For the British style bullet connectors, the method I use is to 'tin' the bared wire end with solder, if the iron is hot enough, then that should only take a couple of seconds which shouldn't be long enough for the insulation to start melting, and then fill the inside of the bullet with solder.
Supporting the bullet, I hold the soldering iron against the
nose end of the bullet until the solder runs, then insert the tinned wire end into the bullet so that it
just protrudes from the hole in the nose, the solder should then run between the two parts quite quickly and the iron can be removed.
You can of course buy the 4.7mm crimp type bullets, but you will need the correct bullet crimping tool to fit them.
http://www.vehicle-wiring-products.eu/VWP-onlinestore/terminalsnonins/noninsbullets.phphttp://www.vehicle-wiring-products.eu/VWP-onlinestore/terminalsnonins/noninscrimps.phpCrimped connections are also said to be more reliable than soldered joints, as the solder can make the wire joint stiff, so increasing the chance of it fracturing.