In an effort to conserve my .22 ammo stash, I picked up a .22 caliber Gamo Bone Collector Maxxim air rifle.   I also grabbed a tin of the Benjamin Discovery 14.3 grain hollow point pellets.   So far, its shooting pretty good but I'm wondering if there is an ideal grain weight range for Nitro Piston air rifles of this power level.

Rated velocity is 975 with PBA stuff and around 750 with lead pellets if I'm reading Gamo's marketing wank properly.

Anyone have any experience to share with an airgun noob?

Is this for just paper/plinking within 30yds or actual hunt/pests?

You need some more pellets in various grains and types to really access what your rifle likes best, but I'd try some H&N Field Target(Trophy Power) brass in 14.6, Gamo "red" Power Points in 14.5(Walmart), Gamo Hunting in 14.5(Walmart), and some Ruger Superpoint in 17gr (Walmart).
This is just a start. Some guns in same caliber/manufacturer will like light(er) grains and others like the heavier weights. You never know.

For my Hatsan95 springer in .177, which has about same 950+/- velocity as your rifle, according to Hatsan's chrono test it came with. It shoots the lightweights around the 7-9grains well, but put in some Crosman Premier Piranha 10.5gr and it has great improvement for accuracy. I shoot it around the 25-30yd mark.

Also, it's sensitive to handhold.

For my Diana Chaser 22 pistol/rifle setup, it likes them all from 14.5 up to the Ruger Superpoint 17 grains, while only needing "up" adjustment of the Sightmark Sureshot Holographic sight, but it's also a CO2 and 500fps velocity. I've tried some heavier 17.9 and 18.2 grains, and it will spit them out, w/fuller than 1/2 12gram cartridge but the drop is extreme and just waiting for a squib to happen when using the rifle barrel. I shoot this at the 10meter mark, but at 20yds it's still extremely accurate with moderate punch, using what I know it likes.

I don't hunt or shoot live game with either of my airguns, and if I did it would only be nothing larger than a pigeon. Now, if I got a PCP, that would change.

The primary use of this airgun is for quietly making Crows and Starlings disappear from my property.   Also, to take Rabbits and Squirrels from my woods and around the garden.   Mostly things I would use a suppressed .22 for, but as a way to extend my .22 ammo stash in this stupid pandemic.

Search eBay for ".22 pellet variety pack"

Best way to find a pellet that your air gun will eat.

go to straightshooters.com  They have a fantastic pack of the most popular pellets.

Airguns are a great way to keep sharp.

I checked that out, but... $20 shipping minimum for a $35.00 order of something that will fit into a USPS flat rate box?  Dang...

H&N Field Target Trophies in the 14.6 grain weight, the JSB exact Jumbo 14.3, and the JSB Jumbo heavy 18.13 are the three that will usually get you the best performance.

Higher velocity, and hollow points don't really do that much on critters with pellet rifles.  The domed or round nose pellets are generally better for accuracy and have plenty of penetration.

i  have the same model and it doesn't shoot for shit............I hope yours is a helluva lot better.