W.A. King on forcing cones

[Rick Riddell]

So based on the aforementioned above, the chamber, forcing cone and bore were designed to to shoot a longer shell to produce an idea chamber pressure and patterns when shooting Parkers during that time frame, but as innovation and technology changes it's probably not best to shoot modern longer shells in them? Do I have that right? Has anyone patterned longer shells in shorter chambers vs shorter shells?

[Drew Hause]

This is the 1907 Hunter Arms Chamber Specification

Forcing cones are slightly less than 1/2". The cone angle was shallower in the 1935 drawings with a length of about 5/8".



The forcing cone appears to be cut straight, BUT this is a Cerrosafe chamber and forcing cone casting, and there might be a slight Ogee



I have an Ithaca Specification drawing from 1935 kindly provided by Walt Snyder, which also shows a straight forcing cone angle

[Drew Hause]

Here you go Rick.

“Long Cartridges in Short Chambers”, Field, Jan. 30, 1892
https://books.google.com/books?id=in...page&q&f=false
2 1/2” chamber 12g
3 Dr. “E.C.” with 1 1/8 oz. shot in 2 1/2” case 1” pressure – 5,475 psi by LUP (+ 10-14% for modern transducer numbers)
3 1/2 Dr. with 1 1/4 oz. in 2 1/2” case – 6,200 psi
3 1/2 Dr. with 1 1/4 oz. in 2 3/4” case – 6,600 psi

“Mr. Griffith on Shotgun Patterns”, 1897 Lecture
https://books.google.com/books?id=in...page&q&f=false
p. 243 “Turnover” - case longer than the chamber
No. 9 2 1/2” case with 1/8” turnover
No. 10 3/8” turnover
No. 11 & No. 12 with 2 3/4” and 3” cases in 2 1/2” chambers = “…patchy patterns, clustering, and frequent balling…” Pattern examples on p.244
p. 245 “balling or clustering”
p. 247 Summary of patterns; Field, March 5, 1898
No. 9 - 1/8” turnover better pattern % than 10, 11 & 12

Pressures with 3 Dr. “Schultze” with 1 1/8 oz.
No. 9 – 2.13 tons = 6,040 psi (converted by Burrard’s formula)
No. 10 – 3.03 = 9,060 psi
No. 11 – 3.22 = 9,700 psi
No. 12 – 3.71 = 11,345 psi

“When long cases are used in short chambers, the paper overlaps the cone and causes greater resistance to passage of the shot and wads. The pressure then goes up considerably, while muzzle velocity and recoil are both increased.”

We all understand the studies used (thick) paper cases; not modern plastic cases and polyethylene wads