What is the OAL of your loaded ammunition & what is the internal maximum OAL allowed by the DBM?
Most long range chooters use uber long bullets like Booger or CEB or Matrix.... sometimes these missiles increase the OAL of the loaded cartridge long enough to make using a bottom metal (of most any brand) a serious PITA.
It can be done however, I ran a 338 RUM & 300SMK's thru a 3.600" AICS mag for quite a while before finally getting tired of waiting for the planets to align in a cosmic pattern of sorts enhancing the gravitational pull of the earth to alllow the SMK to remain seated that far into the powder column...
Ok, so maybe not that difficult but....
Some bottom metals and/or magazines are designed for enhanced OAL which is worth its weight in unobtanium.
The 7RM case is short enough to be right on the border line for me. The 168's should work just fine, the 180's ok.... but, what happens 1200-1500 rounds from now when you have to chase the lands a bit & can't because of internal mag limits?
I don't know if you'll have that problem or not but, you've got some measuring to do- it's something to think about.