Lobos Checklist in progress

Every onward and upward with the checklist

I pressed ahead today and made tremendous headway. First, I fit everything again and made sure that all the parts were squared up. I put in the Pintle bolt, the upper cover screw and the long lower rivit for the trunnion spacers just to line it all up.

The upper cover moves up and down without binding, that the rear plate and buffer can be slid up and out without binding, and that the latch slide moves freely and locks up as it should.

Then I mounted the whole works into my drill press and drilled the eight lower rivits using my cobalt drill and the lower plate as a guide, and the upper cover rivit holes using the upper plate as a guide.

I was fortunate in that this gun had the left side plate still attached.

I then disassembled the gun, and chamfered the holes. Here is where it may be worth the extra money to buy a carbide, or cobalt chamfer.

I used HHS 1/2 inch 82 degree countersink to chamfer. The size was perfect, but the high speed steel was not up to the task. I had to sharpen the bit after every two holes. and by the time I finished the two light chamfers for the top cover, the bit was completely shot.

Not to waste anything, I turned down the countersink, welded it to a small piece of steel tubing, then cut a bolt and welded the threads inside the steel tube. This made for a nice adjustable bucking tool that I used. Since the countersinks were nice and deep and below the level the steel, I wanted a bucking tool that I could use to seat the rivits deep. This works perfect. By turning the body of the device, you can seat the rivit below the level of the RSP. I did this with each rivit, and pressed them home in my 6 ton press. It went smooth as silk. A little slow since each rivit had to be adjusted with the tool, but the end result was worth it.

The two top rear rivits were a piece of cake. I had to ground one side flat to press up against the top of the plate, then I used my AK 47 bolt cutter/rivit tool to squeeze them home. If you are not familiar with this, it is simply a Harbor Freight pair of $9.00 24 inch bolt cutters with the jaws ground to squeeze rivits. Works great.

The front rivit I simply squeezed home with my press. Voila....the hard part is done. Some light filing on the inside to get some burrs and a few high spots......round out the outer rivits a little; and the job is done.

I again checked the fit of the cover, bolted in the lower bolt stop, and removed the pistol grip just to make sure it was all aligned. I rechecked everything with a square and it is all perfect far as I can tell.

Next installment coming soon.

I believe I understand the concern. I have included a closeup picture of the RRCG. The test for fit is actually how it contacts the trunnion. When the trunnion is in place, the RRCG should just barely touch touch it along the bottom. That is the test. That little gap along the RSP is not important. Where it meets the trunnion is important.

It seems to me that if your guide is too high, or too low, you should be able to ream the mounting hole slightly in either direction to correct it. If the hole needs to be made too oval for the rivit to fill in the space, then you may need to fill it with some weld and then refile to size. This is not a crucial load bearing part, and a repair in this manner will be totally unnoticeable after grinding and finishing, and will not affect function or strength at all.


I have included a picture of my finished side plate. It all appears to fit and function well. I do not really have any pictures of putting in the big rivits other than to say this was kind of a pain. I would suggest that you use a fairly large drill press to drill these holes. Or, like me be prepared to drill a series of ever increasingly large holes. My bench top drill press has served me well for a number of years, but was not quite up to the task of drilling it in one motion. I got it started with the correct drill, then used that as a center to drill ever increasingly larger holes until complete. This went well, but took a little time.

Also, the rivits from ORF were HUGE. The head was WAY to big. I discovered that on the first one. I countersunk the RSP and actually opened up the LSP holes a bit as well. I began the rivits with my press....but finished them with a 2 1/2 pound hammer. I still had a ton of metal to grind off. It was slow go and arduous. For the second rivit, I ground the head down before mounting it, left it slightly over size, then started in my 6 ton press. This one went way easier. The big rivits were not particularly hard, but it was the hardest part for me.

I also discovered that the remnant of the original right side plate will make a nice booster remover tool. I'm going to use a piece of pipe slightly larger than the booster and cut two slots and then weld a piece of that original sideplate in it. Voila, a booster tool. I like the idea that I'm using parts from the original gun to do it.

Next installments are the internals.