hogger,
Did you order the magazine I suggested?? It has all the information you need about the 6mm-250. It includes necking cases down, how to, dies and where to get them...The rifle in the article used a barrel with a 1 in 9 twist and would not group the lighter bullets very well. If I were building one, I would probably go with a 1 in 12 twist depending on the general size bullets I planned to use. David Kiff of Pacific Precision Grinding, Inc. in White City, Oregon builds all of my reamers for me and he does an excellent job. I usually send him a "dummy" cartridge with a bullet seated in the case at the length I would like for it to be and he will cut the throat exactly to that length. I also request him to cut the diameter of the throat .0002 over bullet diameter. There are a couple of other things you might want to think about when having the reamer made... If you need any more information, just ask and I'll be glad to help...
George

Also, pac-nor already has a 6mm-250 reamer. They used it make mine. Send your action to them and they true it, thread and chamber your barrel (I like the standard match grade SS with a bead blasted finish). Will run you about $400 or so plus shipping. Mine is a mountain rifle I had built for antelope - it has 1-9" twist and groups extremely well with the Nosler 90 BT and Speer 105. If you plan to shoot only 55-70 gr, go with a 12" twist. If you want to shoot 55-90, go with an 11" (pac-nor makes a 3 groove 11 I believe). If you plan to shoot 55-100, get a 10". If you plan on shooting only big game bullets (90-105), go with a 1-9".

The 6mm-250 is a very pleasant wildcat. Cases are easy to make and the parent brass is very easy to find. Accuracy is top notch and ballistics are surprisingly close to 243 numbers; the 6mm-250 runs at slightly higher pressures (53,000 CUP versus 52,000 CUp for the 243). I've had good results with Re15.

Good luck.