Re: reverse sloping patio?
I do Hardscaping (patios, retaining walls, outdoor kitchens, ect..) for a living. Been doing it for 7 years now and from personal experience there is no "easy fix" for your problem. The problem is caused because your slab was not anchored to your house. When houses are built there is an over dig meaning they excavate a larger whole than the footprint of the house. They back fill after building the foundation and basement if your house has one. The problem is no one ever compacts this space because it is next to your foundation walls and you don't want to risk pushing them. This dirt will settle usually takes a couple of years to completely settle. The best course of action if you are looking to do it yourself is wait about 5 years after the house is built and remove the existing slab and either re-pour (would only be about a yard or so from your dimension) or my personal opinion is that pavers are much better if installed correctly. The best cheap fix is to demolish and re-pour. IMHO the est fix is to demo and install pavers. More expensive shot term but long term much cheaper. If interested PM me and we can talk about it in more detail.
If an inline is just like a flintlock why don't you get a flintlock so you can hunt more seasons?