Taiwan T91S project / clone build
This was a project I have been wanting to do for some time. When Wolf started importing these, I grabbed one. SMGLee is probably the only person that's done a proper T91 rifle clone state-side and he has it documented here:
https://www.m4carbine.net/showthread...-saga-with-pix
I don't think I've seen anyone attempt to clone a T91S thoroughly yet.
This is the only external piston operated AR that I will own as I prefer the simplicity of a well made DI gun (reference my BCM and Colts). This gun is interesting as it predates the HK416 by a few years and comes from a longer lineage of piston operated AR variants in the Taiwanese military that dates back to the 70s. The T91 was adopted fairly recently for service in 2002.
My build differed from SMGLee's as I went with the T91S variant, reportedly a newer model for LE and Coast Guard. In practical terms, the S variant is like the Project Improvement Program (PIP) for the 91 as it went with a heavier profile barrel, removable front sight (newer 2 piece gas block design), more compact BUIS (as opposed to full carry handle), keymod hand guard, and a sound suppressor capable muzzle/adapter. I did this project because it's a bit different than most other typical AR builds (even though it's still an AR). The piston design is pretty smart and is self-contained in a protective sleeve that can be further taken apart.
Project started with a stock Wolf A1 upper with a donor Colt lower in order to function test it:
https://farm3.staticflickr.com/2923/...e3d0a371_b.jpg
The T91 series uses older A1 receiver forgings. Due to time and budget constraints, I did not use an 80% lower with proper engravings as SMGLee did. I used a blemished Brownell's A1 lower when they were still available.
https://farm5.staticflickr.com/4585/...3d416454_b.jpg
I sourced the mil-spec furniture slowly since they're a bit harder to find. This was the gun last year with the original plastic hand guard and correct pistol grip. It's a more ergonomic A2 with a trap door. I thought I would hate it, but actually like the ergonomics of it after handling/shooting with it. This was before I was able to source the correct muzzle and butt stock. I then sourced the milspec BUIS. It uses a proprietary height like the HK416s as the upper receiver is slightly taller than standard AR uppers. The upper shipped with an original shorter front sight post to use with their milspec BUIS. If using commercial US spec BUIS, then you install the taller front sight post. It's worth noting that HK 416 rear sights are compatible with the front sight from other reports. I reversed the orientation of the upper portion of the front sight assembly like how the issued T91S variants are. Not sure why Wolf installed them backwards. Removal/re-installation is done by removing roll pin and sliding out the upper part.
https://farm5.staticflickr.com/4555/...a453561b_b.jpg
I later replaced the plastic hand guard with a drop in Keymod rail as that is what is issued out with the T91S variants. I like the plastic hand guards as they're slightly triangular, but I can see them melting with sustained fire as front of the plastic hand guard touches the gas block. The keymod hand guard does not melt and provides better ventilation for the barrel and piston.
T91S at an expo show (note the newer flash hider, gas block, thicker profiled barre, and hand guard):
https://farm1.staticflickr.com/805/4...3b545b07_z.jpg
Later Wolf A1 uppers came with an A2 styled bird cage vs the correct compensator/flash hider combo. The comp holes are drilled offset, similar to what Surefire would later do with their Warcomp muzzles. Reference SMGLee's build for what the typical T91 muzzle/comp looks like. I opted to go for the XT97's sound suppressor capable muzzle that they began issuing with T91S carbines as seen above.
View from the side, note the "1" is what is orientated at 12 o'clock. The a2 vent slots and compensator holes are drilled from the 12-3 o'clock position.
https://farm1.staticflickr.com/815/3...54882265_b.jpg
The proprietary butt stock and buffer tube. The buffer tube is not compatible with US mil or commercial spec. It is only 3 position, but the bottom strut where the stock latches onto is wider and beefier. Stock locks on tightly onto the buffer tube. Stock has a pebble texture like the hand guard, reminiscent of Colt Canada's M4 stocks (texture). The polymer is much denser and slightly heavier than the Colt N1 CAR stocks. What is interesting is that the stock latch is metal and not plastic. It also uses style knurled nut vs castle nuts.
https://farm1.staticflickr.com/893/4...6fbe2aed_b.jpg
This is what the build is as of right now (sans optic, light, and sling). Parts that are not exactly correct and took liberty with includes the lower, the 16in barrel (vs correct 14.5), the selector (that has a tiny arrow engraved in it), and a donor nickel boron trigger I had laying around.
https://farm1.staticflickr.com/889/4...a601dc36_b.jpg
https://farm1.staticflickr.com/803/4...e1913f5b_b.jpg
The upper pretty over-gassed, but this is a common theme with many piston AR uppers (HK requires use of their heavier buffer). With a H2 buffer, this is a smooth shooting gun though.
I sourced the parts through T91 Tactical as they seem to be the only people importing the parts from Taiwan. These are mil-spec parts and not airsoft copies. As a disclosure, I am not paid or sponsored by them.
Let me know if there are questions and I'll try to get them answered.
