There is never a need to soak a holster.
And you would be wrong. I make leather holsters. Any formed leather holster you buy has been wet molded after being soaked in water between about 120-140 degrees. This temperature range, along with being soaked in water, relaxes the collagen bonds and allows them to be re-aligned in a new shape. The leather will retain this shape. Much hotter and the collagen bonds are destroyed. Any cooler and the holster will not hold its shape. Mind you this requires water and temperature, merely warming a holster up will not do it.
And it depends on your definition of “soak” I suppose. You don’t need to soak a holster for hours to reshape it. You do need to soak it in appropriately warm water long enough for the holster to be wet through and through and to warm up enough so collagen bonds to relax, which I find 5 minutes or so about ideal.
Mind you, if you are soaking an already finished holster to reshape it it will never be quite the same. It’s already been dyed and sealed, and you will have some of that dye bleed in places and the sealant will never “seal” as it originally would again. Some dies are added pre-molding in holster production, some post. Some holster makers use the dye solutions as the hot water baths needed to relax collagen bonds. Almost always, the sealant has been applied post wet molding.
OP if I were you, I would wrap the pistol in several layers of Saran Wrap and holster. Work in and out. Work up to wrapping the pistol in a thread bare old cotton t-shirt and holstering if possible. This SHOULD do the trick and will be the least invasive method for your holsters finish. If this doesn’t work, and you aren’t overly concerned about the finish/sealant, you can soak the holster for a couple 3 minutes in the hot tap water. Wrap your pistol in Saran Wrap, then holster it and wiggle it to stretch the holster out a smidge.
thread is not smooth and I would like to know if there is a remedy
If by thread you mean leather grain is not smooth, some melted beeswax can help some with this. Hard to apply once the holster is already made. And help SOME is the key takeaway. It won’t make it completely smooth. Leather grain has a mind if it’s own.
