what is going to make the difference between a rebarrel job that just barely shoots MOA groups and one that the rifle will shoot 1/2 MOA or less?? what extra steps are taken, lets say you are doing this job on a heavy sporter barrel on a remington 700 action. lets also assume the customer is putting the setup in to a glass bedded solid platform, I guess what I am getting at is all other variables are maximized we are only talking about barrel fitting and chambering essentially

quote:

Originally posted by cummins cowboy:
what is going to make the difference between a rebarrel job that just barely shoots MOA groups and one that the rifle will shoot 1/2 MOA or less?? what extra steps are taken, lets say you are doing this job on a heavy sporter barrel on a remington 700 action. lets also assume the customer is putting the setup in to a glass bedded solid platform, I guess what I am getting at is all other variables are maximized we are only talking about barrel fitting and chambering essentially

The difference will be the quality of the barrel and the skill of the person doing the work. You reduce group size by eliminating errors.

I would also include the person on the trigger.

ok lets say the barrel is of excellant quaility, like I said everything is maximized, its in the hands of the smith, how much does trueing the action help, what are the differences in cutting the chamber etc

How much improvement is very subjective. In days when a factory rifle might shoot 1/2 moa, accuracy can be hard to improve on. Assuming most accuracy gunsmiths can "hit the numbers" on a rebarreling job, you can get the most gains from a top grade barrel. If you're using a factory action that shoots poorly then you can expect a lot of accuracy improvement by putting on a new barrel and having the action and bedding reworked. But, like I said, if it's shooting 1/2 moa now then you're going to pay a lot of money for just a little bit of improvement. You have to ask yourself if another 1/4 inch is worth it?

quote:

Originally posted by cummins cowboy:
ok lets say the barrel is of excellant quaility, like I said everything is maximized, its in the hands of the smith, how much does trueing the action help, what are the differences in cutting the chamber etc

You need only look at those who shoot benchrest to see the results gained from using trued actions, cutting minimum chamber and tight throats, crisp triggers and impecable bedding. Not to mention shooting skill and ammo preparation.

The main difference between that degree of precision and what you are seeking is that the weapon used for hunting has to reliably function when dirty.

Every rifle I have built where I have trued the action and cut a minimum throat will shoot under .5 MOA, consistently. Disclaimer: When environmental conditions are favorable.

When the conditions are not favorable, they will print a better looking group in the dirt hillside than those that are stock.

I have 1 hunting rifle that will steadly shoot 1/2" when it doesn't it is either my reloading or shooting habits. The most accurate rifle I have ever owned was a CZ 527 that would shoot .2-.3" with only a trigger job. Got rid of it because I did not love it.

quote:

Originally posted by tom ga hunter:
The most accurate rifle I have ever owned was a CZ 527 that would shoot .2-.3" with only a trigger job. Got rid of it because I did not love it.

What's not to love about that?

There is so much more to a MOA rifle than just the good smithing required. There is the platform and bedding, bullet to barrel matching, powder choice and load development, and the jerk on the trigger. One of the tell tale parts of accuracy is the shooting mechanics involved when the shot is made. Bad mechanics when the shot is made makes it hard for an accurate rifle to really shine.

tom ga hunter,
I want to say in a nice way you were a fool.
Butch

Maybe, but he shows some class and standards.

quote:

Originally posted by butchlambert:
tom ga hunter,
I want to say in a nice way you were a fool.
Butch

I dunno why you're bothering to be nice about it.

BTW, it won't do me any good at my advanced state of marriage, but I think Tom should list his ex-girl friends.

I think that how the barrel and action are bedded in the stock makes more difference than the way the barrel is mounted, assuming it is a quality barrel to begin with.

I only have two rifles that have shot 0.5" 5 shots 100 yards:

1) a box stock Ruger #1V .223 with 35 gr Vmax, 15 gr Blue Dot, and a 20X scope.

2) A VZ24, Lothar Walther light varmint taper barrel in 257 Roberts Ackley Improved, 75 gr Vmax, 45 gr IMR4895, and a 40X scope.

I can tell you about barrelling the VZ24, the bore was dialed in within .0001" and the rear of the finished chamber was still dialed in to within .0010".

I have been dialing in both ends of the barrel and mounting the breech in the 4 jaw with a wrap of Copper wire to act as a gimbal.

The benchrest guys are telling me to dial in just the breech with a spud, as all barrels are bent, and the chamber only needs to be concentric with bore nearest the chamber.

quote:

Originally posted by Gatogordo:

quote:

Originally posted by butchlambert:
tom ga hunter,
I want to say in a nice way you were a fool.
Butch

I dunno why you're bothering to be nice about it.


BTW, it won't do me any good at my advanced state of marriage, but I think Tom should list his ex-girl friends.

eVER SO OFTEN i GO THROUGH having too many guns so I get rid of some. I simply did not like the CZ so why keep it. It became the 1st center fire for a fine young man. I guess it is sorta like a wife & girl friend. I have had some girl friends were were just increadable in bed but have other short comings so they just get discarded because the good does not out weigh the inconvience.. Sorta like a girl friend calling & talking to your wife.

quote:

Originally posted by tom ga hunter:



I have had some girl friends were were just increadable in bed but have other short comings

it takes a lot of shortcomings to spoil that one, doesn't mean later you don't wanna play with them later, kinda like guns that sit in the back of the safe

The primary requirement for a very accurate rifle is that the chamber be straight and concentric to the bore. A secondary requirement is that the throat be a good fit for the bullet. This is a secondary requirement simply because I've seen too many rifles with those long funnel throats which shot way too well. In general though, I think a close fitting parallel throat works better.
The barrel crown should be square to the bore and free of burrs or other defects.
As far as the action is concerned. The bolt lugs should bear reasonably well (say 60% contact) The bolt face should be reasonable close to perpendicular to the bore (within .0005" or so). The bolt should be a decent fit in the receiver (.005" diametrical clearance). The receiver thread should be aligned with and reasonably concentric to the bore.
Given a good barrel of semi heavy weight, good bedding and a chamber in a reasonable cartridge (maybe a 308), the described rifle would be capable of 1/2 moa in the hands of a good shot. With a relatively homely barrel it's still likely to shoot under 1 moa.
Now, take this same rifle and do everything you can think of to the action to make it perfectly true, tighten up the tolerances, lap the scope rings or glass bed the scope into the rings, and put the barreled action into a BR style stock with a flat forend and you will get down to maybe 3/8moa. More likely .4
Glue the action in a glass BR stock, cut the chamber with a tight neck so neck turning is required, and do a good job of such turning and produce perfectly straight and concentric ammunition and you might get down to .3" To do much better than this with a 308, it will have to be heavier to control recoil or set up with a very slow twist barrel to shoot lighter (110 to 125 grain) bullets (also to control recoil.
It can be seen there is a point of diminishing returns whichis reached fairly early on. For any kind of a sporting rifle the difference between .5 and .4 is meaningless. In fact, the difference between 3/4 and 1/2 doesn't mean a lot more.
It has been only occasionally that the source of a rifle's inaccuracy was a misaligned action; though it has happened.
I have built and owned legitimate 1/4 moa rifles (and I mean REAL 1/4 moa rifles; not ones which shot a 1/4 inch group a year ago last Tuesday. Real 1/4 moa rifles are the ones where I can sit down at the bench and say, "watch this" and be pretty sure of shooting five shots into 1/4 inch or less.) on which I had simply fitted the barrel to an unaltered Remington 40x action and had taken no great pains in doing so. I've also had rifles I had taken great pains with which struggled to beat .350.
If one cuts a chamber which is eccentric to the bore and screws the barrel onto a crooked action, I can almost garantee it won't shoot 1/2 inch. If the everything is straught and looks perfect, I still can't garantee that it will but I can say it is more likely.
I can honestly say that straightness and concentricity are key. Dimensions are less critical except in some areas. Throat diameter is critical. Headspace is semi-critical. Neck diameter is not critical. Neither is body diameter (within reason).
I have always been going to make up a rifle with a universal receiver into which I could introduce various flaws and thereby quantify their effects but such things take time and money both of which are inshort supply at the Leeper household! Regards, Bill.

Good post, Bill!
- mike

Thank you, Bill! One question, if I may. How large do you cut the throat on a hunting rifle? How much over bullet diameter?

I believe the proper throat should be no more than .0005 over nominal bullet diameter. The throat diameter I use on my own 308 match rifles is .3084 and it works fine. I don't throat any 30 cals over .3085. This is, of course, only my preference. The Saami throat for many cartridges is a funnel comencing at the case mouth at about .004" over bullet diameter. If it is concentric, it can work very well; I just prefer the parallel configuration. Regards, Bill.

quote:

Originally posted by Bill Leeper:
I don't throat any 30 cals over .3085. This is, of course, only my preference.

You're in good company. I try to hold all throats to at least .0005 over bullet. Some slip a little below that but that is on purpose.

the last barrel I did was a 223 barrel from ER Shaw.. It was only $150.00 delivered and long chambered...

I can tell ya, that it is not a bench rest barrel by a long shot... but out in the field it was consistently nailed sage rats that were popcanned sized critters out to 300 yds... the scope was a 6 x 24 Weaver and it was set around 10 power at most...

Well after about 750 to 800 shots down the barrel, its groups at the range are tightening up significantly...

in the field however, it consistently is doing as good of a job as some of my factory varmint rifles that shoot much smaller groups at the range...

So yeah, I got what I paid for.. on the flip side, I did pretty darn well for what I paid for... as it is doing everything I expected it to do!

quote:

Originally posted by cummins cowboy:
ok lets say the barrel is of excellant quaility, like I said everything is maximized, its in the hands of the smith, how much does trueing the action help, what are the differences in cutting the chamber etc

A smith fitting a barrel that dont check/true up an receiver thread,face,lug bearing area + bolt lugs&face, is far from getting any of my money.
Anyone who would pay a smith not to check or correct such things probably also drives without having the wheel alignment or brakes properly adjusted...and anyone who dont have a well adjusted trigger probably also runs uneven tire presures.
Basing things on a sound foundation,usually allow it the best chance to reach its potential.
ie:
-stress free concentric&square fitted-chambered barrel.
-trued action&bolt, stress free action to stock fit, to minimise contortion.
If a person has no interest in the sqrness/concentric of an receiver, they may not give too much of a crap about the same measures in a barrel fit.
In any case, A sensible man considers both.

Now if you had two rifles that both did 1/2- 3/4", one carefully trued and assembled, and the other an unknown quantity factory job. I would take the trued unit.
What impressed me about RiflesInc, was the care that went into trueing things up(100%? lug contact)....result?...A 4.8lb 6.5/284 rem700Ti that shot .3" with 140X at 2940mv.

It is great to see a Bill Leeper post.
He is a gunsmith with the ability to write in a way even I can understand.

quote:

Originally posted by Bill Leeper:
The primary requirement for a very accurate rifle is that the chamber be straight and concentric to the bore. A secondary requirement is that the throat be a good fit for the bullet. This is a secondary requirement simply because I've seen too many rifles with those long funnel throats which shot way too well. In general though, I think a close fitting parallel throat works better.
The barrel crown should be square to the bore and free of burrs or other defects.
As far as the action is concerned. The bolt lugs should bear reasonably well (say 60% contact) The bolt face should be reasonable close to perpendicular to the bore (within .0005" or so). The bolt should be a decent fit in the receiver (.005" diametrical clearance). The receiver thread should be aligned with and reasonably concentric to the bore.
Given a good barrel of semi heavy weight, good bedding and a chamber in a reasonable cartridge (maybe a 308), the described rifle would be capable of 1/2 moa in the hands of a good shot. With a relatively homely barrel it's still likely to shoot under 1 moa.
Now, take this same rifle and do everything you can think of to the action to make it perfectly true, tighten up the tolerances, lap the scope rings or glass bed the scope into the rings, and put the barreled action into a BR style stock with a flat forend and you will get down to maybe 3/8moa. More likely .4
Glue the action in a glass BR stock, cut the chamber with a tight neck so neck turning is required, and do a good job of such turning and produce perfectly straight and concentric ammunition and you might get down to .3" To do much better than this with a 308, it will have to be heavier to control recoil or set up with a very slow twist barrel to shoot lighter (110 to 125 grain) bullets (also to control recoil.
It can be seen there is a point of diminishing returns whichis reached fairly early on. For any kind of a sporting rifle the difference between .5 and .4 is meaningless. In fact, the difference between 3/4 and 1/2 doesn't mean a lot more.
It has been only occasionally that the source of a rifle's inaccuracy was a misaligned action; though it has happened.
I have built and owned legitimate 1/4 moa rifles (and I mean REAL 1/4 moa rifles; not ones which shot a 1/4 inch group a year ago last Tuesday. Real 1/4 moa rifles are the ones where I can sit down at the bench and say, "watch this" and be pretty sure of shooting five shots into 1/4 inch or less.) on which I had simply fitted the barrel to an unaltered Remington 40x action and had taken no great pains in doing so. I've also had rifles I had taken great pains with which struggled to beat .350.
If one cuts a chamber which is eccentric to the bore and screws the barrel onto a crooked action, I can almost garantee it won't shoot 1/2 inch. If the everything is straught and looks perfect, I still can't garantee that it will but I can say it is more likely.
I can honestly say that straightness and concentricity are key. Dimensions are less critical except in some areas. Throat diameter is critical. Headspace is semi-critical. Neck diameter is not critical. Neither is body diameter (within reason).
I have always been going to make up a rifle with a universal receiver into which I could introduce various flaws and thereby quantify their effects but such things take time and money both of which are inshort supply at the Leeper household! Regards, Bill.

awesome bill, that is the kind of info I was looking for, death throat is good for other things just not rifles

ok here is another question, lets say the smith essentially just screwed on the barrel, is it possible to go back and true up the action and take all the necessary precautions to insure maximum accuracy can be obtained??

It is possible but can be very involved.
If the rifle shoots poorly and the action exhibits some glaring defficiency, correcting the difficiency might be beneficial.
When a bolt action is trued (some call it "blueprinting" which may or may not be an accurate term) there are a number of areas which are addressed.
The receiver threads are re-cut to ensure they are co-axial with the bore line of the receiver.
The locking lug seats are re-cut to ensure they are perpendicular to the same line.
The face of the receiver is recut to make it perpendicular to the bore line and parallel to the locking lug seats.
The bolt face is trued by taking a light cut on the face.
The rear of the lugs are trued by taking a light cut across their bearing (rear) surface.
If the bolt is a real sloppy fit in the receiver bridge, it might be retro-fitted with a set of "bumps" so that the clearance is minimal when the action is locked.
Obviously, with all this cutting and facing going on, dimensions will no longer be the same. Headspace will likely be different. If the threads were re-cut the pitch diameter will be greater. Plainly, the barrel, as originally fitted, will no longer be right.
It is entirely possible to install a threaded sleeve on the barrel and re-fit it to the action (for those who doubt the efficacy of this, I have done so many, many, times with results as good as if the barrel had been fitted to the action in the first place). It's also possible to cut the threaded tenon right off and rethread and rechamber. This assumes the barrel contour is such that there is enough to work with and that you don't mind a barrel 3/4 inch shorter.
So, as can be seen, it IS possible but it's not the best way to do it.
It was, in the not too distant past, common procedure for BR gunsmiths to mount a Remington action on a mandrel, take a light cut on the face and fit the barrel. It was rare that one gave much thought to rethreading or recutting locking lugs or seats. The locking lugs were lapped but that was about it.Nonetheless, rifles built this way were shooting aggregates under .3 moa and occasionally around .2 moa. This is a pretty good indicator or just how critical (or not) the full action job might be.
I have often read pronouncments to the effect that nothing short of a complete action re-work will produce a decent shooting rifle. This is mostly salesmanship on the part of the 'smith and horn tooting on the part of the customer. The truth is, good workmanship never hurts but where the gunmaker expends his efforts is often dependent upon the rifle and it's intended use.
A good field rifle has to shoot reasonably well and very consistently. More importantly, it has to function perfectly. A 1/2 moa rifle which doesn't reliably feed, extract or eject is of much less value in the field than a 1 1/2 moa rifle which is stone-reliable. Of course, the ideal is the rifle which does both. The shooter decides what is important to him and chooses the gunsmith who satisfies his requirements.
Each action type has design features which make truing of more or less benefit. Some have idiosyncracies which make truing difficult at best. In some cases, so difficult that many gunsmiths would be unable to do the job effectively. If you are trying to get the most out of your P14 build, you probably won't get it from the 'smith who specializes in Remington 700s.
I guess the short answer is, get the action trued prior to having the barrel fitted. Remedial work is as difficult or moreso than doing it right in the first place. Regards, Bill.

quote:

Originally posted by Bill Leeper:
It was rare that one gave much thought to rethreading or recutting locking lugs or seats. The locking lugs were lapped but that was about it.Nonetheless, rifles built this way were shooting aggregates under .3 moa and occasionally around .2 moa. This is a pretty good indicator or just how critical (or not) the full action job might be.

It's been out there a while. I remember reading about the benefits of rethreading and machine truing the bolt lug and seats of Rem 700 receivers as early as the mid 70's. I started offering this service in my shop in 1980.

Yes it has been out there for a while. Initially re-threading was saved for salvaging a really crooked receiver and most 'smiths tended to avoid it. The first one I rethreaded was a 788 in 1978. About then I machined the locking lugs and seats on a 722 where I was fitting two bolts to the action and wanted the headspace to be the same for both. Interestingly enough, the worst actions I saw back then were Shilen DGAs. It was to rethread a DGA that I made up my first fixture to hold actions which were not round.
The whole action truing thing really started gaining momentum when some benchrest oriented gunsmiths started insisting such was mandatory for hunting rifles.
If threads are badly misaligned, it is best that they be re-cut of course. I think it is a good idea to re-thread new Model 70s to eliminate the interupted thread. I also think, from an accuracy standpoint, it means a bit less than we have been led to believe until we get down to BR levels. That's way below 1/2 moa!
Is re-cutting of seats and threads beneficial? Sometimes; it depends where you're starting from. It doesn't do any harm (unless the 'smith screws up of course!).
Usually, if a rifle isn't shooting well, action straightness is one of the last things I look at. There many other, more likely, causes. Regards, Bill