is a 10/22 with a flash hider legal? specifically this one: https://www.basspro.com/shop/en/ruger-1022-takedown-semi-auto-rimfire-rifle-with-flash-suppressor

Yes.  You are currently allowed one of five "evil features" on any semi-automatic rifle that accepts a detachable magazine:
1.  A telescoping or folding stcok
2.  A pistol grip that protrudes from the receiver
3.  A flash suppressor or a threaded barrel designed to accept a flash suppressor
4.  A bayonet lug
5.  A grenade launcher

The pictured 10/22 has a single evil feature, that being #3.  This is the same reason the M1A is NJ legal - because it has a traditional, rather than a pistol-grip, stock, so its threaded barrel/flash suppressor is legal.  Note that you can NOT then take that 10/22 and put it in an aftermarket pistol-grip stock, as it would then be viewed as an illegal assault firearm.  But as it is in stock form, it's G2G.

thank you for the info.

i've been a captive of NJ for nearly 50 years and the laws still confuse the shit out of me LOL.