Thought I'd start a build thread and pass along any info that might be of value.
T91 safety/selector Mod. If you dont' have a mill to hold the selector, use the Dremel method. Use needle nose piers to hold it (it will get very hot while grinding).
Go slow, the pics are self explanatory. NOTE: I found the dimples for the plunger were not deep enough to give a positive "lock" in the selected position. I used a 1/8" ball end mill to make them a little deeper. I also found that when in the "fire" position, the selector was not 90 degree vertical...the dimple on mine was off by the littlest bit. I was able to correct it with a deeper dimple in the right location.
Handguard Mod. I decided to double the cooling capability of the upper handguard by adding 2 holes on top, and opening 2 more slots on each side. The top holes (if you measure from front to back) are about 1 and 5/8" on center, and I found a 5/16 bit got close to the original hole size. The inside channel of the upper handguard is a u shaped channel with parallel walls, so its easy to jig up and hold steady to ream out the side slots. If you open the rear slots, you will need to trim the heat shield...unless you like the look of the shiny shield (guess you could paint or coat the shield) I ended up trimming it down even farther then the pictures.
Tear down tips. (Tearing down for a spray of Moly Resin) I finally lost patience with the ejection post cover, and just took a punch and tapped the pin the rear. Bent the small tip of the spring, but got it out. ( I have a "normal" ejection port cover/setup in route and will use the C clip method.) Sure enough, there is nothing but a groove about half way down the ejection port cover hinge pin. The spring locks in this and holds it all in place.
Front gas block plunger/retainer assembly. You can see from the pic that the designers of this upper love their spring coils that rest in a groove. The spring is conical. If you dis-assmeble this piece, don't pull on the spring until you can pry the coil out of the groove. I used a small jewelers screwdriver. (If you stretch out the spring trying to get it off, have no clue how you'd get a replacement)
I am disappointed that the rear handuard retainer cannot be worked over the stripped down gas block. I am not brave enough to remove that, so will just have to deal with the retainer flopping around as I try and spray it.
Hope any of it helps anyone at all!
A Deplorable build
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Deplorable
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Deplorable
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Trying to get more pics up on this...
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Deplorable
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More
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Deplorable
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Thread Update:
Ejection port cover test fit: I picked up a kit from Midway. Hinge pins are same diameter. There is room for the C clip at the end. Happy with fitment.
Ejection port cover test fit: I picked up a kit from Midway. Hinge pins are same diameter. There is room for the C clip at the end. Happy with fitment.
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Deplorable
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More pics
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Deplorable
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Thread update:
Budget rail solution: I picked up a Magpul polymer rail section on the off chance the holes would line up with those on the top of the handguard...no dice. Decided to mount it to the lower handguard via 2 holes. I had to grind off the small protrusions on the back for the M-lok rail section, but I am glad I got the M-lok for the smaller "nuts". I was going to use the larger nut plates from another section of rail, but the upper handguard would not seat.
Spoiler: If you are asking, how can I be sure this mounting will be somewhat level with the plane of the barrel? When all done, I flipped the upper flat top down on a known level surface. I then placed a bubble level on the bottom of the rail. It was dead nuts on.
Budget rail solution: I picked up a Magpul polymer rail section on the off chance the holes would line up with those on the top of the handguard...no dice. Decided to mount it to the lower handguard via 2 holes. I had to grind off the small protrusions on the back for the M-lok rail section, but I am glad I got the M-lok for the smaller "nuts". I was going to use the larger nut plates from another section of rail, but the upper handguard would not seat.
Spoiler: If you are asking, how can I be sure this mounting will be somewhat level with the plane of the barrel? When all done, I flipped the upper flat top down on a known level surface. I then placed a bubble level on the bottom of the rail. It was dead nuts on.
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Deplorable
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More rail pics. The screws are 3/16, I started the holes with a smaller bit, then opened up.
You will also need to modify the heat shield. It is very thin, so you can use tin ships to nip a V to clear the rear screw.
Mark and drill out the front hole
You will also need to modify the heat shield. It is very thin, so you can use tin ships to nip a V to clear the rear screw.
Mark and drill out the front hole
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Deplorable
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Final batch of pics for rail project.
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codyphillips48
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I like the rail piece added to the stock hand guard. I like the way it looks and it keeps it simple.