Originally Posted by Hired Gun
No disrespect JE. I know you are aware of the different chambering methods but straight barrels are the exception. The method you are using will not reveal the curve in the bore. Chamber run out will not show up either until the barrel is dialed in front of the throat. I guess I look at barrels as if they are all only 2" long.
The technology currently used to deep hole drill barrels just will not produce a perfectly straight bore. I believe EDM would do it but at what expense? If I were to return every barrel that had a curved bore I would be sending 99% of them back, I would spend the rest of my life waiting on barrels and if I kept sending them back I would eventually get black listed. I'm no stranger to sending them back. There are a few companies that I avoid completely now because they just can't seem to be able to get me a decent one.
Unless the barrel has an exceptionally straight bore, the method you are using to chamber I can spot with my bore scope in just a few seconds and on my lathe in a few minutes. Rifles have been built that way for years and do shoot. After bore scoping lots of sub 1/2MOA factory rifles with really crooked chambers I question just how important getting the bullet into the lands perfectly square really is. My experience though a fraction of yours is undeniable that when a barrel is dialed on both ends at the same time a tenth indicator will only run true right where it was dialed. Move in 1" and it will start showing the curve in the bore.
By dialing in one end at a time I can compensate for the curved bore and get my chamber, perfectly in line with the "bore". (throat to 2 inches farther) To overcome the curve in the bore where the chamber is I have to single point the chamber area to bring it inline with the throat and 2" farther in area that the barrel is dialing into. Otherwise the reamer will just follow the curve in the bore and make the point of dialing in on the throat and 2" into the bore pointless.
This gets the bullets straight into the throat as possible and on the crown end I dial in the last 2" and cut the crown and install brakes in line with that. Accuracy wise we are having incredible luck. Look what Tumbleweed has been doing with the 300 RUM we did for him. I believe he is a some kind of long range savant or something. It's along the line of .2 MOA to 1300 yards. Retumbo or H50BMG in 32" 300 RUM?
None Taken Shawn.
With the range rods in the bore "on each end" if you move the indicator and it changes you are right.
it is not a straight bore and depending how long your rang rods are the barrel run out will be more than the reading.
With the new technology , a good barrel maker can do amazing things with a barrel and produce
consistent quality If he wants to. Straight bores are not as hard to produce now as in the past when barrel straightening was the norm, and an art of it's own.
As far as experience goes you may have more than I do. I just demand the best quality I can get
because it helps me. (As a Sage gunsmith on this site says, "You cant make a silk purse out of a sows ear".
There are many ways to do things and I only use the ones that work for me. I don't claim to be able to take a poor quality part and make it work great, so I don't use them. With this philosophy I have been able to produce sub 1/2 MOA rifles consistently with most shooting under 1/4 MOA and some under 1/10th MOA. (4 of my personal hunting rifles will shoot under 1/10th MOA).
If I had to make a living at this ,I would probably starve because I take so long to set everything
up before I start, but being retired I can afford this luxury.
J E CUSTOM