I had problems loading the wasp waited pellet in my gun using only 5 grains of 4f. The skirts would blow off and remain stuck in the barrel and had to be reamed out. The Pyramid air gun slugs are not wasp waisted, they are 30 grains with a hollow point, and a concave base for lube. These were the only .224 caliber slugs that I found that shot really well.
I don't know what velocity I am getting with these slugs and 5 grains of 4F, but the slugs almost completely penetrate a 3/4" pine board at 25 yards, which is good enough for targets, and the few squirrels that I have shot with it.
I looked on Pyramid Air and could not find any Pyramid Air Gun slugs. I found slugs by a number of manufacturers, but noneby Pyramid Air. What slugs are you talking about, please?
Different makes of waisted pellets have different thicknesses of the base itself, some thin, some thick, thus different strengths. .22 calibre Slugs come in sizes from .216 to .218". I have not
seen any larger than those I just listed. Most .22's have a .222" groove diameter, thus the slugs are not .224 or you would not be able to load them. The actual size matters. The actual bore
size of the rifle barrel is important, as a pellet that is just a 'hair' larger might be best. As noted, they come in sizes from .216" to .218" & from a variety of manufacturers, none of which are Pyramid, that I have seen. Details matter.