I have been very lucky with my reloading and have not had to experiment with numerous powders and bullet combinations to achieve (IMO) very good results (this is not an invitation to compare what is "good" )
First calibre I reloaded was .270 some years back with a lee loader
I tried N165 and 130gr Interlocks . average but better than factory results
Switched to N160 and got an instant improvement and excellent results no OAL experimentation required.
.243 - N160 with 75gr, 87gr and 100gr all bugholes with no reall experimentation with length
.222 - N133 with 50, 53, 55gr and 60gr - tricky getting good 60gr loads but all 1/2" or less
Shot lots of fox and deer!
Over this period of years I have been forced into buying a press and weighing charges and measuring stuff with calipers!!
(I know!! but the peer pressure and the need to see what all the fuss was about overcame me!)
Comes to the .300WM
Running out of the ammo that came with (IMR4831 and Fed primers under 185 Lap. Megs) and was keen to work up some 208gr AMax loads to play.
I had some H4831, N165 and N160 all of which seemed to produce good results for others from online searches
Ran some loads of all three with fixed long OAL (91.3mm - 3.594")
Settled on 69.5gr on N160 which produced a 5/8" C2C group (possible that 70gr may have been slightly tighter but for a flyer but nothing in it (and erring on the side of saving powder and caution I went for the lower charge)
this works perfectly as I already use N160 in two cartridges
So I worked up loads of 69.5gr N160 with varying OAL from 91mm (3.585") through 88.6mm (3.488")
91mm was OK, slightly tighter than 91.3mm
next one opened slightly
next opened slightly more
next one slightly more
at this point I was beginning to see a pattern that I have seen in other loads
but I thought I would push on to prove a point only to be surprised
next group tightened up to starting point size
next one slightly tighter still
last one slightly tighter in the main group but the same pattern as all the good ones of 2 or 3 touching shots and the rest a short distance from that.
so I have a whole load of groups, all of which would be MOA or less and four groups at polar ends of my OAL scale that have produced much better but very similar results. (touching holes with holes around between 3/8"-5/8" C2C)
Each shorter group produced a POI higher than the last, so I am assuming a slightly higher MV from the shorter OAL
So what would you do?
fine tune in smaller increments to find better OAL's between the sweet spots I already have?
fanny around chasing something that may not exist?
or just choose one of the good ones and go stalking!?