So many choices.
If diving into the American 'Classics' as listed.
The AH Fox and the Ithaca 'NID Model' will give you least amount of troubles as far as mechanics.
Be assured they can breakdown and wear out. But they are easiest to fix& restore mechanically even counting the ejector mechanisms if your gun happens to have them.
Factory Single Selective Trigger (SST) mechanisms on either can be a nightmare to make them work correctly if they are out of order. Especially if someone has chosen to get in there and 'adjust them' somehow,
This statement about SST's on double bbl guns goes for any trigger mechanism out there.
The LCSmith is about the worst to work on, The Parker next.
Even the highly praised Winchester 21 SST gives more than it's share of troubles.
I have fixed more Win21 triggers in the last 10yrs than all the others together I think. But that may be just because more 21's are used at the range where I shoot than any other classic SxS or OU.
I usually get the gun brought to me by the sad faced owner , 'Can you fix this?
Never one particular issue with any of then. Can be Doubling, FTFire R or L bbl,,Selector doesn't work,,Works R/L or L/R but not the other way around,,or the best one 'It doesn't do it all the time, just sometimes..'.
Double triggers are the Classic set up and are just about flawless as are extractors. That's a hint.
LCSmith guns are fragile in the stock head and many are cracked or cracked and repaired. Heavier loads than the guns were designed for is sometimes the problem. Oil soaked wood another issue.
If you've ever seen how little stock wood actually supports the frame for recoil you'll understand the problem.
The firing pins break fairly often or get peened over at the back end but thats usually from dry firing. The pre-1913 guns will break the FP bushings in the breech face from the same. Just don't dry-fire.
Don't dis-assemble the trigger plate and unleash the top lever V spring unless you really know how to reassemble the frame and plate against that spring tension.
The LCS can get loose/off face like any of them. None are a solid lock up 'For Ever' no matter what the old marketing ads say.
Stuff wears out and has to be rebuilt.
Most is expensive restoritive work.
Don't look for a money pit unless you do the work yourself or are wealthy.
Parkers are very nice. Overly complicated. About a bucket too many small parts inside to make it work the same as an AH Fox. But you won't get any complaints from the Parker fans.
The Ejectors if it has them are also one of the most complicated systems on these USA guns. V spring powered and the rest of the parts are complicated shapes as well.
There's not much more than parts replacement to be done when things break inside the ejector mech & there's not a lot of orig parts around anymore. Some of Parker Repro parts fit as did the Repro SST parts. But they are hard to find now too and pricey.
AH Fox is about the easist to work on, IMO.
No difference inside betw a Sterlingworth and an FE/Special grade.
The Sterlingworth used a snap on forend. The 'Graded Guns' (A-F) used a latch forend.
Sterlingworth ejector guns used a small round escutcheon on the outside of the forend as reinforcement.
The later Fox Model B was a product of Savage Arms Co just after WW2.
The Steven 311 came out just after the Fox Model B was shown.
So the Stevens 311 is actually a plain version of the first announced Fox Model B.
There was an earlier Model 311,,The Springfield 311.
That was made by the orig Stevens Arms Co before WW1 and continued to be made by Savage after WW1 when they acquired ownership of Stevens Arms.
The Springfield Model 311 was built on the old coil spring/straight line striker action.
That was discontinued at WW2.
The Fox Model B and then the Steven 311 with their internal rotating hammers came out just after WW2
Early Ithaca models are somewhat fragil when compared to the last SxS they made,,the NID Model.
The earlier Flues (1912-1925) was a popular SxS but it has a habit of breaking the top of the stock ears off because of the stock to frame attachment design. There's no top tang through bolt in the gun to pull the frame together around the wood. The top tang screw that is in the gun is mearly a stubby wood screw about 5/16" long, and usually stipped at this point in life.
The frame rolls upward slightly in recoil and batters the top of the stock/ears and cracks. The rear of the tang usualy cracks the stock as well.
The Frames are thin on the sides and the breech and was done purposely to make a lightweight gun in most cases.
Quite a few have suffered cracked frames verticaly from the junction of the standing breech straight down the side of the frame on the outside.
Easily seen.
The sharp cornered cut betw the breech face and the action flat didn't help matters.
Flues Ejectors are somewhat of a pain. But they can generally be made to function OK w/o any great investment in parts..just labor. They are fragile and touchy.
A good condition Flues if used with light loads can be a very nice gun. Abuse it with todays OTC stuff and it will not react kindly.
Seeing the Mfg'r dates, you can guess that most are short chambered that incluses the 12,16 &20.
They were made in 28 and 410 as well and offered in Damascus as well as Steel bbls.
The original Syracuse Lefever is a Box-Lock action. The side(lock)plates are just ,,side plates.
I wouldn't recommend an orig Lefever unless in VG -Excl condition to anyone as a gun to start out with. They are complicated and are very expensive to have worked on if you can find someone that can.
Ithaca bought out the Syracuse Lefever Arms Co. For a very short time Ithaca assembled some of the old Syracuse Lefever style side plate Lefevers. They are marked Ithaca/ Lefever Arms Co on the side.
The vast majority of Ithaca Lefevers guns people are familiar with are the
Lefever 'Nitro Special' SxS guns.
These are plain box-lock utility shotguns 12,16,20,and 410ga.
A couple different minor changes in frame shape but essencially stayed the same.
Good solid shotguns. No frills in the standard gun. But they could be gotten with some options.
A step up was the Lefever A Grade (Nitro Special)
This had a better shaped stock, checkering, coukld be had with ejectors, Single Non-Selective Trigger.
A few editions within the series included a Skeet gun and I believe a Trap.
I had a 20ga Skeet. Twin Ivory bead sights, ejectors and the SNST.
The Nitro Specials hold up well and are easily repaired if they need it. Parts abound it seems on places like Ebay and such.
With any of the older SxS's, give them a good look over for the standard issues. Loose ribs, Off-Face/Loose lock-up, Check the lock-up with the forend off the gun. Check trigger pulls (too light/too heavy), Saftey work?, Cracked stock or forend, Working ejectors, Single Trigger mechanisms.
Check chamber length. Have the chambers been lengthened?, forcing cones lengthened. Bore specs,,bore dia, Wall thickness, choke dia's.
Some of this takes some tools and instruments to check, all of it takes some knowledge and experience.
Learn, read and take someone knowledgeable with you when shopping for a shootable vintage SxS.
There are lots of them out there, there are many that have been worked over, and not in a good way.