Can I put bbs into the mortars of a black ops airsoft mortar launcher?

mortar proportions are always expressed as a proportion of cement to lime to sand and always in that order
common mortar made from portland cement has one part cement to one part lime and 6 parts sand ===1:1:6
Cement bags have the mix written on the side for mortar mix or concrete mix or you can get mortar mix cement which already has the lime added

Airsoft guns refer to replica firearms primarily used in airsoft that are capable of firing plastic pellets through a piston driven by compressed gas, spring and electricity or battery. This type of gun is non-lethal and capable of offering more realistic replicas. You can upgrade your airsoft guns with cheap airsoft gear too.

should not be a huge issue to trim off the bottom nailer... trim off with a razor knife being careful not to penetrate the frame. the primary concern is providing support to the frame. Using mortar and wood shims, layer mortar where the window will sit and level it using the wood shims, leaving space to remove the shims after the mortar sets... I'd recommend using screws to afix the remaining fins to the studs to lessen the loss of mortar from shifting the window during install

~~~~] shim [~~~~mortar~~~~] shim [~~~

It depends on what you need to grind. Some electric coffee grinders are very good for certain seeds for example, while substances like basil come out better tasting and with a nicer color when crushed with a mortar and pastle.
Also, if you need to produce big quantities of ground substances it would probably take you a long time to do it with mortar and pestle, and using an electric grinder would help you speed up the process.

Mortar and pestle must be made of a hard enough material so that seeds and plants can be crushed without wearing away the tool, and so that the pounding and grinding won't break it.
The material should also be smooth and non-porous so that it won't absorb or trap the substances that are being ground.
There are a few materials that all more or less fit these requirements: ceramic, porcelain, glass, marble, stone, wood, bamboo, iron, steel, brass and basalt.
The choice among these is based on what use you need the mortar and pestle for.
For example rough ceramic is more fragile than stone but makes a finer powder. While glass, also fragile, is stain-resistant. Wood absorbs more easily but is very good for the grinding of salt and pepper at the dinner table. While metal mortars need to be kept lightly oiled.
I personally would suggest a heavy, thick, smooth marble mortar and pestle, as it is both very resistant to pounding, and grinds pretty finely. Marble is good with both liquids and dry seeds and plants, and it doesn't absorb odors and tastes as much as other materials, even tho it does get a bit stained and sometimes previous substances can still be smelled on it for a while.

Mortar and pestle seem to have been used since anchient times to grind seeds and plants. There are sources of its use both in the Egyptian Ebers Papyrus (1550 BCE) and the Bible.
Different variations of mortar and pestle can be found in almost every culture, all over the world.

A mortar is a wooden/ceramic/stone bowl used with a pestle to grind.

you place ajack under the engine lossen the mounts shake the engine and let the jack slowly till the motor centers evenly on the mounts then retighten bolts

Your fears are well-founded. Here in NW, MO the sand and mortar are heated prior to using in freezing weather.