Probably, improved Slings and Sling use as a shooting aid, led to more solid Prone Shooting, in the early 1900s. The shorter 1903 Springfield Service Rifle likely made the 'Back Position' downright unsafe!
Dr. Hudson still included the "Texas Grip" in his 1903 book, "Modern Rifle Shooting".
(p.s. In my State, we still use the "Michigan Grip". It is like the Texas Grip, but, with mittens).
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