2 groove barrels..

[buffdog]

In his book "The Lee-Enfield Rifle", Major E.G.B Reynolds has the following to say about Wartime manufacture of rifles.

"Barrel making was another serious "bottleneck" in rifle manufacture, and efforts were made to simplify the process. In May, 1941, trials were carried out with barrels having TWO grooves instead of the normal FIVE."

He goes on to comment on accuracy tests and bore fouling. A number of two groove barrels were fitted to No.1 Mk.III rifles and were tested against regular production rifles with five groove barrels. Ten rounds were fired in one minute with each rifle, then shot for accuracy while still hot. This continued in cycles of fifty rounds until 500 rounds were shot through each rifle.

"There was no appreciable difference between the two forms of rifling in either accuracy or barrel wear." and "It was decided to adopt the two-grove abrrel as an alternative form of rifling for all .303 rifles."

Also, permission was given if it helped the manufacturer to use Four groove barrels for No. 1 rifles, and some were made for No. 4 rifles.

In May, 1942, trials were made with THREE groove barrels, and after 5000 rounds had be fired through them, accuracy was still good.

( Source: Reynolds --The Lee-Enfield Rifle -- Page 158 )

Since Savage or Long Branch would not have taken it upon themselves to change specifications of the No.4 rifles without permission from the British, this leaves the question of the Springfield rifle.

The modified Springfield 03A3 was originally developed for the British. When the Japanese brought the U.S. into the war in December, 1941, the focus changed to the 30.06 Calibre for the U.S. military. It would appear that the U.S. Military, in order to speed up production, adopted the British idea of TWO groove barrels. I have a TWO groove Enfield 1917 in 30.06 with a Johnson replacement barrel, but it is dated 1943.

So, I hope this answers the question. It appears the first large scale use of Two groove military barrels was the British, in May, 1941. ( This does not take into account Muzzleloading rifles )