I actually saw a rifle that was re-chambered to 30-06 on Between two fairly good gunsmiths on a Saturday after work-- The same old argument was made that the 7.7 case was too wide at the head and if re-chambered to 30-06 you would get a case head failure- So the next week I was at a local range in carpetersville Illinois and these two fellows were there with a Japanese rfle re-chambered to 30-06 The guy that rechambered it fired the rifle , he spun around and fell flat on his back-- The told you so's were flying around but the rifle was intact aand had no damage- Seems the one guy had re-chambered a Arisaka in 6.5 caliber instead of 7.7 !! See what a few cans of beer can do for you-- Wonder where that rifle is now, when this happened in the late 197-'s you could buy all the jap rifles you wanted for $10-00=$15.00 wach !