What do you expect from slug accuracy?

I am formost a hunter. My go to slug used to be the KO .217, but the last batch was no good. Dies are getting old and apparently they are going to stop making them in .217.
I am happy if I can put a five shot group down in a 1/2 to 3/4 consistently at 50m. The old KO .216 did not work in my barrel but the MK2 .216 seem better , but they still only group at a inch and slightly more. My barrel always seems to be the most accurate at 880fps. The MK1 H&N slugs seems very good and I get very tight groups with the 25grn, but other weights aren't far off. Haven't tested all.
Javelin MK1 used to be ok, but I found the MK2 Javelin and surprisingly I can shoot them much faster. 925fps seems to be the sweet spot with most groups going 1/2 inch at 50m if I do my part. They also buck the wind a lot better than the MK1. My gun doesn't like the 21grn but loves the 23grn. I must still try the 26grn Mk2, which is a good waight for my gun.

Bang for your buck in South Africa
KO .217 (accuracy lacks currently)
Javelin (best accuracy for the price and my current goto)
H&N (very accurate, but a bit more expensive than Javelin and not as good on high speed. Awaiting the MK2 vertion)
Inferno 25.4grn FB (very good but more expensive)
Nielsen (very expensive here, havent tested)

My current setup.
M22 (Simple Workhorse, makes power easy and I like to tinker)
Power plenum (Xtreme Airguns)
Oem barrel (550mm unchoked, pollished)
Retractible bolt probe (Thanks to airgun nation forum and GTA. Wasn't that hard to do)
All porting to 5.5mm
Barrel port 5.5 and then 4.5 elongated the last bit.
Huma regulator
250cc + big plenum
Power (30grn Javlin just under 900fps at max with 150bar reg pressure)
Shots per fill. (30+ at normal power shooting 23grn at 925fps or 25.4grn at 880fps)
The action is very quiet and doesn't sound like it is working hard.

I bought the gun second hand with a Loather Walther unchoked polygon barrel. It hated slugs and was pellet fussy. I was looking for barrels, which was hard in lockdown and found a cheap OEM barrel that was jamed. I did not have high hopes for it, but did some work on it anyway. I found out that it shoots all pellets very well and all good .217 slugs that I have tested except Javelin 21grn for some reason. (H&N 21grn is lazer).
I'm looking for a P10 bullpup for my next project. It seems to have the same powerplant and bolt system. Then put a 800mm barrel on it.

What do you out there expect from slug accuracy group wise?
What barrels are you getting good results with?
What non FX rifles is worth while for slugs?