Within the last year, Mark Beasland sold a NIB SKB Model 100 12ga with 30" barrels. Plenty out there with 26" barrels, but also plenty with 28" barrels. But, like the 700 advertised, not many of either with 30". If you want it that badly, it's still for sale . . . at which point you could hang that old Snipe on the wall. Although, if you're talking ST, there's a certain advantage for cold weather hunting. And since your Snipe has both a ST and a PG, don't know why those would bother you on a modern Japanese sxs?
My BL-4 20ga does have 3" chambers . . . but that does not necessarily "explain" the higher level of proof. While we don't have a proofhouse, we do have SAAMI, to which all American gun and ammo makers adhere. And it was coming on line just about the same time as the NID. And no need for a higher proof for American 20ga (or 12ga) magnum guns than for those with 2 3/4" chambers, because the SAAMI service pressure standard is the same for both 2 3/4" and 3" shells: 11,500 psi for 12ga; 12,000 psi for 20ga. The magnum (or superior) proof on European guns is simply an adjustment they made to make sure their guns accommodated our higher service pressures--which were already higher in standard 2 3/4" chambers than theirs.
What I "read into" the S-56 etc designations is not that a Snipe is a BL, but that Beretta OU's retained the same European designations when Garcia imported them as when Galef imported them. Nothing more, nothing less.
As for the comparison of the NID to the 700, the newest NID's would be about the same age as the oldest 700's. Overlap in the late 40's. You're eager to equate them because you're trying to sell the superiority of the Webley . . . but it's not superior in terms of original proof, because the NID appeared along with the Super-X (explaining the change to a stronger action from the previous Flues guns). Those were the loads it was designed to handle . . . but they weren't the loads the 700's were designed to handle. Gun for gun, the Webleys are lighter, which means both the shooter and the gun are more susceptible to recoil. You're not likely to find anyone using a 700 as a waterfowl gun. The NID, back in the lead shot days, was a solid candidate for both ducks and pheasants--mainly because the standard lead shot load (maybe changing from 6's to 5's or 4's in the Super-X) was just as good on ducks as it was on pheasants. And, as a heavier gun, it was a better choice for a steady diet of those loads.
