Burned Out Barrel

[alberta tactical rifle]

Interest only in the shooting sports and QM's boards of the army rumour service. pics will be credited, that said once something is posted on the net its pretty much public domain.

Tim No problem. Credit is not an issue, was just wondering on what the context wasand just wanted to be sure that there was no negative reference to any manufacturer.
We seem to live in times of wanton and needless litigation.
And thankyou for asking rather than just doing, which you certainly could have being posted on the net as it is.
Cheers
Rick

 

[alberta tactical rifle]

There is more labour required to properly set a barrel back and re chamber than if you started with a new blank. If you are paying to have this done I recommend installing a new blank.

I agree 100%
Occasionally you can get a used barrel to shoot well again, but it is as Dennis states the same or more work, so why not do the job right and know that the rifle will shoot well?
It is not like a Rock, Krieger or any other well respected barrel is going to have burrs or rough spots in the barrel that need to be smoothed out from shooting.
I can not speak for all needlessly, but before I even begin to fit a barrel it is scoped, just cuz!

 

[TimC]

Tim No problem. Credit is not an issue, was just wondering on what the context wasand just wanted to be sure that there was no negative reference to any manufacturer.
We seem to live in times of wanton and needless litigation.
And thankyou for asking rather than just doing, which you certainly could have being posted on the net as it is.
Cheers
Rick

Thanks, I do find that side of precision engineering fascinating, after 25 ish years of heavy and light rail engineering tolerances of less than 1.5mm are such a treat!
I used to be a member of an R&PC in the Black Country manned almost exclusively by serving and retired toolmakers all indentured apprentices. The bits they could make for you were great!

 

[Mystic Precision]

Heres a question for the gunsmiths...

If you had a straight barrel with NO taper, could you just cut and ream a new chamber further up where the throat is not eroded?

Would it be worth it?

Nice pics, I love cross-sections, they help alot.

As Obtunded said, setting back a barrel is done all the time. Results are mixed and really depends on WHEN the barrel is set back.

We know that any barrel starts to wear from the first shot and the best accuracy is usually in the first 500 to 800rds. This is where the average group size may move from being in the 1's and 2's to the 2's and 3's. Not a huge change but something that can be measured and will only get worse with time.

IF a barrel is set back this early in its life, very good results can be maintained. however, that gets expensive and the waiting vs shooting pretty much negates its benefits.

But for competitive shooters with the ability to do their own work or deep pockets, this will help get the most out of any barrel. Usually 1/2 to 1" set back is adequate at this level of wear.

For the average take off barrel you see for sale, it depends on how worn it is. Most barrels are near new only being taken off because of a new project.

I used to think that barrels wore at the throat and not much else. Having autopsied a few of my 6.5 barrels that were shot until accuracy fell apart, I found that the first several inches of barrel was nearly devoid of rifling. This indicates that wear occurs in a cone which can stretch some distance down the barrel.

How much and how severe will be dependent on the cartridge and how it was used.

So is it worth setting back? That will be dependent on the conditions above and what your accuracy demands are.

As an example, my 6.5 Mystic barrels were 30" long (308 case length). I had it cut at 4" from the back to see what it looked like. In both cases, the rifle was just starting to get to full depth. I sold the barrels as used 26" blanks. When the new chamber was cut, it would have extended another 2" or more down the barrel, well into 'fresh' rifling.

Reports have been very positive about the accuracy these barrels are giving the new owner.

So in my case, at least 3" of barrel would need to be cut off the orig barrel to allow for a new chamber to be cut infront of tight rifling. Most barrels don't have this much shank to set back.

Jerry

 

[Machinist]

More Work ??

There is more labour required to properly set a barrel back and re chamber than if you started with a new blank. If you are paying to have this done I recommend installing a new blank.

Just curious about the extra work involved . i recently purchased a old match barrel from a local gun show , the chamber was badly erroded, it has a heavy contour 26 " long , i just simply parted off the old chamber and then re- chambered with one of Dave Manson's piloted reamer's in .308 , machined the thread etc , i lost a couple inches of barrel length in the process , and it has a heavy contour so there is no loss of parent metal surrounding the chamber , the only extra work i did was parting off , Am i missing something here ?? I am just learning so excuse me for the dumb question And the rechambering turned out great Manson reamers are nice tools .

 

[guntech]

Just curious about the extra work involved . i recently purchased a old match barrel from a local gun show , the chamber was badly erroded, it has a heavy contour 26 " long , i just simply parted off the old chamber and then re- chambered with one of Dave Manson's piloted reamer's in .308 , machined the thread etc , i lost a couple inches of barrel length in the process , and it has a heavy contour so there is no loss of parent metal surrounding the chamber , the only extra work i did was parting off , Am i missing something here ?? I am just learning so excuse me for the dumb question And the rechambering turned out great Manson reamers are nice tools .

Sometimes the chambering will turn out...

Used barrels usually have printing and or sight screw holes. If you have to line these up it is extra work but I find it considerable harder to dial the throat area on the worn barrel in to the closest ten thou compared to doing that on a new blank. I prefer to bore the chamber under size and finish with a reamer. This assures better alignment of the chamber to the bore.

Chambering the way you did may work out if the original chamber was well centered on the bore... Not all of them are and barrels are not straight either.

I think one gets more for their money doing this to a new blank. Worn barrels rechambered don't get that much more life for the dollars spent.

 

[Machinist]

Thanks

Thanks Dennis,
I am just practising / learning on old cheap stuff , once i get more experience i will buy a new barrel and re- chamber it , easier on the pocket book than scraping a new blank , i managed to get the old worn bore to .0003 " TIR , its an old Gillard barrel so still in decent condition, i am curious to see how well it will shoot once i assemble the rest of it.

Sometimes the chambering will turn out...

Used barrels usually have printing and or sight screw holes. If you have to line these up it is extra work but I find it considerable harder to dial the throat area on the worn barrel in to the closest ten thou compared to doing that on a new blank. I prefer to bore the chamber under size and finish with a reamer. This assures better alignment of the chamber to the bore.

Chambering the way you did may work out if the original chamber was well centered on the bore... Not all of them are and barrels are not straight either.

I think one gets more for their money doing this to a new blank. Worn barrels rechambered don't get that much more life for the dollars spent.

 

[Obtunded]

I know Dennis is a gunsmithing god and he is an expert. He has forgotten more than I will ever know on the subject. However, I tend to disagree on the economics of barrel set-backs.

A new match barrel blank averages $400+ Chambering a new barrel runs anywhere from $180-300 depending on who does it, so realistically, a new barrel is a $6-800 investment. I am not going to include the purchase of pre-chambered barrel because I simply DO NOT consider these in the same league as a properly installed, custom chambered barrel.

I have never come close to paying that much for a set back. I have had set-backs that have given me 80% of the life of the original barrel so to me that represents a good value. The shorter stiffer barrels have always performed as well or better accuracy wise although there is a slight reduction in velocity to be expected.

CyaN1de has an example of a set back barrel that was better than the original and is a sub .25MOA shooter in 6BR.

It is my humble opinion that a barrel set-back with a match barrel represents an economical and viable alternative to full re-barreling with few if any down-sides.

 

[redman]

It is my humble opinion that a barrel set-back with a match barrel represents an economical and viable alternative to full re-barreling with few if any down-sides.

For someone who makes a living selling new barrels, I'd say that opinion is as honest as it gets.

 

[Mystic Precision]

I am not going to include the purchase of pre-chambered barrel because I simply DO NOT consider these in the same league as a properly installed, custom chambered barrel.

We will agree to disagree

Of the several barrels that I have had, either from a barrel maker like Shilen or from a gunsmith like Guntech, the results of a prechambered barrel has been fantastic and every bit as good as the normal headspaced barrels installed.

yes, I have even used the same action with both styles of headspacing and had similar results. Got to prove it to yourself before you start typing the keyboard.

Cutting a true chamber with either style of headspacing requires the same care and attention, and yield the same results. With a good quality match barrel, the results on paper are also similar.

Of the Shilen barrels that I have shot, all the fired brass measured ZERO runout from the chamber with accuracy in the 1/4 min range. Some groups have been even as small as the 0's and 1's at 200yds for 5rds. Their quality of machining is the same that they put on their SR BR custom rifle builds.

Yes, Shilen does build competition rifles but only for the US market.

A Pac Nor I had a while back was sub MOA accurate all the way out to a mile in a 223. For those that have watched the video, the hits are pretty darn close to the 1/2 min range.

The key is using a Savage or Stevens action. I know many Rem shooters don't see the benefits of a floating bolt head but they are there and allows a different approach to accuracy.

Considering the hundreds of other shooters who report great results, I am not a rare occurance.

Ian, if you have a take off Kreiger with enough shank to mill down to put into a Savage. Why not just set back and give it a try.

The results just might surprise you...

Jerry

 

[Leeper]

I have seen no definite data indicating a smooth chamber increases bolt thrust to any measurable extent. I strongly suspect this is simply one of those things that sounds reasonable enough so it is accepted as fact. Likewise, I have seen no evidence that body taper or the lack thereof has any significant effect on bolt thrust.
Set backs can work out well if the entire chamber is removed and a new chamber cut. If any of the original chamber remains, any runout which existed is likely to be perpetuated in the new chamber. If the old chamber was perfect, the new one should be fine as well. I have set back and rechambered barrels of my own with decent results but they were not really burned out to start with.
I once set back a 7mm Rem Mag match barrel which Bob Hobbs had on a 40X. Bob had fired over 3000 rounds through this as I recall and the throat was about 2 1/2 inches long. I set it back 3 inches and rechambered to 7mm-08. The groove diameter at the breech was still well over .284 as could be seen by the throat. Nonetheless, the barrel shot very well although I can't say for how long.
L. E. (Sam) Wilson had a Hart barrel on his unlimited rifle which had been set back five times. When I asked Sam how many rounds had gone through that barrel he told me he would say because no one would believe him anyway. The barrel had started out at 30 inches and was about 21 inches on the day I saw it. This was in 1980 and he had first fitted it in 1957. It was chambered in 223 by then and he won the 100 yd agg that day so I guess it worked OK. As I recall it had been chambered in 219 Wasp, 220 Wilson Arrow, 22-250, 222, and 223.
I have a 22-250 barrel in the shop which I just replaced. Round count is over 5000. This throat is smooth and actually quite pretty (if you don`t mind the absence of any rifling) for at least 2 1/2 inches. The owner said it was still shooting close to 1 moa.
Jerry,
If the key to success is using a Savage or Stevens action, it just isn't worth it! For most people, it's just too hard to shoot well with a bag over your head! ( I'm kidding, Jerry. I am doing what I can to disguise my Savage though. ) Regards, Bill.

 

[Mystic Precision]

Jerry,
If the key to success is using a Savage or Stevens action, it just isn't worth it! For most people, it's just too hard to shoot well with a bag over your head! ( I'm kidding, Jerry. I am doing what I can to disguise my Savage though. ) Regards, Bill.

Bill, I think the next rig will be rebarreled Mosin Nagant or a Carcano.

That'll clear the line with screams of horror.

Remember, put the bag over the action....keeps them wondering.

Jerry

 

[guntech]

Hey Bill I am glad you posted those experiences... I have not done many set back re chambers but the last one on a 6mm Rem A.I., didn't last long... but several years ago I did a set back on a .222 Rem Mag for Al M. after it shot over 4000 rounds and he continued to use it on gophers for quite some time.

I agree totally with you on smooth polished chambers. I have never encountered a problem. I think it is all theory about bolt thrust and a polished chamber. I have not heard of a definitive test. If you load hot enough for brass to stretch, what does it matter if the case slips back or stretches back until stopped by the bolt face.

 

[CyaN1de]

Most gunsmith/competitors I know say different, Bill Shehane, for one.
I do know that My 6.5WSM di nor shoot as well after cutting back 4" of wash and rechambering, and two of my Palma rifles also di not shoot as well.
These were all rechambered by top 'smiths.
Cat

As Obtunded iterated, my set back Smith barrel shot the tightest 10 shot group I have shot to date at 300m (and still have the target to prove it). Set back by Mick McPhee after I started getting unexplained fliers with a known load, I had Mick cut it back, did some new load development and SHAZAM.....a great shooting barrel for far less $$ than buying and chambering a new barrel. Re-chamber, Re-use, Rejoice

My throat was not near as bad as the pic that Rick posted, but the lands were more of a ramp to the lands for the first 1" or so. We cut 3.5" off the 28" barrel finishing at 24.5"

 

[catnthehatt]

Don't get me wrong here, I get my rifles rechmabered all the time!
In fact, the 6.5WSM I talked about was in fact a Smith barrel and done by Mick as well.
and people like Bill Shehane rechamber their rifles as well, what I am saying is that the barrel itself may not be as accurate in a pure sense, but that does not mean it will still not win matches or shoot pin point accuracy .
Don't forget that the main variable in the whole mess is the nut behind the bolt.
Maybe it has more to do with the rifling itself than the throat in a particular barrel when it comes to rechambering to tell whether it will be more accurate than before, I dunno

Cat

 

[Mystic Precision]

Maybe it has more to do with the rifling itself than the throat in a particular barrel when it comes to rechambering to tell whether it will be more accurate than before, I dunno

Cat

Yep, that is my conclusion.

"Worse" barrel I ever set back was a used Palma barrel of Cdn manufacture. Was shot ALOT and was eventually pulled when the lands literally, fell off the bore. never seen anything like this.

Being young and willing to experiment, it got chopped a bit and another 308 match chamber installed on a Parker Hale Midland action. Well with a bit of load work up, it did shoot very well.

My goal was anything 1/2 min or so. This rifle shot 1/3min average with a few groups in the 1/4 min range. I was thrilled (barrel was essentially free and the smith that sold it to me was also curious so did the barrel work for cheap).

My estimate is 500rds and the trouble started. Groups were wild and eventually I looked into the bore. Yep, small chunks of lands were again missing. What to do? Can't set back anymore as there wasn't enough shank.

Since this was a long action, why not build a wildcat. The smith had a 30Gibbs reamer and I love improved cases so off it went. All that was done was to lengthen the chamber.

The barrel again shot great and averaged 1/3 min at 250yds with 165gr SST's. Used it hunting and it bagged a nice mulie across a cut block. Shot it somemore and sold it. have heard that the same rifle was shot some so it looked like the chambering finally reached solid rifling.

Approx 2" was chopped from the chamber side plus the deeper chambering so 4.5" to reach better rifling.

As I said in an earlier post, wear occurs in a cone and will travel some distance down the bore. When looking from the chamber side, you will still see the lands but the bore diameter has gotten bigger and the lands thinner. Looks good but the bullet is now sloshing down the pipe.

Removing all this and getting back to full lands should allow the barrel to shoot at its previous levels. However, the lands are likely less resistant to wear so this rechambering may not last as long as the orig.

Maybe someone with a metallurgy background can chime in...

As for polishing the chamber, why would you want to polish anymore then is necessary to ensure extraction? From what I hear, if a good finishing reamer is used properly, no chamber touch up should be required. Certainly the many barrels I have had chambered by quality gunsmiths didn't glow brilliantly. And all had a bit of tool marks left in.

Unless I am mistaken, polishing occurs using sandpaper in an unsupported manner. If the chamber is polished to remove every tool mark from the reamer and to a brilliant shine, wouldn't:

a) it also enlarge the chamber?
b) allow the chance to make an out of round chamber?
c) take a long time thus increasing costs or decreasing productivity?

Being off a thou or few wouldn't be hard sanding/polishing freehand. Does polishing this much create 'runout' into the chamber?

Jerry

 

[7.65 Para]

What factory made the barrel on the top? Remington?

 

[Crankbender]

On bolt thrust. Do you guys believe that case lube or oil in the chamber or on the brass increases bolt thrust? I was farting around with a 30-30 one day. As with most 30-30's normally the primers would protrude due to the low pressure. With an oily chamber (bore was not) there was no primer protrusion at all.

 

[guntech]

On bolt thrust. Do you guys believe that case lube or oil in the chamber or on the brass increases bolt thrust? I was farting around with a 30-30 one day. As with most 30-30's normally the primers would protrude due to the low pressure. With an oily chamber (bore was not) there was no primer protrusion at all.

Yes there is bolt thrust but the locking mechanism is designd to handle it...

With modern bolt actions the chamber pressures are extremly high and regardless of bolt thrust it is unheard of for locking lugs to fail. It is not anything to be concerned about.

With actions designed to work with lower maximum pressure I doubt bolt thrust is much of an issue either.

In any case load your ammo using established loading data for the action design.

 

[alberta tactical rifle]

Yep, that is my conclusion.

Unless I am mistaken, polishing occurs using sandpaper in an unsupported manner. If the chamber is polished to remove every tool mark from the reamer and to a brilliant shine, wouldn't:

a) it also enlarge the chamber?
b) allow the chance to make an out of round chamber?
c) take a long time thus increasing costs or decreasing productivity?

Being off a thou or few wouldn't be hard sanding/polishing freehand. Does polishing this much create 'runout' into the chamber?

Jerry

Polishing does NOT entail the use of "sandpaper" At least if it is done properly.
The way I do it here it "may" remove 1 or 2 10000ths of an inch and as the BARREL is turned at high speed, NOT the tool , the concentricity is not affected.
The added 3 or 4 minutes of machine time to do this is not significant enough labor in my opinion to be of concern.
The results however DO improve extracion and feeding, not to mention makes the fired casing less marred