Help with DAMToys (DAM-78090) SPETSNAZ MVD VV OSN Vityaz Grozny figure?

i Recently bought a parted out AK machine gun from the this set and can not get the grenade launcher to go on the gun AT ALL.
i watched a YT vid of someone attaching it and it appears to just slide on the underside of the barrel, mine just does not want to do that and stops half way down the barrel. with the barrel being as fragile looking as it does its really hard to use any kind of force at all as it just seems like it will snap off
If anyone has this set i would love to know if your grenade launcher was easy to put on.

Apologies for posting in the wrong section, i just couldnt think where to put it

No problem, I just hope someone can help you out.