Yes I should think thats ok, mind you they could also go outside very soon, before they become potbound!

Thank you. Perhaps they might branch out more and give me a better harvest ?

I've never pinched out the growing tip of runner beans...

Wait another 2 weeks. Meantime put a short cane into each pot and wind each bean stalk round it anti-clockwise - I think (whichever way they are growing by themselves). They will then be easier to plant out, just tying the short cane to the longer one. Then tie the stem to each 6' cane with old knitting wool, just to give them a little support until they get stronger. This rots and is easily removed in the Autumn. No need to pinch the tops out until they are 6 feet high. I keep a large pot of Lemon Balm Herb sunk into the ground by my row of beans, it deters black fly. If you get black fly the birds come for it, and knock the flowers off, delaying the production of beans. I used to spray in the evenings with a little Dettol in a can of water, as birds can smell and dont like this. It also attracts bees, as they like it. But the Lemon Balm is more effective and saves spraying. Last year I picked beans on July 10th which is a new record for me.

I wouldn't remove the growing tip!

So far as I can recall they do not throw side shoots like say tomatoes and sweet peas meaning you would stunt the plants.

Do as Diane says and cane them up with split canes until planting out time in a couple of weeks time.

Two of my runner beans have had snails take the leading shoot out, and they are completely bewildered (the beans, not the snails) as to how to get up the poles! They are getting a bit bushier, but not doing a lot of climbing. I wouldn't pinch out the growing tip if I were you, until they reach the top of the pole.

Thank a million for your help,what WOULD we do without it ?

Broad beans and other non-climbing beans it is fine to pinch the growing tip out of to encourage them to bush not any of the climbing beans though.