One of my fellow airsofters contacted me enthusiastically, saying that he wishes to install an SRU Bullpup kit on his WE SCAR-L replica. The gun itself was worn and damaged, so a general maintenance was also due. Unfortunately, I received the replica broken. It was mostly unmodified and still having the factory parts inside, the trigger group was really worn out and the bolt carrier simply broke. It came with an RA Tech steel bolt set, but that upgrade was non-functioning. Even though I would really want to go into details how the RA Tech steel bolt has serious quality issues (which would deserve its own article), but I will focus on the SRU bullpup set for now.

The brand SRU (or SR Union) can be traced back to RA Tech, so I was very sceptical in the beginning. Many of you know that I have a strong opinion on RA Tech products and think that only a few selected items are good from their lineup – however, those few upgrades are excellent. With RA Tech and its „shadow brands”, the main issue is the huge deviation in quality control, combined with the awful customer service. Considering how expensive their products are, an airsofter would rightfully expect much less problems coming from the usage of their parts.

SRU is mainly specialising in 3D printed, futuristic conversion kits for replicas. Their portfolio is constantly expanding with new products, including CNC machined slides and lately, real steel parts. Most conversion kits are turning replicas into bullpup guns, meaning that the magazine is behind the trigger.

When the SRU bullpup set was handed over to me, my first idea was to check the quality of the 3D printing work. I do not claim to be an expert in 3D printing, but I own a printer, so I have some ideas about the process. My first observation was that the set was made of PLA material. The printing was made with medium resolution, same goes for the rigidity of the print. Sadly, I saw that many of the details are rough and curved areas are lacking polish. The bottom of the part (which serves as the base/bottom during printing) is warped around the edges, which is an aesthetic problem coming from a bad 3D printing process. Considering the price, this is more than annoying – and also, seeing how the customer prices drop significantly during warehouse-emptying sales, it can be said that the manufacturer and the merchant both enjoy a high margin.

During the build of the replica with this conversion kit I could also perform the installation relatively easily. I had a lot of trouble during repairs, the RA Tech bolt carrier was just simply not machined to the correct dimensions and the pin was of different size. The nozzle was getting stuck and the trigger would not work correctly. The hop up mechanism was breaking BB-s and causing feeding issues. So all in all, installing the SRU kit was the easiest part of this project.

Basically, the two parts of the receiver have to be separated and then fixed with a pin. Then, a rail cover has to be put onto the top picatinny rail to serve as a cheek weld. The
only challenging part was the trigger bar, but this still only required a few minutes.

The resulting bullpup gun became very compact. It was noticeably rear-heavy, fat, combined with an acceptable level of comfort. The bolt catch was relocated to a place that is not comfortable and is a pain to operate. Reloading also became much more problematic, together with manipulating the fire selector. Recoil became much stronger since the kit transfers the energy directly to the user’s shoulder. Honestly, this set is a curiosity with its appearance, it is unique and cool.

And then, the problems came during usage. First, the cheek weld cracked thanks to it being oversized. At the end, it snapped into two parts, basically becoming junk. Then, the original stock hinge part broke into two pieces, rendering the whole set junk.

In terms of pricing and durability, I can not recommend this kit! Durability is practically zero and the print quality is also reminding me of a failed, scrapped print (see the previous comments about the warped edges).

Text: Batmause
Translation: Yssomru
Photos: Batmause