This means that the K31's action is considerably shorter than that of the K11 so while both rifles are roughly the same overall length, the K31 has a longer barrel.
The k31 was and can still be ordered from Haemmerli in 7.5 Swiss, .308, .30/06, and 300 Winchester magnum with the last two being single shot. The 1911/.308 conversion handles .308 chamber pressures of 50,000 just fine