Well, 2010 was the year of the 450b. Though I'm not done with it, my sights this year are on a .300 WSSM semi-wildcat. I say semi because HSM does produce the ammunition and it is submitted for SAAMI registration, but to the best of my knowledge has not been approved. It is based upon a necked up .25 WSSM case and with IMR 8208XBR, can push a 150gr bullet out at around 3100fps from an AR15 platform!
Not much in the way of load recipes yet, so lots of opportunity to contribute to a really nice and informed group of enthusiasts. Right now, Mike Milli of Dtech makes them as well as Olympic Arms. I have their Game Stalker with its 22 inch barrel, topped off with one of Ross' brakes. Their WSSM production line actually produces a quality product at an affordable price and I'm spending a lot of time over at oa2.org lately. It uses a special BCG to accommodate the fat case, as well as a special upper receiver modified to fit the beefier barrel extension and high pressure. Like the 450b, it is constrained by the length of the AR magazine though.
If you think the Hornady 450b ammo is expensive, count your blessings. The HSM 150gr runs around $50.00 per box of 20. I already have the Hornady custom dies and resized 25 WSSM brass ready to go. Unfortunately, comfortable shooting weather is still a couple of months away, I'll be miserably doing my barrel break-in shots in less than optimum weather (0 to +20f). Here's a picture of the upper on my RRA NM lower I also use for the 450b. I may be getting QL to aid in load design for the larger weight 30 cal bullets. Lots of folks over at The WSSM zone who are QuickLoad gurus as well as a few at oa2.org, So' I'll get help picking up the process of using it. Nopoint working up too much while the air temps are so low, but I look forward to hours of fun experimentation, which I truly enjoy.
You'd think the necked down 450b to .308 (Remington AR) round would deliver similar performance, but it doesn't.
Hoot