870 not firing

[GeoffMartins]

Thanks for the opportunity to join the forum.
I have a small business in Australia and do some firearm repairs.
I have an 870 that has a new barrel fitted. It will cock and dry fire but won’t fire a live round?
It will leave an indent on a snap-cap but doesn’t want to fire a live round.
Any suggestions would be much appreciated.

Thanks

[USMA-1982]

Is the new barrel a factory Remington?

This might be too obvious, but is the barrel fully seated and is the magazine cap tightened all the way down? If the cap is loose, or if the barrel isn't fully seated that could be the cause of light strikes on the primer.

[Scorpion8]

Was it brought in to you in that un-firing condition, or is this something that has changed after disassembly and repair?