Unblinking Eye
The Grant Hammond Pistol


The Grant Hammond Automatic Pistol
by Ed Buffaloe

Grant Hammond was a chemist, engineer, and inventor who was born in San Francisco on 14 August 1868.  Apparently Hammond worked for Winchester during the same period of time as Gus Swebelius, who later purchased the Hartford Arms and Equipment Company and renamed it High Standard.  In 1917 and 1918, Grant Hammond was at least part owner of the Grant Hammond Manufacturing Company, which was engaged in the production of parts for the Liberty aircraft engine in New Haven, Connecticut.  We can probably interpolate here that since everyone involved in U.S. manufacture at the time was getting government contracts, Hammond was actively seeking a government contract to manufacture his pistol design.  He was already manufacturing parts under what was almost certainly a government contract or subcontract.  Historical evidence we have available are the remaining prototype pistols (said to number no more than 18), a number of U.S. patents, and various records of the U.S. Ordnance Department.

I probably haven’t located all of Hammond’s patents, but I have found enough to know that he was actively working on various firearm designs between 1912 and 1919.  On 25 October 1912 he filed a patent application for a gas operated blow-forward pistol, and on 16 July 1913 he filed another application on what appear to be improvements to the same design and a third patent on a magazine catch and release.  These patents were all granted on 4 May 1915, and this is the patent date that appears on most of the Hammond pistols.

Patent Drawing of Grant Hammond Pistol

Patent Drawing of Grant Hammond
Gas Operated Blow-Forward Pistol

The gas operated pistol that appears in Hammond’s first two patents is quite complex.  At least one prototype was manufactured, because there is a picture of it in the 2005 Standard Catalog of Firearms, and it looks very much like the patent drawingPossibly as many as 4 or 5 were made.  The gun was chambered for the .32 ACP, though I suspect this was simply an expedient in a proof-of-concept gun, since the .32 cartridge doesn’t require a locked breech mechanism.  The gun has a barrel casing which contains the gasses from the burnt propellant.  This casing is blown forward by the force of the gas, and in its forward-most position the gas pressure is bled off.  By this time the bullet has left the barrel, and as the casing moves back toward the rear it activates the rotating bolt which unlocks the action, ejects the spent shell, cocks the hammer, and chambers a new round.  When the last bullet in the magazine has been fired, the magazine drops out of the gun.  When a new magazine is inserted, the bolt closes automatically and chambers the first round.  I can’t imagine that this gun could ever have been made to work reliably, as its mechanism was too complicated.

But during the same period, Hammond was also developing another pistol design for the .45 ACP cartridge that was somewhat less complex, but retained the fixed barrel concept with a reciprocating bolt (albeit one that did not lock by rotating) and a self-ejecting magazine.  This is the pistol he sought to obtain a military contract for, and of which there are a dozen or so known prototypes.  The breech was locked by a single plunger on the underside of the bolt which interfaced with a lug on the frame just behind the magazine.  The bolt is retracted by two checkered extensions on its rear face.  The gun has something analogous to a slide, which R.K. Wilson refers to as a barrel extension, which does not have nearly the range of motion of a true slide,
Grant Hammond .45

Grant Hammond .45, S/N 13

and which is held in its forward position by a short return spring just above the trigger guard.  When the gun is fired, this barrel extension recoils for a short distance with the bolt.  During this short recoil, the bullet leaves the barrel.  As the bolt moves rearward, the locking plunger in the bolt is forced upward, unlocking the action and allowing the bolt to move all the way to the rear, ejecting the spent cartridge, cocking the hammer, and chambering the next round as it moves forward again.  When the last round has been fired the breech stop inside the barrel extension is actuated by the lip of the magazine, holding the action open, while a lever mechanism on the left side of the grip releases the magazine.  Wilson indicates that the magazine release mechanism “...is ingenius, although complicated and somewhat frail.”  The gun held 8 rounds.  It was said to feel very good in the hand and to point well.

Sometime in 1917 Grant Hammond Manufacturing contacted the Chief of Ordnance to request a test of their new pistol, which they claimed was superior to the Colt Model 1911.  Major J. T. Kenyon, Chief Inspector of Small Arms, detailed Major Charles F. Armstrong, Assistant Chief Inspector of Small Arms at the Winchester plant, to visit the Grant Hammond facility and report on the pistol.  Major Armstrong fired a full 8 round magazine, offhand, from the Hammond and shot out the center of a target.  He declared in his report, dated 13 November 1917, “I believe it to be the most accurate automatic pistol I have ever seen.”  He noted problems with the bolt stop and the magazine, but recommended that the pistol undergo further testing.  We presume that the Hammond company made some improvements to the pistol, and Major Armstrong and three other U.S. Army representatives test fired the gun again on 8 December 1917 at the Hammond facility.  They fired a total of 252 rounds and experienced 11 malfunctions, all of which were attributed to faulty magazines.  Again, they recommended further testing.

Grant Hammond Patent Drawing Detail

Detail from Grant Hammond Patent Drawing
showing a design similar to his .45.  This is from the patent for the magazine catch and release.

The Hammond pistol was tested again on 18 January 1918 at the Springfield Armory.  The pistol was disassembled and reassembled, and the times were noted.  Ten rounds were fired from a rest at 15 yards and the mean radius of the of the resulting bullet holes was 0.9 inches.  However, in firing those ten shots there were five failures to load and one failure to feed.  Four attempts were made to fire four magazines in a row (32 rounds) with no failures, but it couldn’t be done and Hammond was forced to withdraw the pistol.  He presented the gun for an endurance test on 16 March 1918.  A total of 5000 rounds were fired, and the barrel was allowed to cool after every 50 rounds.  154 malfunctions were noted.  Two firing pins were broken, the locking bolt plunger broke, and the extractor spring had to be replaced.  Hammond withdrew the gun again before further testing could be completed.  The Army tested the gun one last time at Camp Perry, after Hammond had modified the magazine release mechanism so that it did not eject the empty magazine but instead dropped it down a couple of inches for easy withdrawal.  No record exists of the results of the Camp Perry test, but apparently they were not good.


The U.S. Navy tested the Hammond on 29 April 1918 and again on 4 June, when it was submitted to a multitude of tests, including accuracy, rapid fire, endurance, sand, and dust tests.  Again, the gun did not perform well.  The Navy Board concluded, “...the Grant-Hammond Pistol in its present form would be entirely unsatisfactory for service use.  It is very complicated and during the tests, the same jams and stoppages occurred as in the first test in April 1918.”

The Grant Hammond .45 showed great promise because of its accuracy, but important parts broke on a regular basis, including the locking cam, the locking bolt plunger, and the firing pin, and the gun experienced regular failures to lock, feed, and eject.  The magazine was temperamental as well.  It remained an experimental gun and never attained the reliability of a true production weapon. 

There are two known examples of a High Standard .45 automatic pistol prototype that are quite similar to one of the last of the Grant Hammond prototypes.  It is probable that Hammond took the design to his friend Gus Swebelius in the hope that he could turn it into a viable commercial product.  One gun, pictured in Petty’s book, is believed to have a barrel and barrel extension adapted from original Grant Hammond parts.  The gun is unmarked.  The other gun, pictured in Meadows’ book, is marked “MADE BY THE HIGH STANDARD MFG. CO. / NEW HAVEN, CONN. / UNITED STATES OF AMERICA / .45 CAL. / PAT. PENDING”.  Apparently, High Standard was unable to work out the bugs in the gun, as it was never manufactured commercially.

Grant Hammond Patents

Patent Number

Date Filed

Date Granted













Magazine Catch and Release




Magazine for Firearms




Extractor Mechanism for Firearms












Means for Attaching Gun Sights to Firearms








Magazine Catch and Release

Copyright 2008 by Ed Buffaloe.  All rights reserved.
Click on the pictures to open a larger version in a new window.


Annual Report of the Commissioner of Patents for the Year 1919
2005 Standard Catalog of Firearms,
by Ned Schwing.  Krause, Iola, Wisconsin:  2004.
High Standard Automatic Pistols: 1932-1950, by Charles E. Petty.  Gun Room Press, Highland Park, NJ:  1999.
Textbook of Automatic Pistols, by R.K. Wilson.  Arms & Armour Press, London:  1975.
U.S. Military Automatic Pistols: 1894-1920, by Edward Scott Meadows.  Richard Ellis Publications, Moline, Illinois:  1993.

Special thanks to Gus Cargile, who allowed me to photograph this gun from his collection.

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The gun in this article is from the Gus Cargile Collection.
Gus is interested in buying unusual Colt Automatic Pistols--
Ace, .38 Super, and .45s.
He can be contacted at any
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