Grendel as a Universal Infantry Cartridge

[stanc]

I've been turning the gears over this AR12.5 receiver set for a while now. There is one option that might not require that route, using existing AR15 receivers, and that would be with the MGI system and a new magwell. I see more hurdles with the magazines than I do the receivers, really. MGI was working on a 7.62 magwell for their Hydra that used M14 mags, but couldn't get it to run reliably. They did fit a 7.62 magazine into an AR15 lower profile, using their modular mag well lower, but lost the space for a bolt catch.

We know the upper will accommodate a 2.5" cartridge I think, although I wonder about live round ejection and clearance. The next option would be to fabricate a billet set from scratch around these new intermediate cartridges, and make mags for them. Using as many existing AR15 small parts, and an enlarged bolt, costs could be kept under control. The bolt carrier group would need to cycle a bit more rearward than a 5.56 though. I think it's very doable.

Thanks.

A 6.5 or 7mm DMR/Sniper SASS with significantly less weight than an M110 would be great, but in the end...what performance advantages will we gain over a 5.56 SPR with 18" pipe pushing 77gr SMK's? It would have to be significant enough to overcome the benefits the SPR currently has with ammo compatibility, lightweight, and mag capacity-per-volume.

Concur.

This makes me look at these new intermediate cartridges as proponents for 7.62 NATO replacement if they can match the ballistics.

Matching trajectory and wind drift appears to be doable. In fact, the chart for the 7x46 w/130gr bullet shows a somewhat flatter trajectory than for 7.62x51.

http://www.thefirearmblog.com/blog/2010/...cartridge/

And the SPC guys are getting close with 6.8x43 loaded with long-ogive bullets, although it sounds like chamber pressure may be on the high side. Also, they are talking about making a "stretched" 6.8x46, a la Tony Williams' proposal.

http://68forums.com/forums/showthread.ph...osal/page5

(P.S. Note that 68forums is way ahead of the 65grendel forum in regard to their avatart. )