Prefitt Criterion Barrels and Indexing

Couple of years ago I bought a prefitt 6.5x47L Criterion barrel from Jim, great service and the barrel looked nice. However, it never shot as well as I thought it would and/or should. I did not attempt to index the barrel, just adjusted the headspace with a piece of formed brass. Just got a McGowan 6x47L and it is showing more promise and I headspaced the same way, with no attempt to index. Has anybody else been under impressed with a Criterion barrel?

I have been reading and find folks have a problem with the Savage nut because you cannot index. There is no reason you can't index a Savage, you will just have a wildcat, you simply screw the barrel in or out to index and you have to fireform and really have a wildcat. Has anybody indexed a Savage barrel and did you see a accuracy improvement?

Bill

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Has anybody else been under impressed with a Criterion barrel?

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Not so far but my sample size has been small.

First statmen is a bit odd beacue I have not read of people having that problem.

You seem to be mixed up on indexing and head space.

Index is down with all rifles that do not have adjustable head space like Savage (very few are like Savage though Remington can be converted)

Actual indexing accomplishes several things. It made sure the barrel was correctly tight but could be removed (i.e. an index mark and not an opinion)
it sets close head space (chamber reamer than finalizes it) and it got the iron sights (which all guns used to have) in correct alignment as well

I am not sure how Savage goes about their sight index with guns that do have iron sights.

However, scoped only rifles you are setting head space no indexing. Head space is a pretty confused issue, it can be very close, it can be so long that you almost hit field reject limits.
I don't know how long is too long but I have shot and reloaded a lot of brass in a Model of 1917 Enfield and done just fine and that reaches field reject.

303 chambers are worse yet as they are long and very loose. 3 times and brass is done. Still fine for one shot use.

So you don't really have a wildcat, you have a fire formed piece of brass that might only work in your rifle unless you bump the shoulder back a lot (long)

The experts keep it very tight, but it is not considered Wildcat its just a very tight 308, 243, 6.5 etc.

If the headspace is really tight (snugged up against a go gauge) than that brass would fit in another normally head spaced gun just fine without resizing.

One firing would move it out more, but its not a wildcat either, just a more normal piece of brass for the cartridge.

A wildcat is a significant change (ala Ackley Improved) be, be it blown out shoulder or a caliber change (using 30-06 case to convert to 6.5 caliber)

That in turn would not fit (or work) in any 30-06 with a normal chamber.

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Originally Posted by wbm

Not so far but my sample size has been small.


Here is an article about Gene Beggs indexing experiments. Noticed on the comments by the editor there was mention of Savage barrels.


http://bulletin.accurateshooter.com/2008/10/beggs-devises-indexing-system-for-centerfire-barrels/

Editor: Beggs contemplated using a Savage-style barrel nut (rather than conventional shoulder). Problem is that the chamber still moves toward the bolt face as you screw the barrel in. Thus headspace is not constant as the barrel is rotated to different, indexed positions.

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Ditto on Criterion: All mfgs throw poor barrels out. More the barrel costs less likely to happen. I find that if it wont shoot its me , setup, ammo, not the barrel.

I saw they discussed changing POI but not accuracy, not sure what that all really means.

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I saw they discussed changing POI but not accuracy, not sure what that all really means.

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Me neither. Before they folded a few years ago Precision Shooting Magazine frequently did in-depth articles about things like indexing....even brass indexing. Seems some liked the "curve" at 12 o'clock, others at 6 o'clock, with a few opinions of other orientations...often ended up with readers like me saying..."who the heck knows". Sure do miss the publication though.

You'd use the same methods you would with a tenoned barrel, you'd need the reamer and go deeper if you need to index from 3 to 12 oclock. At 20 tpi that would be .050" per full turn.

Glad everyone is happy with their Criterion barrels. Now I am wondering more than ever about harmonic indexing. I think 90 degrees off would effect accuracy, i.e. group size. Darn, something more to worry about.

RC20, I am talking about harmonic indexing. Something I had never thought too much about. I have fooled with TC's and to get them to really shoot you usually have to index; case to chamber - sizing die- seating die and even priming. Learned all that from the Schuetzen guys.

Scott, The furthest you would be off is .025 long or short to get to 12 o'clock. And only .0125 if you didn't care if you were at 12 or 6 o'clock and just wanted the harmonics vertical. But how do you know where 12 o'clock is when you are standing there with the barrel in your hand? I am over on Accurate Shooting asking that very question.

I am going back to one shot groups, that way I'll always be happy!

Bill

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I am going back to one shot groups, that way I'll always be happy!

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Tried that. Works quite well.

When they speak of 'indexing' its putting the curve of the bore where its pointed down or up at 6 or 12 oclock. All barrels will have some curve or a banana shape to the bore, an indicator rod is used to determine where the curve is, barrel is marked and when the final reaming for headspace is done the barrel is set up to put the index where desired. Its NOT referring to a bore center that isn't concentric to the OD.

Its another anal thing some people do. For the majority of us it ain't worth worrying about. Unless someone can prove to me it always stays that way regardless of heat, pressure, natural frequency or any other variable I ain't gonna worry about it. Where its true value might lie is with scope centering for long range.

Scott, After spending yesterday on the computer reading about harmonic indexing, I came to the conclusion it was not worth the effort. I think learning to read the light rings in a barrel to tell if it is straight and buying the better barrels is more productive. Read about barrels that were crooked but shot light out!

The CBI barrel I started this thread about shoots .5 to.75 MOA but I hoped for better. Wacked off the barrel and put a brake on it and improved it a little. Now it is more consistent with all loads and the better ones are solid .5. I am back to barrel length being a factor. I don't think the brake helped, but cutting off 4 inches may have. I have a couple of 15 inch hand cannons that shoot much better than I can. Those are the ones I index load for.

Bill

Well that same magazine (never saw it but did red the Houston Warehouse article) says that the barrel needs to be exactly 21 3/4 or 20 3/5, have to dig it up!

The other major aspect was hold consistently, free recoil, modified or whatever, consistent hold.

I am working hard on that, some days I can shoot one shot after another, it all feels right and they go in 1/2 or better.

Other days I spend 2 minutes between shots trying to get it correct and I get 11/16 groups, go figure.

There is a lot to be learned for the BR guys! I never realized how bad my technique was till I got a 36x BR scope. .5 groups are impossible if you can't hold inside of an inch! Next time you are at the bench, get all set up and just dry fire....... if your crosshairs move, there is no need to waste ammo! Like you, some days I can set the gun up, fire and move the gun back and be right on the bull and the next day when I move the gun back, I am 6 feet off. OR, have 3 shots touching, reload 3 more shells and shoot another group that is touching but is a half inch away from the first. You know it is because of the way you set the gun up.... but am sure you did it exactly the same! AND THEN I READ ABOUT HARMONIC INDEXING.

Bill

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Originally Posted by bsekf

Couple of years ago I bought a prefitt 6.5x47L Criterion barrel from Jim, great service and the barrel looked nice. However, it never shot as well as I thought it would and/or should. I did not attempt to index the barrel, just adjusted the headspace with a piece of formed brass. Just got a McGowan 6x47L and it is showing more promise and I headspaced the same way, with no attempt to index. Has anybody else been under impressed with a Criterion barrel?

I have been reading and find folks have a problem with the Savage nut because you cannot index. There is no reason you can't index a Savage, you will just have a wildcat, you simply screw the barrel in or out to index and you have to fireform and really have a wildcat. Has anybody indexed a Savage barrel and did you see a accuracy improvement?

Bill

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Good morning,

If your Criterion barrel isn't performing to your standards, feel free to give us a call and we'll be more than happy to help troubleshoot, repair, or replace the barrel if necessary. My first suggestion would involve purchasing a set of go/no-go headspacing gauges to aid in assembly. Holding those tolerances can be fairly important to ensuring proper function and cartridge performance. With Savage pre-fit barrels indexing is normally less of a concern, but the engagement surface of the receiver/barrel nut surface is definitely something to keep an eye on. This is usually more of an issue with the stock barrel nut, which can be remedied by running an NSS replacement.

Please let me know if there is anything we can help with on that barrel. We'd be more than happy to provide assistance in getting it squared away!

Good response by CriterionBarrels.

308win Shilen barrel I installed with the stock recoil lug and barrel nut, the accuracy was a'ok sub moa. I re-installed in into a different action (a southpaw action for my brother) but this time I used aftermarket thicker recoil lug and aftermarket barrel nut and now it shoots like a dream.