To prevent the player's body from blocking the player's view when looking downwards, RFP2 pushes the playermodel backwards by a configurable amount. When the a CPM model is loaded, this offsets boxes & quads as expected, but does not change the position at which particles are displayed, causing them to appear in front of where they should in first-person view. The issue seems to occur regardless of which bone the particles are attached to, it is not exclusive to arms.

Screenshots:

Model used for screenshots:
steve_particle_bracelet.zip
(Steve example model, slightly modified to demonstrate the issue)