Ty,
I have just placed an order a few weeks ago via Europtic for a DTA with the monopod and the 300 win mag conversion kit. I wanted to get another conversion kit and already have a .308 rifle. Was thinking of the 260, 6.5 Creedmoor or 6.5 x 47. Would like to maintain the Lr shooting ability in a less expensive bullet eater. What are you finding the most consistant? Do all of these operate on the short action bolt and magazine?
You have already gotten good information. Here is my take.
All 3 6.5's are ballistically superior to a 308. They drop subsonic around 1500 yards depending on environmental conditions. We have actually shot our 6.5's out to a mile (1760 yards), but of course there are way better tools for this (like for example your 300 Win Mag).
In a DTA, any of them would require a 308 bolt, magazine, and a short action bolt stop (some guys, like Russ for example, don't use the bolt stop).
Between the 3, the 260, and 6.5 Creedmoor are about ballistic twins. The 6.5 x 47 is slightly slower. Here are the pluses and minuses for all 3 that I see:
260
plus
Lapua brass is available
DTA makes factory barrels
Brass can be easily made from a ton of different resourses
minus
Lapua brass is expensive
Remington brass sucks
6.5 Creed
plus
Excellent factory ammo available at about $25 per 20
Bullets can be seated further out (not much of a plus in a DTA as the mags are so generous)
Hornaday brass is fairly cheap and good (some don't share this opinion)
minus
Only one source for brass (Nosler brass is coming)
Difficult to make brass
DTA does not currently make factory barrels
6.5x47
plus
Lapua brass
small rifle primer
DTA factory barrels available
minus
brass is expensive
I'm not aware of any other source of brass
slower than the other 2
My pick of the 3 is the Creedmoor. Mainly because every barrel we have put out (50ish) all shoot the same load extremely well. I shoot a lot, and don't have time to load develop after every new barrel. We spin a barrel, and it shoots as good as I am able to pull the trigger with the same load every time.
Other folks have excellent results with the other 2 flavors.
Just my opinion,
Ty