Pooch,
If you want to back off even more from a conservative load, that's a personal choice and sure won't hurt anything. But my opinion is that the barrels themselves are not weakened from this condition. But if you are trading utility of the gun in order to back off your load, I would say it is not necessary for this condition. A quick look at some stress-strain curves for steels of similar strength will show that strength from this type of deformation is actually increased, not decreased, albeit a very small amount.
There are literally millions of products made from cold formed steels of similar charateristics to barrel steels. Many of these products carry critical loads. An example is hydraulic and fuel hardlines in airplanes. These lines are made from steel tubing. They are cold formed (bent) to fit the routing in the airplane. The deformation is many times more from this bending than a small bulge in a barrel. The function of these lines are critical to the normal operation of the airplane. These thin little hydraulic lines operate at 3000 psi with pulse spikes to much higher.
