You can stop the rattle...
After finally tiring of of that racket I improvised a stop for it by using a 1.5"
length of a wooden popsicle stick attached to the magazine tube.
A slight taper was sanded on one end of the stick.
The tapered end was positioned to wedge the front of forearm tube snug
against the magazine tube when pushed fully forward. A .25" overlap is plenty.
Adjustment of the amount/angle of taper and position of the stick may be
The wedge material and attachment method are your choices, but to keep
your rig looking slick mount the wedge between the barrel and the mag tube
then paint it black.
"We have done the impossible
and that makes us mighty."