Bore indexing

[Matt P]

my instinct would be to go for 6.00 o'clock.
bruce.

Of coarse it would !!

[bruce moulds]

matt,
i must confess to not being up on this subject.
bruce.

[Rich4]

my instinct would be to go for 6.00 o'clock.
bruce.

Funnily enough I have one here which through a series of events ended up indexed to 6:00 in one action and shoots awesome so far, I’ve not wrung it out yet

[KHGS]

I actually prefer "straight" barrels , many of these do exist by the way, much, much more than 20 years ago. With this talk of indexing, no one has mentioned what to do with straight barrels, how do you all "index" them, just askin . I have seen very few Maddco or Bartlien barrels that do not run true. Krieger not so much, but very good in their larger profiles. Swan parallel barrels are very straight. The quality of the barrel is paramount, but this is of no value if the 'smith does not do a good job. "A good barrel will not work if the 'smith does not do it justice" conversely " a good 'smith will not make a bad barrel shoot well". These are the observations of an elderly practical gun smith for what they are worth.
Keith H.

[Rich4]

The term straight is relative, the worst one I have is a Maddco, but I didn’t buy it from Nev so I don’t know what happened in between him and I, but it’s .038” @ 28” with the chamber running true, interestingly enough it’s also the 6:00 one, I’d love them straight too but I think all barrels are curved (not bent) It’s just a matter of degrees, indexing to me is just aligning the natural curve to the vertical plane, however without proof I feel it’s probably closer to a helix than a straight curve after watching a drill or two, always good to hear from someone who has fitted more barrels than I’ve even seen

[Gyro]

I actually prefer "straight" barrels , many of these do exist by the way, much, much more than 20 years ago. With this talk of indexing, no one has mentioned what to do with straight barrels, how do you all "index" them, just askin . I have seen very few Maddco or Bartlien barrels that do not run true. Krieger not so much, but very good in their larger profiles. Swan parallel barrels are very straight. The quality of the barrel is paramount, but this is of no value if the 'smith does not do a good job. "A good barrel will not work if the 'smith does not do it justice" conversely " a good 'smith will not make a bad barrel shoot well". These are the observations of an elderly practical gun smith for what they are worth.
Keith H.

It amazes me they are as straight as they are re drilling a small hole so deep !
U say some are straight Keith ? Are u ONLY clocking the barrel at each end. All the ones I have chambered were not, as like Matt I clock only at the breach end plus some distance forward, the theory being the boolit at least gets to start it's journey aimed truely concentrically down the bores true axis. From then on it may travel a curve on its way to the muzzle. Then I just point the curve upwards and tell myself everything will be fine. From a purely logical point of view I would think it NOT good for accuracy dynamics to have the barrel pointing away to the side.

Plus clearly the more curvature is in the bore the worse the above mentioned 'problems' will be. And those problems are easy to theorize as being real, as likely to be having some effect.

But who really knows ? Probably we can add this to the great bunch of things in this game very hard to prove ......

Be nice if Frank could add some barrel maker comments here.

[pjifl]

It is very hard to actually measure and map out the straightness in a long bore.

The type of 'straightness' matters here. Does the bore gently curve or is most of the kink fairly close to the muzzle. It is the last few inches of the barrel that determines the direction of flight of the bullet.

Perhaps another thing to consider is your angle of dangle.

A 32 inch parallel barrel droops about 1/3 mm at the end due to gravity and with a heavy tuner this can increase to about 1/2 mm.
Of course this is always in the vertical plane. As far as barrel vibrations are concerned, this can often totally overshadow vertical errors after indexing unless the barrel is quite 'bent'.

Indexing to 12 O clock makes more sense to me. Any error in the barrel is then subtracted from natural droop.

None of this changes the fact that a barrel fitted with great care is always better.

Peter Smith.

[Wal86]

IMO if the barrel is that bad you have to index it, you don't put the f@#king reamer in..

There are more important issues to get right that are detrimental to accuracy, indexing isn't one of em.

[Gyro]

IMO if the barrel is that bad you have to index it, you don't put the f@#king reamer in..

There are more important issues to get right that are detrimental to accuracy, indexing is a long long long long way back on the list..

Great Wal, so when is it too 'bent' ? Do u have any numbers ?

[Wal86]

Ive said enough im not going down that path Gyro, turns into a pissing match.

Too many variables in the setup/measuring equipment used.

What im saying is indexing isn't detrimental to accuracy like a crown is...
(Indexing an average barrel won't make it a screamer..)

[Gyro]

All good Wal, I’ll just go and find a concrete wall to head butt now. Maybe Coronation Street is on tonite ….. alas.

[6.5x55ai]

All good Wal, I’ll just go and find a concrete wall to head butt now. Maybe Coronation Street is on tonite ….. alas.

Ha ha you could always watch Shortland Street if it's a headache you want.
Apparently it is no longer screened in Oz

[Kakaduthunder]

Another gunsmith’s perspective. I dial in barrels with a long stem indicator as Matt P describes. I feel this is the best repeatable method that is also logically the best method to me. As far as indexing the barrel, this is an F Class forum and shooters here are generally in the pursuit of extreme accuracy. Indexing a barrel is another step that tries to limit a potentially undesirable accuracy outcome. That is horizontal stringing or some other angle depending on where the unindexed barrel ends up on the clock face.


Do I do it for hunting rifles - no. Can an unindexed barrel shoot extremely well when well fitted and chambered, absolutely.

I think an accuracy gunsmiths job is to remove as many undesirable variables that are within his or her control. This is one of them and in the pursuit of extreme long distance accuracy should be pursued.

All this comes with a caveat, and that is what is the customers expectation and what are they willing to pay for. I find its funny when a prospective customer says someone will fit, chamber and thread for a muzzle brake for considerably less, why do you charge more? Its all about the time and steps you perform in the process. You can skip some steps and still produce a safe and accurate rifle that may meet the customers expectations however you have not done your absolute best. In the pursuit of tiny repeatable groups at long range, the Gunsmith should take every possible step provided the customer is aligned and is prepared to pay.

This is also one of those things that can never be definitely proved, kinda like blue printing an action, as you can’t keep all other factors consistent when doing a before and after test.

I also agree with the previous statement that this will not fix a bad barrel.

Just My 2 cents

[Gyro]

I have a real problem with your comments Mr Thunder because they are accurate and balanced haha.

But seriously what sort of time and dollar value difference would u say there is between an indexed and non indexed fit up ?

Regards Rob ( F Class wannabe )

[Kakaduthunder]

The difference

Dial in barrel at chamber end only, cut tennon and thread as per usual.

Establish someway to hold an indicator at the muzzle end of the barrel, which in the case of a 32 in fclass barrel is poking a fair distance from the back of the spindle. Establish the point where the ID is closest to the OD and mark this point. Install the action and precisely measure its angular position in relation to the mark you just established at the muzzle. Perform some maths to establish exactly how much you need to take off the tenon to get the alignment at 12 o’clock. Remove this amount and re check.

This takes roughly 20 minutes if everything goes well. Translate that to a gunsmiths hourly rate.

The comment about $$ was more related to the accumulation of many steps, you add 20 minutes here and there for other steps that others aren’t performing, and it adds up.

For an example I know a gunsmith that dials in a barrel with a short stem indicator (about 12mm long) at the chamber end. He then dials in the OD at the back of the spindle (yes you read that right the od) he then chucks up his reamer in a drill chuck and chambers. The results are not good but most people don’t know the process and would not be able to identify that a bad job has been performed. Repeat target shooting customers may be a problem. This individual still charges a considerable amount for his work.

I should also add that this does not pay my mortgage and I do this for fun so I take the time to do it right. I am also incredibly anal…….

John S