Asking for recommendations for a spotting scope. Range I shoot at is 300 yards maximum. Minimum caliber is 6mm, most are 7mm or 7.62. It is for the range only, it is not for hunting or spotting game. Would like to keep price below $400.

I would suggest a used Nikon Earth and Sky 15-45x60mm. They are discontinued, but are a VERY good scope for the money. The come up on eBay pretty often... lightly used to NOS usually sell for $150-200.

The Leupold Gold Ring Compact 15-30×50mm is another really good optic, but they are closer to your $400 max. Stay away from Leupold's Green Rings... you will be disappointed.

I have the Razor 11-33 spotter. It's limited somewhat on magnification, but very, very good glass for the money. You can get it used for around $400-$500.

Are you trying to spot bullet holes in paper at 300? Or hits on steel?

Paper targets at 300

The Razor Brad mentioned will get it done. You'll see 6mm bullet holes in 300 yard paper.

I have a Leupold SX-1 Ventana 20-60x80 that I got from Cameraland. They can be found for ~$400.

PM Sent- I have an older gold ring Leupold 20x60 straight body that would fit your bill for half your budget.

vortex razor 900$

Vanguard Endeavor.

I purchased this model a couple of weeks ago. Excellent features and carries same warranty as the gold rings. A lot of scope for the money that being said I have not shot it to 300. Do some research you will not be disappointed.

https://www.bhphotovideo.com/c/product/1210882-REG/leupold_170757_sx_1_ventana_2_15_45x60.html

Blessings