If you have the HS Precision stock, you could buy the HS Precision mag system that gives a flush fitting drop out mag - the cost is around £300 -the last time I bought one.
They are a drop in fit (bottom metal and magazine)
You could buy a replacement bottom metal from SYSS and and AICS mag (which will give an extended drop out mag) which would be circa £250 (I think)
I am pretty certain there are other options available - these are the ones I have experience of - if you dont like the drop down floorplate you could also replace with the Remington drop out mag system, but that would require inletting the stock and TBH its ugly.
The floorplate system works well for stalking rifles (IMHO)