Sounds like you at least had some good range time. I have been away from my .243's for a while. This said when I was using them I almost exclusively hand loaded all the ammo for them.
Recently however, I purchased a used Sako Forrester. From the outward appearance, it looked like it had a rough time with it's previous owner. In fact the only real reason I picked it up was to use the action for a new build. With the looks of it and already contemplating the new build, the tinkerer in me just had to see if the thing would shoot a group. I spent two full days on the weekend cleaning, and soaking the crud out of the barrel. After half a bottle of solvent, and no telling how many patches I finally got a clean one out the end. I mounted a cheap Weaver scope I keep just for this type of shooting, and stopped off at the local sporting goods store and picked up the cheapest box of factory ammo I could find.
The rifle was bore sighted only when I ran the first round through it. It hit close enough that I decided to go ahead and run some more through just to see if they would group. After the third shot I fully believed that at the 100yds, I had completely missed the whole paper plate I was shooting at, and that the first had simply been a fluke fouling shot hit. I walked down to pleasantly find three edges all touching. I walked back and shot two more just to verify this, and called it good.
To date I have swapped out the scope to a little better Weaver EER for my grandsons benefit, swapped out the stock for a much nicer one, and worked up a load for it using the 100gr Solid Base which I have use in the past in my other .243's. The load I settle don uses the Hodgdon Hybrid-100V powder, which I admit was the first and only loads I have worked up with. The velocity from the 24" barrel is consistently within about 15fps, of 3085fps. The pic below shows my work up and the final loads using two different primers on the lower left. As noted in the pic, the last two rounds of each 5 shot group were climbing due to a very slight rub in the forend of the stock which has since been addressed.
My good friend, and his family have been shooting these same rifles for as long as I can remember. They all shoot the factory 100gr Hornady BTSP into small clover leaf groups like pictured above. They haven't any issues with putting deer or hogs down on the spot with these loads in all the time I have known them. Myself, I have WAY too many components on hand to simply head out and purchase the factory ammo. If I were going to however, I would definitely look towards the Hornady Custom with the 100gr BTSP first. The price is fair for today's ammo, and the previously mentioned performance is hard to shake a stick at.
