Thanks a lot for that Simonsaorsa, That's quite a good article and has confirmed a few ideas I was toying with (ie the longer free bore, and case forming)

Hopefully I will be able to replicate the accuracy and velocity Boxford got from his rifle. I'm still thinking I might stick with the 100gn projectiles just to keep on the safe side.

500Nitro, thats ok, it will be a while in the build stages yet so i've got quite a bit of time up my sleeve.