I bought a haltie harness today for Sam ( not the nose one ,the body one)
I got a size medium because that's what it said he would need on the box, put it on tonight and it was massive(even when made adjusted to the smallest it could go)
I don't know if Sam is just small or if he still has some growing to do but there ain't no way (if Sam is average size) that the medium is small enough for your average cocker.
I will be returning it tomorrow and getting a small......I'll let you all know how his first haltie walk goes
I had to contact "The Company of Animals" in the end as I couldn't get the medium to fit either - but the small is really too small for a cocker - the webbing is too thin for them (I have both)
Try fitting the body-strap further back along the torso.......this worked for us - and you really have to stitch the front ring in place, too
If you PM me your e-mail address, I'll foward you the e-mail I got from the company - with pictures