Ok, Tunnelrat and Moonglum,
it turns out I may have to partially eat my words.
https://codes.findlaw.com/co/title-18-criminal-code/co-rev-st-sect-18-12-214.html
https://codes.findlaw.com/co/title-18-criminal-code/co-rev-st-sect-18-12-105.html
According to the law in CO, it is not illegal to carry at work even if they have a no-guns policy or sign, but if they find out they can certainly terminate me. "No firearms" signs on private spaces do not have the force of law but a private property owner can ask you to leave and if you then refuse, you can be charged with trespassing with a deadly weapon.
Therefore carrying in secret at work is legal with a CCW license, although it might be against company policy. So I'll address your question regarding "how many employer you think are OK with you bringing and SBR to work" at the bottom.
In my case it turns out I am in a special circumstance, because I work at the University and there was a Supreme Court case against CU that barred higher ed institutions from asking employees and students if they are carrying:
https://www.colorado.edu/hr/colorado-concealed-carry-act-faq
"Following the Colorado Supreme Court’s ruling in March that the CU Board of Regents lacks the authority to regulate concealed weapons on campus under the Colorado Concealed Carry Act"
I thought this might apply to every work place in Colorado but weirdly enough, it only applies to higher ed .
So Moonglum regarding your question:
Hard to know, depends on the place of work. I guess that uber-liberal CU and CSU can do nothing about it, whether they like it or not.
But the employer who is
not OK with you bringing
an SBR to work
is not going to be ok with you bringing a handgun either, and that is the reason for concealment.
My bottom line point regarding the OP and also #69: If the firearm is legally concealed, why does it matter if someone chooses to bring a 22lr, a handgun or an SBR to work?