How can i help my horse develope the right headset?

I've been working with my horse on dressage for a while, just our little
stuff we do inbetween the days that we're jumping. I've used draw reins
on him to help him learn how i want his head to be, and how he should
know when i want him ot tuck his head in, and arch up his neck. He does
however, poke his nose out a lot, and then after a while he'll just lose
everything.
I've just recently started my friends horse on the same exact work, but
her horse goes right into it, and holds it in the exact position, does
it have to do with training, the horse, the bit? Is there something else
i could do with my horse to teach him to bring his nose IN? I use a
kimberwicke with him, i might be switching to a doulbe hinged
kimberwicke with a copper roller.

Would it be possible for you to find out about self carriage? Your horse needs to have impulsion from behind to achieve the right headset. By pulling his head in by various means is just creating a false and probably very uncomfortable head position.
If your horse can achieve self carriage and a rounded frame he will naturally hold his head well. It will take time and work to get there though - no quick fix.
It also depends on his conformation how much he will be able to do.
Good luck and less is more where gadgets are concerned

oops forgot [You must be registered and logged in to see this image.]

Couldn't have put it better myself Felicity.
Pen

Thanks Pen [You must be registered and logged in to see this image.]