I bought Crossbreeds Reckoning IWB for my non OSP Hellcat and it fits well and is comfortable to wear. I have several Crossbreed holster for several different types of firearms (all IWB for me). They make several different models for the Hellcat (and other firearm models), IWB, OWB, AIWB, Belly Bands, etc. I like their Reckoning since it's slim, has a small profile, and more importantly, it has two belt clips. The Reckoning in general is nice, because it can be configured by the wearer to be IWB, OWB, AIWB with the purchase of their accessory clips etc. I have one of their other model IWB holsters (not Reckoning model), I bought for my CZ 2075 RAMI BD, that only has one belt clip. Big mistake on my part, as with the heavy weight of the RAMI, if the pants are undone (bathroom etc.), the holster will shift due to only the one clip keeping it in position. Hence my preference of two clips (other people may like the one clip for light guns etc., it's all ones preference).
Good luck on whatever you decide, I posted a link to the Crossbreed reckoning below:
The Reckoning Holster is an incredibly versatile IWB, AIWB or OWB holster by CrossBreed® Holsters. It is perfect for smaller handguns like the Sig P365, medium frames like the Glock 19, or larger frames like the 1911.
www.crossbreedholsters.com