How
Long Will My Savage 10ML Barrel Last?
Once in a while,
this question comes up-- a bit more often than you might think.
It is, of course, not possible to answer with any degree of precision,
although I'd like be able to. But I cann't, anymore than I could
tell you how long your plumbing will last, or perhaps more related--
how long the exhaust system will last in your car. It won't stop
me from trying to answer, though it gets into the "how many
angels can dance on the head of a pin?" type things.
Some shooters
feel that most barrels see more wear from poor cleaning practices
than they do from actual shooting. Perhaps, though I have no idea
how to measure that one. It is reasonable to believe that most muzzleloading
barrels wear out from corrosion, as the battle with corrosive propellants
is an endless one. It is very hard to sand metal back on; that I
can see. When operating the Savage 10ML-II with the non-corrosive
propellants it was designed for, the rust, pitting, and corrosion
problems that has destroyed thousands of blackpowder rifles is not
an issue.
My great-grandfather,
farmer and market-hunter, was really rough on guns. They were just
implements. I remember the little line of guns in his kitchen next
to the fridge, looking neglected. They looked sad enough that I
asked if we could clean them-- that was forty years ago, and I was
just a little fellow. "Next time," Great-Grandpa
said. He must have meant "next time he'd say next time,"
for they were never cleaned. They survive to this day: a Remington
Model 11 with the rib shot off, a Marlin "Safety" in .38-55,
and a damascus barreled Ithaca double-barrel. They all operate,
but by the time they were passed down they were solid rusted plugs
of metal. I'll presume you take a bit better care of your guns than
my Great-Grandfather did.
Guns are wearing
parts. Rifled barrels wear with every shot we take. Throat erosion
is nothing new at all-- but, scant few big-game hunting rifles,
and even less muzzleloaders will ever see 500 shots in a lifetime
of use. I have only one truly "super high mileage" firearm--
a Browning B-80 12 ga., with a legitimate 100,000 shots through
it. Aside from the recoil spring in the stock that has been replaced
several times from a "preventative maintenance" standpoint,
it is as received when I cought it new. The only thing that ever
broke was the cocking lever on the bolt, a small die cast piece.
I ordered a replacement from Browning, they sent me a dozen of them,
but it never broke again. A smoothbore scattergun cannot be rationally
compared to a rifle, though.
A older US
Navy document states, "The single base nitrocellulose powders
contain proportionately less oxygen than the double base powders.
The resultant gases from the single base powders contain therefore
relatively less of carbon dioxide, CO2, and relatively more of carbon
monoxide, CO, than do the double base powders. The heat liberated
by equal weights of the two powders is therefore greater in the
case of the double base powders, since the heat of formation of
CO2 is greater than the heat of formation of CO. The conversion
of carbon to carbon monoxide produces a greater volume of gas than
its conversion to carbon dioxide. The single base powder therefore
produces a greater volume of gas, though less heat than the double
base powder. From a thermodynamic standpoint, it is therefore somewhat
less efficient, but it has the advantage of causing less erosion
in the gun because the resulting temperatures are lower."
All barrels
have throat erosion, there is no doubt. The problem is that no two
barrels are alike. None are perfectly smooth, and none is perfectly
straight, nor is it of the exact same inner dimensions. So barrels
wear at different rates. Douglas barrels have gained a reputation
for being soft, and wearing quickly. Pac-Nor, Lilja, and Kreiger
barrels have better reputations. In other words, one .300 WinMag
barrel may produce noticeably reduced accuracy at 1,000 rounds (or
even less) while another .300 WinMag with a similar barrel may
continue to shoot extremely well at 2,000 rounds or more. It is
just not possible to accurately predict barrel life. Many sources
claim that a "good .30-06" should last for 3000 rounds
or so and still be accurate. Depending on who you listen to, the
.223 WSSM, .220 Swift, and .22-250 all can be real barrel burners.
Barrel life is a function of pressure and heat-- so the fellow shooting
38-40 grains of VV N110 in his 10ML-II with a 250 gr. sabot is likely
to have longer barrel life than the guy shooting 42 - 44 grains
of N110 pushing a 300 grain saboted bullet. It is fair to say that
it is the mark of an accomplished shooter to realize when reasonable
accuracy life is at an end.
The rifling
in a 10ML-II is only three and half thousandths deep, as it is in
most rifles. To compare, a sheet of newsprint is typically .004
to .005 in. thick. When 4000 degree F. hot gas is blown through
it, the lands wear faster than the grooves.
Thanks to expert
ballisticians like Hartmut Broemel, we know a lot more about it
than the US Navy apparently did "back in the day." Erosion
is directly related to pressure and heat. The "heat of explosion"
value is a significant factor in erosivity of powder-- though it
is not generally published. That, and working pressures are both
factors. The powders used in the Savage 10ML-II are moderate to
slow powders, certainly very slow in relative burn rate compared
to the faster shotshell powders ("Red Dot") and the faster
pistol powders ("Bullseye"). The operating pressures of
the Savage 10ML-II are very moderate to very low by center-fire
standards, in the mid 30,000 PSI peak pressure range. Use of a relatively
soft sabot that must be loaded from the muzzle precludes suitability
of fast, high-pressure powders. Compared to the by now, ancient,
.30-30 Winchester, the first cartridge loaded with smokeless from
its inception despite the old blackpowder style of designation,
the 10ML-II is a low-pressure rifle. The .30-30 has a SAAMI MAP
of 42,000 PSI-- well above that produced by any Savage
10ML-II recommended load.
The Savage
10ML-II that I put 5,000 rounds or so though was inspected by Savage,
showing so little wear that it passed all Savage factory new barrel
tolerances, inclusive of air-gaging. After all those shots, the
original breechplug showed very minimal, normal wear. It still shot
inside 1 MOA after all those rounds.
I have no idea what the life of a specific 10ML-II barrel might
be-- however, I think it is very reasonable to expect no more than
9000 - 10,000 shots without at lest some degradation of accuracy.
That's three times the life of "ye old .30-06"
by most accounts.
After the 9000 shot mark, it just makes sense to send your 10ML-II
back to Savage to have it evaluated at the factory and likely rebarreled.
That would be my approach. Some would have blown through $9000 -
$12000 (or more) or bullets, powder, primers, and sabots
by that time. A new barrel at that point is a tremendous bargain
by any rational comparison. For many (most?) muzzleloading
big-game hunters, that means a round-trip to the Savage factory
once every 180 to 200 years. Please let me know, I'm always interested
in this kind of thing-- though, it may well require the services
of a medium to get the note through to me.
