When Orkan was around I believe he reported that he tried the Dasher, BR, BRA, BRX and other similar cartridges that length were simply too short to feed reliably out of the DT magazine, on the feed ramp, through the extension and into the barrel.
Reportedly the cartridge would pop out of the magazine and be too far from the feed ramp, sitting parallel with the barrel and not slightly angled upwards as the magazine tries to position the cartridge for proper feeding, which causes a jam. The Dasher and 6BR max brass length is around 1.56” (+/- .01 based on your reamer) while the 6.5 Creed max case length is 1.92”. If you run the Desert Tech bolt slow enough on the 6.5 Creed and allow the cartridge to pop out of the magazine, you can get it to jam up too.
I have had my 6xc jam up whenrunning the bolt slow and it’s the same length as the Creedmoor. I haven’t had my 260 or 308 jam when going slow though and they are only slightly longer at 2.03” (+/- a few).
The WSSM’s look like they would also be a problem but I haven’t ran one or heard of anyone using one in a DT.
I know some folks have taken their feed ramp off and modified/polished the feed angle, which helps with feeding, but not enough to make a help a cartridge as short as the Dasher or BR variants feed every single time.
That must be a byproduct of having a chassis that can handle most everything between the 37XC and a 223. There aren’t many downsides to this platform but not every rifle can do everything.
