the p-14 is in no way a #3. it's basically a mauser action built by winchester under british contract, mine in 1918. i was wondering if anyone had reloaded for both
please read
http://en.wikipedia.org/wiki/British_military_rifles if you have the time...
"Pattern 1914 – also known as Rifle, Number 3
Pattern 14 rifle (derivative)Main article: Pattern 14 Rifle
With the outbreak of the First World War, the change to the ammunition for the Pattern 1913 was abandoned; however, to supplement SMLE production the new design was to be produced chambered for .303. In 1914, the Pattern 1914 rifle (Pattern 13 chambered for .303) was approved for production by British companies, but production was superseded by other war priorities, and three US firms Winchester, Eddystone, and Remington began production in 1916.
TThe Pattern 14 rifle did not gain widespread acceptance with the British since it was larger and heavier, held fewer rounds and was slower to cycle than the SMLE. The P14 was well-regarded as a sniper rifle (with telescopic and fine adjustment iron sights) but largely disregarded outside of emergency use"
Your cases will simply last longer in both if you do not full-length size
And it's easy to confuse Rifle No 3 with the SMLE Mark III (Rifle No1 Mk III) which I think you may be doing