6.5Grendel vs 5.56NATO as General Purpose AR15 Chambering

[LR1955]

Stan's concern about strength variations can be at least partly satisfied by doing a hardness test. Hardness and tensile strength of steel are linked.

"Mild" steel only needs a minimum tensile strength. I once saw a set of predictive calculations get invalidated because the vendor used steel that met the minimum strength, but was actually about 50% greater than the nominal strength. We discovered this only by post-mortem trouble shooting. I knew to ask the question because I had seen the problem in copper plates. BTW, a colleague had the insight to ask that earlier question so I learned from him!

The good news is that, by ensuring the test panels are cut from the same plate, comparative tests like the one being done will likely be OK.

If the added security of knowing hardness variations between the plates makes a difference, local machine shops are likely to have testers on site. Testing labs may also be able to do on-site or in-house tests too for a somewhat higher fee. Portable, even pocket-size, testers are available too.

Joe:

Not going to run the test after all. Stan realizes it is a bit too much and way too late.

I am sure that when ever someone gets some of the Serbian ball ammo that they intend on issuing if they go with a Grendel, that they will test it.

I am pretty indifferent towards the whole thing but won't spend money unless I think something can be realized.

LR55

[JASmith]

Understood -- and probably a wise decision.

[LRRPF52]

[m796rider]

It'd be cool to convert one of the new Bren 2s in 7.62x39 to shoot Grendel. I wonder if the Bren 2 7.62x39 mags would feed reliably; I'm given some hope by the fact that the C Products 26 rounders look like AK mags now.

[VASCAR2]

It really depends on the 7.62x39 platform and particular magazine. There were people trying to use 7.62x39 mags with the VEPR 6.5 Grendel without much success. The best results with the VEPR 6.5 Grendel was with Tapco polymer 7.62x39 mags which would feed a few 6.5 Grendel cartridges after modification. In the AR-15 I’ve seen where people have used CPD 7.62x39 mags to feed 6.5 Grendel cartridges in AR-15’s. I’ve never tried to use 6.5 Grendel mags to feed 7.62x39 in a 7.62x39 AR-15.

A Friend bought a 7.62x39 upper so we might have to try a 6.5 Grendel mag with his 7.62x39 upper.

[m796rider]

It really depends on the 7.62x39 platform and particular magazine. There were people trying to use 7.62x39 mags with the VEPR 6.5 Grendel without much success. The best results with the VEPR 6.5 Grendel was with Tapco polymer 7.62x39 mags which would feed a few 6.5 Grendel cartridges after modification. In the AR-15 I’ve seen where people have used CPD 7.62x39 mags to feed 6.5 Grendel cartridges in AR-15’s. I’ve never tried to use 6.5 Grendel mags to feed 7.62x39 in a 7.62x39 AR-15.

A Friend bought a 7.62x39 upper so we might have to try a 6.5 Grendel mag with his 7.62x39 upper.

Since the Bren 2 converts between 5.56 STANAG mags and their proprietary 7.62x39 mags with the use of a simple mag well insert, I'd guess it'd be possible to run the 7.62x39 bolt and a Grendel barrel with an AR Grendel mag... Or heck, someone could design a bigger Grendel mag to fit into the 7.62x39 mag well. I know, if wishes were horses...