Richard, the rail I shot last weekend was chambered exactly like I described, it was so straight way up in the bore it was surprising. I could run the Grizzly rod 4 inches past the throat at 90 degree intervals and it wouldn't hardly wiggle the Interapid test indicator. The muzzle had about a half thou of runout. So I chambered it and you guys saw it shoot. That was my second ten shot rail match. I like straight barrels!
JerrySharrett
Senile Member
While it certainly doesn't hurt to have a straight barrel many winning shooters have proven curved barrels can shoot well too when properly chambered.
.
Greg Walley
Member
Good explanation Mike. I think it is more important than what many shooters think to control the release point in relation to the tenon, so the whole length of the barrel is perpendicular to the face of the action. I also have evidence that is is very important to have the first few inches in front of the chamber to be concentric with the the chamber/bore. Usually this isn’t much of a problem with barrel blanks that come from the “custom” barrel makers these days, although it can be if one must cut off an appreciable amount from the rear of the barrel. Therefore, even when chambering a blank through the headstock, I think it’s beneficial to turn a journal on the rear of the barrel blank that is concentric to the bore - between centers, as one does when chambering using a steady rest.
Greg Walley
Abraxas LLC
Paul, as I said
earlier, I indicate the throat-crown for my data points. But what I do is check ahead of the throat by the length of the base to ogive of the bullet. If for some reason there is an issue I'll move up the bbl to another spot.
I can do that because the first thing I do is cut the chamber. I don't cut the tennon or threads or anything until the chamber is fully done. I have had great results doing it that way.
I have had people tell me the chamber will grow when the tennon is cut. I haven't seen that according to cerrosafe casting before and after. I don't do castings anymore because it's a PITA. But I did on the first bbl's because I thought the chamber would be bigger.
I just like the flexability of putting the chamber where I want it (within reason)
Richard
earlier, I indicate the throat-crown for my data points. But what I do is check ahead of the throat by the length of the base to ogive of the bullet. If for some reason there is an issue I'll move up the bbl to another spot.
I can do that because the first thing I do is cut the chamber. I don't cut the tennon or threads or anything until the chamber is fully done. I have had great results doing it that way.
I have had people tell me the chamber will grow when the tennon is cut. I haven't seen that according to cerrosafe casting before and after. I don't do castings anymore because it's a PITA. But I did on the first bbl's because I thought the chamber would be bigger.
I just like the flexability of putting the chamber where I want it (within reason)
Richard
jackie schmidt
New member
Richard, I rough out the tenon within about .010 of finish diameter and length and then establish the best chamber I can in the barrel in alignment with two predetermined spots, that being the area where the throats will form, and the muzzle.
All subsequent machining operations are then machined true with this chamber.
coyotechet
Chet
Six or seven years ago I took 3 what was good shooting rifle barrels now shot out from 3 different top barrel makers. Marked a straight line on the outside of each barrel then cut them into four inch lengths. What I found was they all had more than one curve, don’t really remember the numbers in thousands of the bow of the curves. That is why from that day forward I always indicated both the Chamber end and the Muzzle end 2.5 to 3 plus inches into the bore as I cut them and let the other end go wild. I want the Throat and Chamber along with the Crown to be as straight to the Bore as I can get them.
One time I cut the muzzle end off 5 or 6 inches to crown the new chambered barrel and found the bore was off center too much and called the maker they sent me a new barrel and said two trash the bad barrel.
Note: This was a light weight barrel around .650 at the finished crown and it showed up in the finish crown.
Chet
One time I cut the muzzle end off 5 or 6 inches to crown the new chambered barrel and found the bore was off center too much and called the maker they sent me a new barrel and said two trash the bad barrel.
Note: This was a light weight barrel around .650 at the finished crown and it showed up in the finish crown.
Chet
Barrel drilling is not exactly a rigidly guided thing.
The actual drill is the diameter of the hole and a long thin piece of drill rod in most cases.
You can easily flex a length of drill rod .20 in in diameter and 30 inches long.
The slightest variation in the material being removed will put a sideways load on that long bit and it WILL flex.
That is the reasoning behind my comment that a straight hole is more likely from very uniform material.
And to add to that we add things to the metal (like sulfur in stainless) to make chips from machining the material
break off in smaller pieces.
Otherwise stainless is a very 'gummy' material and sticks to cutters and makes long chips.
They will not clear in the narrow passages available in a 'gun drill' bit for them to exit from the cutting 'face' way
down in that hole through the narrow flute in the side of the bit.
mike is right about point of impact being close while putting the muzzle in front of the chamber. For me though, thats small potatoes. It doesnt take any effort to make an adjustment with the scope. I make my adjustments while breaking the barrel in. Even with the Gordy method, if you clock the bore to 6 or 12, your never more than an inch or so out anyway. Im not going to say one method is better than the other. In my mind though, we know the bore isnt straight, so why in the world would i indicate 20 something inches away from the work? I cant personally picture that. Stubborn maybe?? Lots of good shooting barrels chambered both ways, thats for sure. Lee
Pete Wass
Well-known member
I indicate both ends
mainly so the muzzle end wont try to whip out of balance. I have a spider back there and just keep it close to being concentric but not to the degree I do the chamber end. Of course I only do one or two barrels a year sooooooooo.
Pete
mainly so the muzzle end wont try to whip out of balance. I have a spider back there and just keep it close to being concentric but not to the degree I do the chamber end. Of course I only do one or two barrels a year sooooooooo.
Pete
Mike Bryant
Active member
Lee, I’m not saying one way is better or worse than another. I just haven’t seen that it makes a difference which method that is used as to how the barrels shoots when we are done between the way I use and yours. I think a lot of what we do is in our heads. I think as long as the freebore is centered in the bore when we’re done, the barrel has as good a chance of shooting to match winning capability as another one indicated in by another method that also has its freebore in the center of the bore. I think it’s real easy to overthink chambering barrels. We are so used to indicating in to as close to zero runout as we can get, that we forget as to what tolerances we are using. What we all want to do is to have barrels that won’t shoot be very very few and very very far between. What I have found over the years is that there are lots of ways to get to the result that we want. I’ve always recommended that people use what method works for them. It’s one case where one way isn’t right and another wrong, just different.
JerrySharrett
Senile Member
Pete Wass
Well-known member
I had an interesting thing happen the other day
I had an old cull barrel from a previous rifle and decided to set it back for a rifle with a different tenon thread. Had the room to do it. I dialed the barrel in to where I had .000" with a .0005" Best Test indicator on a straight pin that fit the hole well.
I noticed the screw that holds the bushing on the reamer seemed on the skinny head size but seemed to hold the bushing on fine by finger feel, at least. On the third retraction of the reamer I noticed the bushing was not present on the reamer. Upon investigation, I found it wedged in the bore.
I went to the next smaller bushing and proceeded to finish the chamber. When I had finished and had blown the oil out of the barrel. I borescoped the chamber area and found that I had cut two lands down noticeably more than the others, both side by each!
My conclusion here is that I found a crook in the bore, that is sometimes spoken of and that the lands that were cut more were proud in the crook.
Am I way out in left field here ? I had a barrel in the past done by a Smith of some note that looked similar. The barrel shot OK but wasn't a hummer by any stretch.
Pete
I had an old cull barrel from a previous rifle and decided to set it back for a rifle with a different tenon thread. Had the room to do it. I dialed the barrel in to where I had .000" with a .0005" Best Test indicator on a straight pin that fit the hole well.
I noticed the screw that holds the bushing on the reamer seemed on the skinny head size but seemed to hold the bushing on fine by finger feel, at least. On the third retraction of the reamer I noticed the bushing was not present on the reamer. Upon investigation, I found it wedged in the bore.
I went to the next smaller bushing and proceeded to finish the chamber. When I had finished and had blown the oil out of the barrel. I borescoped the chamber area and found that I had cut two lands down noticeably more than the others, both side by each!
My conclusion here is that I found a crook in the bore, that is sometimes spoken of and that the lands that were cut more were proud in the crook.
Am I way out in left field here ? I had a barrel in the past done by a Smith of some note that looked similar. The barrel shot OK but wasn't a hummer by any stretch.
Pete