The father of the alleged Georgia school shooter reportedly took only his most precious possessions when the family was evicted -- his guns ... abandoning the dogs and family photos.

Colin Gray, dad of 14-year-old suspect Colt Gray, allegedly forced his way back into their rented home by kicking in the door for only his firearms ... their ex-landlord claimed to The Independent.

Among possessions left following the eviction were their two German Shepherds, a golf bag, an archery set, assorted tools, and wedding photos, per the outlet.

TMZ previously reported Colt -- currently facing 4 felony murder charges with more likely on the way -- came from an "absolutely horrible" home life ... with authorities called to the prior rented house several times.

Neighbor Lauren Vickers told us she called Child Protective Services 4 times for such alleged incidents as Colt wearing the same clothes daily, and his 2 younger siblings being locked out of the house at night, screaming and crying to get in.

Colin has since been arrested and charged with murder ... and he's facing 4 charges of involuntary manslaughter, 2 counts of second-degree murder and 8 counts of cruelty to children.