Can I convert a RB Townsend to a Fountain?

[Redmen34]

I recently received a Cross Townsend rollerball pen as a gift. I have always wanted to get a nice fountain pen and I am wondering if I can turn my Townsend rollerball into a fountain pen by simply purchasing a replacement nib from Cross and then some cartriges. I would be looking at the 23 karat plated nib that is listed for $40 since my pen has gold accents and I do not want to spend too much. I am relatively new to Cross pens and this would be my first fountain pen so I do not know much about them. If it would be possible to just buy a replacement nib, would you recommend the 23 karat plated nib? Also, what width do you recommend? I generally like 0.7mm widths in my rollerball/balpoint pens, so what width would be closest to that? Thanks for helping out a newbie!!

[refillczar]

The only difference between the two is the spring in the barrel that pushes the RB refill to the tip. If you try and put a second cartridge in the barrel for storage you'll have problems. You might be able to pull the spring out but the adhesive is pretty good.