Prevent shrinking sheath

[Treesner]

after a lot of use in the rain mud ect finding my sheaths to shrink in the rain and become difficult to pull out. Anyone else have this problem?
Using 5/6oz veg tan leather.
Water formed
Eco flo water stain.
After that dries I heat up leather with a heat gun and apply a sno seal coat to the outside.

Was considering trying the baking technique another member described in a tutorial

 

[Hengelo_77]

Heat shrinks leather, so it may be that treatment that does it

 

[Horsewright]

I think it may be the weight of the leather that you are using not so much the heat. I assuming from your post that they fit well prior to use? If so and you are not using the heat gun to dry them every time they get wet but only on the original construction I wouldn't see how the heat would be the culprit. 5/6 oz is on the light side for sheath work. Many years ago I used it quite a bit for some sheath work but I moved away from it with time. While it molds well it just didn't have the durability I was looking for. The lightest I use now is 7/8 oz and depending on the sheath and the size of the knife often 8/10 oz and occasionally 10/12 oz. What leather are you using, T Treesner ? The quality of the leather will really make a difference too. Any pics?