As I get older (will be 56 in 6 weeks), the hills steeper, & the miles longer; I use a 20ga; and a Mossberg® by choice for several reasons:
• I got tired of the heavy weight of a 12ga & the heavy recoil of the same. The 20ga is about 1½ lbs lighter & the recoil significantly less.
• While I'm right-handed, I'm left eye dominant & thus shoot a long gun left handed. The ambidextrous top-tang safety was a big plus for me. Additionally the Winchester® & Remington® guns only have a 2 year warranty & the Mossberg® has a 10 year warranty.
• Remington® guns require Remington® chokes. Within gauge however Browning Invector®, Mossberg®, SKB®, Savage®, Weatherby® & Winchester® chokes ARE FULLY INTERCHANGEABLE!
• A Remington® 870 Express, on sale where I Iive costs $269.99+tax & comes with one choke, no sling or swivels. Conversely for $50.00 less I got a Mossberg® with three chokes, slings, and swivels. (You get the picture).

I'm not knocking the Remington® or Winchester; it's just for me, the Mossberg® offers more for less money. The Mossberg® is not a cheap gun; it's an inexpensive gun, there's a big difference between the two. Now as to patterns & performance; chokes & ammo, this is what I have found & direction I'm heading (20ga Mossberg® specific):

Mossberg® X-FACTOR™ Extended Ported TURKEY Tubes (lead only) Models 500®, 505®
20 X-FACTOR-Ported Turkey tube .584" 95231 $36.00
Mossberg® Accu-Choke™ Tubes (Models 500®, 9200® and Maverick 88™)
20 Full .590" 95215 $15.00
20 Modified .600" 95220 $15.00
20 Imp Cylinder .610" 95225 $15.00
20 X-Full .585" 95230 $15.00
 

Carlsons® 20 GA FLUSH MOUNT
DISC ITEM# CONST PRICE
Cyl #10107 .620 $19.99
Skeet #10101 .615 $19.99
I.C. #10102 .610 $19.99
Modified #10103 .600 $19.99
Imp.Mod. #10106 .595 $19.99
Full #10104 .590 $19.99
X-Full #10105 .585 $19.99
Turkey #10108 .575 $19.99

Hastings®SPECIAL 20 GA. EXTENDED TURKEY CHOKES FOR LEAD SHOT ONLY (wrench included)
Stock No. Description Price
I20562 20 ga. Chokes .562" Parallel Diameter $29.99
I20566 20 ga. Chokes .566" Parallel Diameter $29.99
I20570 20 ga. Chokes .570" Parallel Diameter $29.99
I20574 20 ga. Chokes .574" Parallel Diameter $29.99
I20578 20 ga. Chokes .578" Parallel Diameter $29.99


The tubes shown in red are the ones that I have. All are rated for Hevi•Shot® with the exception of the Carlsons®. My son & I have experimented with many load & choke combinations (his gun is a Winchester® 20ga pump). What we did was use the same, exact, choke tube in my Mossberg® and his Winchester®. Clearly understand I DO NOT MEAN TWO CHOKE TUBES EXACTLY ALIKE; I MEAN WE USED THE TUBE IN MY GUN THEN PUT IT IN HIS GUN. My Mossberg® has a 26" barrel; his Winchester® a 28" barrel. We used 3" Mag Remington Hevi•Shot® 1¼oz #4, 5, & 6 shot & 3" Federal GrandSlam® 1 5/16oz #4, 5, & 6 shot. Our findings were:

• All chokes, in both guns, WOULD NOT PATTERN #4 SHOT IN A DENSE PATTERN SUITABLE FOR TURKEY HUNTING.
• The same choke & shot combination DID NOT PERFORM THE SAME IN EACH GUN. (I'll cite below)
• Conventional wisdom states that Hevi•Shot® needs a more open choke than lead shot. WE DID NOT FIND THAT TO BE TRUE.
• Hevi•Shot® doesn't always pattern "tighter" than lead.

My son's Winchester® has a definite preference for #5 shot. The absolute best load and choke combination for him was Carlsons® .575" Turkey Choke and the Federal GrandSlam® 1 5/16oz #5 copper-plated shot. My Mossberg® with any of our chokes DOES NOT pattern #5 shot as well as my son's Winchester®. My Mossberg® is at is absolute best with #6 shot and the Hastings® .570" Choke Tube. Using Hevi•Shot® or Federal lead it consistently puts 27-29 pellets in a 3" circle out to 40 yds. (With the Hevi•Shot® it's always 27 pellets! Using Federal lead shot its 28-29 pellets). My best target is before me from last year's tests. It reflects 61 pellets in the head & neck with 16 pellets in the brain & spine using Federal GrandSlam® 1 5/16oz #6. (This target DOES NOT reflect the 3" circle). I stated earlier the same choke doesn't perform the same in different guns; let me illustrate. When I shot the Federal® lead load of #5 shot with the Carlsons® tube I got 17 pellets in the 3" circle on the target. When my son used the same combination in his gun he puts 25 pellets into the 3" circle. When I use the Hastings® .570 tube & Federal #6 shot I put 29 pellets in the 3" circle. Using the same combination in his gun my son put only 11 pellets in the 3" circle. SAME CHOKES & SHOT YET THEY PATTERN FAR DIFFERENTLY. Thus you can see why my son uses the Carlsons® choke & lead 5's and I the Hastings® choke & lead 6's.

What my son & I hope to do in the next couple of weeks is try Winchester Double-X Magnum loads & see how they perform with the above chokes; (#5 & 6 shot only). Additionally I will purchase the SWARM® Tube, & see where those tests take us. If we run out of Hevi•Shot® due to our testing oh well; both of us have proven performers in the Federal Grand Slam loads.

Sorry to ramble on so much. Lastly take a look here:

http://www.walmart.com/catalog/product.do?product_id=3163692

David, thats one good review with some interesting info.  Looks like I'll definately be looking at some #6 shot.

:D Dang fine post, Thanks for posting, Yep ole moss'e offers you your moneys worth, And i have never owned one, I used a winchester model 37 in 2 3/4 for years with a ex-full ck in it, I did a post with 6 pic's, with some ck's, but they were lost when the page went down a few weeks back, I got win-super-x2 in 3 1/2, i used in the last 3 seasons, done very good with it, This last spring I used a model 59 win  in a full ck, 2 3/4  using #6 to get my last turkey with, check out this page, on some ck' pattrens   Hey keep it coming, Ron
 
http://www.wadwizard.com/Patterns.htm

Quote from: RatherBHuntinDavid, thats one good review with some interesting info. Looks like I'll definately be looking at some #6 shot.

Thanks for your kind words. Are you using a 12ga or a 20ga?

Quote from: buckshot roberts:D Dang fine post, Thanks for posting, Yep ole moss'e offers you your moneys worth, And i have never owned one, I used a winchester model 37 in 2 3/4 for years with a ex-full ck in it, I did a post with 6 pic's, with some ck's, but they were lost when the page went down a few weeks back, I got win-super-x2 in 3 1/2, i used in the last 3 seasons, done very good with it, This last spring I used a model 59 win in a full ck, 2 3/4 using #6 to get my last turkey with, check out this page, on some ck' pattrens Hey keep it coming, Ron
 
http://www.wadwizard.com/Patterns.htm

My son has my late father's Winchester Mdl 37 12ga, 3" with a 32" Barrel with a Extra Full Fixed Choke (.655"). When he carries that gun it brings back a flood of memories for both of us. When you know how to call like my Dad; one shot is all you need. We both miss him but now that I'm a grandfather it's still 3 generations chasing the deer, elk, & turkeys.

I'm using a Model 500 in 12 ga and my son has an 870 in 20ga that he really likes.  Hopefully we will get some Turley hunting in this year, I haven't done that before.  The last stand I sat deer season I saw 4 toms and a jake.  Got me pretty pumped up.  
 
 I hear ya about bang for the buck with the Mossies.  That shotgun is what I used for a couple of years for deer, rabbit, dove and ducks among others.  Out in the rain, sleet, snow, blazing sun and everything in between.  When I was in Texas, the area I hunted was shotgun only, no slugs.  The tang safety is my favorite too, my Savage 110 has it in the same place and it just seems right.