In the late 1950s the US military began development of a bomb capable of destroying deeply buried bunkers. The result was a bunker busting unguided thermonuclear bomb. Durng a visit to the Atomic Testing Museum, in Las Vegas, Matt had the chance to take a look at a decommissioned B53 up close.
The B53 is a two-stage high-yield thermonuclear weapon, designed as a bunker buster, that could deliver a massive shockwave deep underground to the deepest Soviet command and control bunkers. Developed between 1958 and 1961, the B53 was intended to combat deeply emplaced Soviet bunkers with a yield of 9 megatons. It used a highly enriched uranium core as its primary fission stage with Lithium-6 deuteride as its second stage fusion element. The warhead itself was developed from the earlier Mk46 warhead, the experimental TX-53 was tested at the Pacific Proving Grounds as part of Operation HARDTACK I, which saw no less than 35 nuclear test detonations. Codenamed HARDTAK OAK, the TX-53 was detonated aboard a floating barge on 28th June 1958, with a yield of 8.9 megatons. The detonation created a cloud 78,000 feet (23.8 km) tall.
Designed to be dropped from the Strategic Air Command’s B-47, B-52 or B-58 bombers, the B53 is a gravity bomb which free fell to its target and could be air or surface detonated. The bomb itself weighed 8850 lbs or 4014kg and the casing is 12.5 feet long (3.8m) and just about 50in (1.27m) in diameter. The bomb’s outer-casing is split into a nose section, a two-piece central casing and the rear assembly with four fins which housed the parachute assembly. They were built by the Atomic Energy Commission between 1962 and 1965, over 340 bombs were built. Initially designated the Mk53 it was re-designated the B53 in 1968, when the US Air Force updated its ordnance nomenclature.
The bomb itself could be deployed in four ways: a delayed surface burst, a free fall air burst, a parachute retarded air burst (the B53 had five parachutes at the rear which can be deployed) or an immediate contact surface burst. Here we can see the panel to control the parachute deployment, with markings for safe, free fall and retard.
The B53 was obsolete in terms of its safety by the early 1980s with none of the more modern safety features such as an Enhanced Nuclear Detonation Safety (ENDS) additionally its explosive lens, consisting of a mix of RDX and TNT was not an insensitive munition – meaning it wasn’t designed to resist detonation from external stimuli or damage. The B53 also had no Fire-Resistant Pit (which prevents the spread of radioactive material in the event of a far), Permissive Action Link (which prevent unauthorised arming) or Command Disable safety measures.
Many of the B53s in US inventory were decommissioned in the mid-1980s, and by 1987 just 50 were retained in inventory. The last of these were disassembled and decommissioned by October 2011 – after being in service for 50 years. The B53 was replaced in its bunker busting role by the smaller B61 Mod 11.
In this week’s video we compare two of the last roller-delayed production rifles: the Spanish CETME Modelo L and the Heckler & Koch G41. These rifles represent the last evolutions of two strands of the roller-delayed development tree – the Spanish and the German.
Both rifles use the roller-delayed blowback action and are both chambered in NATO SS109 5.56x45mm ball round, have have 1:7 twist barrels and feed from STANAG magazines. Both were developed during the 1980s and both are also capable of firing rifle grenades.
The CETME L
The CETME has a bit of a reputation for being cheap but this relatively unbattered example feels solid enough. Both of the rifles disassemble in much the same way with the butt assembly being removed to allow the bolt to be pulled out of the rear.
Most notable about the CETME’s bolt is the long rod protruding out the back of the bolt assembly. This acts on the recoil spring housed inside the butt. The L’s recoil spring, unlike the G41s, is captive inside the butt rather than nested inside the rear of the bolt carrier. The CETME’s bolt is also much squarer than the G41’s which probably simplified the machining of the bolt and designing the receiver stamping.
The L does not have a provision to lock its bolt back in a slot like the HK (no CETME slap for Spanish soldiers), however, it does have a bolt hold open, with the release located in the rear sight base.
The CETME has simpler folding aperture sights with 200–400m adjustments. It weighs in a 3.72kg or 8.2lbs unloaded and is 92.5cm or around 36in in length. The CETME has a simpler fire control group, with safe, semi and full-auto settings. It is not ambidextrous and only has a selector on the left side of the receiver. The CETME L has largely been replaced by the weapon that superseded the G41 – the gas-operated HK G36.
Heckler & Koch G41
We have full article and video examining the G41 in detailhere.
HK finalised the G41’s design in 1979, a refinement of the 5.56x45mm HK33, it sought to modernise the platform and borrowed features from the M16 family of rifles including a bolt release catch, dust cover and forward assist.
The G41 has a butt assembly that fits into the receiver rather than around it. So its cross pins are at the top and bottom of the receiver rather than both at the bottom. This spreads the stresses on the receiver vertically rather than laterally.
The G41 has both the classic HK hold open notch and a AR-style paddle bolt release. HK’s dioptre drum sights have adjustments from 100 to 400m, and can mount a scope using an HK claw mount. G41 is the heavier of the two rifles, weighing in at 4.31kg or 9.5lbs. The G41 is also slightly longer than the L at nearly 100cm or 39in in length.
The HK has an ambidextrous selector with positions for safe, semi, 3-round burst and finally full-auto. The G41, unlike the L, also has a folding carrying handle near its point of balance.
The Type 64 is an integrally suppressed submachine gun designed in China in the early 1960s, taking several design elements from other Combloc small arms. The guns were manufactured at one of China’s State Factories (with the factory’s ‘66’ in a triangle marking in the left side of the receiver – this indicates the factory number, although available sources differ on which it refers to, either 66, 626 or 366).
Designed concurrently with the Type 64 suppressed pistol during the 1960s, the Type 64 SMG was developed for Communist China’s special forces for use in clandestine operations. Chambered in the standard 7.62×25 ComBloc pistol round, the Type 64 functioned best with Type 64 subsonic ammunition, a special subsonic spitzer projectile variation of the standard 7.62mm pistol round. It did not chamber the low power 7.65x17mm round used by the Type 64/67 pistols.
The Type 64 fed from 20 or 30 round double stack magazines which were reportedly developed from or at least influenced by the Soviet PPS-43’s double stack, double feed magazines. The weapon used a conventional blowback action and fired from an open bolt. Its maximum effective range was approximately 200 metres with two position flip up sights ranging out at 100 and 200 metres.
The Type 64 had a milled receiver with lightening cuts and weighed in at 7.6lb or 3.5kg unloaded. It took its bolt from the Russian PPS-43 submachine gun and a trigger group inspired by the ZB vz.26 light machine gun’s, which was well liked by the Chinese military.
The Type 64 shared a number of external similarities with the standard Type 56 AK-clone including its pistol grip, safety lever and under-folding stock (which is similar but slightly different to the Type 56-I’s under-folding stock).
The weapon has a number different controls including a conventional AK-style safety-come-dust cover, on the right side of the receiver – which blocks the travel of the bolt. On the opposite side of the receiver it has a two-position fire selector for semi and full-auto – you can just about reach these when the stock is folded. The forward position is for semi and the rearward position is full-auto. Finally, the 64 also has an additional trigger block safety, taken from the SKS, which pivots forward to prevent the trigger from being pulled.
According to a report written in October 1971, by the Small Arms Systems Lab of the US Army Weapons Command Research and Engineering Directorate, the weapon has an extremely high rate of fire of over 1,300 rpm.
A cyclic rate that high was the result of a combination of back pressure from the suppressor, the ammunition used and its blowback action. The Type 64’s chamber was fluted with three longitudinal cuts to aid extraction at its high rates of fire. It should be noted, however, that the 1971 US army tests were carried out with standard velocity ammunition – rather than the specialised subsonic Type 64.
The top cover is removed by pushing in what at first appears to be a spring-loaded detent, but is actually the recoil spring guide rod. The front of the top cover is held in the receiver by a lip which fits into a slot just above the breech. The top cover itself is a thin piece of stamped sheet metal with the serial number stamped at the rear.
With the top cover removed we can see inside the action. The 64 has a single recoil spring held in place by a guide rod. At the rear of the receiver is a small plastic buffer, designed to both soak up some of the recoil energy and to help reduce action cycling noise. There is an ejector on the left side of the receiver and guide rails along which the bolt moves. To remove the bolt it is pulled fully to the rear and then tilt it upwards.
The Type 64 is a pretty compact weapon despite the length of its suppressor. It has an under-folding stock, with two spring-loaded buttons at the rear of the receiver which have to be pushed in to fold and unfold the stock. When folded the weapon is 25in (or 63.5cm) long, with the stock adding 8 inches when it is deployed. The weapon can be used with the stock folded, although some of its controls are partially obscured.
The suppressor is contained by a housing which attaches to the receiver by an interrupted thread. The Type 64’s barrel was ported with 36, 3mm vents at the muzzle-end while the suppressor has 12 metal dished baffles held captive on a pair of guide rods. The weapon’s sights are mounted on the suppressor housing which attaches to the receiver by an interrupted thread. Sadly, I didn’t have time to strip the suppressor itself but the photos below, from my friend Chuck over at Gunlab, show the Type 64’s ported barrel and baffles well.
The 1971 Small Arms Systems Lab report found that the audible report of the gun, was 150db at the rear of the receiver and 157db 12 feet down range, however, this is probably not the best indication of the Type 64’s capabilities as the report states that the gun was tested with Chinese Type 51 standard velocity 7.62x25mm ammunition. Ideally, the weapon would have been used with subsonic Type 64 ammo specially developed for China’s suppressed pistol-calibre weapons. Chinese sources reportedly put the weapons noise level at 84db when using subsonic ammunition. The US report did note that while its noise suppression wasn’t outstanding, it very effectively hid its muzzle flash.
It appears to have been primarily used by Chinese scouts and special forces and saw action during the 1979 Sino-Vietnamese War. In the late 80s the Chinese replaced the Type 64 with the suppressed version of the Type 85 submachine gun, also chambered in 7.62x25mm, which used the same magazines, the Type 85 had a tube metal and stamped receiver which was simpler to manufacture than the 64’s machined receiver. The Type 85 has subsequently been superseded by guns like the bullpup Type 05.
Special thanks to the collection that holds this weapon for allowing me to take a look at it. As always guys thank you for watching. If you enjoyed the video please share it with friends and help us
The Cody Firearms Museum, at the Buffalo Bill Centre of the West, holds a number of interesting select-fire M1 Garand rifles, adapted by Winchester during the 1940s. In this article we’re going to examine one of the prototypes, the rifle is believed to date to the late 1940s, and appears to be chambered in one of the earlier iterations of the T65 .30 Light Rifle round, which would eventually be adopted as 7.62x51mm.
Very little information is available about the rifle and little has been written about it previously. It is believed to have been developed by Winchester engineer Harry H. Sefried II with former Cody Firearms Museum curator Herbert Houze crediting Sefried with the rifle, which he described as adaptation of the M1 into a ‘squad automatic rifle’. After some archival research and combing Winchester’s patents from the period we can now attempt to shed light on a little more of the rifle’s history.
Externally, the rifle has a number of instantly recognisable distinctions from the standard M1 Garand. It has a reshaped stock with an added pistol grip, a proprietary box magazine and a combined bipod and conical flash hider. If we look closer we’ll notice that the stock has a swell just ahead of the breech, flaring out in an almost triangular bulge. These changes to the stock also distinguish this rifle from Winchester’s other select-fire M1 adaptations, which retain the standard Garand stock profile.
From the patents available combined with an examination of the rifle we can learn a lot. We cannot rely on patents to tell the whole story of the rifle, however, as many of the elements that make up the weapon appear to have gone unpatented. The substantial external and internal changes made to the rifle suggest that this was not an attempt to adapt the M1 with a minimal number of component parts changes but rather an effort to generally improve the rifle, making it conducive to fully automatic fire.
In summer 1944, Winchester’s CEO Edwin Pugsley directed Sefried to begin work on a select-fire conversion for the M1, to rival those being developed at Springfield Armory and Remington. Winchester’s select-fire Garand went though a number of iterations which resulted in two patents from Sefried. The first, filed in August 1944 (US #2479419), incorporated an elongated sear actuating lever and a selector on the lower, right side of the receiver. Winchester’s first attempts at a select-fire M1 conversion resulted in rifles with extremely high, uncontrollable rates of fire of over 900 rounds per minute. Sefried filed a second patent later in January 1948 (US #2464418) which used a catch to hook the sear. The rifle we are examining appears to have yet another select-fire system, one for which I have so far been unable to find a corresponding patent for. Winchester’s work on the select-fire adaptation came to a halt with the end of the war. It appears, however, that Winchester again began to work on adapting the M1 in the late 1940s, with Sefried again working on the project, filing his second select-fire mechanism patent in 1948 (US #2464418).
The rifle’s receiver was originally a standard Winchester-made .30-06 M1 with a serial number of 1,627,456. This means its wartime production gun, dating from May 1945. It would appear that rather than the rifle being lifted from the rack finished, it seems that it was earmarked for prototype development because the receiver forging lacks the cuts/forgings needed for the en bloc clip release lever. This makes sense if it was known that the receiver was destined for use in a prototype which fed from a box magazine. However, the timeline of the rifle gets more complex when we consider that it was a late-war production rifle. There are a number of possibilities. The rifle may have been simply set aside for internal prototype work in May 1945 and not used until a T65 chambered rifle was developed later. Alternatively, it is possible that the rifle was converted during the initial attempts to create a select-fire M1 but was later rechambered from .30-06 to the new developmental T65 round.
This prototype’s trigger guard assembly, which also comprises the magazine well floorplate, is a self-contained assembly and does not interact with the weapon’s trigger mechanism or action. While Sefried had a patent for his own magazine system (US #2386722) this rifle uses a slightly different magazine release and floorplate, which is similar to one seen in Stefan Janson’s 1956 patent for a stripper clip-loading box magazine for the M1 (US #2894350). The magazine used in this prototype, however, is not the same as Janson’s. It has fixed feed-lips and a projection at its rear which appears to house an anti-tilt tab for the follower.
The rifle does not to appear to use the full-automatic system seen in either of Sefried’s patents. Similarly, the safety selector is located on the left side of the receiver, forward, in line with the breech. It has two positions with an arc of about 90 degrees. This position does not match Sefried’s patents for select-fire conversion, however, it does match the position patented by David Marshall Williams but not Williams’ selector’s orientation of travel. I have been unable to find a patent which matches this rifle’s selector or method fully-automatic conversion.
The pistol grip is an interesting addition as neither of the other Winchester select-fire prototypes nor the original select-fire Springfield prototypes incorporated one. Visually it is very similar to that seen on the later Italian Beretta BM 59 Mark II. In an effort to lighten the rifle the prototype also has an aluminium buttplate. One of ingenious internal changes is the milling of the bottom of the barrel flat, this not only has the effect of lightening the rifle but also allows a new, straight operating rod to travel rearwards under the barrel. How this impacted on the barrel’s harmonics is unclear. The rifle certainly feels lighter and handier (when unloaded) than you would expect, weight is estimated to be around 7 or 8 lbs.
The bipod, patented by Sefried in April 1945, (US #2420267) comprises a pair of tube steel legs, which have a set height, and a conical aluminium flash hider. The legs are spring-loaded and the entire assembly attaches via a latch which seats over the rifle’s bayonet lug. The bipod is the only element of this rifle that can be attributed to Sefried directly. And by the bipod’s very nature of attachment may simply have been attached later.
The best documentary source available for the prototype is the entry in the Winchester Factory Museum’s collection inventory offers some tantalising clues but no definitive answers:
#1504 U.S. Model M-1 rifle (Garand)
Cal. 30-06; experimental semi or full auto.
3rd type 20 shot box mag.
Special butt plate for shoulder rest
Bipod and aluminum flash hider attached
From H. Sefried 10-26-45
The suggestion that the rifle is chambered in .30-06 is seemingly an error given the internal changes made to the rifle. ‘3rd type’ suggests an iterative development of the rifle’s magazine while “special butt plate for shoulder rest” may allude to the aluminium butt plate but the prototype’s plate has nothing resembling a ‘shoulder rest’, instead it is a simple chequered aluminium plate about 5mm thick. While ‘From H. Sefried 10-26-45’ may refer to the whole rifle, I believe it more likely refers simply to his bipod.
The prototype appears to be chambered in an iteration of the .30 Light Rifle round, which later became known as the T65. The rechambering was achieved by installing a metal block which shortened the magazine well. Unlike earlier Winchester select-fire conversions this rifle feeds from a proprietary magazine designed to feed the T65 round. This magazine does not appear to closely follow the pattern used by Winchester on several other designs during the period. The projection from the rear of the magazine slides along a channel cut in the metal magazine well block. It has font and rear locking shelves, with the front shelf acted on by the magazine release lever.
Development of the .30 Light Rifle round, which would eventually become 7.62x51mm, began in 1944, with the round first being referred to as the T65 in 1946. It appears that the rifle is chambered in a version of the T65 cartridge, but which iteration exactly is unknown. However, its chambering does support the theory that the prototype may date from 1947-48. The T65 didn’t take on the now standard 7.62x51mm dimensions until 1949 in the form of the T65E3 round but without a chamber casting it is impossible to know the rifle’s exact chambering.
While Winchester continued to work on adapting the M1 Garand into a select-fire rifle none of their rifles were seriously considered by US Ordnance. At the same time John Garand was working on his own series of select-fire, magazine-fed prototypes (the T20 series) at Springfield while Remington had also been awarded a contract to develop a similar rifle, tested under the designation T22. These projects subsequently gave way to a number of other designs, all chambered in the T65 round, including the T25/47, T44 and T48. These were all tested before the Garand-influenced T44 was eventually selected in 1957, becoming the M14.
Harry Sefried II served in the US Army Air Corps during World War Two before joining Winchester as a firearms designer in 1944. In the 1950s he left Winchester to become Ruger’s chief engineer until he retired in 1979. He died in 2005, aged 84.
The Johnson is already one of the 20th century’s most interesting military rifles, in terms of both design and history, and this rifle, serial number R-14, is perhaps even more interesting. Johnson’s military rifles were initially designated the Type R – for rotary magazine, it was the ‘R’ serialised rifles which were used during US military testing in 1938-40. We are most familiar with the classic handguard-less appearance of what became known as the Johnson M1941. Few examples of a Johnson with a handguard survive.
The rifle was developed by Melvin Johnson, a USMC Reserve Captain, in the mid-1930s, Johnson began work on the rifle just as the M1 Garand was adopted. Johnson was granted his first patent protecting his rifle in September 1937. His rifle was tested in 1938-39 by US Army Ordnance but advanced no further than testing. Johnson lobbied politicians leading to a bill being introduced in an effort to have Johnson’s rifle adopted. On May 29th, 1940 the US Senate’s Military Affairs Committee met with Johnson and military representatives to discuss the rifle and the Bill which had been proposed, S.3983, to ‘Provide for the Adoption of the Johnson Semiautomatic Rifle as a Standard Arm of the Military’. The bill, however, led nowhere and the M1 Garand’s introduction continued.
The handguard fitted to R-14 was actually an optional extra offered by Johnson Automatics. It appears to have been an attempt to address one of the main concerns raised by the US military – the Johnson’s unsuitability for bayonet fighting. As the rifle uses a short-recoil operated action the barrel recoils about ½ inch on firing, this means that the weapon’s barrel isn’t actually fixed in place meaning when the bayonet was used the barrel moves backwards ½ inch when it contacted something or someone with enough force.
From the Senate Committee hearing we know that there were real concerns about the rifle’s bayonet fighting characteristics. With US Army Ordnance noting that “this rifle is very poorly suited to bayonet fighting.” Noting that the exposed barrel was too narrow to grasp properly and was also un-insulated if the barrel was hot from firing. The non-fixed, recoiling barrel was also highlighted as another ‘deficiency’. Major Grant Schlieker, the Infantry Liaison Officer at the Aberdeen Proving Ground, shared similar concerns. In addition to concerns about the lack of handguard to grasp when bayonet fighting he noted in his statement that during their testing the Johnson has struggled to cycle properly when fired at a depressed angle with a bayonet fixed and that striking something with the bayonet hard enough lead the rifle to extract and eject a chambered round.
Johnson refuted these concerns by stating that the barrel was exposed with good reason so that it could cool rapidly, suggesting that enclosed barrels like the Garand’s became too hot to grasp after sustained firing thus also making bayonet fighting difficult. Johnson also noted that a ‘Johnson Sword Bayonet’, which extended forward under the barrel from the Johnson’s normal forend had been developed to address the problem but the ergonomics and usefulness of this terrifyingly long bayonet are unclear.
You would imagine that a fixed, full-length stock with the barrel recoiling inside would have been a more elegant solution allowing the bayonet to be fixed to a nosecap rather than the barrel. But it would seem that Johnson was passionate about having the exposed barrel to allow cooling.
It is worth noting that the bayonet issued with the M1941 was the lightweight spike-type, developed in order to elevate potential issues with cycling while the bayonet was fixed.
A proponent of the rifle, USMC Captain, George Van Orden (who commanded the Rifle Range at the Marine Corps Barracks at Quantico) went so far as to claim that the recoiling barrel had a positive impact on bayonet fighting “a recoiling barrel can provide extra thrust in bayonet fighting, as in the case of a boxer who in striking a blow, at the moment of contact… straightens his elbow smartly.” The Johnson Automatics manual for the rifle even claimed that testing against pine board showed that “the short recoil of the barrel actually tends to increase the penetration of the bayonet.”
From the May 1940 Senate hearing records we know that the R-14 wasn’t always fitted with the barrel with the enclosed handguard. It was one of several rifles used by Captain Van Orden to test the rifle’s accuracy and there is not mention in his account of the rifle’s barrel being shrouded with a handguard. This isn’t too surprising as the Johnson’s barrel can be removed easily and readily swapped out.
The bayonet lug appears to be designed to mount a US Army M1905 bayonet, the sword bayonet issued with the M1903 Springfield. The assembly also has a sling swivel. R-14’s barrel is 23.75 inches long – this is a little longer than the standard 22 inch barrel, but 24 inch barrels were an option offered by Johnson Automatics. The round wooden grips panels are held in place by three pairs of slips and the nosecap and the guide collar.
Other than the forend this rifle also has a slightly different style of rear sight compared to the M1941 production rifles. The receiver markings are also simpler with calibre, patents and a plain maker’s mark, with serial number at the bottom.
The addition of the handguard certainly does allow a greater area for the forward hand to grip the rifle. But what is less clear is the effect the added mass of the handguard, nosecap and bayonet (when mounted) had on the cycling of the gun. Logic would suggest that any weight added to the barrel would slow the its travel and potentially cause reliability issues. The handguard and bayonet would have added at least 2lbs. Sadly, I’ve been unable to find any documentary evidence to tell us how the rifle functioned with the forend. No mention of the handguard is made during the Senate committee hearing but a ‘fixed-type’ bayonet is mentioned which is described as “not in any way interfering with the recoil of the barrel.” This was presumably referring to the long Johnson Sword Bayonet. Despite them being offered as an official option it is fair to presume that the rifle would have struggled to operate properly when fitted with the handguard.
When the Johnson finally entered production it was with an exposed barrel as he intended and R-14 remains one of the few examples to have the Johnson’s optional handguard.
Many thanks to the Cody Firearms Museum for allowing us to examine and film the rifle and take a look at a rare example of the Johnson Automatics optional extra handguard.
Military Handbook of the Johnson Semi-Automatic Rifle (1939)
The Johnson Semiautomatic Rifle: Hearing Before the Committee on Military Affairs, United States Senate, Seventy-sixth Congress, Third Session, on S. 3983, a Bill to Provide for the Adoption of the Johnson Semiautomatic Rifle as a Standard Arm of the Military and Naval Forces, May 29, 1940 (source)
Johnson Rifles and Machine Guns: The Story of Melvin M. Johnson, Jr. and His Guns, B. Canfield (2002)
The Model of 1941 Johnson Rifle in Marine Service, B. Canfield, American Rifleman, (source)