Never mind

If it weighs the same as your H buffer it isn't the 9mm version

IIRC the 9mm buffer weighs substantially more

But are you giving it the "one in each hand" weight comparison? When it comes to a n ounce here or there, its difficult to be precise.

There is a very informative buffer discussion here somewhere, I will see if I can find it to shed some light..........................

This one starts out on other buffer types but gets around to all of them : 14 pages

This one has a couple of pictures

and lastly, if you can weigh yours with some degree of accuracy this may help....(credit to Slash)