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Lancaster;

Thank you for your comment that "every suhl made double gun action made between 1949 and 1990 is the Real thing for building a double rife. every!" This comment really intrigues me as I want to find another shotgun action candidate for building DR's.

I have built some double rifles using shotgun actions previously, but I have not built a double rifle on a Simson action (which seem to be excellent actions)even though I wanted to do so, as I could not find one that had what the English gunmakers call striker discs (what Americans call firing pin bushings). Instead I decided that the CZ zp49 action of 1950's and early 1960's best suited my needs(as the service pressure of the cartridges that I was building the DR for would be around 40,000psi and the test firing that I would do to test the barrel strength was at 54,000psi--two shots per barrel) as they had striker discs and I could make (and drill the reduced size firing pin hole needed and hardened/temper the disc) new striker discs from O-1 alloy steel and new strikers (firing pins) of the diameter of about .060" in order to reduce the risk of cartridge primer rupture as well as the inherent safety of the striker disc/striker stopping or reducing gas discharge back into the action from a ruptured cartridge primer.

However, your comment above causes me to consider that there are a large number of Simson double shotgun actions of those years that must have striker discs and that I have missed finding any. Will you be so kind as to elaborate further on how to identify these 1949 to 1990 Simson actions that can be used for double rile building. The Simson action would be significantly easier to build a DR from the standpoint of restocking and increased strength in the head of the butt stock (no sidelocks plates as well) over the CZ zp49 sidelock. My friend the late Bob H. of Iowa (Birdshooter) only built one zp49 actioned DR and the butt stock restocking issue was a real pain to him and he said that he would never build another one. I must say though, that the butt stock strength has not been an issue or problem for me, even on much higher pressures that what Bob would build a DR. The zp49 top lever coil spring container "box" was the strength killer for the head of the butt stock in Bob's mind. Bob actually sent the zp49 butt stock replacement to another for him to built it for Bob.

The need for striker discs on a DR and for those discs to be made properly and the associated firing pins (strikers) fitted properly to the inside and rear of these discs came home to me in a very dangerous event where my eyesight and my face was kept out of danger--maybe my life. During the regulation of a DR using a zp49 action of 1963 I was using some propellant that is known to be heat sensitive and many DR shooters shy away from using it, 3031. The time of the year was in August and in South Carolina and the ambient temp for that day was about 95 degrees F and I was under the shade of the roofed cover of the range's shooting benches. I had built this DR with very heavy barrel breech ends of 1.000" diameter extending from the breech forward towards the muzzles for about 3 inches where the taper began, and the barrels were made of 4140 alloy steel that I had tested to about 54,000 psi chamber pressure. I had fired about 8-10 rounds of the cartridges and was about to fire the last two cartridges for the day and had inserted the two new live cartridges into the DR barrels, when the range called for the shooters to stop shooting for about 5 minutes. I neglected to remove the two cartridges form the barrel chambers, but the DR was open and pointed down. When in 5 minutes shooting resumed and I fired off the rounds. I thought recoil was a bit brisk, but other than that I had no other indications that there was any problem with the the shots. When I opened the DR what I saw was terrible, as the cartridge base and remains of the primer came out in pieces. Further the face of the striker discs had deep gas erosion circles and pits even though they were made of hardened O-1, also the firing pin faces were similarly damaged. Subsequent examination of the action and barrels showed no issues and measurement of the fitting of the barrels to the breech face showed no issues and no cracks were found at the root of the action's standing breech. New striker discs and firing pins were made for the DR though. I used my cell phone to call my friend Shep Kelly up in Illinois as he is a forensic ballistic consultant. The resulting expectation was that the overheated cartridge had produced in about 65,000 psi of chamber pressure.

When I got home and disassembled the entire action there was not even the slightest evidence of any propellant gas that had escaped by the back of the firing pins into the action and onto the butt stock. Since then I have fired another 300 rounds of cartridges with the above service pressure.

My friend, the late Bob H. (who built the below photographed .405 Win DR) over the years discussed several times with me the absence of striker disc in his .405 Win Simson actioned DR. Like me he was concerned about primer rupture, but he decided that with the size of the head and the overall strength of the brass at the base end of the .405 and .45-70 cases that if he kept the cartridge pressure relative low the risk was reduced for a ruptured primer. Therefore he would not build a double rifle on shotgun actions using the large diameter shotgun firing pins for cartridges such as .375 H&H Flanged Mag NE pressure and up. Of course, the .375 H&H Flanged Mag NE is lower in chamber pressure as compared to its sister the .375 H&H belted mag NE.

On another note, Bob H. was strongly of the opinion that the retrofitting of striker discs into shotgun actions a poor and dangerous idea as it weakened the the action standing breech. From and engineering perspective it would be difficult if not impossible to disagree with Bob on this.

Bob' favorite double shotgun action for a "donor action" (as he like to call them) for a DR was the older Beretta' boxlock SxS's, but in the last years of his life he found extremely difficult to find any of these guns. His favorite DR cartridge was the .45-70. However, between the two cartridges, I would choose the .405 Win. "big medicine" cartridge.

Kindest Regards;
Steve

Edited by transvaal (30/04/19 01:28 AM)