What did Kent W. Kimberling do wrong to get 2 years in federal prision?

[Gos]

Greetings,
I've always been interested in putting together a cannon, but then I read where this person, Kent W. Kimberling was arrested for doing just that by BATF.
What did he do wrong, or what are the rest of you doing right?
Also, Try as I might, I can't locate a permit or application for what he built.
Is that something on another government webpage that I'm just not finding?
Thanks in advance,
Gos

[Double D]

I found two news stories on this man.  Both appear to be from the same source.

No details were listed on how the gun was constructed.  The reference to bore size by its self would not be sufficient to indicate a destructive device. But the antique exemption is pretty specific.    Some vital pieces of information about construction of the gun are missing.

To much information missing from the news stories to come to any conclusions.   

We have always suggested if you have any questions about whether the cannon you wish to build complies with the law send your design and plans to ATF Technology Branch and ask for a determination letter before you start building.  I have a couple of these letters.

[Gos]

Any chance you could share an example? The "directions" on the process look to be very vague considering the ATF has a reputation for pouncing on any missing information.

[Double D]

I think you are asking to see my letters. 

It use to be pretty simple to pull these up.  I had them in my Fototime account, but Fototime was wiped out in the Cloud fire last spring.  So that means the are out in the boxes of files.  Do need to find them.  Give me a couple of days and I will get them.

One letter was to determine if a muzzle loading bowling ball mortar  built to look like a stokes mortar was considered under the antique exemption of NFA.  https://www.gboreloaded.com/forums/index.php?topic=244359.msg1099442125#msg1099442125

I also cited that letter in the build of my bowling ball mortar.
 https://www.gboreloaded.com/forums/index.php?topic=246774.0 .  That build is nearly done.  I only have wood to paint.   

A second letter was sent tp ATF and took 10 months to get a response.    This letter was reference building a scale mode of Long Cecil with a 20mm barrel. The gun was built in 1899 so not an antique.  It also was a breech loader, but using fuse ignition.  https://www.gboreloaded.com/forums/index.php?topic=243416.90

When I dig these letters out, I will post new photo' in the appropriate threads.

[Double D]

I just found the bowling ball mortar letter on an old  back up hard drive. I am head out to church right now and will update the old posts and look for the second letter when I get back.

[Double D]

https://www.docketbird.com/court-documents/USA-v-Kimberling/INDICTMENT-as-to-Kent-Kimberling-Count-1-AN-Courtroom-Deputy/waed-2:2020-cr-00006-89319-00001



Here is the indictment by the  grand jury.



Not only did he have a cannon he had an explosives device for that cannon.



The Grand Jury charges:

On or about August 6, 2019, in the Eastern District of Washington, the Defendant, KENT KIMBERLING, did knowingly possess a firearm, to wit:
- a red, white, and blue, cannon destructive device having a bore diameter in excess of one-half inch; and
- an improvised explosive projectile further described as a small metal compressed carbon dioxide gas cartridge and soda can; not registered to the Defendant in the National Firearms Registration and Transfer Record, in violation of26 U.S.C. §§ 5841, 5861(), 5871.