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I'm this close to having a rifle rebarreled to 257 Wby for use as an open field deer rifle. The 257 is tempting, but I'm wondering how many rounds I can expect out of a 257 barrel with 100 "X"s clocking 3700 fps. For those on the board with 257s, how many rounds have you put through these barrels, and what are your experiences re accuracy fall-off and throat wear? Thanks.


Anybody who seriously concerns themselves with the adequacy of a Big 7mm for anything we hunt here short of brown bear, is a dufus. They are mostly making shidt up. Crunch! Nite-nite!

Stolen from an erudite CF member.
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Have you read this?
http://www.google.com/groups?selm=b...u&oe=UTF-8&output=gplain

C/ Does anyone have the complete (barrel life) equation?

Yes, I do. I originated it on rec.guns years ago. And yes, it's
empirical. Over many years of competitive shooting, I learned from
all the top-scoring shooters their loads and rounds of accurate barrel
life. The key thing here is "accurate" barrel life by their
standards. In highpower competition, accurate barrel life ends when
shots missing where called by about 1/3rd more than when the barrel
was new and in its prime. In other words, when the barrel's grouping
ability is about 33% bigger.

The most common cartridge used until the mid 1960s was the .30-06 with
powder charges about 48 grains of powder. Top shooters would
typically rebarrel at about 3000 rounds; most would not enter the
Nationals with more than 1500 rounds through their current barrel.
Note that this number is based on shots at a rate of one per minute
for 10 to 20 minutes. For rapid fire at one shot every 6 seconds for
one minute, each of these rapid-fire shots is worth two of the
slow-fire ones. If lots of rapid fire is done, then naturally the
barrel life is shorter. I started looking at some fact about this
cartridge I could equate to its barrel life. It just happens than the
cross sectional area of a 30 caliber bore is about 48 square
millimeters (calculated with bullet diameter). It would seem that a
powder charge equaling 1 grain for each square millimeter of bore
cross sectional area means 3000 rounds of accurate barrel life.

Then I looked at other competition cartridges' barrel life as reported
by top scoring competitors:

.222 Rem.; 24 sq. mm, 21 grains, 4000 rounds.
.22 PPC; 24 sq. mm, 24 grains, 3000 rounds.
6mm PPC; 30 sq. mm, 28 grains, 3500 rounds.
.243 Win.; 30 sq. mm, 38 grains, 1600 rounds.
6.5x55 Swede; 35 sq. mm, 42 grains, 2000 rounds.
.264 Win. Mag.; 35 sq. mm, 72 grains, 600 rounds.
7mm-08; 41 sq. mm, 41 grains, 3000 rounds.
7mm Rem. Mag.; 41 sq. mm, 61 grains, 700 rounds.
.308 Win.; 41 sq. mm, 43 grains, 3500 rounds.
.30-.338 Mag.; 41 sq. mm, 65 grains, 1400 rounds.
.300 Win. Mag.; 41 sq. mm, 72 grains, 1000 rounds.
.300 Wby. Mag.; 41 sq. mm, 91 grains, 800 rounds.

This was a most interesting discovery. Cartridges using powder
charges equaling bore area (bore capacity?) got about 3500 rounds of
barrel life. Those using charges twice bore capacity got about
one-fourth of that or around 750 rounds. And those using less got
more than 3500 rounds. I've wondered where the term "over bore
capacity" came from; maybe this is why.

I did some trial-and-error math routines to come up with formulas to
plot a curve that fairly well tracked these numbers. Such empirical
processes have been used since the 1920s to calculate non-linear
ballistic cams used in military mechanical analog computers for aiming
large caliber guns with great accuracy results. So, I figured it
would work for this situation, too.

My formula is:
1. Calculate the bore area in square millimeters using bullet
diameter.
2. Use one grain of powder for each square millimeter. This is what I
call the reference, or bore capacity powder charge. Example: .30
caliber bore, .308-in. (7.82 mm)bullet diameter = 48 square
millimeters. Bore capacity powder charge for .30 caliber is then 48
grains. A .30 cal. cartridge that burns 48 grains of powder (.30-06)
gives a barrel life of about 3500 rounds of best accuracy.
3. If a larger 30 caliber cartridge is used and it burns more powder,
the accuracy life in rounds for that bore size is reduced. The amount
of reduction is determined by:
a. Divide the increased charge by the bore capacity, then square the
answer.
b. Divide that answer into 3500. Example: A .300 Wby Mag. has a bore
capacity of 48 grains. This cartridge burns 91 grains of powder.
(91/48) squared is 3.6. 3500 divided by 3.6 is 972 rounds. Three
competitive shooters told me their .300 Wby. rifles gave them between
800 and 900 rounds.

This also seems to work when using powder charges less than bore
capacity. The .222 Remington was the winning cartridge in benchrest
matches until the PPC family came along. It burned about 21 grains of
powder in a barrel whose bore capacity is about 24 grains. So,
(21/24) squared is 0.7656. 3500 divided by 0.7656 equals 4571 rounds.
Top benchresters in the �50s and �60s rebarreled their triple-deuce
stool guns at about 4000 rounds.

But this empirical formula has limits. The old .22 rimfire long rifle
burning 1 grain of powder in a bore whose capacity is 24 grains would
calculate to give a barrel life of some 1,728,000 rounds. But the top
international shooters I've talked to rebarrel their $4000 Anschutz
free rifles at about 25,000 rounds. And then there are thousands of
folks who claim a .22 rimfire barrel will never wear out.

And bore material and manufacturing processes can make a difference,
too. Most top-quality 30 caliber barrels get about 3500 accurate
rounds for the .308 Win. There's one make that gets about half that;
but they've been used to win the Nationals and other big highpower
matches more than once.

The intended firearm use and accuracy expectations comes to play, too.
Take the M1 and M14 service rifles. Their typical combat barrel life
established by arsenals is about 10,000 rounds with service ammo.
It's accuracy requirements was (as I remember) about 3.5 inches at 100
yards. Compare this to top competitive highpower shooters
requirements of no more than 1/4th inch at 100 yards. That's what it
takes in highpower to stay under 1/3rd MOA at 200 yards, � MOA at 600
yards and 3/4ths MOA at 1000 yards.

If anyone can shoot a hole through this theory, I welcome that shot.
This is more or less an emperical process based on accurate barrel
life in several calibers as reported to me by lots of folks plus a
couple dozen barrels I've worn out. All I did was study the data and
determine what math would give a best-fit formula. And if someone has
a better method, I'd like to know what it is.

And if your experience differs with this data, that's fine. Make your
own barrel life determinations based on what you observe using your
own accuracy standards. I don't expect everyone to have the same
standards, but it helps when they're realistic for the shooting
discipline. We all get to decide the most we want to miss where we
call the shot on the targets of our choice; animal (game & varmints),
mineral (metallic silhouette) or vegetable (paper targets).


There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps
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Rick:

Didja get that??

JimF

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Unfortunately no formula can take into account proper cleaning and not allowing a barrel to overheat.I put over 1000 rounds through a custom stainless barrel on my 257wby and it would still easily shoot groups under 1/2".I was using 100gr bullets at 3500fps as 3700fps is pushing it.My own barrel had very little freebore which may have slightly limited velocity but did improve accuracy dramatically over the factory barrel.

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RickF Offline OP
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Interesting stuff! Thanks for the input guys.

According to the above formula, a 257 Wby is good for 630 rounds assuming a 72 grain powder charge. That's assuming a cartridge with a 34 grain powder charge is good for 3000 rounds.

The reason I was concerned is that my gunsmith has experience with 257 Wby barrels being badly worn after 300 rounds, and believe me when I say this guy knows what he's talking about. In his words, the 257 is a fine way to go, because if I'm not happy with it I won't have to put up with it for very long as it'll soon be ready for the next barrel anyway! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

As this rifle won't get used a lot other than field shooting at deer, the 257 sounds like a great way to go. I'll hopefully work up a load with the 100 XLC or 3-X, and then not shoot it much except for hunting. But the 270 Wby and 7 Rem are tempting as well...




Anybody who seriously concerns themselves with the adequacy of a Big 7mm for anything we hunt here short of brown bear, is a dufus. They are mostly making shidt up. Crunch! Nite-nite!

Stolen from an erudite CF member.
IC B2

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I just sold my 257 weatherby but really liked the cartridge. don't see how you can wear out the barrel on any big game rifle unless you shoot it off season at PDs.

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Fascinating. Unfortunately the barrel life of my 7mm Ultra Mag is apparently even less than I imagined. I just hope that not allowing the barrel to overheat will extend the projection somewhat. The thing is a fantastic shooter now but I am fast approaching 500 rounds and if I am calculating correctly 545-550 ought to get it.

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The formula is based on competitive shooting! I don't know ANY reasonable person who subjects a hunting rifle to that kind of abuse...10 shots in 60-70 seconds..Pause less than ten minutes and do it again!

Mike


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stubblejumper,

Quote
Unfortunately no formula can take into account proper cleaning and not allowing a barrel to overheat.


True so very true. Also no formula takes into account the shooters that just burn their barrels up by shooting max loads, or higher. I've got over 1,000 rounds thru my .257 and it still shoots around .75". I have a .300 Weatherby that I rebarreled a few years ago that was pushing 2,800 rounds before the accuracy went away. Like anything, the better you take care of it the longer it will last. Lawdog

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I should confess that I am not a 257Wby fan before writing futher. Let me explain why.

I've handloaded for three 257Wbys for several decades; my current rifle has 1,500+ rounds and accuracy hasn't deteriorated from new, staying around .80MOA, five shots. I shoot the 100gr Noslers with a 3,610 muzzle velocity; while not a max load, it is accurate and adequate for the game hunted.

Too, I have a Ruger No1 in 25-06. Like the Weatherby it has a 26" barrel and shoots the same bullet to the same velocity with slightly better accuracy. This rifle has over 3,500 rounds through it and continues to deliver 5 shot groups @ .50 MOA.

With both rifles I always allow two minutes between rounds when bench testing.

I want to develop some 257Wby loads using Reloder 25 and see if the velocity can be improved enough to justify owning the rifle as I like the workmanship and advantages of the rifle itself. In chronographing other 257 Weatherby rifles at several ranges, the same mediocre performance has been recorded. When I say mediocre, I am refering to velocity vs case capacity vs advertised claims when compared to the actual performance of the 25-06 or 25 Gibbs.

One other criticism deals with muzzle blast and the resultant assault to the ears. Let me attest that the 257Wby will definitely ring your ears unless you intend on hunting with ear plugs. Its similar to other high intensity cartridges such as the 7STW and ilk. When a followup shot is needed in the field, these rounds can deliver significant pain to the ears. I suspect the should also be equipt with spark arrestors.

Overall, I have found the 257AI and the 25-06 to be far more versatile and just as effective as the 257 Wby under hunting conditions.


1,992 coyotes since 1964
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Charlie has a 257 Weatherby barrel on the for sale adds here. Maybe that will help.


[email] <a href="mailto:[email protected][/email]">[email protected][/Email]</a>



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I pressed Bart for what was the accuracy drop off that caused the competitors to rabarrel, and never got a staight answer. For one thing, he shoots 20 shot groups and does not think in terms of my five shot groups. The best groups with my best rifle have been .6" at 100m, but I average .8". If that average climbed up to .9", I would not re barrel, but I am sure a competitor would. I would not re barrel until the average got to 1.5", and maybe not then.

The NRA published information shows a .308 getting more accurate for 10,000 rounds.


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I have hunted a great deal with the 257wby,7mmstw and 300ultramag and have no problems with noise with any of the three.I do not wear ear plugs while hunting and according to my annual hearing tests my hearing is just as good as it was when I hired on at my present job 23 years ago.However one shot with a boss equipped 7mmremmag rifle had my ears ringing for a couple of hours.I will never own another muzzle brake again.

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You better not shoot at any animals that are close and have a reflective surface close behind them. A good example is a close shot at an animal with a big rock right behind them

I fired my .243 into a drainage pipe and my ears rang for days.



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ClarkM,

First, are you calculating the surface area, cross sectional area, or what of the barrel in square millimeters?

Second, pressure is what causes throat erosion, and pressure does not correlate with (only) powder weight. 48 grains of powder with a 30-06 will have a lot higher pressure if used with a 173 grain bullet than with a 125 grain bullet, even if different types of powder are used. I think this is a "hole" in your theory.

Also, modern high power shooters often use the .223 Remington (more powder than a .222) and 6000 rounds of barrel life is not unexpected.

Indy


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Indy,
I am not calculating anything there, just clipboard and paste.

Bart Bobbit is one of the best shots at 1000 yars in the world. He has competed for a long time.

I am NO ONE in the accuracy world, but I am in the top .1% of applied math in a recent IQ test [I am 52 but can still do my Jr High math].

I don't think it is a calculation Bart does, and much as a rule of thumb.


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Quote
But the 270 Wby and 7 Rem are tempting as well...









You wouldn't regret doing a 270 Wby, that's for sure! Mine gives 130s over 3500 fps and shoots under an inch. Sighted in 3" high at 100 yds it is less than 7" low at 400.



That, my friend, is flat and it kills like lightning!



Tell ya more about it the next time we talk.




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I can't believe our largest proponent and probably most experienced with the cartridge hasn't weighed in yet!!

I would expect barrel life to be somewhat shorter than a .308 or .270 but it's a hotrod not a plinking rifle.

Mike


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