Such as...my daddy served in the Navy in the South Pacific during WWII. He told me stories of Marines who had been issued rifles rifled with only 2 lands and grooves, basically one step above the smoothbores of 1812. Could not be, I thought.
Then in the early 1960's when you could mail order military surplus shipped directly to your home, I like so many others ordered a Remington made M1903. Paid $35. And as some of these two groove rifles began to appear, the stories began to surface in some of the, as Jank describes it, gun p o r n magazines. Accusations were made of sub contractors taking short cuts and endangering our troops.
My comment 4 or 2 was meant to be sarcastic as the 2 groove was approved. It may not be a tack driver, but suitable for battlefield zero and proved it's worth against anything the Japs could throw at it including themselves. Like Dire said...greeting the Axis.
For more information
https://www.google.com/webhp?hl=en#fp=d376bad89d5753b2&hl=en&q=springfield+1903+2+groove