Thanks Roscoe for posting and sorry for the description delay.

Per H&H Ledger Page:
10 Bore Royal Hammerless
Built November 5,1910 for a Mr Daw
27" Steel Barrels, 7 lbs.1oz.
Loops for sling, Ckeeckpiece, recoil heelplate
Weight 13 pounds, 7 oz.
Sights for 50 yards
Shot with 55 grains of revolver cordite and a 920 grain solid core ball. Lead 1 in 16

I have had loads pressure tested by Tom Armbrust. Results below
58 grains of Blue Dot - 1410 FPS, 12,500 LUP
56 grains of Blue Dot - 1355 FPS, 10,400 LUP
54 grains of Blue Dot - 1300 FPS, 9,500 LUP
52 grains of Blue Dot - 1250 FPS, 8,599 LUP

As per "The Shooting Field" the Holland results with 55 grains of revolver cordite was 1416 FPS and 6.37 tonnes or 13,973 LUP

My accuracy results were a 3" group at 50 yards somewhat vertical, 10 and 4 o'clock.
These guns were built as replacements for the 8 bore as the cordite was introduced. The steel core bullet was used in this gun, though my shooting was withan all lead projectile.
Hope this helps.
John