RB;
I must have missed it, what cartridge are you shooting, ?, distance?
Some of the posts are 'rifle' and some pistol.
Do you weigh your bullets..?
I used to weigh all my bullets in a batch and would separate out the light ones.
Those I would use for sighters
I found that the light ones would have a void, usually off center.
These were 515 gr 459 Postel style.
RG in my case here it was a Savage 110 LH in 30-06' at 100 yd with a selection of jackets , it was before my enlightenment .
It turns out that the rifle was obtusely sensitive to case capacity . The sister rifle in 308 was a garbage disposal as long as I didn't break 175 gr , it shot 2" within 4" of poh .
My casting enlightenment and skills have long since reached a point where visual is good enough to get me inside 1% generally .
I once had an expectation of groups to be of a certain level . At some point I came to understand or maybe recognize that what I was expecting simply wasn't within both my skill set and the level of build quality in my rifles .
I did get that 1965 110LH dialed in I had to get case weights/volumes down to under a .8 gr case weight variation per case lot . FL sizing was not an option in that rifle either . I was shooting IMR 4350 in it and with a Hornady 150 .3 gr was the difference between 5 touching at .900 OD and 1.5" ctc . With a start load I was getting 2700 fps across the Chrono .
I guess my point is that there can be any number of things that will effect the location of holes at 100 yd and while good consistent bullets are a big part of that they aren't the only significant contributor .
110 LH case capacity resolved 18" groups .
110 LH same gun sizing removed 2" from groups .
SKS x39 primer change cut 2.5" from 50 yd groups .
340C 222 it just won't shoot a bad load .
325C 30-30 bullets under 1.2 inches in length won't shoot over 2" .
Dad's 25-06' , 75,85,100,115, 117 gr .750 and less for 5 on demand. 120s ? Best load ever 1.25 ctc . Forget shooting Hornady in this rifle it wants Sierra and Nosler and prefers FC primers and isn't real fussy about brass brands . The NOE .260-120 is playing nice but appears to want to be run wide open without regard to powder selection but I'm a long way off there yet .
The 1895G in 45-70 shoots 3" . Bagged , elbows , 3 point sitting , tree lean , with 3 405 gr class , 350 , and the NOE version of the 535 Postell all at 100 yd . The HB 400 gr Lee was a disaster and the 462-420 MP PB and HB don't bring me any joy until they are into concussion/whiplash levels at 417 and 380 gr . The Rapine 458-201 , a 255 RF at .459 with a thin base band being intended for a .458 dia SAA delivered 2" 4 of 5 with the 5 round tossed at 2000 fps 10' from the muzzle . The toss was wholely on me not the light , FP sighted Remlin .
I had a pair of 45 Colts M92's with 1-32 twist . With focus golf balls were subject to flight from 25-75 yd . At 110 the skinny end of a barn was at risk but in little danger . Ballistic calculators , Strelok , put transsonic at 79-84 yd depending on MV and the particular bullet . Between 78-82 yd the bullet would up set and depart line of flight at 10:00 and 30-40° . In that last 35 yd it would literally go from 75 yd pygmy cottontail in the pot to missed the 10' berm with the base at 105 yd and 60° face .
Then we have thread choke , roll marks , dove tails , screw pressure , temp , humidity , altitude , barometric pressure , latitude , spin drift vs earth rotation ...........
There are about 10 long range competition things a rack hunter grade rifle put into my cycle before I knew they were match level things . Also I'm a carburetors are a stupid simple device , breaker points ignition and windwings are a huge technology loss mechanic that looks for a root cause of a failure/defect an tries to describe it in such a way that both the guy that knows how to get gas in the tank and the PhD can get a visual of what I'm trying to say ........it doesn't always work .