Pardon me, but why? You'll still need specialized magazines. What's so troublesome about using a different bolt head?Originally Posted by caporider
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Senior Member
Pardon me, but why? You'll still need specialized magazines. What's so troublesome about using a different bolt head?
Senior Member
Because 6ARC is too similar to 6.5 Grendel to bother with it. 6mm MAX using the 5.56 bolt is very interesting to me, and we'll see how the bottlenecked rounds stack vs the parent straight-walled cartridges. The Grendel/ARC case taper does not help with stacking in AR mags, hopefully MAX does better.
Scout Rider for the Mongol Hordes
Member
Using the 5.56 bolt is a bonus, to what end, however?
I'm not denigrating the round, I think it was a great concept when it was done before (.22 Nosler pops into mind), and I think it is a great concept now, but I also don't think it matters much.
It doesn't allow the AR-platform to operate at bolt-gun pressures and the vast majority of casual end users - who are needed to move the needle in the marketplace to elevate the round out of the 'novelty' arena - could not possibly care less. It isn't difficult to find any of the various sundry bolts to run any standard cartridge in a small-frame AR anymore. Plus, what drives market success is ready availability of complete firearms with consistent ammo and brass availability.
One only needs to cruise the end-user online platforms for a short time to discover the most significant 'problem' with the ARC - ammo and brass availability. If the comparative manufacturing monster that is Hornady can't meet consumer demand for a product it put a significant portion of the reputation of its brand behind, how will a smaller and relatively unknown developer avoid the same fate with a completely different concept?
Again, a great concept...but will it matter to anyone other than niche users?...and, if not, how long can it last?
Senior Member
SOLGW is making barrels and complete guns... And they're shooting for $1.50/round for loaded ammo, which is comparable to ARC. I'm kind of excited for the round because it's just a barrel swap and maybe a few 350 Legend mags to convert over, and it uses the same powders as Grendel.
I do agree it'll be a niche cartridge, but that's just fine with me. I still think Grendel is a niche cartridge and I shoot it a lot. Grendel had a moment when Wolf steel cased ammo was $6/20, but those days are an unprovoked invasion behind us now. Maybe AAC making Grendel ammo will make a difference.
Scout Rider for the Mongol Hordes
Senior Member
Durability.
The 6.5G/6ARC bolt head walls are incredibly thin (as is the extractor). By increasing the bolt wall thickness you're increasing durability/ longevity of the bolt and extractor. Most people who've shot more than a few thousand rounds of ARC have seen a bolt failure or two. If you look at the barrels out there, most gas systems are far longer than seen with other cartridges for a given length, to attempt to reduce pressure on the bolt. We all know bolt life is an issue with 6.5G and 6ARC.
Using a thicker walled bolt and thicker extractor while pushing a nearly identical projectile (for basically the same or better performance) is a major way to guard against a rifle going down hard in a match (or worse). 6ARC was never meant to be for everyone, and neither is this... but folks who've shot enough ARC to break a bolt or two are probably paying close attention to see where 6 MAXX goes. It has a lot of potential, it's just a question of how well it catches on and how available/ economical it can get as adoption of it grows.
SOLGW Deputy Director of Sales
Senior Member
I acknowledge that your new cartridge outright avoids the problem, but I don't know why industry standard for 6.5 Grendel and 6mm ARC hasn't moved to a stronger bolt and barrel extension design within the same envelope, like Knight's has.
"We must all hang together, or, most assuredly, we shall all hang separately."
Senior Member
Doesn't Ruger use a proprietary bolt in its 350 Legend rifles? I assume it is something similar to the bolt in the SFAR. I'd think something like that would be a good way to get around the weakened bolt face.
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“The rifle itself has no moral stature, since it has no will of its own. Naturally, it may be used by evil men for evil purposes, but there are more good men than evil, and while the latter cannot be persuaded to the path of righteousness by propaganda, they can certainly be corrected by good men with rifles."
Senior Member
Myself and a bunch of other Grendel shooters didn't get that memo.I wonder if ARC is running at higher pressure?
I've got multiple thousand rounds on one and never had an issue. Maybe not 5k+, but easily 2-3k.
I have seen one broken extractor on a new 6.5G bolt after ~100 rounds that I attribute to a manufacturing issue. Still should not have happened.
Bolt thrust is a real issue and why the Grendel isn't hotter than it is. If the max can run at much higher pressures with the rebated case head that could be an advantage.
Senior Member
I might be misreading this but I don't believe a rebated rim can reduce bolt thrust.
Senior Member
You are correct, bolt thrust is based on the internal case head size and is independent of rim size.
What I was trying to say is perhaps the new cartridge can run higher pressure due to more meat on the bolt.
If it is not rebated and is no larger diameter than 5.56 I don't see how they'd have enough powder capacity to beat most of the other beyond 5.56 cartridges.
My understanding is that both grendel and ARC need to run at 52k psi because of bolt thrust limits. Both can be loaded hotter with the risk of bolt breakage.
I don't know enough about the new cartridge to speculate so will go back to listen mode.
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