Howa mini-action in grendel to be released in mid-2016

[adamjp]

Adam, please don't take this discussion as a personal affront. I didn't realize your close involvement in this. I read where you've been shooting Howa mini actions for a while; are you saying you've tested one chambered in 65G?

I've never shot Lapua 65G cases at or around 60k psi, but I seem to remember Bill Alexander saying they could handle it and were top quality in line with the rest of Lapua brass. I could well be wrong; I'd have to ask him again, but he'd be a good source since he, along with Janne Pohjoispää then of Lapua, designed the case.

Your experience in this matter is very valuable, so what is your basis for saying 65G Lapua brass is not rated for 60k?

Basis? How about a few years of shooting Lapua 6.5 Grendel brass in a bolt action (NOT a Howa Mini as they are not yet available). When I got my Grendel I tried a number of different loadings, some of them well over the design pressure. I didn't pop primers, but I have a dozen cases on their fourth reload that don't hold a primer any more. These cases are now givaways to collectors or Grendel fanciers who want a dummy case for reference.

My frustration is down to repeatedly stating that the brass is the limiting factor and yet y'all keep running down the 'we need a bigger action' route. If you want the higher velocities, get a bigger case.

You have made some assumptions that since the Grendel is derived from the PPC and that from the 220 then 7.62x39 that the Grendel brass is built the same as the 6mm PPC case. I have owned rifles in both cartridges and whilst the exterior dimensions of the head are the same, the internal construction isn't. The head also appears to be softer than the Lapua high pressure brass (220 Russian, 6mm BR, 6.5x47 Lapua and 6.5x284).

I don't pretend to know what the Grendel brass was originally specced for, but I suspect that it was designed for the target rifle - the AR15. The SSAMI specification appears to be 52k PSI (average) which makes 60K PSI a significant overload. A pressure rating of 52k PSI will work nicely in a 50k PSI action such as that found in the AR15. Stoke it to 60k PSI in an AR15 and the action will let go, but in a (good) boltgun like the Howa Mini the action will work well (their design failure is possibly in the 70 to 80k PSI range like most bolt actions) however the brass becomes the weak link in the system as it will still stretch and fail quickly with repeated loadings.

My hunting load is a 100gn NBT or TTSX over 31.5gn of BM 8208 (IMR 8208XBR in the USA) which delivers 2980fps out of the 21in barrel of my Zastava m85 based rifle. It is probably quite warm, dancing at the 55k to 58k range (sadly we have noted before that Quickload does not seem to model the Grendel very well at all) but is all-year capable (temperatures range from -5 to 35 deg C). I note that the Hodgdon load data for the same load is maximum at 30.8gn and 2730fps from a 24in barrel at 47,600psi, some on this forum have gone further in their AR15s, and others have noted bolt failures too.

As LRRP has noted, don't chase velocity. Chase accuracy and let the bullet BC do the job - even the 100gn bullets really do work well.