Re: How to determine Barrel Top/Bottom
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brodie</div><div class="ubbcode-body">wnroscoe, do you use a cathead on the rear of the spindle? If so do you mark the barrel for timing before adjusting the cathead? (I'm imagining this is how it would have to work?) </div></div>
Yes, other wise known as an outboard spider.
The method I use to indicate barrels dictates use of the outboard spider. When doing the breech work I work by the breech end only using the four jaw and spider to indicate the barrel. The muzzle is worked the same way but only after the barrel is changed around in the lathe. I work at the chuck, in the headstock, for all operations.
The range rod is read at two spots to achieve this, one at the breech and one about .250" from the opposite end of the rod. To make the rod run true at the breech I adjust the chuck and to make the opposite end of the rod run true I adjust the spider. Once running .0002" or tighter I thread and fit the barrel to the receiver but don’t cut the bolt nose recess. At this point, the timing mark I spoke of earlier is lined back up and if needed, cuts are made to the barrel shoulder to allow the receiver to screw on farther if needed until TDC of the receiver is at 12:00.
With quality barrels, the most TIR I've seen at the muzzle after all is indicated is .010", about the thickness of a standard business card. This is one of the major reasons why I only promote two barrel manufacturers on my WWW.
I've installed barrels from just about all of them. Based on my own personal observations and experiences, Krieger and Bartlien are the most consistent barrels on the market, PERIOD!! Barrel to barrel, both makers barrels machine the same, every time. Consistency is the name of the game and both have it down to a science. Look at the 1000 yard BR results and equipment list from the Williams Port 1000 yard results. Accuracy is accuracy and the results speak volumes.
