Chambered for 2 3/4" (12ga) shells from the start of production according to Remingtons advertisments of the day.
But,,,it was common for the mfg of that era,,Remington included to 'short chamber' the 12ga chambers to a length of 2 5/8".
It was still considered fine for use with 2 3/4" shells.
This slightly short chambering was done from test pattern results that the slightly shorter chamber lengths,,,,and with the paper sheels, cardboard and fiber wads of that time...produced better patterning than the actual 2 3/4" chamber length did.
AH Fox, Parker, and other SxS makers of that time generally used the 2 5/8" chamber length when still adv a 2 3/4" chamber as well.
A very short and abrupt 'forcing cone' was another feature of the time that sealed the bore well with the cardboard and fibre wads used.
The forend wood crack is very common. Should be fixed or it'll just continue to crack further.
Make sure the friction ringS are all present and undamaged.
The Remington 11 unlike the FN A5 has a buffer rivited to the back wall of the recv'r inside.
It's there to buffer the bolt as it slams to the rear and stops before returning to the forward position. It protects that back recv'r wall from damage from the recoiling bolt.
The Buffer is a round washer of white fibre material held in place with a blind steel rivit thru it's center.
The entire buffer is planted right onto the rear flat inner surface of the recv'r,,that upright squared form.
Many (most) of the original factory installed buffers have since crumbled and disintegrated from age and use.
With a very brite flash lite if you look along side the bolt/bolt handle towards the rear of the inside of the recv'r, you can just barely see the buffer and rivit..if it's still there. If not then only the stud of the rivit post will be there.
Replacement buffers are available from Numrichs and likely others.
You have to completely TD the recv'r and make or buy a couple of simple tools to install and then re-rivit the new buffwer washer into place.
Some people feel none of that is necessary and don't bother with it at all if missing of crumbling away.
The FN engineers told Remington it was not a necessary change to the A5. Remington thought otherwise back then and went ahead and incorporated the buffer into the gun.
Take your pick,,,but at least you know about it and that it is supposed to be there.
The 12ga Mod 11 gun itself with the cut stock w/ pad (and a new pad needed) and the PolyChoke installed would likely be a $250/300 gun in WNY.
Someone would probably buy it at a show here for $250 and make another Riot Gun out of it and try to resell it for $450,,take $400
JMO