Like the screw mounts in the back of the muzzle, there are a number of things you immediately see that give the PAK 40 away as a molded item. One of these give-away features are the ‘hollow’ backsides of items such as the carriage cradle forks, sliding barrel shield, and the pivot points for the carriage cradle forks. I used thin sheet styrene to close off the carriage cradle forks and the carriage table’s pivot points, but filled the barrel shield with resin as I did not want to add any thickness to the shield and trimming it down would make it too thin. In the picture of this filling process you can see the travel limiting stud, which I later sliced off as unnecessary and the notched out sides blocked off with modeling clay to allow the shield to hold the liquid resin. The notched out sides give the shield more movement, allowing the weapon maximum depression or elevation. The original shield is connected to the gun carriage by 2 arm pieces, thus when the carriage is elevated or depressed the shield slides right along with it.

 

 

Note Notched area was closed off with modeling clay to hold the resin in until it set. The stud was later cut off and the entire back side filed off smooth.

 

 

 Back side of pivot pin prior to detailing.

 

Pivot pin with scrap piece of vinyl sheeting added to close off the "open" backside. The piece was glued into place with CA, filed off flush to match the original and the joint smoothed over with green putty.

 

Photo showing original construction and the open backside of the carriage forks that give the item an unrealistic “molded” look. A thin piece of sheet styrene was glued over the backside of both forks to close this area off and make it more realistic.

In the pictures above, the pyramid shape of the end cap, the much shorter round rod sections in the middle of the cap sides, the greater forward travel of the barrel, as well as the retaining band and hardware are very evident. To make the 21st Century Pak more realistic in these respects I started by making the barrel slide further forward.

The barrel is held on to the carriage by 2 ‘T’ fixtures glued/molded to the bottom of the barrel assembly. The arms of the ‘T’s hold the barrel and slide to the carriage because of ledges inside the carriage (right and left sides, as well as the forward end). It is the ledge molded at the end of the carriage that limits the forward movement of the barrel. In the photo below you can see two of the ledges (right side and end ledge). As stated above it is the width of the ledge at the end of the carriage that keeps the barrel from sliding all the way forward. This was easily fixed by cutting the forward ledge back about a quarter inch.

 

By cutting into the end ledge a 1/4 inch, the barrel is allowed to slide further forward, as the picture below clearly indicates:

 

 

Another detail you notice in these last two photos is that the barrel slide actually projects beyond the neck of the barrel. This inaccuracy was corrected by removing the slide and cutting a thin slice out of the center (See the picture below). The shortened pieces were then glued back together and reinforced with an added flat piece overlapping both sides of the butt joint (note area marked in light blue). The reinforcement piece can not cover the whole width of the slide, as that would prohibit it from sitting down on the carriage low enough for the barrel assembly locking ‘Ts’ to reach the ledges in the middle of the carriage.

 

 

Also obvious in the photo above, is the re-positioned rear ‘T’ lock. The real Pak 40 of course does not use such a device to connect the barrel to the carriage, and visibility of the ‘T’ lock detracted significantly from the realism of the model in my opinion. For this reason I sliced the ‘T’ lock off and positioned it far enough forward that the shadow cast by the breech/barrel would hide it, as indicated in the light green markings.  It was glued and screwed in place for added strength.

 

When I first started looking for photos of real Pak 40s it seemed all of them showed the carriage end cap with a pyramid shape or design, like the real, green Pak 40 shown above. For that reason I decided my Pak 40 had to have the same feature. Later on, as I collected more photos I did come across some that had carriage caps shaped similar to the one molded by 21st Century, but by that time the work had already been done!

 

 

To change the end cap I drew a line and cut off what looked to be a proper amount of the upper ‘square’ side. I then used a piece of styrene to make the new upper side of the ‘pyramid’.

 

 

View of the new upper side before it was trimmed down flush. Note that the lip on the lower side was filed off to resemble the end caps of original Pak 40s I had located pictures for on the inter-net. The long rod like pieces in the center of the sides were cut down to better match the length of those in the same pictures as well.

 

The following pictures are comparison photos showing the ‘empty’ and plain nature of the interior of the carriage on a real Pak 40 versus the 21st Century Toys 1/6th scaled version:

 

 

 Real Pak 40 carriage

 

The interior of the carriage is highly visible at the block end of the gun and contains a number of features that clearly indicate the Pak 40 is molded plastic. The ledges on each inner side of the carriage (as well as the rear travel stops) do not exist on the real Pak 40. As I had moved the rear ‘T’ lock forward to keep it out of site, the ledges were no longer needed in this part of my Pak 40, and were cut out with a Dremel tool. The screw mountings and other structures were likewise cut out, and the upper lip that extended to the interior of the carriage was cut off flush as well. The carriage was then simply glued together with gap filling super glue. A styrene reinforcement piece was glued in the molded depression at the rear of the carriage, and then everything smoothed over and given added strength by using thin sheet styrene to laminate the entire visible section of the carriage interior.

 

 

Above: the rear locking T in its original position. As I had made up my mind to remove the locking T rail in the highly visible rear section of the carriage and far enough forward that it would not be easily visible, this locking T had to be moved forward. I still needed it to hold the barrel assembly to the carriage and keep the barrel assembly in proper alignment, so it was cut off flush with the breech and re-secured to the barrel slide far enough forward that it would not be easily visible, and so that the normal recoil could be ‘re-created’ without the locking T coming off the end of the remaining ledge. The T was secured using two 00-90 screws and JB weld.

 

 

In this photo you can see many of the final modifications. The trimmed down new upper ‘pyramid’ side, the cut-down rod sections in the center of the cap sides, the greater forward barrel movement, simulated rivets on the end of the front barrel skid and the lower bullet shield, barrel band and band attaching hardware, as well as the barrel skid sitting back from the barrel neck.