Question re: Colt M4 ( Calif compliant )

[Skipper]

OK, a close relative asked me about the status of his bullet-button M4 and I thought I'd ask here to get some valid info.
His rifle is in the " 10 round mag locked " configuration. Can he legally use a standard capacity magazine purchased on April 1, 2019?
Since it's mag-locked, can the bullet-button be removed?
We've received about 5 different answers from "Gun store lawyers".

[colossians323]

Is it a BBRAW or a fixed mag?
If registered yes
If fixed mag, no
Remove mag lock, Make featureless yes

[Skipper]

It's the original 10 round bullet-button magazine that has had a mag lock installed.

[beanz2]

It's the original 10 round bullet-button magazine that has had a mag lock installed.

[OniKoroshi]

There’s so much confusion around the term “mag lock” these days. Pre 2017, Bullet Button, Raddlock, etc. were called “magazine locks”. Now there are ARMaglock, and others that forces you to open the AR upper receiver before reloading.

What’s the proper term for pre-2017 magazine lock and post-2017?

Mag lock “pre”

And

Fixed mag “post”

[OniKoroshi]

Is it a BBRAW or a fixed mag?
If registered yes
If fixed mag, no
Make featureless, Remove mag lock yes

Fixed order of operation

[tonyxcom]

Is it a BBRAW or a fixed mag?
If registered yes
If fixed mag, no
Remove mag lock, Make featureless yes

Be very careful with the term 'registered'.

There is bought after Jan 1, 2014 and registered like a handgun. And there is Registered Assault Weapon, which meant sending in photos sometime in the last 18 months or so.