A few weeks back I filled several bottles from my keg of summer ale (just a simple ale with some rye in it). I don't have Blickmann gun so I just used a piece of tubing pressed into my picnic tapper nozzle to fill the bottles. I topped the bottles off so that there was foam coming out the top and then I capped them. I waited about 3 weeks to try them and found that they really didn't have as much carbonation as the beer that comes out of the keg.
I imagine that over time I could perfect the process since I have read that many people do this. However, I have two different brews in the fermenter and I'll be giving some of this out to friends for Christmas. I am thinking that when it comes time to keg them, I will rack off 2 gallons from each batch into my bottling bucket and rack the rest into my kegs. That way, I know the bottled beers will be as well carbonated as the kegs (and as a bonus, I can sample each and compare).
So my question is this - other than calculating the required amount of sugar to use in the bottling bucket for a 2 gallon batch, is there anything else I need to take into consideration. I still have about 2 weeks before the beers will be ready to transfer so that gives me plenty of time to think things through.