So would it be okay for active military to simply bring in banned items or is there some sort way of going about it. Also would it matter as to where these items are kept while the individual is away? And lastly any shops keep a stock of the banned items (mag's,rifles) I know delta keeps lowers in stock but maybe something more would be nice to look at.

If the military member of the military or naval forces of this state or of the United States is "transferred" to CT they can bring in their AW's and LCM's and register or declare them within 90 days to DESPP.

https://www.cga.ct.gov/current/pub/chap_943.htm#sec_53-202d]Sec. 53-202d. Certificate of possession of assault weapon. Certificate of transfer of assault weapon to gun dealer. Circumstances where possession of assault weapon authorized.
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(d) Any person who moves into the state in lawful possession of an assault weapon, shall, within ninety days, either render the assault weapon permanently inoperable, sell the assault weapon to a licensed gun dealer or remove the assault weapon from this state, except that any person who is a member of the military or naval forces of this state or of the United States, is in lawful possession of an assault weapon and has been transferred into the state after October 1, 1994, may, within ninety days of arriving in the state, apply to the Department of Emergency Services and Public Protection for a certificate of possession with respect to such assault weapon.

https://www.cga.ct.gov/current/pub/chap_943.htm#sec_53-202x]Sec. 53-202x. Declaration of possession of large capacity magazine. Regulations.
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(d) Any person who moves into the state in lawful possession of a large capacity magazine shall, within ninety days, either render the large capacity magazine permanently inoperable, sell the large capacity magazine to a licensed gun dealer or remove the large capacity magazine from this state, except that any person who is a member of the military or naval forces of this state or of the United States, is in lawful possession of a large capacity magazine and has been transferred into the state after January 1, 2014, may, within ninety days of arriving in the state, apply to the Department of Emergency Services and Public Protection to declare possession of such large capacity magazine.