Page "Smith & Wesson Model 29" Paragraph 13

Some S & W model 29s were rebuilt by the AAI Corporation to make the Quiet Special Purpose Revolvers ( QSPR ).

These had new, short, smoothbore barrels ( 35 mm / 1. 375 inch ), with. 40 " / 10mm bore, and with cylinder chambers reamed to accept special QSPR ammunition which externally resembled metal-cased. 410-gauge shotgun shells but internally worked as a piston to trap the gases.

This special ammunition was made by AAI.