Thread: should I have gone for a 4th shot

IMHO

that group is just fine for showing that you are well sighted in. 3 shots gives a basic approx estimate of the mean point of impact (mpi), which I believe will likely be somewhere within a circle enclosing the 3 shots.

It's not enough shots to estimate the group size. certainly not enough to discern any double grouping. ie cold bore vs hot group mpi. unless you have a prior estimate like half a dozen 1" groups at 200. to estimate the mpi for cold shot vs hot you need at least 3 or better 5 cold bore shots and corresponding hot shots straight after.

I discipline myself to decide how many shots I am going to put down before I start a group. sometimes I see its way out and decide a sight adjustment is in order after only 3. if the first 2 or 3 are widely spaced I takea deep breath and try extra hard to put the last 2 into the middle of it. for me, a 1.5" 5 shot group (100m) is creditable but 1.5" for 3 is a bit weak. it is tempting to stop after 3 close shots but statistically very dodgy. I would have quite a few 0.5 groups on record if I'd allowed myself but they would mean little. never stop if you've started well. its just pulling and you know it.

ps if you're using factory ammo and trying to economise then you have to accept the handicap of doing without high quality information on your gun's grouping capability and cold / hot / fouling behaviour. you can still sight in and get trajectory data from 3 shot groups.