Hammer Grip for Smash
I’ve never heard of a different grip for forehand in singles vs doubles..i’ve never heard or seen it mentioned before until you and cheung have mentioned it in this thread. I’ve not seen it in any prior posts here. A variety of grips are used in badminton, whether singles or doubles.
It’s also not clear to me what somebody means when they say “hammer grip” either. One time I heard somebody say hammer grip, they meant standard forehand grip e.g. handshake, position the V etc. What some might call an axe grip.
Another time I heard somebody say “hammer grip” they meant panhandle grip. Some people might not want to say forehand grip or backhand grip on the basis that there is a range of grips one might use on either side. The terminology on the backhand side can be clarified as the thumb grip , and the bevel grip. But maybe terminology on the forehand side hasn’t been figured out so well.
I have heard of some on the RTH side for some shots using a panhandle grip as opposed to a forehand grip, because with the forehand grip you have to rotate the forearm quite a bit to get the racket open.. so a panhandle might feel more natural. But iirc when at the very back, forehand grip might be preferred.. But was a while back when I looked into that. But that’s not really singles vs doubles.. Unless one wanted to say it happens more in doubles. Somebody might say that doubles is faster and less time to change grip so somebody might end up with some in between grip. But usually with more training one can change grips.. and that even applies to smash defense and even with drives many would say you can change grips(or choose not to),and it comes down to which method you train.
Some in doubles might say that there’s more moving up and down the racket like serving holding the grip higher up.. But you’re not talking about that. Whereas singles players might be inclined to just hold the middle. But you/they are not referring to that
So I don’t know what they mean. Sounds like a mystery to me. Have you asked them?