Younger readers may not be aware of an article in the American Rifleman which appeared back in the 1950's.

A gunsmith sent in a rifle to the NRA Technical Staff for evaluation with the following story:

A customer appeared in his shop with a Japanese Arisaka rifle which he said kicked too hard, and wanted to know if the smith could correct it. He further stated that it was a caliber 7.7mm Arisaka, which he had rechambered to .30-'06. He had test fired it by holding it on the opposite side of a tree while shooting it and then used it to kill a deer, but the recoil was too much for him to bear.

The gunsmith told the customer that he had made a mistake, because the rifle he brought in was a caliber 6.5 mm Arisaka, and such a rifle could not be rechambered to .30-'06, because the reamer pilot would not enter the barrel. The customer replied that he only had the one Arisaka, and that he had solved the problem with the pilot by grinding it down until it would enter the bore.

The gunsmith verified that the rifle had, in fact, been rechambered to .30-'06 before sending it to the NRA technical staff. The technical staff decided to fire the rifle under controlled conditions. They were able to recover the bullets, which were pictured with the article next to unfired bullets of the same description. Both military and civilian hunting bullets were fired. The fired bullets were significantly longer than the unfired ones.

Other than having difficulty opening the bolt after firing, the results were unremarkable. The headspace was within acceptable limits at the conclusion of the testing. Evidently firing caliber .308" bullets through a caliber .264" bore was not a dangerous practice, as long as there was sufficient neck clearance for the bullet to be released when the cartridge was fired.