Arts and Crafts Guns

Resuming the build

Thanks to the magazine catch on my lower being out of spec, all work on the skirmish rifle had to come to a halt. The slot for the magazine catch is supposed to be 0.250″ but looking at the measurement, you can see that this is not the case:

Since it is several thousandths too small, the catch doesn’t fit. I sent this photo to 5d, the maker of my 80 percent lower, and they shipped me a new one. As soon as I get a day off, the build will resume.

9 replies on “Resuming the build”

I wonder if someone put in the wrong end mill. I take it you’re planning on measuring the replacement?

What are you reading as the dimension?
I may be wrong but it looks like 0.255″ to me. (6.48mm on the other scale)

That is reading 0.245. the zero line lines up close to the 0.240 and then you look to the right to see where two hash marks line up exactly. I’m seeing that happen at 0.005.

And of course I go back and see that I might be wrong. Regardless, dm can read it in person and know for sure.

I would concur with your read.

But it’s been a very long while since I used a vernier scale, and as you note, neither of us are there in person looking over his shoulder. 🙂

Inside measurements are hard for me, because that scale is tough. I put a micrometer with 0.001″ resolution on the mag catch and got 0.2435. The catch was too large to fit in the hole.

The machinist method would be to put a pair of adjustable parallels in the slot and adjust them to a snug fit. Then use a micrometer to read across the parallels.

Each of the smallest marks on the top scale contains 25 counts, not 20. See that the vernier scale goes up to 25? Zooming in the picture, I read it as 0.254″. Maybe the mating part is too large?

No. A dial micrometer shows the mag catch at 0.2435″ I also tried a second mag catch and that one didn’t fit either.

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