30 Gorilla
As Paul stated, I have been using my own version of the 6.5 Grendel necked up to 30 for several years. Some have their own version of a similar design, but theirs is called the 30 Major. Mine is just a little different. I use a 35 degree shoulder instead of 30 degree to give me just a hair more case capacity, better feel in the die , less neck growth and a turbulance point inside the neck that is just a wee bit closer to the back. Also, instead of the zero freebore that is so common in the 30s, I use .035" freebore and in some cases as much as .060". I have found that this gives me a little more case capacity and, in my experience, more precision.
When I first started this project, I called Alexander Arms, who owns the name "Grendel" and asked them if they would mind if I called my creation a 30 Grendel. They were nice enough to reply, but informed me that the Grendel name was a propriatary title and I could not use it in any way. I then asked if 30GR would be acceptable, and they agreed. I have since changed the name to 30 Gorilla because I am starting a small company called Gorilla Precision, LLC.
In my set up I use only bullets made on the .925 length jackets which allows me to use barrels in the 19 twist range. With 112 grain bullets, this combination gives me less upset in the bags and velocity up to 3050 fps. I also use IMR 4227 powder, which gives a real quick burn time inside the barrel, which has the added benefit of reduced muzzel blast and thus less recoil. A word of caution, 4227 max loads must be approached with extreme caution, because this powder is very fast and will give dangerous pressures with just a little extra heat of the day or other pressure building changes. My loads are down near the bottom of the neck. Start at about 28 gr. and work up very carefully.
In most cases I go to a match with about 60 preloaded rounds. Since I cannot change my loads during the match or if the weather gets hot, I keep my loads on the mild side and make any necessary adjustment with my tuner. I have found that I can make a chart with density altitude vs. tuner setting that comes out quite linier. As the day progresses, I adjust the tuner by looking a DA on my chart and setting the tuner as indicated. This is so much easier than keeping a 6PPC in tune using the normal methods.
Hope this is helpful.
Larry
