BACKGROUND OF THE INVENTION
This invention relates to modular multi-caliber conversion kits using interchangeable center fire barrels of different calibers and lengths in slides adaptable to Colt Government Model Pistol (aka M 1911 .45 caliber or simply “1911”), its copies and variants and new pistols.
The 1911, which evolved from several earlier John Moses Browning patents, is a short-recoil locked-breech pistol: at the start of the firing cycle, slide and barrel are interlocked by two lugs on top of the barrel into corresponding grooves inside the roof of the slide. As a shot is fired, barrel and slide recoil together for a short distance until the rear end of the barrel is forced down by its pivoting link and stopped. The downward movement of the barrel disengages it from the slide which continues rearward compressing the recoil spring, extracting the spent case from the chamber, ejecting it and cocking the hammer. After the slide reaches the limit of its rearward travel, the recoil spring pulls it forward stripping the top cartridge from the magazine and feeding it into the chamber. At this point, the pivoting link moves upward the rear end of the barrel which twin lugs engage the grooves inside the slide locking the breech, the slide achieves its forward movement and the pistol is ready to fire again.
On the early Thirties, John Moses Browning patented for the Belgian High Power 9 mm pistol an improved version of this principle. The operating cycle of the High Power remains similar to that of the 1911 but its slide has no removable barrel bushing and the rear end of the barrel is not moved vertically by a pivoting link but instead a slot in an integral extension at its rearmost part which contacts a hardened cross bar inside the frame. After the short rearward movement of the slide and barrel assembly, the slot engages the bar, the rear end of the barrel is drawn downward by the camming action of these two parts and stopped while the slide continues to recoil in order to complete the operating cycle.
The French 1935S pistol was still using a pivoting link barrel but it offered another improvement: instead of two lugs fitting on corresponding recesses, its barrel has on top of the chamber an integral sharp shoulder which engages a cut inside the slide. The combination of the High Power and the 1935S locking methods is currently in use on all modern pistols working on the tilting barrel locking principle.
Franz-Joseph Peters U.S. Pat. No. 4,920,676 for an interchangeable barrel pistol uses a special slide having a spring loaded claw opposite to the extractor to support different size cartridge bases on the same breech face. On his further U.S. Pat. No. 5,133,142, , the same inventor states about his previous one: “In this known solution, however, the production and assembly of the resilient holding claw involve a relatively high outlay. The contour of this holding claw and the elastic pressing force of the holding claw have to be carefully coordinated, so as to guarantee that the pull-out system functions perfectly”, and he replaces the additional claw of U.S. Pat. No. 4,920,676 by an adapter piece which has to be manually adjusted on the slide according to the dimensions of the new cartridge base.
The present invention represent a considerable improvement over the two above ones as it needs less components of a simpler design, and switching of barrels requires no previous manipulation of an adapter.
SUMMARY OF THE INVENTION
This invention is based on the observation that in a semi-automatic handgun using the Colt-Browning tilting barrel locking principle exposed above, different barrels having the same external dimensions corresponding exactly to the internal dimensions of a pistol slide will automatically remain in the same position inside the locked handgun. As a result, in any of such barrels having a correctly centered bore, the primer of a loaded cartridge, regardless of its caliber, will always be exactly in front of the firing pin hole on the breech face of the slide when the pistol is ready to fire. This particularity makes possible production of conversion kits having interchangeable barrels of different calibers which can be directly installed in alternance on the same slide. Conversion kits built on this principle can replace the slide assembly of all pistols working on the Colt-Browning principle, from the century old Colt Government Model Pistol to single or double action modern semi-automatic handguns or being used to build totally new ones.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right side view of a pivoting link short feed ramp barrel with its bushing;
FIG. 2 is a right side view of a pivoting link extended feed ramp barrel with its bushing;
FIG. 3 is a right side view of a linkless short feed ramp barrel of the second model conversion kits with its bushing;
FIG. 4 is a right side view of the linkless extended feed ramp barrel of the second model conversion kit with its bushing;
FIG. 5 is a right side view of the locking block used on second and third models conversion kits showing in a the inclined top lug and in b the integral long recoil spring guide;
FIG. 6 is a simplified right side view of an exploded 1911 type pistol frame showing in c the longitudinal milling cut required to install on such a frame conversion kits using linkless extended feed ramp barrels;
FIG. 7 is a right side view of the new design square chamber short feed ramp of the third model conversion kits, used indifferently in new model slides with or without barrel bushings;
FIG. 8 is a right side view of the new design square chamber extended feed ramp linkless barrel of the third model conversion kits used indifferently in new model slides with or without barrel bushings but requiring the FIG. 6c milling cut on the pistol frame or a new frame originally built as such;
FIG. 9 is an exploded left side view of the new design slide with barrel bushing showing the integral top extension of a square chamber short feed ramp barrel interlocked in the open top of the remodeled ejection port;
FIG. 10 is an exploded left side view of the new design bushingless slide showing the integral top extension of a square chamber extended feed ramp barrel interlocked in the open top of the ejection port.
DETAILED DESCRIPTION OF THE INVENTION
Multi-caliber conversion kits for 1911 type pistols using interchangeable barrels of different lengths and models in slides having internal dimensions corresponding exactly to the external dimensions of said barrels. These kits include all necessary interchangeable parts and accessories making possible a fast change of caliber on the same handgun. They are designed in three models, the two first ones using a common slide with main specifications identical to those of the original .45 caliber Colt Government Model Pistol except for an external groove necessary to install the interchangeable extractors adapted to the required caliber.
The first models use pivoting link barrels of the original short feed ramp design (FIG. 1) which install directly on regular pistol frames or extended feed ramp ones (FIG. 2) of a type already in current use which require frames modified by milling cuts in front of the magazine well.
The second models use improved linkless barrels of the short feed ramp design (FIG. 3) having integral underside ramps which engage the inclined lug (FIG. 5 a) of a removable locking block or extended feed ramp linkless barrels (FIG. 4) using the same type of locking block either on pistol frames modified as on FIG. 6c or on new frames originally designed as such.
The third model kits have slides of a new design and linkless barrels built with underside ramps identical to those of the second model ones in order to also use the same type of locking blocks: the short feed ramp barrels will fit regular frames, the extended feed ramp ones either frames modified as on FIG. 6c or new ones originally designed as such. Slides are made with removable barrel bushings (FIG. 9) to permit installation of heavy bull barrels and readily available custom accessories and as simplified bushingless models (FIG. 10). New model square chamber barrels (FIG. 7) and (FIG. 8) are installed from the bottom of the slides and interlock the modern way in top of the enlarged ejection ports by integral extensions over their squared chambers (FIGS. 9) and (10) instead of the original grooves used on the two first models of kits.
All kits are of simple and proven design without additional small parts and several of their components are made to fit the different models in order to reduce production costs. The removable locking blocks (FIG. 5) used with the linkless barrels in the second and third model kits are machined or cast in hardened steel or any other suitable strong material to fit exactly inside the original barrel link assembly housing of a 1911 type frame where they are securely held by the slide stop cross pin. While short recoil spring guides or captive spring removable units would also work on these locking blocks, integral long recoil spring guides which front end slip inside the drilled recoil spring plugs (or the apertures in front of the bushingless slides) have the advantage of practically eliminating any possible play of the moving parts in a locked pistol, improving the potential accuracy of the handgun.