Girardoni

MEO shoot - small

Shooting the Girardoni

With all new guns comes tuning for performance and efficiency.  Various factors effect the tune,  some fixed, others variable. Valve orifice diameter is a variable which effects gas flow.  As can be seen above,  it is directly proportional to power (FPE) and and inversely to efficiency (FPE/CI).  The efficiency is...
GirardoniNo.2FIREDforFIRST TIME 012

Girardoni rifles completed

The rifles were completed by January 1st, 2013.  Here are some pix: Hank’s (below) is more original.  Mine (above) has a 4″ longer barrel and modified reservoir.   Here I am shooting Hank’s rifle for the first time.         Transfer port and firing pin. A video of...
valve semi

Airgun Valve

The original valves on the Lukens and Girardoni rifles used horn and leather seals in conical or bellshaped valve seats.  I have made them using delrin and UHMW valve  heads that are conical or flat with the seal into a tapered orifice. The valve on the right demonstrates the tapered...
pressure test

Girardoni conical flasks

The original pressurized buttflasks of the Girardoni rifles were made of rolled and hammered iron sheet.  This was riveted and brazed together with a hemispherical end.  Herr Girardoni had a high failure rate during testing possibly due to inferior materials.  The narrow end was internally threaded to accept the valve. ...
lap with rifling

Lapping barrels

Last weekend I lapped the barrels.  This consists of making a close negative of the barrel bore and rifling in pure, soft lead, coating with an abrasive paste and pushing and pulling it through the barrel repeatedly.   This  smooths out machining marks and irregularities.  Also one can determine if there...
Barrel comparison with rifle

Tapering Barrels

Today I tapered the two octagonal barrels.   A jig was made from a 4 inch square by 3 foot long block of 6061 Al.   A slot with a 45 degree undercut was cut.  Allen head bolts were inserted to tighten against a steel bar to clamp the barrels. Three round...
Gir rifling

Rifling Girardoni Barrels

  Built a new rifling head and cutter for the Girardoni rifle barrels.   The design is modified from “The Modern Gunsmith” by James Virgil Howe.  His design is based on a scraper rather than cutter as used on the 1902 Springfield rifle barrels.  It operates/cuts in both directions.  I’ve made...