Opinions on my bolt action percussion gun idea
Posted by inserttext1@reddit | GunnitRust | View on Reddit | 9 comments
So I wanted a bolt action percussion gun and all the antique ones are prohibitively expensive so I thought I'd design my own. The general gist of it is the bolt goes into the breech plug, then the striker hits the percussion cap and goes boom. To reload you pull the bolt back, pull the breech block backwards then upwards, put the paper cartridge in, then breech block back down, recap, then push the bolt forward and fire again.
staffma@reddit
I would recommend you look at how the French Chassepot and Dryse needle rifles work if you haven't already. Looks like a fun project.
inserttext1@reddit (OP)
I used to own one back before they got to be pretty pricey. Shot it to heaven and back
staffma@reddit
Oh nice. those early ones are truly funky. Still kicking myself for missing the unmodified chassepots that I believe royal tiger had. I checked and they do have one but it's converted to 11mm gras.
BoredCop@reddit
I'm sorry, I don't quite understand your drawing.
What are you using for a gas seal? And does the paper cartridge go into a hollow pivoting block in the front of the bolt, or does it go into the rear of the chamber with that pivoting block thingy going behind it? If the latter, don't you think the flame from the primer has rather unnecessarily far to go from cap to chamber? What is the purpose of the pivoting action, accessing the front of the (hollow?) pivoting block?
inserttext1@reddit (OP)
Like other early breech loaders gas sealing will be done with a brass cone with matching inverse cone to slide into. It would go through the block but I will experiment with that. The pivoting block would swing upwards like on a trapdoor to allow loading into the chamber. The block is the breech not hollow
BoredCop@reddit
Sorry, still not understanding your drawing.
It says pivot way up front on the bolt assembly, in front of what you describe as a brass gas plug? And the bolt has locking lugs behind that? And the gas seal bit is behind the pivoting part? Do you unlock the bolt, pull it back, then pivot open a trap door? Why both have a locking bolt action and a trap door? Or is the bolt action solely used for the percussion cap, and then there's a completely separate trap door type breechblock?
A brass gas seal needs to be cup shaped and have chamber pressure expand (obturate) the cup walls such that they seal against steel walls around them. And a brass obturator is a poor choice for this unless you treat it as an expendable part that is replaced after a couple dozen shots or so, because brass work hardens and eventually cracks. In modern cartridge firing guns this problem is solved by making the brass obturator be an expendable single use part of the ammunition rather than a part of the gun.
inserttext1@reddit (OP)
I do remember a trapdoor rifle that works closer to what you described and will look into it
TacTurtle@reddit
Your brass plug is backwards, a conical shape like this will make it will function like a giant gas piston to increase bolt thrust as soon as there is any fouling or mismachining preventing a perfect seal.
You want your gas seal to be cup shaped so the pressure helps it seal.
inserttext1@reddit (OP)
Thanks wasn’t sure what direction it would have to go