bought a stevens 311 that originally had 30 inch barrels. the barrels were cut to 28 inches. heres my question. im trying to figure how much choke would have been removed? what diameter would the front tubes measure to be considered cylinder bore? i took it to the range for the first time last weekend to shoot some clay birds and im kind of guessing not all the choke is gone due to the fact a few times my point of aim was a little under the birds and achieved a clean miss at about 30 yards. i reasoned that a cylinder bore probably would have taken them out anyway, am i wrong?

Maybe. Depends on the pattern, and whether it shoots high, low, or anywhere in between. I'd suggest patterning it, to be sure.

Cylinder bore is just that; you'd need to measure the rest of the bore to see whether there was any constriction. The nominal measurement for a 12 ga. is 0.729" or thereabouts, but there are manufacturing tolerances.

Best guess is that 2 inches of barrel removed got rid of all of the choke, or nearly all of it. There could be plenty of holes in the pattern by 30 yards. It could also vary a bit by the individual load.

Pretty much with 2 inches lopped, your running cylinder right now.

there are companies out there, like Briley
http://www.briley.com/
that will install a set of chokes for you, allowing you the freedon to use whatever choke you purchase from them. I have used Briley in the past, the work impeccable, and prices reasonable. Quick turn around too.

in reference to your misses, is this the first time you are shooting a SxS? I tended to aim low with my first, and remeber, follow-thru is everything.

Pretty much with 2 inches lopped, your running cylinder right now.

there are companies out there, like Briley
http://www.briley.com/
that will install a set of chokes for you, allowing you the freedon to use whatever choke you purchase from them. I have used Briley in the past, the work impeccable, and prices reasonable. Quick turn around too.

in reference to your misses, is this the first time you are shooting a SxS? I tended to aim low with my first, and remeber, follow-thru is everything.

i had the same model gun since i was 14 years old only it came new with 28 inch tubes on it, improved and modified as i remember, the gun was stolen about 25 years ago so i picked up this 311 h series that had had the tubes lopped off to 28 from 30. i was about two inches low at about 30 yards or so on two of the shots i took, the rest while right on destroyed the clays perfectly. it just made me wonder if some choke was left at that distance and only a few inches under. seemed a wider spread from a cylinder bore should have taken a piece out of it anyway. many thanks for the info.

My M311 also has 28 inch barrels.From the factory.
A quick lookat my catalogues only found 28 inch barrels for the M311 Stevens.
Frank