I'm curious what those .243 reasons are if you would tell them Al.
I've spent some time trying to find the ultimate 6MM long range setup. Back when I bit the bullet and bought the big one I decided to try the 243AI. It was about 1993 or so and the 243AI was kind of challenging the competition at the time. The Ultimate 6MM was the 6X284, it got so popular that they started making brass for it. Pretty much all the shooters still believed that speed meant something and the 6X284 is speedy. BUT..... times change, each record broken set the bar higher and the 243AI was posting some amazing scores even against the huge 30's (the 30X378 was another big contender) so I went with the 243AI. I worked with 5 different reamers, almost a dozen barrels on 3 different proven platforms and just NEVER got what I wanted. But I learned a ton about case prep, maintenance and reloading. In the course of about a dozen years I ended up flogging the 243AI to exhaustion, trying other rounds alongside it and in the final tally being a huge fan of the 6BR. And I was hanging out here on this board as it gained ascendancy, even got a forum of it's own
http://www.6mmbr.com/index.html and I reluctantly conceded that the 243AI was a lost cause.
ANYways..... over time it seemed that cases shrank and accuracy requirements went up. Trial and error does show honest results over time and the results are pretty much irrefutable, the Lapua 6BR brass allowed for loading to velocities that just reset the clock. The case is remarkable, and easily modified. 6BR based rounds like the "Dasher" and BRX were soon walking all over the larger Super Sixes.
But WHY???
This was the question I asked.....WHY?
What makes THIS case stand out from the herd?
And I found an answer. After extensive testing I've an answer, for me.
And the answer is, small primer/small flashhole allowing for higher safe pressure levels.
The 6BR performs because it's a better case, a better pressure vessel.
But Charles and yourself are right, it's small.
But wait! There's hope and change!
Good Things in the offing.
Gotta' Love Lapua
Lapua again answered our prayers. First they came out with the 6.5X47 case and now the new Palma case. The 6.5X47L IMMEDIATELY became a success in 6MM, challenging the 6BR, and the new Palma case brings the 243 into the 21st century....
Soooo, circuitously I can now recommend the 243 wholeheartedly as a viable 1000yd chambering. Done correctly it'll ROCK your world, easily pushing 105's over 3200fps. NOT the 243AI, I don't recommend it for anything, but the 243.
In the interest of saving you money I'm offering it as a good alternative since you already have reloading gear.
I'm trying to steer you away from The Equipment Graveyard. Mine is HUGE and full of busted dreams.
And stacks of used up dollars.
So, there's some of my reasons. There are many more but that's a quick and dirty view
al