AbHobyist, I am not a total sap...I have here, some 20 gauge data for lyman "sabot" slugs. Just like in your post, these look like BIG overgrown air gun pellets.
Wad-20S1, Primer-Fed. 209A, 20 bore 2 3/4 inch Federal case, 27.0 grains of Blue Dot, Velocity of 1306 fps. Slug weight-350 grain
I have an Ithaca M37 Featherlight, that I put a 20 inch rifled barrel on, and with iron sights had 2 inch groups at 35 and 75 yards.
Only one flier, we believe caused by improper wad seating pressure.
Be warned in slugs, the wad seating pressure, makes for a huge difference in POI.
The lyman sabot slugs came from,
hankypanky1945@hotmail.com
Unfortuneately Ammomart, often are sold out of this mould....
Its been a long time since I dealt with him,so the email may be upper case too!
I could be wrong, but he could be the small supplier from New Jersey and adverts at Shotgunworld.com, which also hosts the A.S.S.A. (Amercain Slug Shooters Association)
Cheers
