Bronco Models
37mm Anti-Tank Gun M3A1
Included with
Bronco Models 1:35 Scale Kit No. CB35107

Review by Terry Ashley
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The 37mm Gun M3 was the first dedicated anti-tank gun designed by the US and was introduced in 1940, first used in the Philippines in December 1941 but by 1943 was generally considered obsolete against German Armour in Italy and NW Europe but continued to be used in the PTO against the thinly armoured Japanese vehicles with great success up to the end of the war. It was also used as an infantry support gun firing HE and canister rounds and the gun itself was mounted on a number of armoured vehicles such as the M3/M5 Stuart, M3 Lee/Grant, M8 Greyhound and T17E1 Staghound among the most widely used types.

The M3 on M4 carriage was the most widely produced version with the M3A1 differing only in having a threaded barrel to take a muzzle brake but this was never used due to issues firing canister ammunition and the M3A1 went into service with the standard barrel and is basically indistinguishable from the M3 gun. The M4 carriage was later upgraded in 1942 with the M4A1 carriage with only minor modifications over the M4 carriage.

The kit:
While this kit of the 37mm M3 Anti-Tank gun is included with the Bronco kit #CB35107 GPW ¼ ton 4x4 Utility Truck (Mod.1942) it is really a kit within a kit and is bound to be released as a stand-alone kit in the future (speculation on my part) and as such I will review this separately from the GPW Jeep, opps sorry ¼ ton 4x4 Utility Truck.

The level of detail in this miniscule gun is amazing but comes with a price, there are many very small parts that need extreme care in both removing from the sprues and during assembly with a number of the miniature sub-assemblies being designed to be movable after assembly as shown in the instructions. You may find it easier to simply glue these in place as some are very difficult to glue together to be movable given the very small size and clearances of the parts involved.

This is not really a kit for the inexperienced modeller due to the many extremely small and delicate parts and a few fit issues and isn’t really helped by some rather vague instruction sequences in a few of the steps but with patience the end result is a stunning little kit of the US 37mm Anti-Tank Gun.

The kit gives you a choice of early civilian style tyres and the later standard non-directional combat tyres as well as being able to pose the gun in firing or travel modes with alternate tow hitches for the chosen configuration. Two additional small sprues contain a couple of 37mm AP and HE rounds plus spent shells and four 10 round ammo boxes.

The37mm M3 kit consists of:

Etched parts
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The Gun:
The main barrel is in three parts, the rear section, the central collar and front barrel tube. The barrel sections are one piece with just the fine mould lines to be sanded, the muzzle is slightly indented but you could drill this out further for a better appearance. The two part breech with separate breech block is fitted to the rear of the barrel and there is also the separate breech handle and this should be positioned forward for a closed breech and rearward for an open breech depending on how you fit the breech block? There are two very small etched parts, one added to the breech and the other to the breech block; both need extreme care in handling. The part (Pa9) has no clear locating mark and you should check the illustration in the next step to see where it should go.

The cradle fits snugly around the barrel assembly but the two top joins will need some minor filling and they don’t mate together very well, and the two trunnion mountings (parts Ka33, Ka34) also fit either side without any problems. Added to the left side of the cradle is the large shoulder guard, this is provided as a full plastic part (Ka36) or with just the plastic frame (Ka37) and the perforated shield as an etched part (Pa6). The plastic guard is a little thicker than the etched part but is a lot quicker and easier to assemble; just a quick note on the plastic shield, this had a moulding imperfection with the lower holes not formed properly, but on a second kit this was formed properly so this may be an intermittent issue?

Plastic guard moulding issue on one of my two kits.
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Fitting the etched shield to the frame is quite as exercise and is only something for the experienced modeller. First you need to anneal the etched part using a candle flame or similar to make it easier to bend, but you will still need to use an etched bending tool to do the job. The bend is very close to the edge of the shield and this makes it quite difficult to bend without forcing the plastic frame out of position.

After annealing the brass and letting it air cool, I then glued the plastic frame to the etched shield using cyanoacrylate making sure the frame sat naturally without any distortion, I then firmly clamped the plastic frame and etched shield into an etched bending tool and carefully bent the brass around the half curve of the plastic frame. I repeated this for each of the four sides of the frame where the brass contacted, the two longer sides being the trickiest not to force the plastic frame out of alignment in the process. Once the brass was bent I then lightly filed the curve as there were some irregularities due to the bending and in all this is a time consuming and tricky process and I suspect many will just go with the full plastic shield for ease of assembly.

The top carriage is in two halves fitted around the cradle sleigh but I found it easier to fully assembly the many smaller parts to the left carriage (part Ka29) as per step 27, especially the lower base (part Ka38) before joining the carriage halves to the cradle assembly as this will make the process easier. As it is this is quite a fiddly operation getting the two carriage halves to line up while at the same time fitting part Ka15 onto the pin Ka6 previously added to the cradle as well as to the lug on the right carriage and you may as I did glue part Ka15 in place to reduce the hassles. To get the two top carriage halves to fit together I had to slightly trim the bolt detail off the two trunnion mountings (parts Ka33, Ka34), this can’t be seem after assembly so isn’t a big problem detail wise but makes this assembly probably the trickiest of the whole gun.
It should also be noted that if building the model in travel mode the sight (part Ka16) wouldn’t be fitted but stowed in the box attached to the front shield.

Next comes the very delicate traverse and elevation linkage assemblies made up of 8 plastic and 3 etched parts and these do need great care removing the small plastic and etched parts from the sprues and during assembly. The two part etched bracket (parts Pa5, Pa11) needs special care not only for the small size of the parts but getting these aligned correctly with the small locating marks on elevation arm, this is important to mate to the etched part Pa13 added later. The instructions are a little vague as to how part Ka23 attaches to part Ka26 with the exploded view giving the impression Ka23 fits ‘over’ Ka26 when in fact it should fit ‘under’ part Ka26 as seen I the accompanying fully assembled image, so take care when gluing these parts together.

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Fitting the traverse and elevation assembly to the carriage is again a fiddly operation as the large notch in the base of part Ka26 has to fit over the lug on the side of the carriage while at the same time the pin at the end of Ka26 fits into part Ka15 added previously and care is need to align all these connections correctly.

The main shield is moulded cleanly without any pin marks and there is an etched strip added to the front of the shield attached by four raised bolts, the fit here is very precise so there shouldn’t be any problems. Just be careful while handling the shield not to deform the etched strip between the bolts as the strip sits fractionally above the shield surface as it should for an excellent appearance. Also the small etched ‘lever’ (part Pa2) fitted to the front of the traverse assembly should be left off until after fitting the shields to avoid damage.

Fitting the shield is a rather frustrating exercise as the instructions are very vague as to how the shield is supposed to fit in relation to the other parts with just two upper support arms being the only attachments shown and it was only by way of reference images was I able to determine the correct positioning on the shield. The top two support arms (parts Kb5, Kb7) fit to the front of the gun mountings as per instructions and the lower left of the shield sits on part Kb10 while the right side attaches to the front of the gun mounting (part Ka28). You have to ensure the shield sits perfectly square and level to the gun assembly while fitting. Also note the shield sits ‘behind’ the front of the travers assembly (parts Ka12, Ka13 and front of Ka23) with these parts visible in front of the shield after fitting, unfortunately nowhere in the instructions is this shown clearly and I’ve included an image of the actual gun to show this.

Reference image showing the location of the shield.
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The five part storage box is added to the rear of the shield and this assembled without any problems and the long thin etched handle (part Pa13) should fit through the brackets fitted earlier if everything was aligned as it should be, this handle should meet up with the small etched ‘lever’ (part Pa2) fitted to the front of the travers assembly.

Lower Carriage/Trails:
The lower carriage/axle assembly is in two parts that fit flush together and you should make sure the mating surfaces are perfectly smooth for a precise fit, there are two brackets added to the assembly (parts Kb28, Kb29) but the part numbers are transposed in the instructions so just swap them around.

The wheel supports (parts Kb26, Kb27) are added to the ends of the carriage and these can be fitted raised or lowered depending if you are building the kit in travel or firing models, the fit of these parts is very snug and you don’t need glue. The lower shield can also be attached raised or lowered depending on the mode and there are some extremely small parts here, the two eyelets (parts Kc2) and the two hooks (parts Kc1) holding the shield in the raised position and these do need care in handling.

As mentioned you have a choice of early civilian style tyres and the later standard non-directional combat tyres which use a common inner rim and partial tyre wall (part Kc8) so you end up with only one full set of tyres. The tread pattern is very well done on both tyres although there is a large central mould line on the civilian tyres that will need careful sanding to not damage the surrounding thread pattern. The tyres have “Firestone” and data embossing on the side walls as well as very good rim details and contours, the only thing needed is to add the valve stem.

Alternate wheels in the kit.
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The inner rim is designed to attach to the axle stub by way of a small boss (part Kc4) to allow the wheels to rotate but given the small size and lack of clearance between the parts this would be difficult to do in reality and just gluing the inner rims in place would be the easier option. If you just glue the inner wheel rim to the axles it allows you to quickly slip the outer wheel rim/tyre in place to change tyre patterns, the fit is very good between the wheel segments so no filling in needed.

Each trail arm has the full length outer U shaped section with separate inner ‘filler’ panel that also includes part of the spade support, there is a fine mould line along the top and bottom of the main arm and this can be left to simulate the weld line on the actual trail if you wish? Added to the front of the trail arms are the extensions for securing the arms in the splayed firing mode as well as very small rear locking mechanisms for travel mode and again there are some very small and delicate parts here. The two spades fit easily into place but the small etched parts will need care in fitting, on top of the rear trails is an O ring (parts Pa1) that you form by bending the supplied etched part around a 1mm drill bit, all very easy but the location of these and the forward small brackets (parts Pa4) are not very clear in the instructions. Other items added to the trails are the two grab handles and barrel cleaning rods along the trail sides plus the rear towing hook provided with a complete round loop or with a section cut out for easy fitting to the Jeep towing pintle, use either depending on the final setting for the gun.

Trail ends with delicate etched and plastic parts.
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Fitting the trails to the lower carriage sees the trail brackets just ‘clip’ into the locating holes on the lower carriage but there are a few modifications needed to display the arms splayed in firing mode unfortunately. Firstly the small notches on the lower carriage don’t mate with the indentations in the trail extensions and you will need to carefully cut off the notches and reposition slightly more inboard to fit properly, test fitting will make sure these line up correctly. If you are fixing the arms in the firing position just cutting off the notches would suffice as you can’t see these afterwards in any case.

Second you need to slightly enlarge the underside cut-out of the two carriage brackets (parts Kb28, Kb29) to allow the arms to sit properly, likewise the inner edges of the trail ends between the locating brackets need to be bevelled to again allows the arms to sit in the correct splayed position, these are all small modifications but add a little to the work needed to fit the arm to the lower carriage for the firing mode. If fitting the trails in the closed travel position no modifications are needed as they fit perfectly with the rear locking mechanism mating nicely. There are extremely small pins that fit into equally small holes in the trails to hold the trails in the fireing position, these pins fit into the 'storage' holes in the travel mode and again care is needed handling these miniscule plastic pins.

Trail modifications as per review text.
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Final Assembly:
The fit of the assembled gun mounting to the assembled lower carriage/trail assembly is by way of a small pin in the underside of the gun base fitting into the hole in the lower carriage but the pin is quite small and doesn’t provide an sort of positive fit if you want the assemblies left unglued, of you want to just glue them together, then just glue them but leaving them separate will aid considerably in the painting process.

To remedy this I simply replaced the moulded on pin on the gun base with a length of 1.5mm plastic rod (about 5mm long) and this then slipped into the lower carriage hole without problems to a positive fit, just note the gun will come adrift if you upturn the kit so be careful. The last thing is the lower travel lock (parts Ka32, Pa12) added to the mountings on the lower carriage and positioned either lowered for firing mode of mated with the small notch on the underside of the gun for travel mode, all very easy.

There are no specific decals provided for the 37mm gun with the instructions just indicating to paint it all over in Olive Drab.
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Overall this is superb little kit of 37mm Anti-Tank Gun with a high level of fine details and features, the small parts do come at a price with some extra assembly and minor modifications needed in a few areas but the end result is a superb little kit. The parts are moulded very cleanly and assembly good but some areas need a little care due to the many small parts and the rather vague instruction in a few sequences.

Given this is the first injected plastic kit of the 37mm M3 in 1:35 scale it’s hard to see anyone bettering this effort and hopefully Bronco will release this as a separate kit shortly as the diorama possibilities are endless.

Rating 9/10

Build Detail Images
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The Sprues:

Kit Sprues
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Silicon Valley Scale Modelers Website Gallery: 37mm AT Gun

Thanks to Hobbyeasy and Bronco Models for the review kits.

Page created March 5, 2013

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