modern +P is loaded only 2,000psi higher pressure than previous specs - existing in 1967 - for non-+P.
First point,"
only 2,000psi" is more than 10% of the .38 Special's pressure. Current data says SAAMI spec for the .38 Special is 17,000psi and .38 Special +P is 18,500psi, and that's not even 2,000 difference its 1,500.
SAAMI pressures are standardized RECOMMENDATIONS for MANUFACTURERS, intended to be safe in ALL firearms. They are NOT the max safe working pressures possible, and they have been LOWERED for some calibers over the last have century.
SAAMI recommendations are what they feel is best for the industry, not what individual shooters can safely accomplish in some individual guns.
The Colt Agent has an aluminum frame, and a steel cylinder, its not going to "blow up" from .38 Special +p pressure. What can happen, over time, firing enough of the overpressure loads is that the frame can deform (stretch), which could lead to an inoperable condition, or worse, an operable but unsafe condition.
NO ONE, including Colt, knows exactly how many +p rounds that would take, only that enough could do it, which is why they asked to check the gun after 1,000 rnds of +p.
Limit +p use to sighting in and duty carry, shooting standard pressure ammo for all other uses and the Agent should last a long time.