Old topic, but just want to share my experiences,
I have been loading 7x64 Brenneke for quite a while - mainly for LR purposes. For that, I have used 162gr and 180gr ELD-Ms
One should now the anatomy and design of the 7x64 - especially the throat. If the 7x64 chamber is cut as a standard chamber the throat will have a very gentle lead angle = long freebore, making it impossible to seat bullets close to the lands. The design was made to keep the pressure down and to boost velocity. I shoot a modified Tikka T3 with AICS LA magazines. I load all my ammunition to a COAL of 87.00mm which gives me a crazy long bullet jump. Taking the design into consideration one should focus on concentricity and an optimum guiding of the bullet by utilizing full contact between bullet bearing surface and case neck. It can to some degree be compared to the 6.5x55 which also accepts very long bullet jumps.
Dies: In the absence of FL bushing style dies I bought a standard FL RCBS sizer die. I got my gunsmith to ream the neck section out so that it would only size the body and push the shoulders back. Fireformed brass will be sized so that shoulders are pushed back 0.002". I size the neck with a 7mm Rem Mag, Lee Collet Neck Sizer - yeps it is generic and works perfectly! You can buy different mandrels to play around with neck tension, brass brands etc... I have two - one for Lapua brass and one for GECO/Ruag brass. Concentricity is kept at or under 0.002" runout.
For seating, I use a Forster BR seater - very nice die! Forster actually makes a Bump, bushing die for 7x64 Brenneke. This die will only push the shoulders back and size the neck. It will not resize the body.
About powder choices;
N560 has been a nightmare to work with. No matter what I did I could never get ES under 10m/s. There would always be pressure spikes. I always use premium brass, primers, load techniques. I load to very tight tolerances and even tried annealing, but nothing helped. I should say that I have loaded for one rifle that shoots like a dream. It is also a custom TIkka T3 with a 24" Lothar Walther barrel, 1:9" twist. It shoots 180gr ELD-Ms loaded with N560 through one hole with MV of 835ms. ES is very low. This is the only rifle chambered in 7x64 in which I have managed to get good results with N560
I have used N165 and 160 but velocities are low and max pressure is reached too fast...
After changing to RS70 things got much better. For my own rifle, I load 162gr ELD-M on top of 56.1gr RS70, Lapua brass, COAL 87.00mm, RWS 5333 magnum primers, trim to 63,70mm, neck tension 0.002". The barrel is a 21" Schultz&Larsen 1:8.5" twist. MV is 863ms...
So far temperature sensitivity has been ok - but I haven't put it to extreme tests yet.
J.
