Thank you for your replies! I feel better informed about the dynamics and working characteristics of epoxies in general. In this particular instance my Devcon question was prompted by a specific set of circumstances. My friend and I have used this product successfully on several occasions so we weren't unfamiliar with its use.

In this case, however, we had two identical packages of Devcon Plastic Steel. In a side-by-side comparison, under the same environmental conditions the mixed contents of the first package hardened within five minutes while the mixed contents of the second package remained very workable for over one hour. An apples to apples comparison under the exact same circumstances.

While we enjoyed success with this product on another of my rifles; this situation caused hours of extra work work. That was a surprise & disappointment for both of us, and I wondered if anyone out there had experienced anything similar with Devcon Plastic Steel.