That's a great question. For Smersh PKM pouches, there are two sizes. The 'small' and the 'big' ones...I don't have anything but PCC drums kicking around the house here at the moment [which the small pouches will ABSOLUTELY fit like a glove]. But I know the measurements of an RPK drum, so, i'll measure up the smallies. The small ones would also fit every caliber of Promag-style aftermarket drum perfectly [which i've test-fit before].
I have a pair of the 'Big' ones at my storage unit I can sell with the rig, instead. and they would absolutely 100% fit RPK drums. I need to go there to pick up a few other things, too. So, if interested i can go get them.
*For reference. These are the dimensions of an RPK Drum:
Okay sir, after measuring, the Big pouches are the ones that fit RPK drums. I'll sell you the rig with them for the same price [even though the big pouches are physically worth more than the smalls]. And I'll ship the rig and a GP-25 to you in the same box if you want one too. I can get everything in the mail tomorrow, too.
Here is an example image [of trash-assed chinese knockoffs] of what the big pouches look like vs the small]
I have a pair of the 'Big' ones at my storage unit I can sell with the rig, instead. and they would absolutely 100% fit RPK drums. I need to go there to pick up a few other things, too. So, if interested i can go get them.
*For reference. These are the dimensions of an RPK Drum: