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Introduced in 1979 and intended to offer superior performance, compared to the 7mm Rem Mag, the 7mm STW case was then a bit much, capacity wise.  We just did not have propellants that would allow us to take advantage of so much case capacity in the 7mm bore size.

As with any high-performance round, barrel heating is a significant concern.  Allowing plenty of time for barrel cooling can significantly increase barrel life.  Conversely, overheating the barrel by rapid firing can render a barrel uselessly inaccurate after surprisingly few shots (see the 264 Win Mag text).  For a big game hunter this might not be much of a concern (see 7mm Rem Mag text).

Even today, with the best modern propellants, it can only offer about 80-fps over what the 7mm Rem Mag can do with 175-grain bullets and practically 100% of that advantage results from higher working pressure.

When loaded at the same pressure with the same bullet and the best available propellant, performance is essentially indistinguishable.  But, of course, we cannot ignore SAAMI pressure specifications and when loaded within those, the STW does have an edge over the Rem Mag.

While 80 fps might not seem like much, velocity is always king.  Velocity is why we gave up throwing fists and graduated to rocks; then gave up rocks and graduated to spears; then gave up spears and graduated to an atlatl; then gave up the atlatl and graduated to arrows; and then gave up arrows and graduated to bullets!

As was a host of standard belted–magnum cartridges, this case was derived from the circa 1912, 375 H&H.

The text associated with the cartridge description reflects opinions and conclusions of the author, M.L. (Mic) McPherson. Lee Precision and its employees do not necessarily either agree or disagree with any of his comments. We present these with due deference to his recognized expertise in the firearms field. His acumen extends to handloading and all aspects of ballistics - internal, external, and terminal.
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