The U.S. Carbine Caliber .30
- Infrared -
Part I: Research & Development
With the onset of war being imminent, two organizations within the War Department (the official designation of the U.S. Army) were interested in night vision devices. One was the Ordnance Dept., for driving at night and artillery sighting. The other was the Corps of Engineers, for nighttime reconnaissance and nighttime traffic control (road markings, traffic signals). Both requested the assistance of the National Defense Research Committee (NDRC) with research and development of these devices.
Night vision technology was still in its infancy during this time and consisted primarily of the use of near infrared and ultraviolet light to avoid detection with viewers specific to each. The only successful night vision device that had been invented in the United States, along with the electron image tubes that made it possible, used near infrared light and were still undergoing research and development at RCA's research laboratory in Princeton, NJ. When the NDRC was founded in 1940, RCA's scientists and laboratory were contracted by the NDRC to handle the research and development of night vision optics.
On behalf of the NDRC, RCA's scientists researched all such devices for Ordnance, the Engineers, and the Navy. All shared information but were separate organizations who would conduct their own tests, make their own decisions, and issue their own production contracts.
As noted on the introductory page, research and development of night vision optics involved four basic elements. Each with its own strengths and weaknesses that warrant a short review here before proceeding further.
Navy night vision equipment was for signaling and marking positions. Generally, this did not require a high level of clarity. Their viewers and lights could be ship mounted and/or powered. The infrared light the Navy wished to view was directed at their viewer(s). Size, weight, and power under those circumstances were very different than the devices Army Ordnance and the Engineers required.
The infrared light Ordnance and the Engineers wished to see through their viewers was reflected off objects illuminated by their light source and required clarity to distinguish friend from foe. The amount of light reflected varied depending on the object. The light had to travel to the object, with whatever amount was reflected traveling back to the viewer. This significantly shortened the distance the light could be seen. Increasing the amount of infrared light increased the size and weight of the light, power supply, and batteries. Man portable equipment was carried by one person. Equipment used for driving could be mounted on the vehicle. Increased brightness of the infrared light also increased the amount of visible light projected.
NDRC Electron Imaging Telescope Prototypes   
The Electron Imaging Telescope prototypes developed by RCA's scientists were a continuation of the research RCA had been doing for civilian purposes. Redesigned and adapted to meet the needs of the U.S. Military.
R.C.A.'s Research Laboratory in 1935
The design of an updated and improved version of RCA's Electron Microscope, designated the Type D, was used for many of the NDRC prototypes developed for use as infrared imaging telescopes. This design provided the best combination of size, weight, handling, and durability for image quality and portability.
Most prototype telescopes developed using this design varied only slightly in size and used a variety of different objective lenses and eyepieces. The image tube body was made of 30-mil mu-metal (nickel-iron soft ferromagnetic alloy) to provide magnetic shielding against external fields.
NDRC image tube research produced a number of different prototype image tubes for use in the various prototype night vision telescopes. This research was ongoing throughout the war and continued well into the 1960s.
Driving at Night: the Type B Prototypes   
For driving at night, two Type D telescopes were paired together to form a set of infrared imaging binoculars, designated the Type B. The objective lens was an F/2 plastic lens. The cable from the instrument was attached to a small battery-operated power supply held in a plastic case. The power supply for the Type B had two focus controls (one for each telescope) compared to the single focus control when used with the Type D.
The majority of the Type B binoculars were provided with a 2.5-inch objective lens and 8X eyepiece. Some, however, had a 3.5-inch objective lens and 1X eyepiece with a magnification of 2:1. The angular field of the former was about 25 degrees and of the latter about 18 degrees.
The image tubes initially used were prototypes never put into production. Eventually when the 1P25 image tube was introduced it was possible to reduce the size of the telescope and to develop stereoscopic binoculars for the perception of depth.
on the front of the jeep with one 600-watt searchlight mounted on the right front.
Power source was a generator located in the rear of the jeep.
Lights included four 450-watt IR lights mounted on the front and one 600-watt searchlight
atop the turret. Power source was a Waukesha multi-fuel model 2 1/2 T.G.U. engine generator
mounted in the left rear sponson.
Final tests of the Type B binoculars for driving at night and gun ranging equipment were conducted by the Armored Force Board at Fort Knox, KY in April 1943. Their recommendation was the equipment was unsuitable in its present form.
All factors contributing to this recommendation involved the methods of mounting the binoculars to the vehicles. The driver's face was used to move the binoculars and hold them in place. Mounts that allowed the binoculars to pivot required the driver's head and body to move left, right, up, and down. The driver's face had to remain in contact with binocular eyepieces to prevent the infrared light from illuminating the driver. Movement generated by the surfaces the vehicle traveled over was a constant and moved the binoculars in such a way it could make the driver sick.
The answer to these issues was to mount the infrared viewer to the driver's head instead of the vehicle, for which the Type B binoculars were ill suited. NDRC research and development for driving at night continued with head mounted optics. A device was eventually acceptable to all but not put into production before the war ended.
aircraft and gliders. To include night-time paratrooper drops when used with an infrared ground beacon.
The Type B binoculars never entered full production. They remained prototypes only.
As the research, development, and testing of the Type B binoculars for night driving improved the Type B, they also improved the Type D telescopes. So much so that the Type B units used during the driving tests at Fort Knox in April 1943 convinced both Ordnance and the Corps Engineers the technology had advanced to a degree it could be used for night-time reconnaissance as a man portable unit.
In response to a 15 May 1943 memo from the Signal Corps recommending consolidation of all Army night vision under one Service Corps, on 16 Jul 1943 all further Army night vision devices became the responsibility of the Corps of Engineers. The Signal Corps had no night vision devices being researched. Their interest was the logistics involved in supplying the batteries for the equipment. The Signal Corps recommended all efforts for procurement and deployment should be expedited as intelligence had determined progress being made in Germany would soon produce infrared night vision equipment for use by their military. 
Army staff communications during this time indicated the Navy had placed orders with RCA and Farnsworth for 15,000 Model 1P25 infrared image tubes. Neither manufacturer had yet to determine their manufacturing methods. Production was expected to begin in Fall 1943 with final deliveries of the current Navy orders by Fall 1944. Army staff noted the image tube was the most critical component, for which the Army had yet to initiate procurement. The Engineers were directed to expedite procurement with RCA or another manufacturer. 
The Prototype Snooperscope
On 20 Jul 1943 Headquarters, Ground Forces communicated to the Commanding General, Army Service Forces, their need for two infrared devices. A small, simple device for detecting enemy IR in the event it is used. The other being an individual man-pack viewing and illumination set that would allow the user to move freely in absolute darkness using infrared light not visible to the eyes, weight not to exceed 15 lbs., a range of 235 yards, clear definition, and a 6 hour power supply. On 26 Jul the Chief of Engineers received orders to initiate and expedite development of the two devices. 
NDRC research at Rochester University in New York developed the small, simple device for detecting enemy infrared, in the form of a metascope designated the Type F. RCA was contracted for the production of the prototypes of the man-pack unit, NDRC designation Type K1, Engineers designation Snooperscope.
The two devices were completed and demonstrated by members of the Engineer research and development laboratory to representatives of the Army Chief of Staff, Ordnance Corps, and Engineer Board on 24 Sep 1943, at Ft Belvoir, VA. Attendees were advised future research would include a means of mounting the telescope to the U.S. cal. .30 carbine as a night vision Sniperscope. The Army Ground Forces Jungle Warfare Committee verbally requested immediate procurement of 500 Snooperscopes and 1000 Sniperscopes for shipment to ground forces operating in the Southwest Pacific. On 27 Sep 1943 the Chief of Engineers directed the Engineer Board to develop and procure the requested Snooperscopes and Sniperscopes, with development to include toward combining the two types into one standard, interchangeable, compact, and waterproof device, providing that delivery is not thereby delayed. The method of mounting the Sniperscopes on a .30 caliber carbine was to be coordinated with the Small Arms Division, Office of Chief of Ordnance.  
For further information on the Type F metascope, refer to the web page devoted to the metascopes.
The combined weight of all the equipment was 20 lbs.
Mounting the RCA Prototype to the U.S. .30 caliber Carbine
Concurrent to, but separate from, the development of the night vision equipment the Ordnance Small Arms Division had contracted the Inland Division of General Motors to develop a means of mounting a 2.5 power Model M73B1 daylight optics sniper's scope to the .30 cal. carbines. The carbines developed during this project were designated the U.S. cal. 30 Carbine, Model M1E7. Testing of the M1E7 prototype in November 1943 proved the mount to be a reliable means of mounting a scope to the carbine. But the damage sustained to the internal parts of the M73B1 scopes and a commercial Weaver Model 330 scope during testing prevented the project from proceeding further.
Since Inland had developed the M1E7 carbine they were tasked with modifying the M1E7 carbine for use with the infrared scopes. The modified carbine was designated the U.S. cal. 30 Carbine, Model T3.
The U.S. Caliber 30 Carbine, Model T3
contract to the Small Arms Division of U.S. Army Ordnance. The mount was brazed
onto a carbine receiver that had been modified to accommodate the mount.
The Demand Exceeds the Technology & Supply ... with a little help from the U.S. Navy  
Communications during October and November 1943 indicate the Corps of Engineers was in possession of a total of only 5 infrared image tubes. Farnsworth had yet to work out their needs for a production line. RCA tube production during October was 75 a month and expected to increase to 1200 a month in March 1944. Anticipated total available by 01 Jan 1944 was 550, all for the Navy. The 1500 required by the Army was estimated as being available by June 1944. The Army realized if they wanted to obtain all or part of what they needed before then they would have to be obtained from the inventory of the Navy. The Navy had been asked and refused.
On 25 Nov 1943 the Army Assistant Chief of Staff reported the Navy Commander-in-Chief, U.S. Fleet, indicated the image tube production rate had been below the extensive Navy requirements. The Navy CiC recommended use of all infrared viewers by the Army be deferred due to Navy concerns of the equipment being captured and used against them. The Japanese did not have, and weren't aware the U.S. Navy was using infrared. The Navy CiC recommended all requests for image tubes by the Army be denied until the Navy deemed "production for their purposes are adequate". Meaning until the Navy decided the capture of one of the Army infrared viewers was no longer a risk to their ships.
The Navy considered their infrared Nancy equipment (Navy code word for infrared) strategic to their overall progress in the Pacific. They considered the Army infrared viewers tactical in nature.
What followed was an ongoing battle for the Army that would last until July or August 1944. Eventually, the Army and Navy reached an agreement with the Navy inspecting and forwarding half their infrared image tubes to the Army. Approximately 25% of the image tubes the Army initially received failed to meet the Army's specifications. Navy specifications required an image tube for viewing direct infrared light from signals and markers. Image tubes that passed Navy inspection failed to meet Army specifications that required an image tube for viewing much more detail using reflected infrared light. The high rate of rejection was attributed to "disparity between test conditions" at the Naval Research Laboratory and RCA along with "deterioration of the tubes between testing". Efforts to rush production in quantity had produced image tubes with various problems. The issues were resolved by having RCA inspect image tubes for the Navy by Navy standards (tubes marked 1P25) and tubes for the Army by Army standards (tubes marked 1P25A). This practice continued for a number of years after RCA had resolved their production problems, thereafter producing identical 1P25 and 1P25A image tubes to the higher standard.
None of the communications indicated if the Army was aware of the extent to which the Navy was using infrared. Even if they were told it may have been difficult to fully appreciate.
Although the Navy use of infrared was briefly covered on the previous page, at this point a little historical perspective is warranted given the impact this had on the deployment of the snooperscopes and sniperscopes during WWII. Keep in mind ships in the Pacific as small as subchasers were equipped with at least two infrared viewers. The larger ships had as many as 12 or more. Each ship was equipped with at least one infrared beacon, sometimes more. To illustrate the importance of the infrared equipment to the Navy, their Flagships are a good example.
The Army Keeps Marching Along...
As the initial procurement request for 500 Snooperscopes and 1000 Sniperscopes proceeded through the various parts of the normal review process the procurement quantities occasionally changed. The quantities were finalized by the General Staff Corps, Army Services Forces, 29 Nov 1944 as 1420 Snooperscopes and 715 Sniperscopes. The Engineers were directed to have the scopes manufactured and prepared for shipment to the Pacific Ocean areas. To "immediately" expedite tests, final standardization and overall requirements. No mention was made regarding the image tubes .
On 08 Dec 1943 the Subcommittee on Standardization authorized the Chief of Engineers for a unit cost at approximately $1,000 each with an expected completion date of 01 Apr 1944. On 10 Dec 1943 the Engineer Technical Committee classified the Snooperscope and Sniperscope as Required Type, Development Type, Limited Procurement Type, Secret. This meant the development of a limited quantity was required, standard procedure for the development and testing that preceded final standardization and establishing the overall requirements. Unlike the Ordnance Technical Committee, the Engineer Technical Committee did not designate the model number as part of their procurement or standardization orders.
On 17 Dec 1943 Electronic Laboratories of Indianapolis was contracted by the Corps of Engineers for the production of the Snooperscope and Sniperscope, later to be designated as the Model M1. 
Researchers at the Engineer Research and Development Laboratory at Fort Belvoir, VA, began testing the prototype Snooperscope and prototype Sniperscope on 18 Jan 1944. Approximately 4000 rounds of ammunition were fired with the sniperscope without major failures of the viewing device and infrared source. However, a number of defects in design became apparent. 
The Engineer Board also noted "The prototype Snooperscopes and Sniperscopes produced by RCA were not weatherproof nor were they designed to withstand field use. They were laboratory prototype models."
Expedited Testing Precedes Production Models
Standing and kneeling positions:
- up to 200 feet, seen and readily identified
- at 300-450 feet, seen with difficulty, outline is too indistinct to identify them as targets
- cannot be seen at ranges greater than 200 feet
Under normal conditions with no obstructions the practical useful range is 200-225 feet. Depending on a variety of circumstances commonly encountered in combat the range may become as short as a few feet.
Cross illumination employing more than one light reduces the glare from vegetation. When the light is placed at 90 degrees across the line of sight of the telescope, personnel hidden behind brush appear as bright objects against a black background and foreground.
Using a 450-watt or 2000-watt spotlight covered with an infrared filter the distance increased approximately 100 yards when used in open terrain. However, at a distance greater than 100 yards the image of a person is too indistinct to identify what is seen as a target.
Visible light emitted by the lamp can be seen at 60 feet by close scrutiny when the light is directed at the face of the observer. The light could be seen with more certainty at 30 feet when directed on the face of the observer but disappeared when the beam was directed at the waist. Reflected green glow off the operator's face can be seen at 54 feet. With the operators face against the rubber eyepiece there was no green light visible.
No malfunctions of the carbine were encountered during these tests. The telescope did not obstruct ejection of the empty cartridges.
Firing ball ammo didn't affect the operators night vision. Tracer ammo blinded the operator for a few seconds. The firing of weapons, both day and night, could be seen with the naked eye more effectively than with the electronic telescope.
The equipment is of little or no value to personnel while in movement. Employment of the equipment is limited to troops on security and reconnaissance missions.
There is no substantial difference in effectiveness for observation between the Snooperscope and Sniperscope. The Sniperscope will do all that the Snooperscope will do and adds the ability to destroy the hostile individual as soon as he is detected. Any slight advantage in handiness in favor of the Snooperscope does not offset this decisive feature. No sufficient reason for having both types is perceived.
The Sniperscope is suitable, in its present state of development, for immediate adoption and distribution.
The one objection to the equipment is its physical bulk and weight. Its very nature renders it somewhat more vulnerable to damage from ordinary service than most other infantry equipment and the recharging of the batteries at regular intervals will be a nuisance and require special arrangements and planning.
"These tests appear to establish as fact that both the Sniperscope and Snooperscope enable the user to see in the dark without disclosing his own presence. Whatever the situation involving security or reconnaissance missions at night men on such missions can certainly, with the aid of such equipment, perform their functions of detection and observation of hostile elements many times more effectively than when they have to rely solely upon the sense of hearing. In jungle warfare, against an enemy habitually addicted to infiltration by night it would seem that endowing personnel on security assignments with what is equivalent to a cat's eye ability to see and recognize both friend and foe at a reasonable distance by night can hardly fail to have a far reaching effect upon the security and confidence of our troops." 
That the Sniperscope be adopted as a standard article for issue to infantry troops. Issue to infantry regiments on a basis that will provide a pool under control of combat team commander in a ratio of one for each rifle platoon.
That no further consideration be given to the Snooperscope for Infantry use.
That development continue with a view to increasing the effective range, battery life, and ruggedness and reducing weight, bulk and vulnerability to damage in field service of the Sniperscope, without delaying production and issue.
This story will continue with
Part II: Production
 Image Forming Infrared; Summary Technical Report of Division 16, National Defense Research Committee, 1946
 "An Infrared Image Tube and its Military Applications" by G. A. Morton and L. E. Flory, Research Department,
RCA Laboratories Division; RCA Review Technical Journal, Sep 1946
 Science in World War II Series; Applied Physics: Electronics, Optics, Metallurgy by the National Defense Research Committee, 1948
 "Report 908, Snooperscope and Sniperscope, Project XR 441", 30 Jan 1945, Capt. Edmund R. Ricker, Corps of Engineers,
Fort Belvoir, Virginia
 ibid, Appendix A, Exhibit 1
 ibid, Appendix A, Exhibit 2
 Infantry Board Report #1595, Fort Benning, GA, 20 Apr 1944
 ibid, Appendix
 Alphabetic Listing of Major War Supply Contracts, Cumulative, June 1940 through September 1945, Civilian Production
Administration, Industrial Statistics Division, 1946
|The Newsworthy section of our forum has a number of different articles that include various articles on the infrared scopes and equipment used with the .30 cal. Carbines.||
In addition to providing a means to communicate with other owners and those of us doing the research, there are short articles on the various aspects of the infrared equipment.
Also, several posts on the ongoing research showing contract numbers, dates, quantities, serial number blocks, and more that are updated as additional information becomes known.
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