What should I consider an E-6 who takes an excess E-4 slot for a deployment?

During Desert Storm, I was assigned to lead patrols on the perimeter of our camp due to previous training and experience. I was an E-5, yet would sometimes get E-6, and even E-7, personnel detailed to me. I respected their rank, of course, but they always let the rest of the patrol know that I was in charge, and that they would obey any lawful orders I gave. This is exactly how your E-6 should be acting. Good leaders are good followers, too.
I would suggest that you bring the matter up to your actual chain of command, as his behavior is likely causing disruptions to the work flow, as well as creating friction in the unit. I wouldn't confront him directly about it, if I were you, as it could lead to more problems.
Personally, if I were filling an E-4 slot as an E-6, I would enjoy the vacation from the normal responsibilities of a staff NCO and just do my job and chill.

A SSG is a SSG is a SSG. So yes you consider them a SSG. I put a 12C SSG in the S1 for a time because the section lacked discipline and we were short, the admin SGT was technically savvy and did well at the Admin tasks but was overwhelmed by the additional leadership tasks required to run the shop (normally an SFC).

What I noticed with our NG round out unit in 03 was that in some cases the "go to guy " wasn't the guy with the most stripes and that the unit took folks from all over to bring it up to strength and folks were working in MOSs and slotted in grades that they hadn't been in, in years just to fill the unit. They did a great job for us but it took a minute to figure out who was who.

Point is; regardless where the SSG is slotted on the MTOE if they have the MOS as a secondary or third the Commander and 1SG can utilize them where they need them. Even if they don't have the MOS but there is a need that they best fill they can go where the Commander and 1SG need them.

CSM Richard StCyr pretty much hit the nail on the head. Regardless of the MOS, the rank is still the rank. That does not mean that is the best person for the job. I understand you may not like this but it is the challenge of dealing with difficult people. This is a leadership challenge for you to learn how to earn the respect of someone who outranks you, even if you are upset with them. That aside, when that SSG is acting as a 92Y and if that is not his lane; smile, be professional, and move out. Your best authority comes from the Army Regulations (AR 710-2) and DA Pam (710-2-1) and when an order violates that, point it out and move out! You appear to be frustrated and looking for a way to negate the leader that was placed above you. My career was 30 years and at least 27 of them I had people that outranked me that were in some cases, clueless. Regardless of the "power" I may have had, those people still had the "Authority". Respect, Respect, Respect, PERIOD. Learn from the experience and just don't repeat bad behavior. I get it, easier said than done. Been there. SGT McMasters, Deep Breath...Roger that... Move out!!! Airborne, All The Way!!!

Chief

He is an SSG (E-6). He is a body in a spot that was needed. He still retains his rank as an E-6 however he is not the one in charge of the detail, section, squad etc. It sounds like the SSG needs to be taken to task and reminded that while he has the rank of E-6, he is not in charge and while his experience is valued, he has a task and this is not it. This should be done with a counseling statement by whomever IS in charge of him.

Additionally, if the problem persists then you should seek out your platoon Sergeant or First Sergeant and apprise of same. Use your chain of command. This E-6 is disrupting the orderly flow, good discipline and moral of your unit it sounds like and needs to be reminded of why he is there, what his duties are etc., most ricky tick.

You should consider him a SSG, and treat him accordingly. With that being said, let him know tactfully that he's out of his lane regarding the supply operations. If he continues to intervene, let your NCO support chain know of his involvement, and let them resolve the issue.

What duty position is the E6 in? If he is in an 11B slot he needs to stay in his lane.

He is an E6. He did not receive a downgrade. He cannot be made subordinate, he can be told to follow your guidance as the SME. You are both NCOs and should be able to work this out with no issue. Thank you for your service.

Yes. It called rank. Just do your job and remember the mission. You’ll be justly awarded.

There are a couple problems with this. First, E-6 is a pay grade, not a rank. The persons rank is SSG. No matter what, they are still a SSG.

There are two types of authority, command authority and general military authority.

The situation I think you are finding yourself in is a SSG that was out in charge of a HQ section in a HHC. If your 1SG has out him in charge he has command authority over you period. He can prioritize your work, give you lawful orders on when and where to be and what you are to do when you are there.

If he is an NCO in another section a medic NCO in the same company for example he has general military authority over you, he can make on the spot uniform corrections maintain good order and discipline just like any other member of the armed forces that outranks you. It sounds to me like you need to discuss with the first member of your NCO support channel above you and find out who you report to and who is responsible for your day to day supervision. A sergeant should never ask “do I treat a SSG as a SSG?”