a Factory Barrel?
If you own a
14" or longer Contender barrel in 7mm, .30 cal, .35 cal, or .44 cal, you
really should consider rechambering it to a cartridge based on .444 Marlin
someone want to rechamber in the first place when the factory has so many
thin brass for all the larger diameter chambering such as 7-30, .30/30, .35
Rem., and .44 Mag, is by design meant to operate at pressures less than 40,000
psi. The .375 Win. is the only large diameter factory cartridge meant to
operate at pressures above 40,000 psi, yet you need higher pressures to get
maximum allowable performance from other calibers.
Winchester is too hot for the Contender, IF WE ACCEPT 45,000 psi AS THE
MAXIMUM SAFE PRESSURE FOR CARTRIDGES LARGER THAN 3/8" DIAMETER, but smaller
than .45/70 (see Note 1).
If you start
loading 7-30 Waters, .30/30, or .35 Rem. to 50,000 psi or thereabouts, which
is approximately the SAAMI max. for .375 Winchester, you will most likely find
yourself troubled with extraction problems and potentially a stretched frame.
So how does
the .375 Win get away with these kinds of pressures? It is the 1) straight
sidewall, combined with 2) the strength of the heavier brass in the .375 Win.
case itself. But, wildcats on this case require custom dies.
strong .444 Marlin brass lets one operate at nearly these same levels safely,
and common .308 Win. type dies afford the first parameter, that of the
straight sidewall for my .444-based cartridges.
The rim of
the .444 Marlin is another plus. Rimmed cases simply work better and easier.
However, the other all important reason to rechamber is to cut a longer
chamber to get rid of the misaligned or poorly designed part of the old
factory chamber. I've thoroughly examined thousands of T/C factory
barrels, both Custom Shop and production barrels. The majority are seriously
deficient in the throat area (see Note 2). Once a new precision chamber throat
is cut in the barrel, ahead of the factory's chamber throat, you WILL get
outstanding accuracy from virtually all barrels without a factory muzzle
brake, and most of the barrels with the factory brake, the only noted
exceptions so far are isolated instances with 7-30 Waters Hunter barrels.
Marlin brass is the only readily available quality brass that gives all these
benefits in one neat package: 1) strength, 2) length, 3) compatibility with
standard dies for straight sidewall cartridges, 4) a substantial rim, and 5)
an economical price
that utilize full length .444 Marlin brass are long enough to clean up all
factory chambers. .444 Marlin brass is THE brass to use for all calibers
7mm and up. (With a little extra work it is also preferred for .25 and
6.5mm, and, yes, I chamber for 375x.444 aka 375 JDJ). Plus, my series of
chambers use common .308 Win-type dies with a very minimal body taper to
reduce thrust back to the frame. 7mm-08, .308 Win, and .358 Win. dies used to
form and load my 7mm Bellm, .308 Bellm, and .358 Bellm are far more economical
compared to custom dies required for most of the various other wildcat
chamberings available. Any full length size die sets are fine, but may not
size the web area of the case small enough. If this occurs, simply run cases
through a .444 Marlin size die which usually sizes much smaller than common
7mm-08,.308 Win., and .358 Win. dies will. Using the .444 die only when
required permits a quasi neck size/"shoulder bump" when leaving the web area
as fireformed to the chamber.
UNLESS you use a .444 Marlin size die in addition to the standard size die, I
must have the size die you will use so I can match the chamber to it. This
also means you may end up with a bulgy web area, since most common dies are
meant for larger factory type chambers. If you want a close tolerance web
area in the chamber, you must use a .444 Marlin size die with it to size back
to near new brass web dimension.
of course, uses standard .444 Marlin factory ammo or standard .444 Marlin dies
This is how
you get the full maximum potential for accuracy, trajectory, and energy from
your Contender. And, using standard dies, you do it very cost-effectively,
transforming your factory barrel into one that out-performs many high priced
custom aftermarket barrels. Performance, that's why you should
rechamber, and because of the experience I have rechambering thousands of
factory barrels and the way I go about it, I should be the one to do it for
you. Why settle for less, especially if you get less and pay more elsewhere?
Note 1: I've
fired thousands of rounds of 45,000 psi factory ammo (.250 Savage, .300
Savage, .444 Marlin, etc.) in Contenders for nearly 20 years and test fired
with one primary frame for nearly 10 years before any signs of stretching
appeared. 45,000 psi IS OK in the Contender when brass meant for this
pressure range is used.
Note 2: T/C
chamber throat deficiencies: To varying degrees, the majority of T/C's
chambers and chamber throats are misaligned with the bore. Anyone with at
least one decent eye can readily see the misalignment when they are shown what
to look for. Most of T/C's throat diameters are much greater than is
required for top accuracy. Current .30/30s have no throat, only an overly long
neck and a chamfer on the ends of the rifling. The .30/30 barrels give very
mediocre accuracy in factory form. Most .357 Mag, .357 Maximum, and .44 Mag
barrels have a revolver type forcing cone instead of a cylindrical throat
section which is required to support the shank of the bullet as it engraves
the rifling. The throats I cut are of minimum diameter
for accuracy, moderate length, and centered with the bore. They are done as a
separate precision operation without any interference from forces produced
cutting the body of the chamber. THE THROAT IS THE MAIN ELEMENT TO
ACCURACY IN ANY BARREL. Yet it is so commonly neglected, even in most custom
For data and
information about the Bellm .444-based cartridges, go back to home page and
click on The Bellm Triad Cartridges.