I know the A1 has the metal trigger guard and safety button but is that is?  Why pay so much more for just that?  Also what is the advantage to having the ghost ring sights?  I plan to get on the local PD and will need my own shotty.  I had a 500A but sold it because of lack of modifications available, also want something a little more sturdy.  Thanks for any advice on this.

I thought the 590 was the a1.  As far as I know, the a1 is the military designation for how they like it.  I could be wrong about that though.  Those ghost ring sights are niiiiiiiice though.  You should look through them once.  It's niiiiiiiiice.  I don't have it on mine but if I was going to modify, that would be on the list.  It's niiiiiiiiiice.  Did I say it was niiiiiiiiiiice?  That front post jumps out at you with both eyes open and the ghost ring is there but not, you know what I mean.  It's not alot different than an ar besides the side posts and ar's front post isn't usually orange and the ghost ring is bigger.  But those horizontal notches appear like they'd aid in accuracy. I don't know and  I'd like to test it but you may even be able to see it (front post) in the dark which would make it that much niiiiiiiiiiicer.

The A1 has a much thicker barrel than the 590;this was due to a Navy spec requirement:concerns about damage in cargo holds and rogh seas with the thin wall 590.The ghost rings are not on all A1's;mine is a bead.You also cannot  add a heatshield to the thick wall barrel.

Quoted: I thought the 590 was the a1.  As far as I know, the a1 is the military designation for how they like it.  I could be wrong about that though.  Those ghost ring sights are niiiiiiiice though.  You should look through them once.  It's niiiiiiiiice.  I don't have it on mine but if I was going to modify, that would be on the list.  It's niiiiiiiiiice.  Did I say it was niiiiiiiiiiice?  That front post jumps out at you with both eyes open and the ghost ring is there but not, you know what I mean.  It's not alot different than an ar besides the side posts and ar's front post isn't usually orange and the ghost ring is bigger.  But those horizontal notches appear like they'd aid in accuracy. I don't know and  I'd like to test it but you may even be able to see it (front post) in the dark which would make it that much niiiiiiiiiiicer.

They sure are niiiiiiiiice!

When I picked up mine I was amazed at how fast the ghost ring sights acquire the target.  I shot a coffee can, starting at 15 yards, and walked it out with consecutive shots to about 40 yards, firing quickly.  A solid hit each time.

On my next trip out I'm going to see what my max effective range is with slugs.  This is a fun shotgun!

So is the thicker barrel really necessary for most situations?  As mentioned before I intend it to be a duty shotgun once I get on the force.  I doubt the heat shield is really necessary for a weapon that will likely be more of a target weapon than anything else.

I do like the sound of the ghost ring sight if it aid in accuracy very much.  Can slugs be shot out of a 590 without a rifled barrel?  How accurate would that be?  I shot 5 slugs out of my 500 and never hit a thing.

(edited to add) There are many variations of the 590.  Look on the Mossberg website, there are the 14" Cruizer models, the "DA" trigger models and many others.

I don't understand your premise;if it is a duty gun your department will spec what you can and cannot carry  and will issue same.I like the heavy barrel because I can pop someone in the head with it and avoid a lethal option without damaging the barrel.For lethal options no difference.I like ghost rings but if I can't hit my target with a 9 round shotgun,I might as well give up.

Quoted: You also cannot  add a heatshield to the thick wall barrel.

I did and mine has ghost rings. A picture of it is posted in the thumbtack thread on page eight.

Please post a link AtLarge;thanks.

Sure...

This is it

about halfway down the page.

Thanks AtLarge;there is something about a 9 round shotgun with a bayo;I love it!

Me too. Adds a little levity at the trap shoots too!

I saw a 590A1 with ghost ring sites that had a mossberg factory heatshield installed. I have the pic saved with the description of how it was done because I plan to do it to mine

If you get one trash the flimsy factory shell follower and get the high vis high strength plastic one from Choate.  Its a solid chunk of bright orange plastic with a spring guide built onto it.  I put that & an oversize spring in mine.  Lost one round of capacity but it gives very positive feeding.