 6 ARC -- but use a longer barrel. Probably little need to look at other bullets if longer distances and high accuracy is the goal.

6.5mm is a little different. 6.5CM works best at long distance with 130 and especially 140 grain bullets. These bullets are way too heavy for 6.5 Grendel. For accuracy & distance the Hornady 123 ELD seems to be commonly used in the Grendel, but I haven't seen it used in the Creedmoor. I know the Hornady 120 ELD shoots well in the Creedmoor, but I don't know if people use it in the Grendel. For a shared bullet by Hornady, the 120 ELD (or similar) may be a reasonable compromise.

But Hornady's 6.5mm 120 ELD has a lower BC than that of the Hornady 6mm 108 ELD. Thus, advantage 6mm for shared bullets at distance. IMO the 6.5 Grendel just doesn't have the boiler room to push a good 6.5 bullet. The 6 ARC does a little better in MV, relative to bullet weight.

IMO both 6CM and 6.5CM work. Recoil is noticeably lower in 6CM. Both are very accurate. Both are very capable at longer distances.

I suspect 6 ARC recoil will be a little lower than 6.5 Grendel. Both should be very accurate. 6 ARC should be better at longer distances.

My answer is no answer, just internet flap flap, flapping... lol

Is there really an answer to this question? If there is, can we honestly give it, things being what they are?

"Precision bolt gun" is too wide a term. I could mean trying to shoot groups as small as possible at 100 yards, or trying to hit steel at 900 yards. The best bullet for one, won't really be best for the other. And neither of them would be something you'd want to burn though any real quantities of in an AR.

Even if we could say bullet "X" will work well enough for cartridge/rifle/use "Y" and well enough for cartridge/rifle/use "Z", it's all pretty irrelevant if you can buy bullet "X". And that's where we are.

Worst case, the only overlap would be the size of the hole in the barrel and not much else. Best case, you might find a "compromise bullet" that works well enough for both of your uses. But I've never been a fan of all the eggs in one basket, and times like these drive home the point.

As fritz stated could shoot 105 class bullet in either 6mm. The Berger 105 Hybrid is an excellent bullet that has shot very well in my 6mm bolt rifle calibers as well as friends 6 Grendels. Don't know anyone with a 6mm ARC.

So you got a bullet that'll shoot well in either 6mm. Could go further and consider a smaller case 6mm for the bolt rifle, such as a 6x47, 6 Dasher, 6BRA, 6BR... that'll share a powder like Varget.

Constrained to the 6mm or 6.5 only…
Bolt-243
Ar-6x45

During the shortages of the past couple of years, 6mm Creedmoor rounds remained available. I think I almost always saw a box or two sitting on the shelves. The other cartridges not so much, with 6.5 Creedmoor being totally unavailable 99% of the time. If you reload you may have better luck, but reloading components for anything have been pretty unreliable around here at least.

Thanks for the comments about the commonality of bullets that can be used for both cartridges. Powders would be a plus, but bullets are my number one consideration. I suspected there'd be overlap in 6mm bullets for the Creed and the ARC.

Can you get small primer brass for 6mm Creed?

quote:

Originally posted by Perception:
During the shortages of the past couple of years, 6mm Creedmoor rounds remained available.

It's not nearly as uncommon now as it was in recent years, that is no doubt the reason.

This question/problem has too many wrinkles currently.

I’d go with 6.5 from the sole basis of breadth of choices available.

There’s a lot out there in 6.5 and it’s here to stay.

Personally, I have an AR in 6.5 GR and bolts in 6.5 GR, 6.5 CR (2x) and 6.5x55 SE.

The 6.5 GR is a complete pussycat to shoot.

Leaves you open for plinking, target and hunting.

quote:

Originally posted by Oat_Action_Man:
Thanks for the comments about the commonality of bullets that can be used for both cartridges. Powders would be a plus, but bullets are my number one consideration. I suspected there'd be overlap in 6mm bullets for the Creed and the ARC.

Can you get small primer brass for 6mm Creed?

Lapua 6mm Creedmoor brass small primer.

If you want to giggle with the bolt rifle, chamber a 6BR. Silly easy to get one to shoot with powders that'll work with a 6MM ARC. Mag feeding a 6BR has been well sorted out in the last few years.