So after hearing Mike M. had some .22 b-50's in stock I had to try one. Ordered from him bone stock, straight off the boat from China.
When it first arrived it held some pressure but leaked down to around 1k
so I tore it down (sorry no pictures as I had just gotten it) and put in a replacement o ring that it was shipped with. O ring #18 in exploded view here:
http://i99.photobucket.com/albums/l3..._schematic.jpg
This solved the leaking down problem but the next day the fill valve o ring and breech seal blew as well. I will say that the #006 seals were probably in the worst condition on this gun.
Once I let it sit overnight and knew it wasn't leaking down I did some rough chrony testing with 2.8k fills. Sorry, I'm still figuring out my chrony lighting situation so I don't always get the best strings but the gun was shooting 15.89gr JSB's at a high around 900fps and stable around 885fps, easily hitting between 25-28fpe out of the box (not bad)
Moving forward, I opted to look into 2k fill tweaks for the b50 since I do not have a 4500psi tank (yet)
I was lead towards the "book" found here:
http://www.toolfarm.no/ViewFile.aspx?itemID=430
And placed an order for the McMaster-Carr spring, part #94125K125
They come in a 5 pack and are relatively inexpensive.
In the next section I'll discuss installation procedure for the spring and my terrible chrony work will rear it's head yet again.