Kegging With A Few Bottles Question

I am planning on kegging almost all my beer from this point on, but I would like to have 4-8 22oz bottles per batch for longer aging, sending to friends etc.

I hope to just force carbonate my kegs, but what will be the best way to bottle condition the 22oz bottles?  Is there a proper measurement of sugar I can put in each one?

I think I have seen people using a beer gun out of an already carbonated keg, is this a good option?

Thanks in advance.

using a beer gun (or other counterpressure bottle filler) is a good way to do this. the beer guns are highly thought of. if you want to bottle condition a small number of bottles, try googling carbonation drops. they are essentially sugar pills. you drop a number of them (determined by the level of carbonation desired) into your bottle, fill, cap, and wait.

I think those drops are exactly what I am looking for, thanks so much!