I'm curious about those 20mm's that were available via mail-order in the 50's and 60's.

They were declared DD's in '68, right?

What happens when they are found nowadays? I could see something like a 20mm might rarely be taken out, and forgotten about for decades, and discovered after an elderly person passes away.

Is there any way to make them legal? Could one torch, or surrender the receiver, and make a "parts kit"?

It would be a shame if they must be destroyed.

Just curious, as I would have to move and win the lottery to own one of these works of art.




ETA: wait, weren't these DD's as per the '34 NFA? If so, how did folks get them via mail-order, and cash & carry at surplus stores?

Link to another board



IIRC these were Dewat's. Fill the barrel with lead and remove the firing pin and they weren't firearms. GCA 68 changed this.

They had to be amnesty registered in '68. This registered Dewat is a machine gun or in the case of the Lathi a DD.

ETA: Unregistered MG would be contraband. Unregistered DD would need a letter to the ATF, as I do not know. If contraband perhaps it's receiver could be surrendered and the parts kit kept. I just don't know.

Not mine

These appear to be fully functional:






ETA: sorry posted the pic 2x

The NFA made them DD. Perhaps the importer got a waiver? 12 gauge shotguns have the same sort of waiver. 577 nitro express isn't DD either. They got a waiver as well.

There was one at the surplus store when I was a kid. The barrel was plugged and had a hole drilled in it. I wanted that thing soooooooo bad.

Destructive devices were not addressed by the NFA of 1934.  They were completely legal to own, shoot, and order by mail until the GCA of 1968 when they came under the purview of the ATF with the newly defined "Destructive Device" class of weapons.  This also addressed the ammunition fired in these guns, which was also previously legal, including high explosive ammo.

These differ in definition from a machine gun, which can be the whole gun or just the bare receiver, either of which is an NFA firearm in the eyes of the BATF.  A destructive device is a combination of parts, generally a receiver or breech ring and a barrel larger than .50 caliber.  A bare receiver from such a weapon is no different than a normal shotgun or rifle receiver, and not subject to NFA registration.  So you take a 105mm howitzer breech ring and attach a .30-06 Springfield barrel with a big, fat sleeve......legal, and not NFA. Take a 105mm howitzer barrel and attach that same breech ring, or somehow attach that barrel to a 1903 Springfield receiver......NFA registration required via Form 1.

The concept of how a DD is defined is important when considering what to do with odd things found in the attic.  If there is no barrel present, there is no DD.  The receiver and all the rest of the parts can be owned without any more restrictions than a rifle (in most states).  You could certainly take a Lahti or Solothurn receiver, file the Form 1, find or make a barrel, and put your new, legal DD together.

I'm sure, in the 46 years since the GCA of 68, a few unregistered  DDs have been found that had their barrels removed, papers filed, and then reunited with the rest of the parts. Officially, that is prohibited by BATF as the barrel should not come from the original receiver it was mated to.  In their view,  if the gun exists as a complete assembly, it's already illegal and subject to confiscation.  Just remember that when the forms are filed, you are essentially certifying that you only have half of the total and are looking to find or make the other half.  If you already have both the barrel and receiver, you are in constructive possession.  And if the original barrel miraculously appears and gets reattached to your receiver, a later inspection by a saavy BATF agent might just produce some difficult to answer questions like...."I see the fit, finish, and serial numbers match on this 20mm cannon you manufactured on a Form 1...how is that possible?  Where did the barrel come from?"

So yes,  it can be done, and big, heavy chunks of cannons don't necessarily have to go the torch.  But there are pitfalls and difficulties to negotiate along the way.

By the way,  I don't remember the details but recall there was a batch of 20mm Lahtis that were sold in the1980s? that were rendered unserviceable and sold on 4473s like a rifle.  I always assumed the barrels must have been pretty well destroyed or BATF would have required them to be sold as Unserviceable Destructive Devices, still requiring NFA registration, but without payment of tax.  Struck me as odd at the time but never dug into the details as I wasn't a Lahti guy.   The Solothurn guns all came in Pre-68 and were all live when sold.  Like the Lahtis, a lot of them got registered during the 1968 Amnesty, but a lot of them didn't, either because the owners never heard about the requirement or were afraid of the Government and didn't trust them.

I had a neighbor who passed a few years ago.  He had a Lahti in the attic of his family home in Maryland.  I was offered it sight unseen for $500 if I would remove it from the attic to settle the estate.

When I drove to the house to pick it up, I found a complete Lahti cannon with all the parts, coffin, spare parts kits and spare magazines.  There was no ammo to be found other than about 20 fired cases.  When I checked the barrel, it was obstructed at the chamber and at the muzzle brake (inside the barrel proper).

With 3 people, we lugged the monster down 3 sets of stairs to the ground floor.  I was given a set of very old papers from Ye Olde Hunter dated in the early 1960's.  It was an Interarms (Interarmco) retail front down in Alexandria, VA that did the mail order business for certain Interarms surplus items.  Took it all in my truck and drove the 5 hours home to old Virginia.

When cleaning the Lahti I found that the barrel was not pinned or welded to the receiver.  With an overnight soaking and very light torqueing I got the barrel off.  I ended up getting a bit of the willies since I already own a Lhati from Interarms in the 1980s.  I called a friend who was a BATFE Enforcement agent about the cannon.  He came over that day to look at it.  From his inspection and checking with someone in DC (Maybe NFA Branch in WVa), he said  the Lahti was ok in its present state since the barrel was not serviceable and the number on the barrel and receiver were not matching, i.e. not a DD.  He looked over the paperwork and told me that I could turn it in if I wanted, but there was no violation.  He said that I could Form 1 the receiver and when approved could add a 20mm barrel for it to be a DD, or I could add a 50 BMG or 416 barrel and be good to go as a Class 1 rifle.  He left, but later dropped by for a beer and to drop off some copies of the Forms 1s and print cards and info about filing the forms with a Trust.

Now, knowing this and from previous experience and handling about 20 Lahti's and 2 Solothurns, 99% of police and BATF contacts with a similiarly configured Lahti or post 1898 cannon would end up with a seizure/forfeiture.  This experience I had seems to be an oddity, but some of the BATFE agents local to me have been more involved in more pressing matters than seizing welded up or blocked bore, obsolete pieces like the Lahti.  

Note, I am not a Lawyer, nor am I a BATFE agent.  Your experience may vary.  I ended up trying to grab one of two Lahti cannon barrels from someone who posts here on ARFcom ahile ago.  Those two barrels were discovered with receivers and other goodies, but I lost contact with that owner and they are probably assembled as compete legal pieces.

I have also noticed that very few of the Lahtis that are floating around have barrels with numbers that match their receivers.  Having the two match is actually a bonus point when selling them.  My foundling Lahti was registered after a year long wait, and I found the bore was actually obstructed by someone inverting an AP round in the chamber and filling the edges with soft solder (not a legal demil process), and the muzzle was inspected without the brake and it was found to have a piece of small rebar inserted in the bore and surrounded with solder also.  With a little heat both obstructions came out and a slight lapping cleared out the bore and the piece was ready for blasting.  No ammo was readily available so it was resold to a collector in New Hampshire who sits on a large cache of reloaded 20mike mike from the later Kent Lomont.

Best to heed the advice of Ordnance, but Lahti's are great guns if you have the range and ammo to shoot them.

I still have one, but I always smile when I run across them in the wild.