Chamber inserts/adapters for rifles

[Jim Watson]

The old M1903 single heat treat receivers have been known to blow with "plinking" loads of 8-10 grains of Bullseye and a round ball.

Another new one on me.
Slamfire's buddy, J. Hatcher, reported cases of brittle actions breaking from the guard cartridge with the 150 gr service bullet and 9 gr Bullseye.