One point loading fiber wads in plastic hulls, specifically the older Ljutic 'Mono wads' is that they stretch the hulls enough to make one wonder about the pressures being generated and make the hulls unusable for additional reloading. I've never noticed that happening in paper hulls, but it is a frequent occurance in plastic hulls. I never had the loads pressure tested, but they were from older published data. I stopped loading them in plastic hulls for that reason.
FWIW, I've had some minor conversations w/a gent in England who has been doing a lot of pressure testing w/dif wads & has found increases above acceptable CIP levels w/some loads when switching to fiber as opposed to plastic, other factors remaining equal. I'm sure he is not using Ljutic 'Mono wads', rather some currently available fiber wad.
I'll also state that I have experienced off-sounding or 'blooper' loads w/fiber wads loaded in both paper & plastic hulls in a Browning Citori target gun intended to take advantage of all the 'then current' bells & whistles w/lengthened forcing cones [3" chambers originally] and the bbls. 'back-bored' to .750, ports[gad!] & a recoil attenuation devise in the buttstock. Never had an issue w/plastic wads, but I'm sure some obturated better than others based on their design & the amount of the cup's lips present to seal.
In the same breath, I have a friend w/a Charles Daly Lindner 10 ga. w/12ga. Briley chamber sleeves [his second one, now] that has zero issues firing modern 12 ga. ammunition loaded w/plastic wads. I don't know the nominal bore diameter of either of those guns' bbls.
Just some stuff to think about, eh?
