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Winchester 1964 SPIW: Flechettes and a Blow-Forward Grenade Launcher

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Today we are looking at the Winchester company’s entry into the 1964 SPIW (Special Purpose Infantry Weapon) trials. The SPIW program was an attempt to increase small arms lethality by increasing hit probability with ideas like hyper-velocity flechette cartridges and burst fire trigger mechanisms. In addition, the weapons were required to incorporate area-effect elements – aka grenade launchers.

This design used a 60-round drum magazine firing a high velocity flechette as well as having a blow-forward semiautomatic 40mm grenade launcher attached to the muzzle. One of the biggest challenges in the development was the flechette cartridge itself – the sabot holding the dart in place had to be loose enough to cleanly detach at the muzzle, but also tight enough to pull the dart down the barrel.

Ultimately, none of the 1964 trials weapons were successful, and this Winchester design was particularly unsuccessful. In addition to terrible balance and handling, it was not particularly reliable in the firing trials.

Thanks to the Rock Island Arsenal Museum for allowing me access to film this very interesting rifle! If you are in the Quad Cities in Illinois or Iowa, the Museum is definitely worth a visit. They have a great number of small arms on display as well as an excellent history of the Rock Island Arsenal.

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