So, how much accuracy does a fitted bolt really add to a precision rifle.  All esle being equal, what kind of changes would you expect if the "fitted" bolt was replaced?

-- Nothing that you would notice.

I'm just curious since some of the top barrel makers ship their barrels with the headspace fitted specifically for the included bolt.

----5.56/.223  barrels ship with headspaced with batches of bolts that were checked to fit on the tighter end.  When I receive 15 5.56 barrels for WOA, I receive a baggie with 15 "fitted" (not matched) bolts.  

AR10 bolts/barrels are more finicky, they usually come with matched bolts.

Mostly the "matched" bolt is just bullshit from the dealer to make the buyer think they are getting something extra.  I've seen more than a few uppers/barrels from dealers with "matched" bolts and I have never been able to find any marks on the bolt, to "match" them to a specific barrel. If you bought a "matched" barrel and bolt take a close look at your bolt and see if you can find any markings.  On the AR10 bolts from WOA, you'll see a 3 digit number electro penciled which matches a number stamped on the barrel over the chamber.

Has anyone tried this to see what kind of accuracy changes they get?  Someone should take three bolts--one fitted for the barrel and two not--and have them blindly installed (have your buddy do it) to see if you can spot the "fitted" bolt.  What are the chances?

---You would never see any difference.

Quoted: So, how much accuracy does a fitted bolt really add to a precision rifle.  All esle being equal, what kind of changes would you expect if the "fitted" bolt was replaced? I'm just curious since some of the top barrel makers ship their barrels with the headspace fitted specifically for the included bolt. Has anyone tried this to see what kind of accuracy changes they get?  Someone should take three bolts--one fitted for the barrel and two not--and have them blindly installed (have your buddy do it) to see if you can spot the "fitted" bolt.  What are the chances?

THE TOLERANCES TO WHICH THE BOLTS ARE HELD IS KEY HERE. IF THEY'RE ALL NEW, ALL WITHIN 1/10,000 OF AN INCH OF ONE ANOTHER, I'M SURE YOU WOULD NOT SEE A DIFFERENCE. IF ONE HAS SEEN 5,000 ROUNDS FIRED, IT WELL COULD MAKE A DIFFERENCE.

I AM QUITE CONFIDENT THAT THE TWO CUSTOM BARRELMAKERS WE USE, FRANK WHITE OF COMPASS LAKE AND JOHN NOVESKE OF J-N RIFLEWORKS, ARE MEN OF THE HIGHEST INTEGRITY AND ARE NOT SELLING A PIG IN A POKE EVERY TIME THEY SUPPLY A FITTED BOLT TO A BARREL.

WES GRANT
M.S.T.N.

If you are talking to a benchrest shooter, about the fit bolt in his 6XC, shooting carefully assembled hand loads - soft seated(final seating is done when the bolt closes the bullet against the lands), when fired from a vise bolted to a bench, it matters.   Consistancy of chambering a round in a bolt gun is one thing, an autoloader is another.  That fit bolt will lock up the same evertime a round is chambered.

An auto loader isnt even in the same ballpark. A bolt fit to minimum headspace will lock up more consistantly.  But you are splitting a hair so fine, you would never know it (unless you were backing out primers because the headspace was so far off). Auto loaders have too many things going against them. No repeatability of chambering, bullet setback, bullet jump, shifting of recipricating weight, magazine feed,  the little variables are too many to add that it would ever matter, or you would ever notice.

Buy a set of head space gauges for your AR, then get a few differnt bolts that all "pass".  Swap those bolts in with your "fitted" bolt and you will never see any difference in accuracy.

BTW - All the production WOA barrels shipped with a bag of bolts, actually come from Frank White at CLE.  Do a search of range reports on any of those barrels, if you want to know how they shoot.

The bolts we get with barrels that CLE does for are serialized to each barrel.  They may come in a bag, but they are numbered to match each barrel, not the batch.  They also can supply bolts that are within tolerances but not individually headspaced.

There are different ways to control this. Lothar Walther hones all their chambers and they presort bolt heads and barrel extensions to very tight tolerances. They can hone them to a minimum, and consistent headspace dimension this way and not need to mate a particular bolt ro a particulaar barrel.  

While it is hard to see accuracy differences at shorter ranges, I have seen them at longer (beyond 300 yard) ranges. No true empirical evidence, only anecdotal, but less than perfect headspace, even in a semiauto, seems to result in higher velocity variations, which translate into vertical dispersion at longer ranges. True, there are a lot of variables that may be present. Single loading versus loading from a magazine can yield vastly different results in guns not set up properly. But this only means that it is harder to identify where a variation is coming from, not that it isn't there. While the majority of AR shooters may not detect the difference, it is still present in many cases.

If I never shot beyond 1-200 yards I would not even think about it.  Beyond that, why not use every advantage you can get?

Cant say I notice the difference between guns I have that came with fitted bolt, and guns that have not, however I can say my Compass Lake Krieger barrel came with a fitted bolt, both barrel and bolt had the #18 etched in them. I presume this to mean that bolt was speicifically fitted to that barrel.

Quoted: Beyond that, why not use every advantage you can get?

Anyone who thinks it gives a real advantage, needs to spend more money on practice ammo.


Quoted from John Holliger

As the bolt and ext wear in, you are going to gain about .0005-.001" of headspace anyway. And I have proved it to myself many times, that headspace has absolutely no effect on accuracy.

Considering how many Regional, State, and National Titles John has won, along with the number of  people shooting his equipment who have stood on the winners podium, its an obvious clue to me.

Quoted: Considering how many Regional, State, and National Titles John has won, along with the number of  people shooting his equipment who have stood on the winners podium, its an obvious clue to me.

While I dont know enough to contradict anything said, and without trying to imply that a fitted bolt helped, Im still genuinely curious to know if Mr Hollinger or any of the others got to the podium using guns that didnt have the above mentioned "fitted bolts"?

Quoted: Quoted: Considering how many Regional, State, and National Titles John has won, along with the number of  people shooting his equipment who have stood on the winners podium, its an obvious clue to me. While I dont know enough to contradict anything said, and without trying to imply that a fitted bolt helped, Im still genuinely curious to know if Mr Hollinger or any of the others got to the podium using guns that didnt have the above mentioned "fitted bolts"?

Thats the point of AR bolts, they are all "fitted".  Bascially all a "matched" bolt is, is a fitted bolt serialized to a specific barrel.

PS There's no "n" in Holliger

Quoted: Quoted: Thats the point of AR bolts, they are all "fitted".  Bascially all a "matched" bolt is, is a fitted bolt serialized to a specific barrel. Can you clarify what you mean when you say they are all fitted?  Are you saying that there is no difference between fitted and non-fitted bolts or just that the difference is not significant in terms of accuracy?

Basically, yes. If the bolt passes when gagued, its fit.  Its that simple. And there is no difference in accuracy.

If I was turning a batch of SS Match style barrels, I would cut all the chambers to exactly the same depth, which I determined by measuring sample bolts from the batch I plan to use with these barrels.  Once the chambers are cut and extensions installed, take those bolts, check headspace with the proper gages, and all is good. Done.

I'll throw my two cents into the mix as well...

I custom fit bolts to barrels when I am making them.
In many cases, "fitted" purely means that it passed headspace checks.
Not so with me.
I am also fitting for endspace.
This accounts for the length of the locking lugs.
I tighten up this dimension.
When the extractor snaps over the case rim and reaches the point where it would begin to rotate and lock up, the bolt has to stop against either the rear of the case OR the rear of the barrel.
The typical specs call for about 0.010" of space here.
As typical headspace is about 0.003", it's easy to see that the bolt would always stop against the cartridge.
In some cases (federal's soft brass comes to mind), the bolt can actually SIZE the case before the bolt locks.
In this situation, you would end up with differences in headspace from shot to shot which can cause very minor differences in chamber pressures and velocities.
By shortening endspace, the bolt can now hit the end of the barrel when it's camming into a locked condition instead of bearing on the cartridge case.
This ensures more consistent locking as you can remove the consistency of the ammo from the equation.

This type of fitting is not for everyone.
I would never setup a battle rifle this way.

I can't say with any certainty that fitting the bolt this way is going to have a guaranteed effect on accuracy, especially at shorter ranges, but it's never going to hurt.

I don't engrave a number on the bolts when I fit them because I have a simple system of bins on my shelf where a customer's parts live together from beginning to end.
This same thing applies when I custom fit a barrel to a specific gas block to that it's as tight as possible without needing to press it on.