Form-1 can over bore allowance?

I googled a little bit and didn't find the answer.

I'm planning a form-1 can and was wondering how much overbore is allowed?

What I'm saying is, typically, for a .30 caliber suppressor it is common to use a 3/8" drill bit.

So, when you put caliber on the form-1, you list 30 caliber, even though the hole is physically .375"

All manufacturers use over bore to avoid problems with concentricity and instability.

But the ones I have all list the intended caliber on the markings.

However much you want. No one is going to measure your work.

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Originally Posted by markm

However much you want. No one is going to measure your work.

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Thanks. I suspected as much. Appreciate the feedback.


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I think you give it a caliber designation, but the bore can be whatever you want. When we did Pappabear's F1 can, I just matched up a drill bit to a factory can.

Quote:

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Originally Posted by markm

I think you give it a caliber designation, but the bore can be whatever you want. When we did Pappabear's F1 can, I just matched up a drill bit to a factory can.

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Yeah, I think it sounds like the caliber you list is basically the minimum diameter.

Like, as long as it can do what you claim it can do, it should be fine.


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Yep. If I did another kit can I'd just designate it as 7.62 even if it was a 5.56 project.

I put .22 on form 1's for everything. It doesn't matter what size the bore is, or how it's threaded, .22 will go through it.

Quote:

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Originally Posted by markm

However much you want. No one is going to measure your work.

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This.

In 20 years of shooting NFA stuff, not once have I seen or even heard a rumor of an engraving/paperwork spot check/issue.

For 300 BLK I put 30 in the caliber section.