All three of my BX25 mag started having issues lifting the stack fast enough to beat the bolt going forward. The rounds were being hit on the side and bent by the bolt.

I tried simply cleaning them and it got better, but once I wiped the surfaces where the case rim and bullet tip with a slightly oily rag the issues cleared up completely. I just happened to have a little fluid film in a rag I used to wipe down the internals with and it seemed to work like a charm.

My takedown continues to impress. Repeats very well!

I have had a similar situation with a new BX15 mag.  When I got home, I emptied the remaining rounds from said magazine.  Then I sprayed a small amount of Ballistol into the mag and worked the innards with a small dowell rod.  I then re-loaded the mag with 15 rounds and it functioned great, so far.

Personally I'm not a fan of using oil on mags,  I did get good results with dry graphite lube.

Spray on a rag(cut old t-shirts) then wipe the internal parts.

http://homedepot.com/p/Blaster-5-5-oz-Industrial-Graphite-Dry-Lubricant-8-GS/202597501