Phorwath, I thought I was the only one silly enough to build a barrel burner like this...
I can't help ya much, but I built a 25-300 Weatherby with a 28" Shilen. I worked up some quick loads for deer season and this is all the data I have right now.
Fed 215 GM
81.5 gr of Retumbo
Berger 115 VLD
average velocity 3700
accuracy at 300 under 1 moa.
Also have this.
same as above with
80 gr of Retumbo and a 110 accubond @ 3720 and a few started to show pressure. This load was not as accurate.
Let me know how you make out as I need to do more work with mine. I am not impressed so far. I could get close to these velocities with a standard .257 Weatherby.
If you have a rifle chambered like this ........ Well that explains you opinion on rangefinders...