The MCX handguard is now rough fit and attached to the front of the gun. It's time to connect the the front sight post and the red dot mount to the top of the handguard. The connection to red dot mount is particularly critical because it is going to be the rear anchor for the handguard.
Let's start with the front sight...
I'm using an LPA shotgun front sight as the foundation of the front sight and am modifying it to 1. attach to the handguard, 2. receive the fiber optic cable and jade bead, and 3. align with the small backup iron sights on the Sig Romeo Zero red dot.
The first step to mounting the front sight on the rail was removing some of the picatinny raised sections to make a flat mounting point.
Note: I could have avoided having to do all this cutting by selecting an AR-style picatinny mounted front sight. The problem with these sights is that they stick up so high that they wouldn't work with the low profile mounted Sig red dot. Using a shotgun front sight and mounting it below the rail ridges gets the front sight bead in co-witness range of the red dot.
This mounting style also requires that I flatten out the bottom of the LPA front sight. It's built to be attached to the barrel of a shotgun and so has a rounded base. A bit of sanding with my Dewalt Random orbital sander took care of that.
The front sight post also needed to be shorten about 1/8 of an inch to fit in the flattened part of the rail. More sanding.
The most delicate modification to the front sight was making space for the bolts that attach the handguard to the gun. The space between the heads of these bolts is less than 1/4" so I didn't have much room for error when cutting into the front sight post from each side.
I needed to not cut so deep into the sight that I ruin it's ability to adjust vertically. One of the reasons I selected the LPA sight is becuase it can adjust up and down. Ruining this function would be a big fail.
Rough fitting done, bolts in place, time to mount it on the gun...
Shifting gears to the back of the rail....
The handguard mounts directly to the gun on the front. In the back, I'm going to connect it to the red dot mount which has a bolt securing it to the gun. The connection will be through both natural compression of overlapping parts and a bolt. I walk through the steps below.
The first step is to remove material from the underside of the front of the red dot mount so that the rear end of the rail can slide underneath it. You can see the first cut in the image below. The material I removed only serves to fill a visual gap between the bottom of the mount and the gun so removing it won't reduce the mount's stability.
Then I did the inverse on the rail - removed a picatinny ridge so that it can slide under the mount. I also opened up a slot to fit a modified T nut. You can see in the image below that a piece of the rail chipped out while I was making space for the T nut. This will be OK, but doesn't look good.
I drilled and countersunk a hole in the top of the red dot mount to accept the T nut and its bolt. The font of the mount is only about a 1/4" thick now, so I had to be careful to not countersink too deeply.
The image below shows the components ready to be attached: the drilled red dot mount, the cut rail, and the modified T nut.
A couple close up shots of it all assembled. You can see in the first image that the T nut underneath the rail doesn't touch the gun and that the bolt doesn't extend above the top of the red dot mount.
The top view. Notice that I sanded the bolt in the red dot mount down a bit to make sure it doesn't impact how the Romeo One mounts. Again, trying to get as shallow of a countersink as possible.
Pleased with the fit, I used some JB weld to hold the T nut in place and get a little bonus bonding power between the rail and the red dot mount. I can mount and remove the rail and red dot mount from the gun in one piece, so having them permanently attached is no problem.
All that done, here's where the Space Force 6 stands now. I'm almost done working on the rail and optics. Once I make a few finishing touches, I'll turn my attention to the fiber optics and the grips.
Another shoutout to my main man Mr. Dremel. It's truly amazing how much this little tool can do. 75% of this project so far has been Dremel work.