About your 243. EVERY gun barrel is different. Just like women. One might shoot one grain bullet and one might not.One might shoot a certain grain bullet,but with a certain amount of powder used. one has to go throught many loads some times to find the right combination of bullets,powders.and powder weights to get the right load. Your 243 might llike 100 gr bullets,or 90,s,or 70,s ect. find out what grain bullet your factory ammo is and if it like them,then work up loads for that grain bullet. Sometimes it just takes time,when you find the combo,then you in. vangunsmith