Yes both the 11-48 and the sportsman 11-48 are the same gun. The only difference is the sportsman came standard with a plug to limit capacity to 2+1 to comply with hunting laws.
You will need a good gunsmith. The information you seek is not readily available in published material.
You have answered your own question.
I'm not sure, but I think the sportsman has a different barrel configuration. They might be compatible, i say about a 1 in 4 chance of it working. I've never looked at a sportsman pumps barrel, but I've noticed how different model 870 barrels arent always compatible. if the years of the barrel and sportsman are very far apart, you can lessen the chances of compatibility. i suggest you email the Remington website and try to get a professional opinion from them. I'm not sure, but I think the sportsman has a different barrel configuration. They might be compatible, i say about a 1 in 4 chance of it working. I've never looked at a sportsman pumps barrel, but I've noticed how different model 870 barrels arent always compatible. if the years of the barrel and sportsman are very far apart, you can lessen the chances of compatibility. i suggest you email the Remington website and try to get a professional opinion from them. I'm not sure, but I think the sportsman has a different barrel configuration. They might be compatible, i say about a 1 in 4 chance of it working. I've never looked at a sportsman pumps barrel, but I've noticed how different model 870 barrels arent always compatible. if the years of the barrel and sportsman are very far apart, you can lessen the chances of compatibility. i suggest you email the Remington website and try to get a professional opinion from them. IT WILL WORK PERFECTLY. BAD INFO. GIVEN ABOVE!
NO! The 1187 barrel was for remington shotguns,the auto-5 shotgun is a browning shotgun.
no
no
AFAIK, no.
no but it will fit a mossburg 500
No there are ways, it invalves drilling holes to vent gas witch operates the gun.
IF it is possible, stick with Remington parts.
700 ADL Long Action
Without seeing it, almost certainly not.