What do I need to shoot slugs?

Usually most airgun manufactures are using chocked barrels for better results with pellets. That doesn’t mean that you can’t shoot well slugs. Personally i own a Daystate Wolverine 303 and I am shooting pretty well NSA slugs. Very good but not perfect. Because the barrel is made to shoot better pellets.Regarding the Liner you mentioned ,Fx is producing a type of barrel to shoot perfect slugs. I hope I help you. 
 
In order to shoot slugs "well" you need to find one that is suited to your barrel!

This generally involves buying assorted slug weights and styles by the metric tonne and trying 10 per box until you "might" find one that does actually group in the same zipcode!

It can be a very expensive testing session, FX spent a long time developing barrels that shot slugs well and even then FX slug liners will only shoot a narrow band of weights and styles well, you still have to go through the same process!

You will undoubtedly end up with a whole drawer of slug failures, some find this experimentation fun and some don't!
 
The question I have for you is... why do you want to shoot slugs from the flash? It's like putting racing slicks on your dad's station wagon. It can work - albeit not as well as it will with the tires/pellets that it is designed for. The Flash is an entry level PCP that can shoot pellets decently well. The flash has a trigger that can be tuned quite a bit, it shoots 2-3 mags on a full fill, is not silent when shot - but it ain't loud either. OVer all it is a good, inexpensive place to enter the PCP world, but it does not have endless upgrade possibilities.


 
First thing , you don’t need to replace the barrel right off the bat . What you do need to do is get a proper measurement of the land and grove diameter of the barrel as well as find out the twist rate ( Hatsan are typically 1:17,7” ) like the Lothar Walther but until it is measured is not known . Next is the guns power output , what are your expectations , eg : shooting a heavy slug takes big power to push to a reasonable speed . Now if your barrel measurements and expected power output don’t match something will need to be either modified or replaced or both . 

From the experience I have with a multitude of Hatsan rifles , I think the power is easily achievable with some hammer spring adjustments to shoot modest weight slugs eg: 21 to 25 gn in .22 cal and 30 to 40gn slugs in .25 cal . That should also fit with the 1:17.7 twist rate . With bullets I usually get them to .001” over grove dimensions , that way I can size them down if the barrel likes smaller diameter bullets . 

Hope that helps . 
 
The question I have for you is... why do you want to shoot slugs from the flash? It's like putting racing slicks on your dad's station wagon. It can work - albeit not as well as it will with the tires/pellets that it is designed for. The Flash is an entry level PCP that can shoot pellets decently well. The flash has a trigger that can be tuned quite a bit, it shoots 2-3 mags on a full fill, is not silent when shot - but it ain't loud either. OVer all it is a good, inexpensive place to enter the PCP world, but it does not have endless upgrade possibilities.


lol I guess ive just been reading alot about slugs on here and ive been looking for the ultimate knockdown power, I dont have to be that precise since im shooting chickens under 50feet and going for body shots with a heavy pellet seem better then head/neck shots with a accurate lighter pellet like polymag. but im not sure a slug would have more knockdown power then then 32grain eujin pointed pellets ive been using for body shots and ive had a 100% kill rate with those. I'll might try the jsb beast jumbo 34grains too so ill prolly stick to pellets for now.