French Gevarm .22 rifle

[ironglow]

  Gevarm made a semi-auto .22 rimfire rifle that was relatively unique, in that it fired from an open bolt.  This method of firing was often referred to as,
   "slam fire", in that the bolt  being open..when the trigger was pulled, it simply allowed the bolt to slam forward, firing the round.

    https://www.invaluable.com/auction-lot/gevarm-model-a-3-22-lr-caliber-semi-auto-rifle-106740-c-cfe4f739d5

  It seems such a rifle could easily be converted to full auto, simply by allowing the trigger to be held back.

 My M3 "grease gun" oissued to me as a tanker, is the only slam fire gun I have ever fired.  That was full auto, being that it would run so long as the trigger was held back. 30 @ 45 ACP rounds could be dumped in seconds..

  Voere of Austria also once produced a slam fire .22 rifle.

[Bob Riebe]

Yes.
I had a chance to buy one for 100 bucks 15 years ago but at the time did not have 100 bucks or a credit card; by the time I got back it was gone.

                                                             https://www.forgottenweapons.com/gevarm-a6-an-open-bolt-semiauto-22-sporting-rifle/


                                                           

                                                              
                                                            Gevarm 20 Round Magazine
                                                                +++++++++++++++++++++++++



This is/was a open bolt carbine but it was so easily converted into a submachine gun the ATF reclassified it as a submachine gun.

                                                                 

You would have to look up the history of the Eagle/Spitfire to get the total story.
A Grease Gun Bolt can be inserted into a Spitfire to reduce rate of fire substantially, Spitfire with factory bolt runs a 800 rpm.
The Volunteer was modified so it could no longer run as full auto so is not a NFA firearm.

                                    https://www.forgottenweapons.com/spitfire-the-semiauto-that-became-a-machine-gun/

The Spitfire is a firearm with an interesting importance in legal history. Originally designed and marketed as an open-bolt semiautomatic-only carbine, it was determined to be a machine gun under the law in 1968, and all examples were required to be registered or destroyed. The reason was not its open bolt design, but rather because the safety lever could be used to hold the sear down and allow fully automatic fire without any alteration to the gun. This example was duly registered, and it now a transferrable machine gun.

Aside from this brouhaha, the Spitfire was simple a very poor man’s Thompson lookalike – although functionally it is much more like the M3 Grease Gun than the Thompson. It uses M3 magazines, and is cocked by simply pulling the bolt back with a finger, like the M3A1. The construction is extremely crude. Following its machine gun ruling, a series of very similar guns were produced by the same designer which used a closed bolt operating system to avoid the legal issues – the Volunteer carbine in particular