I joined a gun club and now I have access to 25,50,75,100 yard and a 200 meter
distances . My question is could I do my load development at 50 yards to see which
charges give me the best groups, then after I find the right charge weight shoot those at 100 yards? The reason I ask this is because this guy I met at the range sayS that is how he does his load development.

Do your load development for the distance you'll be shooting the most. The further away the better.

i wont test loads closer than 100yds...

closer than that, things can be too tight to read...

for example, i shot a 1 ragged hole group with a charge at 35yds or so when i was getting my scope close...100yds that same group was well about a 2"er...same results twice at 100yds..at 35yds it looked like a winner though...

200yds IMO will involve more shooter error and make things hard to judge....

I like to do my load tests at 100 and 200. I usually load 6 rounds for each load. So I shoot 3 at 100 and 3 at 200. If I find something promising, I hone in on that with OAL.