Barrel accuracy or barrel life

R

rotdog7.62

Guest
Much info. is posted in various sites about either barrel accuracy or barrel life. I do not see much relating the two subjects. They seemingly would be connected in conversation, but generally is not.
This topic is not related to the age old question of best barrel rifling makers/ type, but perhaps touches on barrel hardness, smoothness, rifling depth cartridge chamber type, throat, loading intensity, and frequency of use simultaneously.

Any thoughts? The specific question is related to which barrel makers balance these issues for longest period of practical barrel usage.


rotdog7.62
 
Barrel Life

Since this is primarilly a Benchrest Site, let me say that we shoot specific brands of barrels that are manufactured with what we do in mind. Barrel life is of little consequence. Barrel accuracy is of paramount consequense.

For what it is worth, one major barrel maker that does stress barrel life is Lothar Walthar, due mainly to the Stainless Steel alloy that is used in their barrels. But, I can't think of one 100-200 yard Benchrest Shooter that uses them.......jackie
 
Hart rifle barrels has been working on longer life barrels. So far no report as yet/ You may want to talk to jack sutton on this one. He has been playing with Barrel life and hardness
 
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Gerry

Making barrels that are up to the accuracy standards demanded by 100-200 yard Benchrest is sort of a trade off. Everybody asks, "why do they use 416R for the premium accuracy barrels.

The answer is simple. Machinability. The simple fact is, when you want to establish a straight, true, finally finished hole in a long piece of steel, with acceptable tooling life, 416R fits the ticket to a T.

There is a trade off. 416 is not, (in idustrial applications), known for it's resistance to corrosion and heat. It is used mainly in applications where a heat treatable stainless, with a free machining quality, is needed, but in an atmosphere of moderate corrosion and heat. Pump shafts are a good example. Hydraulic fittings another.

Lothar Walthar has the right idea in using their L-50 proprietary Stainless in their barrels, it does have a superior resistance to corrosion and heat scaling than 416R. I suspect it is some sort of age hardenning Stainless, probably in the same familly as 15-5PH and 17-4PH. They are infatic when they say "it is not 17-4". But there is a whole slew of Precipitating Hardenning Stainless alloys out there. You can bet it is one of those.

The drawback is, whether they admitt it or not, the stuff is a bear to machine when compared to 416R or even regular Chrome Moly. I know several Gunsmiths who won't even fool with it.

It will be interesting to see what Hart is working on. You can increase the RC Harness of 416R, (which might help), or maybe they are working with some other alloy to hit that much wanted barrel life combined with the finest in precision......jackie
 
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410

410 is basically the non free machining version of 416. The only enhanced property in poccesses over 416 is that it does not suffer from the malady that infects most free machining steels, that being a reduction in ductility.

As an example, look at standard 4140, as compared to 4140L, which has Lead added to enhance machinability. The tensil and yeild strengths are quite similiar at the same RC hardness, but when it comes to Ductility, as measured by any of the popular destructive test, (Charpy V-Notch, IZOD Impact), the standard 4140 is superior..........jackie
 
Optimization of steel for barrel blanks goes well beyond basic alloy selection and includes such key features as maintenance of homogeneous micro-structure, precision straightening and precision stress relieved bars. Also key is maintaining process control to provide consistent quality from lot to lot and year to year.

The high grade barrel makers here in Wisconsin (Badger, Bartlein, Broughton, Brux, Krieger, Obermeyer and Rock Creek) plus others elsewhere have usually used the special barrel bar 416R from Crucible Steel (of Syracuse NY) for many years.

If properties and processing suggestions would help your understanding, please see the attached data sheet.
 

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  • 416Rv4.pdf
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Fred

I never thought of it, but does the 410 that barrel makers use have the same strict manufacturing dictates as does 416R??

For that matter, does Chrome Moly?.........jackie
 
jackie schmidt said:
There is a trade off. 416 is not, (in idustrial applications), known for it's resistance to corrosion and heat. It is used mainly in applications where a heat treatable stainless, with a free machining quality, is needed, but in an atmosphere of moderate corrosion and heat. Pump shafts are a good example. Hydraulic fittings another.
Click to expand...
One of our local barrelmakers used a worn out competitor's barrel (with the manufacturer's stamp prominently displayed) as the carrier for the coolant spray heads on his CNC profiling machine. :cool:
 
I listened to a conversation at a long range match one day about a new process that they were trying.
I dont remember what it is called but it was something about AFTER you break in the barrel you can send it off for a special process that involves some kind of super hot salt bath that is suppose to make it extremely hard and resistant to wear.
What its called I dont remember and if it would work for us in BR would be interesting. Cost didnt seem too overwhelming and might be well worth while if/when you found a barrel that shoots well. IF it could really extend the life long enough to make it worth while.

Maybe someone else will chime in.
 
Thanks for the disussion, and a question.

I am a retired gunsmith. Some custom guns building, but mostly warranty repair for all of the majors, so I look at the competition issue from that vantage point. In other words, I fixed others guns. I do not shoot any competitions, but shoot for practical accuracy.

In the trade off for ultimate accuracy, how do costs figure in the mix. Do most not buy equip. based on rifle longevity at any level, but only accuracy. What is your expectation from equipment? What about the expense factor?

Further, how do you measure this accuracy factor at high levels. Example: various human factors, or a bad day shooting, winds, etc., etc., verses beginnings of equipment failure. At what level is equipment upgrade the answer?

Thanks for the education,

taylorwkrs

Here is a link to an unrelated project of mine.

http://www.rimfirecentral.com/forums/showthread.php?t=334933
 
jackie schmidt said:
I never thought of it, but does the 410 that barrel makers use have the same strict manufacturing dictates as does 416R??

For that matter, does Chrome Moly?.........jackie
Click to expand...

Jackie,

When I was doing my research on barrel steel I was focused on stainless steels but did not find any other case of attention to the end use and consistency of quality focus as Crucible's 416R reported by the barrel makers I spoke to. I only found one maker that had experimented with 410 but it was a non-standard variant primarily having to do with stress relief process for the bars intended for barrel blanks.

Each of several barrel makers had preferences as to supplier of Chrome Moly but not nearly as unanimous as for Crucible's 416R in stainless.

None of the "experts" would share what their individual criterion was for a "hummer barrel" but they all suggest that a higher probability of making one from Crucible's 416R bar.
 
A few years back...

Black Star (I think I've got this right) claimed three times the barrel life for their $900 barrels. The interior was surface treated and mirror bright. They advertised greater accuracy, and three times the barrel life. They also provided chambering instructions for gunsmiths since their barrels were super hard.

Result; where are they now? From the few shooters I knew that bought them, the accuracy results were not good and the company sold off their manufacturing rights to someone else.

The strange part is that the parent company of the barrel manufacturing division was well respected in their steel treatment process for increasing the life of tooling in the semiconductor business.

Oh well, no matter how great the barrel looks or how the specs read; there is still some "art" in the barrel business and I know of no serious benchrest competitor that would trade one-one thousands of accuracy for double the barrel life.

Virg
 
Black Star Super Hard Steel

Virg, When you say Black Star has a barrel that is super hard, do you have a number on the Rockwell scale? 25-32 is optimal for 416r which has less sulphur than 416 for machining purposes as someone said earlier. Just to add my very humble opinion to the mix. Heat, friction & corrosion are enemies of the rifle barrel. As far as nitrocarbonization goes, here is some food for thought. Roughly the same process is used to blue Chrome Moly as it does not have the protective qualities of SS. The same corrosive that eats your car is used to protect your rifle, kind of ironic. But to what degree does a barrel makers claim necessitate $900 a barrel? We all know that the softer bullet we shoot, the less barrel wear & a 1:12 twist won't cause the wear a 1:8 will (less bullet rotation). I am a little superstitious & shoot with a damp towel the length of the barrel on my .338 Lapua when I'm pounding lead downrange & when she heats up, I stop. I guess simple cleaning & oil storage helps stop fouling & keeps her ready for next time.
 
Where is Blackstar now? I believe Lothar Walther made their barrels out of what they called LW50 that Jackie thinks is similar to 14-4. I agree. I know several gunsmiths refused to chamber them. Some had problems with the material and some didn't have enough bushings to cover the wide variety of bore sizes for each caliber.
Why would you buy a barrel blank that had a small chance of shooting well along with the other associated problems?
I had rather buy a barrel that would have 1000 rounds of great accuracy rather than a barrel that last for ever that wouldn't allow me to win. I do think Joel Kendrick's Melonite treatment has great potential to increase barel life without hurting accuracy.
Butch
 
I was...

50Browning50 said:
Virg, When you say Black Star has a barrel that is super hard, do you have a number on the Rockwell scale? We all know that the softer bullet we shoot, the less barrel wear & a 1:12 twist won't cause the wear a 1:8 will (less bullet rotation). I am a little superstitious & shoot with a damp towel the length of the barrel on my .338 Lapua when I'm pounding lead downrange & when she heats up, I stop. I guess simple cleaning & oil storage helps stop fouling & keeps her ready for next time.
Click to expand...

I was never interested enough in these barrels since I was well satisfied with my first Hart barrel which I couldn't out shoot. To my knowledge, Black Star is no longer in business. Most of the 6ppc shooters I know have come to accept a few thousand rounds of accurate barrel life and accept this fact as part of the game. If someone comes up with a "super life" barrel that gives nothing up in accuracy...and it proves itself in competition, then we'll see it dominate the line in short order.

virg
 
Correct me if I am wrong...

Did Crucible Steel not file for Chapter 11 back a year ago or more?

Are not the barrel makers now having to buy from different vendors?

Have the barrel makers not gone through several sources including Italian, Spanish, and now German suppliers?

I chamber about 250-300 barrels per year. I use many different manufactures barrels and my customers send what ever they buy.

Not wanting to mention any particular maker, but I have seen a dramatic change of several barrel makers barrels over the last year.

While machining tenons I have noticed hard and soft spots in barrels that were less frequently found in the earlier Crucible steel. I have also had tight and loose spots in the bore of several barrels. This causes problems of extreme spreads and fliers.

I hope the barrel makers can get their stainless steel problems resolved.

I would love to see a couple of the barrel makers step in and tell us the truth about the stainless steel they are using in making our barrels.

I know there are differences in hardness between the different barrel makers.

I have customers who say they have barrels that shoot great and at about 500 rounds go south. I have other customers who get 3000-3500 rounds out of barrels. I hear of others who get 4000 plus rounds out of barrels. Of course different shooting discplines put different stresses on barrels.

Recently I have been both bore scoping and slugging barrels. My eyes can't see what my hands are feeling. I don't have an air gauge but am not sure that again my hands may not be a better gauge. I would like to thank Gordy, and Dave for their advice. What they told me have proven to be fact, not all barrels are created equal.

Variations in hardness have an effect on buttons and cutters. Lapping out tight spots in a bore tend to make loose spots fore and aft of the tight spot.

Again I don't make barrels and would love for a few of the premium makers to step up and tell us what is going on.

Nat Lambeth
 
Barrel replacement signs

What are the signs of barrel replacement? With the variables involved, what would be the data driven, general figure for replacing a barrel? Is it group size alone? What else?

I have known several competition shooters that change barrels like my wife changes shoes. They seem to be driven by about anything except specific reasons.

I am sure there are data driven reasons, but they do not seem to have any.

Any thoughts?

taylorwkrs
 
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