Indicating Barrel

[Tozguy]

In theory a barrel dialed in to .0001" should be more accurate than one at .001" but can the shooter tell the difference?

There is so much more to hitting the bull than just how the barrel was dialed in. It would be an onerous task even for experts to do a proper test and be able to answer that question.
Regardless, this statement sums it up well for me

There's many, many links in the chain between the lathe and the bullseye. There could be many deficiencies along the way. One deficiency that won't be is my machine work.

And once the barrel is dialed in there is the question of your reamer work.

 

[pontiac428]

We do all kinds of things to accommodate the problems with manufacturing. Imperfect chambering is why we fire form. Banana barrels or off-axis chambering is why we measure cartridge runout and index loads in the chamber.

If I had 2 minutes of inaccuracy on the firing line resulting from my hold, I'd pack it up and go home. A match winning hold is under a minute. That's why the 10-ring is 2 minutes across. You have that space to work in if your setup is perfect and you are proficient on the loading bench. In other words, there isn't more than 1/2-minute in the rifle to play with, so it needs to be right. Anything beyond that chalks up to wind reading skills and the fundamentals of marksmanship. That's why we chase the zero-tolerance dragon. Squeeze the accuracy out at every step, so that anything not hitting as called can be blamed on the shooter alone.

I don't like to think about my equipment in competition. I don't want to ponder my loads or my setup. I just want to mind my come-ups and work the wind. It should be simple as that... So we justify perfection to lay equipment thoughts to rest when the range goes hot. With that in mind, .00005 is better than .001 when doing barrel work on the lathe.

 

[mickri]

John is correct that once you get to the firing line you can't have any doubts about your equipment. If you do your scores will suffer.

 

[Ike Carlson]

On the other hand, overestimating your equipment will have you spending money chasing quality when it's really just you.
More common that you think. Just sayin....

 

[Tozguy]

Like the winner of a world class competition said when he was was asked what went into making his rifle so accurate........''I don't know, I just shoot it''

 

[Earl]

I compete in short range Benchrest (100-200 yards). The two greatest equipment factors after a quality action, trigger and stock are barrels and bullets. Only about 30% of the rifles at the line are capable of winning. Half of the barrels are carbon or copper fouled or they were not competitive when new. No amount of shooter skill can make up for a bad or fouled barrel. I was at a two day match last weekend. I started out great. 5 shot groups and 5 targets to a match. I got beat by less that 2 and a half thousands of an inch! (one shot out a little) The second day, my groups started to get larger. I clean my gun after every target but I was not cleaning effectively. When I got home and borescoped the rifle, I found severe carbon fouling. I was using an old lot of powder that was very "dirty." That powder has now been used as fertilizer.
Some shooters have "practice" barrels that have a high round count or were just not competitive in the first place. You can't learn anything with them. You shoot and then wonder if it was me, the barrel, or the conditions when the shot goes out of the group. I saw a shooter at the practice day come with a brand new barrel. He shot about 6 groups and took the barrel off and gave it to another competitor saying "You will never beat me with this piece of junk!" That guy is one of the top shooters in the sport and recognized very quickly that the barrel was not competitive. I have had a few barrels that wouldn't shoot competitively but it took me a lot longer to figure it out. I guess that what I am trying to say is that you have to have the best possible equipment and components just to be able to learn from your practice. I am very lucky that my best friend is a hall of fame shooter and when I think I have the proper load and setup, I ask him to shoot a group or two with my rifle. He will tell me immediately if I need to "make some changes" or "leave it alone." He will do that for any competitor at the practice day for the match. He wants them to be shooting their best when he beats them!

 

[epanzella]

If you use a range rod you're indicating in two places only a few inches apart so .0001 indicator would be handy. If you have the barrel thru the headstock and indicate on either end 26 inches apart .001 is pretty good. Of course, now you're indicating on the exterior of the blank and not the actual bore. This is why when I build a rifle the first thing I do is turn the exterior true with the bore. One end of the bore is always more concentric than the other because that's the end where the blank manufacturer started the gun drill. I put the worst end in a center at the tailstock end and turn it true with the other end in a 4 jaw. Then I switch ends and start doing 6 inches at at the chuck end at a time and keep choking up until the last ten inches or so gets me right to the tailstock. It's very important to put something narrow between the 4 jaws and the blank to allow it to pivot or the jaws will bend the barrel. Below is what I use but you can copper wire or anything like that. Of course I'm no gunsmith but the bolt action rifles I've built using the procedures above group 3/4 MOA to 200 yds. I did build one break open that groups about twice that but deer don't walk away from it so I'm good.

 

[INTJ]

I shoot 1000 yd BR. I got my PM1340 GT a couple years ago primarily for chambering my BR barrels. In LR BR there are no compromises made in equipment or shooting technique. While a 1/4 minute barrel is good enough, it needs to be able to shoot 1/4 minute 5-shot groups at 1000 yds in good conditions. Ten shot groups need to be under 1/2 MOA at 1000 to be competitive.

I was able to have immediate success with barrels I had chambered. The best barrel I chambered shot a 3.855" 10-shot group that was a 100-3x. I initially cut the chamber too tight and then had to polish it out on a friend's lathe while mine was in storage recently while our house was being built. I over polished the chamber. However, because I had the barrel dialed in well and cut the throat straight it shot well.

I messed up another barrel a couple years ago by making a rookie mistake and got the back of the chamber too large. Again, the throat was straight and this barrel shot well too.

So in my limited experience, the throat are being straight is the most important part of the chamber job, and we get a straight throat by making no compromises while dialing in the barrel.

 

[Tozguy]

by making a rookie mistake and got the back of the chamber too large

I hesitate to ask what happened and how but it would be good for us to know.

Did you have to make a custom resizing die for that chamber?

 

[IamNotImportant]

I hope to get time to chamber two blanks from the same manufacturer and find out if there’s a noticeable difference in accuracy. I will use hand loaded ammunition and the same receiver to eliminate as many variables as possible. I was just wondering if anyone has tested this yet?

Not every barrel will shoot the same they say, but one year when at Camp Perry, in the shoot off for the Leech Cup at the National Long Range Championships, watched John Whidden's rifle trigger break in mid string, got up and walked to his truck and pulled out another rifle. He didn't change ammo, that rifle shot the same load as the other. He went on to win.