Pesky rear sight issue on the 590A1

[megawatt]

Background- dusted off the 590a1 today and shot about 60 shells of centurion .650inch single ball ammo rated at 1400 fps. Surprisingly accurate ammo capable of pulverizing clay pigeons at 35 yards. Wish I bought more than one 250 round case of it last year.

Issue- the rear sight does not stay centered on the elevation drum and will walk to a side after approx 10 shells. The rear LPA sight on my SPX does not have this issue but the A1 sight is definitely of a lower quality and completely different design. I understand shooting heavy thumper ammo will shake things up but either I need to add some type of material like grip tape to the drum surface to provide grip for the sight or Look at an alternative rear sight. Does everyone else with a A1 have this issue with their rear sight ghost ring not staying put when shooting many slugs? I totally get that a shotgun is not a rifle but the A1 and slugs or big ball ammo is actually accurate for being a smooth bore barrel, might as well have sights that keep a setting.

Thanks in advance for any replies.

 

[LAZY EYED SNIPER]

I run the 51663 w/GRS.

All I shoot are slugs, a lot of the same Centurion you were using and my rear sight has never budged. That's definitely not normal...

 

[megawatt]

Ok mystery solved - first is my apology to Mossberg for describing the A1 rear sight as a low quality. Turns out the GRS will definitely hold a setting and it is as robust and built for heavy use like the rest of the gun.

The rear sight was taken off a while back when the gun was cerekoted. When it was reinstalled it was not 100% torqued down. Directly in front of the peep hole is the windage adjustment screw that clicks when turned. I turned the screw down (this tightens down the sight to the base) but this also causes the sight to move to the left. I then had to use a flat screwdriver to slide the peep hole sight to re center its position. Now it takes great effort when compared to how it was before to lift the sight to rotate the elevation drum. Everything is solid now, and good to go.

 

[LAZY EYED SNIPER]

Glad you got it figured out bro...