I don't think they've released more info than what is on the website yet. It's my understanding that H&H is still going through the CIP(?) process, similar to the U.S. SAAMI testing. Until these rifles actually hit the market H&H may not release that info. Most folks are betting that H&H is wanting to keep the propriatary(sp?) info to themselves for market reasons. I feel that is a pretty good bet for them, because their rifles are so expensive and ammo are so expensive. Most folks will make one of their own when the specs are released instead of paying H&H 20 large for a magnum length bolt action rifle they can wildcat the cartridge for. I've been thinking a rechambered and rebored Ruger M77 or No.1 would be just the ticket and still not have quite a bit less than 1K in the rifle. Of course, the same could be said for a CZ or Winchester, also.
Rumor through the grapevine has it that H&H has finished specing out the 400H&H and will have both the rifle and cartridge on display at the SCI in Dallas. It's my understanding also that there are a couple of English ammunition firms that have already starting producing factory ammo. Knowing that I could never afford an H&H rifle, it might work to buy a box of cartridges, and ship one off to a gunsmith and die maker for chambering of the rifle of your choice and die maker of choice, if you are in a hurry. Factory made rifles here in the U.S. might be a long time in coming, but if you want to wait 6 months or so, I'm sure RCBS, Z-Hat or CH4D will have dies. I think both the 400 and 465 will be based on the 375 H&H case, but may require full length sizing before expanding the neck. I have no idea what the taper of the case will be, but it is supposed to retain that for easy chambering and extraction. If it remains unchanged, the shoulder may move back and may steepen, though I really have no idea, since it will headspace on the belt.
I spent a few minutes at the Holland booth at SCI looking at these cartridges. The 400 is based on the 375 case but the 465 has a larger rim and belt similar to the 378 WBY. Bullet weights and velocities were spec'd out by computer with a target of 2375 fps. at the muzzle. The .400 with a 400 gr. bullet will have 5010 ft/lbs of energy while the .465 and it's 480 gr. bullet will have 6013 ft/lbs of energy, both at the muzzle. The 480 grain bullet is the same one that H&H uses for their double rifle cartridge with a diameter of 0.473".
* In an amazing departure from the past, H&H will not declare these two cartridges as proprietary. These will be available to the public through any venue that chooses to make use of the design. Their loaded ammunition run is nearing completion after testing and will be an extremely small run, I believe 5000 pieces. Look out collectors!
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