I would go with a go kart over ATV, more protection and less skill required to operate. Kart has more safety features (seat belt, cage, low center of gravity). Biggest plus is I can sit next to him and kill motor or grab wheel as required.
My 6yr old:
Reinvest that Tax return check boys , girls, and Xim's Xer's etc.
Impress friends and neighbors with this detachable mag black goodness.
Help handicap veterans enjoy shooting with the pistol brace and vertical grip.
Procure some FREEDOM from the tyranical NY State gun laws.
Let that freak flag...
shameless plug. tools parts optics
https://nygunforum.com/threads/squibs-winter-tag-sale-nv-ar-parts-ammo-blow-out-sale-2-27-update.42347/post-899411
It would help if you posted what type of black rifle you want to build. battle, service, carbine, or Other:cool:
I would suggest a crossbow with a built in crank mechanism. Much easier on the shoulder loading and unloading.
A crossbow basically has the same rules as a muzzeloader except you need less room.
It is illegal to discharge a firearm, crossbow or bow: So that the load or arrow/bolt passes over...
I hate Lapua brass when new, the primer pockets are very tight. Sometimes the brass has "staining" from the foam in the box that looks like a poor annealing job. Enjoy the brass, you will have many firings from it.