Grendel as a Universal Infantry Cartridge

[cory]

Look to have a general purpose (universal) cartridge it is going to have to be between 6.5 and 7mm. The 6.5mm works better due to less recoil.

The next aspect is getting the round to 2500 fps out of the barrel using a 140 grain bullet. That is the standard, set by the 6.5x55 Swedish Mauser. So far the .260 Rem, the 6.5 Creedmoor and and the 6.5x47 Laupa meet those requirements but with longer cases. As do wildcats like the 6.5 BRM which is based on the .30-30 case. The problem is that we can get a 140 gn. bullet to go 2500 but it takes a longer case than would fit into the current AR platform.

So could we make 6.5mm GPC that pushes a 140 gn. bullet 2500 fps? And make it smaller than a .308 (7.62x51)?

Are you talking 2500 fps out of a 24" or a 20" barrel?

If we're talking a 24" barrel I believe that's possible with the Grendel and the current AR15 platform. I've pushed the SST 140gr to 2400 fps using CFE and have some loaded that I believe I'll get to 2450+ fps. It will likely be a hot load though. Note: I don't have a particularly fast barrel.

Now if we introduced a powder designed for the Grendel and a 140gr projectile, I believe we can do that safely, but the COL tolerances in the manufacturing process will have to be strict, as it'll need to be loaded to mag length.

Our current limitation is not the case but the platform. Let's be honest if the military switches to a GPC, it won't modify any of the current m4s. It'll simply buy new rifles and give the old ones to foreign countries who will eventually shoot at us with our own rifles.

The greatest advantage to using a cartridge that fits in the AR15 platform is it does NOT require retraining our military forces on a new platform. It allows them to keep using a platform they are very efficient with.

Let's take this opportunity and build the AR12. The Grendel needs more mag width as much as it needs more mag length. However, it only needs an additional .01"-.02" both ways. (those measurements are off the top of my head and may not be exact.) It also needs a beefed up barrel extension and bolt, preferably with rounded lugs.I'm assuming we'll need to push the Grendel to 58 ksi for military purposes.

With all those changes we'll still have significant weight savings over the AR10 and a platform that our military is efficient with.

Side note, I believe this platform would lead to a 7mm AR round, that'll be limited but very capable, much the same way the Grendel is in the AR15.