My take, and happy new year.
It looks like you are trying to put a center-feed neck on a CCI Phantom.
There are two methods.
I'll start with the aftermarket adapter that is shown.
This will work. It has only the single hole on the front that matches CCI stock feed bodies. Some Kingman Spyders had two holes but using just one would line up the feed port...And it says "clamping" feedneck although I don't see any clamp.
There's a risk when using adapters like these.
Using only one hole to secure a 10rnd tube is one thing, Slapping the weight of a hopper on that same single screw is just inviting a visit with Mr. Easy-Out.
This one will not work on a Phantom. It has to do with the body the feedneck has to attach to. Perhaps somebody misquoted CCM but Phantoms have a single 10-32 hole for mounting a stock feed.
My opinion is that these adapters are weak & unreliable.
CCI does make a center-feed body.
Part number 9009CF
In my opinion the best bet for the money.
More $$$ than a cheap replacement that doesn't do what you want it to, and it's an entire body for less $$$ than that second choice adapter that won't even fit.
This will require the same Vert-type elbow (the straight-up kind) that you would need with the first adapter shown.