Mmhf.22 barrels shoot nsa slugs?

Mine did not do so well but I could not shoot the ones I had fast enough, around 830 fps. I would like to get some lighter ones like 19gr and try them. My MMHF will shoot JSB 18.1 pellets better than my FX Impact. I love my Marauder modded and this barrel. It is always my close range go to gun. I got my Impact for longer range slugs but so far after about 800 rounds I am not impressed. I have tried everything. Anyway the choke on the MMHF barrel may be to tight.
 
I have the first version of the MM LW barrel ( no mention of hammer forged at that time) on my .22 Mrod. It shoots around 1-1.5 MOA with JSB 18.1g doing 865fps.

I bought an NSA 0.217" sample pack, cranked up the power and tried all four weights. The 19g doing 840fps (JSB @ 920fps)) was about 1" groups at 50 yards, more than adequate for pigeon busting at 50ish yards. The heavier weights were closer to 2" groups. The slugs dropped the pigeons much more convincingly than the JSB.