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First frame build, easy right?

Contribution from USMC-ATC

I got home from work today to find this on my kitchen table!

This is my first build so with MGB’s vids I should be done in no time right? I’ll post what I get done as it happens. Hopefully I can get the frame fabrication done before vacation next week.

Wish me luck!

Got some time to start on the 940c. I drilled the holes out first, came out okay. One of the pins is a little off because of the uprights inside the frame. Not by much, just enough to be annoying.

Pardon our in progress. 🤣

I still need to clean up the holes a bit. The pins seem to run through fine. Pictures REALLY bring out the work that needs doing

Next up was the tabs. Got those chopped off. Used end nips then my woodworking chisels to get the rest down. I am a little perturbed that on either side of where the tabs were, is an ever so slight dip. Possibly from the molding. I had to sand down ALOT more to try to get rid of those. Turned out okay I suppose.

Started with 220, moved to 320 wet, 600 wet, 1000 diamond card(wet), 1500 diamond card(wet), 2000 paper wet. Top of the rails are smoother than the rest, just need to find some back to black I suppose. It’s chalky when dry.

All done by hand, took about 3 hours. Let me know if you see something amiss! The 3m compound was not used.

I used my Shopsmith drill press and clamps to hold the jig down. Brad point bits turning @ 10k rpm worked well.

I spent most of the morning trying to fit the front block. From P80, the rear legs were 1/2mm too wide. Got those to where they insert nicely, then the front was riding high. Tried to get the front legs to sit down, and they just wouldn’t. I fear I am going to have to get a replacement for it.

I hope I can get this fixed. It just doesn’t want to drop. Holes in front won’t even come close to lining up.


Tip: watch the video


Started on the channel today.....yeah...

Not so steady with the Dremel. You will see a couple of places where I wasn’t cautious enough and my ball bit jumped the edge. I can’t for the life of me figure out how to get it looking nicer. Green polished just kinda smoothed it out, but still doesn’t look great. I’m hoping that I can find something to clean up the edges. I was thinking an exacto but don’t think that will work. This definitely is “chalkier” than I want it to be.

Got home to a package from Polymer80. They replaced my front block! Ended up getting the silver front block this time and it works with minimal work!

Front and rear in with pins.

Slight concern with the trigger housing. I know it is supposed to sit flush, however, the housing itself isn’t flush.

Here are a few of the pieces before and after the first round of polishing. They were incredibly filthy, as you can see. Side note for those that are new: I found that after cleaning, if I went through with a high grit sandpaper and gave it a good once over, it polished up much better. I used 2000 wet/dry automotive.

I feel I should clarify “giving it a good once over”. I didn’t remove any material unless there was a bump or burr. I just put all the scratches in one direction and made certain that the surface was nice and uniform.

For the slide, I bought a Gen 3 OEM from Spinta Precision. It was only $109 shipped so that was nice. Stainless finish but I can always Cerakote it later if I want to. The barrel was a VooDoo threaded that I purchased from Adams Arms. It looks slick, this was the one on the deals page that was on sale awhile back.

The peepers are from Strike Industries. I want to say that it was posted on the deals page, but I can’t remember. They are ”modular” which just means that the front blade can be replaced/swapped. However, the entire front post has to be removed.

Overall, I am pleased with these purchases. There are a couple of issues with these parts.

  • 1. The slide milling on the inside for the front post prohibits using the front sight tool. Because of where this is cut, the tool will not fit. I was forced to use a pair of needle nose to get it tight.

  • 2. The hood. In the attached picture you can see where I had to file a radius on the hood to allow the barrel to drop and cycle a round. Before this modification, it would chamber fine, but the slide would lock up. The barrel and the slide mated up beautifully, however, there was more than 1/8in drop to get the barrel past the edge of the hood. They were so tightly mated, I couldn’t slide a piece of paper in there. I ended up going through every video of MGB’s to try to fix it. I believe I found a forum post maybe on the p80 Reddit thread, that said to check the tolerance between the barrel and the hood. In the pic, on the right side is the radius I filed, on the left is the wear from the cycling of the firearm.(about 200 rds)

  • 3. The only complaint I had of the barrel was the fact that it didn’t come with a crush washer/O-ring for the thread protector. No major deal. I ended up wrapping the threads in Teflon tape to secure the protector.

After I had assembled everything, I had a trigger problem that kept creeping in. I came and asked on the forum and got some great responses and advice. Read it Here -> Trigger Problem <-

The rest of the assembly went as planned. No more major surprises. No more problems.

She’s still dirty from the range. I took her out and ran about 200 rounds through her. I had one Light strike in the first mag. Also had one brass to the face, encountered by a buddy who shot it and loved it. BTF may have been a bounce off the stall, he wasn’t really paying attention to the brass. Overall it’s a smashing success. Shoots smooth, cycles well, I may need to change the connector or do something with the trigger. It just feels kinda mushy to me. Maybe just hafta get used to it. Sorry for the delay in posting. I know it’s not super detailed, I didn’t want to repost basically what everybody else did.

I hope you enjoyed it. If you have questions or I was vague, please feel free to ask !!

Thanks for reading!!

Semper Fi

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