Ati makes an aftermarket 6 position stock ... using the shims supplied by Hatsan you can maintain the factory stock angle.
These guns have had a longer run in the UK (in bulk ) than Canada so do not forget the UK as a source for parts
This is a licenced copy of the Fabarm .. Fabarm is a copy of an HK shot gun, so expand your searches when seeking say a pistol grip stock or other accessories.
After market mag guide remington 870 fits.
Remember this is a semi-auto, you will find lots of posts re Hatsan plus two mag extenders, but you will be prohibited if you go any larger than " one" on this semi-auto. These posts are for the pump
Posts will say that the o-ring is like the 1100 .. the rings brownell sells are half as thick for the 1100, you get two extra o-rings in the box, but if like me and two extra is not going to fit well into your idea of best future prep, there is a gun shop in the UK selling OEM rings on eBay. I have read many posts on the web, they vary from 1000 rounds on an original ring to just a few, but they are rubber and can be affected by solvents, so the odd short round count post I have dismissed as user error ..
Some posts on you tube re assembly will have you putting the o-ring in the wrong place, reducing the unit to a club on light loads
I use a lee slug 1oz , had to move to 19gr of red dot from 18 in my 590 to get a recycle I could count on ( look up your own load data ) This is with a Winchester trap hull reloads ..crimped or rounded over.
You will need a rail extention ( coming to the back ) to attach a forend vertical grip .. I am 6'2" with long arms, so finding a thin rail extention is pricy. I could easily reach, but was not comfortable. Not every one wants or sees a need for a vertical forend grip.
I really like this unit .. my ATI stock combined with 1200FPS reloads, and a gas system, mean I can shoot this unit all day .. that is exactly what I wanted .. being an out of shape old fart my sholder continues to love me.
PM if you have a Question ...