Assuming your IMP feeds reliably, I cannot see a downside to improving the round. Although I am not a gunsmith (I have a real job) asking a standard version to feed well would seem more of a sure thing than with the improved ... you rolls the dice and takes your chances there.
Your velocity gains will be very modest - my own 338-06 imp gains about 20 - 25 fps at what I think are pressures comparable to the standard version. YMMV but not a lot one way or the other.
Still, the cartridge looks cool, feeds well in my rifle (model 70 classic) and has a lot of thump for a modest amount of recoil and muzzle blast.
The often cited downside of having to fireform brass seems a non-issue to me as that can be done during practice sessions we all should engage in. The brass does not seem to stretch but that little bit of saved effort is really a non-issue as is the slightly greater cost of improved dies.
If I were burdened by an abundance of common sense, I would have just bought the magnum and had done with it, but building an 338-06 improved has been a lot of fun and that is kind of what is is all about for me. I built an improved, had fun and got it out of my system.
Last edited by OregonCoot; 04/19/14.
