This is veering from the original poster's question but I hope he doesn't mind.
On a few other internet places I read about how some guy took one gun, one barrel, cleaned it, shot a group of three or five, measuring their velocity, cut an inch off the barrel, and repeated the process from a 24" barrel down to a 16" barrel.  He claimed from that point on that the best velocity was obtained at 16.5".   
For the sake of science (and personal interest) I've dove down this rabbit hole and I must say it's been a very deep one.  I rarely take someone's opinion if it's backed by "marginal" proof.  It's taken some time and it's still in process but I'm doing an experiment with a single gun/single barrel but I'm not cutting it off at the muzzle, it's at the chamber end so the last thing the bullet remembers about that firearm is the same... AHAH!
 
Merkava,
I have many folks that reply similar to how you did.  Practical and realistic use of the double deuce beyond 100 yards..?   
I compete with CF shooting out to a mile a couple times per year, and several times to the 1000 yd ranges.  The d-deuce at 400 is very similar in reaction and results, taking less real-estate -in other words - fits on my range.
I also use several d-deuce singles, semi-autos, and gate latch guns when we go for prairie poodles on the north 40K acres.  With fragmenting bullets, we shoot in and amongst the stock with exceptional results and no issues.  With some of our setups, the rodent's mortality runs high - both in direct and wound results.  With full mags, good scopes and laser range finders, 500 yards is still an effective range - the little pill still has about 30'# at delivery and scooting along at 600 f/sec. - the poodles know they've been hit.  These don't get the gory results like my CF 22's, 6's, 6.5's or .30's but the threat from strays has proved non-existent.
my Nickel's worth.

Joe I need to try and do one of those someday.   
Might actually be a new shingle shot falling block fad. 
After I do one in metal flake red with Flames.

GT wrote on Dec 13^th, 2021 at 6:34pm:

It seems like the effective range of a 22 past about 200 yards, depend more on your ability to measure distance than bullet performance. 

By 400 yards, a 5 yard mistake in range often has more vertical error than your target standing on hind legs.

JLouis wrote on Dec 13^th, 2021 at 7:54pm:


Not quite completely true. In target shooting with known distances, I agree. Field shooting or hunting, as being discussed, it’s false.

A standard velocity, 1050 fps 40 grain bullet, zeroed at 100 yards, drops about 2” every yard at 400 yards

So a 5 yard mistake of range in a perfect world, nets you 10” or more vertical error. It only gets worse in a real world.

Or to out it another way, if you have compensated, as you put it, for an error in distance, you’re not compensating at all. You have learned the actual distance, and you are no longer compensating.

Don’t mind at all drifting from the question at hand. Decided to go with a round profile.
Thanks for the lead regarding the Bridgeport but looking for a 48” table.
Carry on!
Cheers Richard
“So much to do so little time”

I've got a Hepburn a friend is rebarreling currently with a .40-65 Green Mountain barrel in #4 weight full octagon. Have another Rolling Block that has the same barrel in full round I put together many years ago.
So once the Hepburn project is completed I'm planning on taking the same loads and both guns to the range, and test the round vs. octagon theory. With the only difference being the actions they're on, maybe I can see which of the two shoots smaller groups at various distances. The old round barrel Roller has been a wonderful rifle, and proved to be very accurate. So hope the full octagon is it's equal.