"pet loads" "classic loads"

When i first started reloading 38 special and 357 magnum cases with speer 148 MBWC and 158 SWC...   I couldnt get any reasonable accuracy with Bulls Eye powder..  I was happy to get 6" groups at 20 yards. And with green dot and red dot i was getting 3" groups and better. 

Now what is the rule of thumb to use when comparing other peoples loads to what your own gun has down with the same powder?

Meaning should i devote my final 1/2 can of BE  to just "range time, trigger re training ammunition"?  My remaining 1/2 cans of Red Dot and Green Dot to the same cause as well why sacrifice primers to a powder that just isnt available right now.. 

And do the sensible thing and just switch to a more accepted powder like HP-38?

I still have around 450 of each of these speer bullets i need to use up.

Not sure what a 148 grain MBWC is.  Is that a typo and do you mean a HBWC?  I have had good success with 2.9 grains of Bullseye and a 148 grain HBWC, for bevel base wadcutters of the same wait a heavier charge seems to work better.

.38 special target loads are well established.
No real need to experiment.
BE, WST, 231, HP38, 

All work.

2.7 of 231 or HP-38 will get you there.