load them as long as the gun will take them, this will lower the peak chamber pressure. look into getting an oversize firing pin, EGW sells them, that will more or less eliminate primer flow.
all the guys round here use precision coated bullets(black bullet) loaded with winchester super target. because many of them use the same primers in their limited guns as thier open guns, they use small rifle primers.
with a 180, you only need 917 fps for major, need about 940 fps to make major all the time. i dont like getting too close to 165, i normally keep mine at 172 or so.
something to look at with the 40, is most reloading data is fired in a 4 inch barrel, your gun has a 5 inch tube, expect higher velocities than published data shows.
5.8 grains is listed max with U clays. i find montana golds make more pressure than other jacketed bullets, therefore your load may be a max 40 load, also hodgdon shows 1000+fps with this load, may be little too hot for IPSC, but could prove usefull for bowling pins.
give super target a try, it works good, makes major and is soft shooting. also get a chronograph, your loads may be generating lots more velocity than you think, and even if the pressure isnt max (primer flow?? bet its hot) you could be causing accelerated wear on your gun
hope this helps.
