Need help identifying this gun
 

Hey guys, usual story. I'm a gun guy, but not a shotgun or old gun guy. This is a family gun and the owner seems to think it's very valuable. I'm not sure if it's a valuable as he thinks.

I know nothing about this shotgun, so I appreciate anything you can tell me. I've blurred out the last 3 digits of the serial number.

What model? What gauge? How old is it?

Is it ok to clean the rust? I know for coins you should never clean them. I don't want to find out that by cleaning it I ruined the value for him.

Thanks,
Gene

the whole serial number is important to know the gun's original specs such as stock configuration and barrel length

rust can be safely removed with Frontier pads (keep them off the wood)
https://www.big45metalcleaner.com/

The missing digits are 458.

thanks

unfortunately - that number is missing from the serialization book

but there are factory records for a research letter - go to the home page and follow the link on the left

that will tell you information such as the barrel length it left the factory with - likely where and when it was shipped, stock configuration and maybe more

there are markings on the barrel flats and rear lug that help - and a picture of the muzzles and the muzzle end of the rib

the 3 on the water table id's it as a grade D (H or HE depends on ejector or extractor)

what gauge is it and how long are the barrels?

The gun is a D grade (grade 3).
The buttstock has been heavily modified from its original configuration. The gun was originally a pistol grip and it has been since converted to a straight grip. And the butt treatment (pad) is not original.
In regards to value, these above mentioned things alone effect its value a lot. What that value is... a matter of opinion. To be realistic, a DH 12g. is relatively common and ones that have been messed with a VERY common. If all else is in order and the gun is safe to shoot/functional, the value may be around $1,000. But that could be a stretch.