For accurate target shooting....
Trying to understand the technical reasons 6mm Basher seems to be more accurate(popular) than 243 winchester?
Why?
They are so close to being the same cartridge?
Is it all default barrel twist?
Will a 243 with 1:7 or 1:8 be just as good as 6mm Dasher?
Are there additional reasons?
Does the 6 Dasher deal with long VLD bullets better?
Better rifling land engagement?
6 Dasher has been around a long time in the world of 1000 yard benchrest competitions, it started winning records ~20 years ago. The Dasher was dominant for a long time, now you see more of a mix between 6 Dasher and 6 BRA (both very similar cartridges). Those benchrest guys really only care about how small of a group they can shoot at 1000 yards, regardless of what caliber it is. So I would say that the Dasher became popular because it is a more accurate cartridge.
Dasher picked up popularity with the PRS crowd maybe 8 years ago because it had a high level of accuracy and was also a low recoil cartridge which is perfect for the spotting your own misses in competition. It's been pretty prevalent in PRS since then, I'd guess at least twice as many matches have been won by Dasher in the last 5 years compared to anything else.
As to "why" the Dasher is more accurate than a 243, I'll reiterate some of the same things stated above. I think it's simply because the Dasher is a shorter, fatter, small case with a steeper shoulder angle.
When powder burns in a cartridge the combustion starts at the primer and works its way forward. The progression of that burning powder wants to push the powder at the front of the case forward. A really tall/skinny case will allow a lot of unburned powder to move forward during combustion and a shallow shoulder angle allows that powder to move into the throat of the barrel. A short fat, steep shouldered case tends to keep all the powder burning inside the brass cartridge. This results in more consitency from shot to shot, as well as a more efficient case - it takes less powder to make the same bullet speed.
Realistically though you can have a super accurate 243 and shoot fine with it. No need to change to a Dasher just because benchrest or PRS guys have found that it suits their needs.
