A few notes on motor retainers.  

Loki Research 38mm reloadable rocket motors are designed differently than those offered by other companies.  Because of these differences, some of the methods used to retain motors made by Aerotech and Cesaroni Technologies should not be used with Loki Research motors.   

Traditional motor retention methods such as screws with washers or "Kaplow clips" can be used with Loki Research motors.  However, remember this: Nothing should ever be placed over the end of the motor.  Clips or washers should retain the motor by catching on the thrust ring, not the end of the motor case.

Case in point, the PMR-29/38 motor retainer by Public Missiles.  This item was designed to work with 29mm single use motors and 29 or 38mm reloads by Aerotech.  It should never be used with Loki Research 38mm reloads as it will cause damage to the hardware, which will likely result in a CATO.  

The problem is illustrated in the picture below.  When placed on a Loki Research 38mm motor the PMR-29/38 appears to clear the nozzle adequately.  However, this is not the case!  Exhaust gases will be trapped below the PMR-29/38 that will rapidly overheat the motor case and soften the aluminum.

The PMR-29/38 placed on a Loki Research rocket motor.

At Loki Research we liked the general idea of the PMR-29/38, so we made one just like it that will work with Loki Research motors and 38mm motors from other manufacturers.  The re-designed motor retainer fits over the end of the motor and retains it by the thrust ring (see picture below).  The holes are placed to match up with the original PMR-29/38.  NOTE: Our new retainer does still work with 38mm motors from other manufacturers.

The new retainer can be ORDERED HERE.