Winchester Supreme 780

Here’s a 200-word summary of Winchester Supreme 780 based on available information:

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Winchester Supreme 780 is a smokeless rifle powder originally developed and used by Winchester in its Factory Supreme ammunition lines for medium to magnum rifle cartridges. It is a ball (spherical) propellant, meaning the powder granules are roughly spherical in shape, which generally helps with smooth metering and consistent charge weights — an advantage for both factory loading and handloading alike. 780 has a burn rate comparable to Hodgdon H4831, placing it in a medium-to-slow category suitable for larger rifle cases. 

Historically, Supreme 780 was used in Winchester factory loads for calibers such as .243 Winchester, .270 Winchester, and .300 Winchester Magnum, among others, and provided good velocity and accuracy characteristics for those cartridges. It was intended as a magnum-class powder bridging the gap between faster propellants and very slow magnum powders.

As a handloading powder, Winchester 780 was valued for its consistent flow, reliable burn characteristics, and accuracy potential. However, like many Winchester propellants distributed through Hodgdon, availability has varied over time, and 780 has been discontinued or hard to find in recent years, prompting reloaders to substitute comparable powders such as H4831 or others in that burn-rate range.

Because it was formulated to match the performance of Winchester’s own factory ammunition, handloader manuals caution against exceeding published loads and emphasize verifying data from reliable reloading sources when using this powder.