Butch,
I'm trying a few newer methods to set up for chambering as I know there has got to be a more accurate method than I have been using. In the past I would set the barrel between centers, and cut a straight section at the muzzle leaving a shoulder of about .100 followed by a short straight section that would be used to fun an indicator off of. A very light clean up cut would be taken at the chamber end so the steady rest would be riding on a point concentric with the bore. Then the muzzle end would be held in a 4 jaw and indicated off of the short band that had been turned earlier. The chamber end would be held with a center in the tailstock, and the steady rest set. It was a quick setup method that in conjunction with a manson floating reamer holder would give some very good results for the type of rifles I have typicaly built. (Live varmint, and predator rifles typically shooting in the low .3's)
On the past couple I've done I set up through the head stock. Initially they are indicated as close to zero as I can get at the muzzle and chamber ends using 2 indicators on the exterior of the barrel. This is only intended to get things close enough to indicate off the bore with an indicator with a longer probe. When indicating on the bore I indicate at 2 points on the chamber end. One point just inside after cutting about .75 off, and then the second point as far in as I can reach about 2". I make any adjustments needed to get these 2 points running on the same axis with each other, and do my threading and chambering from that point. The theory being that the bullet will be starting into the bore on the same axis as the bore. I haven't had to adjust out more than .001 over those 2" on any of the barrels I've used this method with. In this particular case it was within .0002 already so I left well enough alone. I'm still using the floating manso holder as my tail stock is right at .008 high, but square and in alignment is all other aspects. The Manson holder corrects for this very nicely.
I went to use the same method to align off the last couple inches of the bore for the crown removing 1.25", and couldn't get it to align. The bore started straight, and then developed a curve that got progressively worse as it neared the muzzle. The bore is exactly in the center of the barrel at the muzzle, but runs out rapidy as you go back from the muzzle. With the barrel spinning in the lathe the chamber, throat, next inch or so of the bore, and the bore at the crown appear stationary. The interveening area looks like a jump rope.
What I ended up doing to cut the crown was to indicate off the outside of the barrel at the chamber end, as it had already been dhown to be concentric to under .0002 with the bore. At the same time I indicated off the bore at the muzzle end, and when both ends were showing effectively no needle movement I crowned the barrel at that point.
The other barrels I have used this method with I have been able to setup the chamber to be inline with the first couple inches of the bore, and the crown to be square to the last couple inches, but this one just had too much curve in the last couple inches at the muzzle to make it happen. I tend to cut all my crowns as recessed 90 degree because I feel it is the easiest to make clean, sharp and concentric. It also works well to protect the crown on rifles that tend to spend a lot of time riding in the truck or in the field.
for the
