You can't it's a pop toy rifle. Not meant to shoot BB's
On the back of the pistol you will find a long lever, slide it to one side and load in your BBs. Under the barrel you will find a thumb loader to load each shot into the firing chamber between each shot.
I suggest you contact Daisy Directly and ask for an owners manual. See the link below.
To load a Daisy Model 99 BB gun, first ensure the gun is pointed in a safe direction and is not cocked. Open the lever to access the BB reservoir, then pour in BBs until it's full, usually around 50 BBs. Close the lever securely, and then pull back the cocking mechanism to prepare the gun for firing. Always remember to follow safety precautions while handling and using the BB gun.
This model was made by Daisy. Its a model 1894 and shoots standard .177 caliber BBs'
See the link below for the owners manual.
To load a Daisy 35-shot repeater (2003 model) CO2, first, ensure the CO2 cartridge is properly installed in the magazine. Next, pull the magazine out of the gun and place BBs in the feeding slots until full, ensuring they're seated correctly. Reinsert the magazine into the gun, and you’re ready to shoot. Always check for proper functioning before firing.
It would help if you stated the model. Sears sold several different BB guns.
Put in the magazine. load the magazine, and shoot.
750 fps. for BBs, 665 fps. for pellets.
See the link below for the owners manual.
Depends on the size of the BBs and the weight of the shot. I.E. A 12 gauge 2 3/4" target load that has 3/8 oz shot in #7's will have over 200 BBS while a goose load in a 12 gauge 3 1/2" shotshell with BBBs will have more like 20 or so BBs
Apx 5.1 grains for a standard Zinc BB ----------------------------------------- Hi - Today I weighed BBs. New Daisy zinc-plated steel BBs. I made 15 runs of tests with a 200g 0.01g scale that tests very accurate with my calibration weights. Results of my Daisy zinc-plated steel BBs - Weighed 15 times in lots of 100 & 200 BBs each time - Averages - Each BB calculated out to 0.349 grams and 5.386 grains. 349 mg & 5.386 grains each. Results were very consistent. Surprisingly consistent. New Daisy zinc-plated steel BBs. .177 caliber Premium-Grade Precision Max 4.5mm steel BBs. -----------------------------------------