Low Brass has nothing to do with low pressure! Low brass shells often generate higher chamber pressures than high brass loads because these so-called promotional or Wally World loads will use a smaller charge of faster burning powder which generates higher chamber pressures. You can handload to keep pressures below 7500 psi or you can buy commercial low pressure ammo from RST or other sources. Also, there is nothing on your barrel markings to suggest that your gun was originally built with 70 m/m or 2 3/4" chambers. So until you get better info to the contrary, it would be wise to have your barrel wall thickness evaluated by a good double gunsmith who is familiar with vintage doubles.

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