6.5 Grendel Blowing Up Guns?

[LR1955]

John Paul also reported a Grendel blowing up. This was when he first started making Grendel uppers. He attributed it to Wolf 123 grain Soft Points when they were the only commercially made Grendel ammo. This ammo was notorious for gross copper and carbon fowling and apparently it so clogged the barrel with crap that it created a bore obstruction and blew the upper apart. If I recall correctly, he also said the guy was doing a lot of rapid fire so was going through a bunch of ammo.

LR-55

[Fess]

Thanks for that. GRT way overpredicts Grendel, and this is the first good explanation I've seen on why that might be.

The poor pressure prediction of QL for the Grendel created a big ruckus in the first few years after the cartridge was introduced. IIRC, QL was predicting well over 60K psi for loads that had been pressure tested at below 52Kpsi. I recall that Marty ter Weeme (458 SOCOM and Teppu Jutsu) was credited at the time for coming up with the idea that the case volume was changing quickly because the primer started the bullet moving prior to main powder ignition. A few years ago, I asked if QL has fixed the problem for the Grendel and never got a satisfactory answer. I think that some advanced users just used a larger case volume to get closer to the correct answer.

[HoustonHipster6.5]

I love the musical theatre reference in a gun forum!

[JASmith]

Gotta love the musical theater!

The poor pressure prediction of QL for the Grendel created a big ruckus in the first few years after the cartridge was introduced. IIRC, QL was predicting well over 60K psi for loads that had been pressure tested at below 52Kpsi. I recall that Marty ter Weeme (458 SOCOM and Teppu Jutsu) was credited at the time for coming up with the idea that the case volume was changing quickly because the primer started the bullet moving prior to main powder ignition. A few years ago, I asked if QL has fixed the problem for the Grendel and never got a satisfactory answer. I think that some advanced users just used a larger case volume to get closer to the correct answer.

That might partly explain the default volume in QL now being 37.5 gr, when few or no cartridges have that much space.

And, yes, QL seems to do much better with standard weight bullets these days.