Fitz - Thanks for the info.
Maybe I should shed some light on what prompted my question. This may not be the correct forum for this - but I know there are those of you who have taken vintage single shots (those that are strong enough for smokeless) and have upgraded/converted etc...
I have a vintage 44 1/2 that has been turned into a 2 barrel rifle (original .32-40 and now .17 Ackley Hornet). CPA did the re-barrel (I will also add that Paul and Gail have been wonderful to work with as I trouble shoot this issue). A #2 half oct/rnd barrel with a .172 hole in it is a conversation piece at the range.
During my load development for the 17 AH, I have been experiencing "splashing" of the primer metal back into the fireing pin hole. This splashing is occuring at well below start load data that I have from Ackley and various modern sources. When the block is openned it scrapes this metal off and it typically falls into the action or at times will make it's way into the chamber
I've even installed a new breach block and firing pin from CPA (maybe original was too worn, etc...) - checking headspace again - splashing is still occuring. I've tried CCI and Remington BR primers - splashing occurs with both. 2 different powders - splashing with both. There are no other signs of excess pressure evident on the brass - it extracts easily, etc.. Brass was fireformed in this chamber and are only shot in this rifle.
Backing the load to nearly half the start load - no splashing. I've slowly worked my way back up to where signs that splashing may occur with the next .2gr increment of powder. This is where I'm currently at - no splashing of primer metal - but far cry from what this cart's potential is with good/safe/published load data. I understand that most load data will be for modern bolt rilfes - but I also know that this action is capable of handling pressures produced by this cartridge - as the parent cartridge is the 22 Hornet.
Is this something that I would expect to see with the free floating firing pin design that's part of these 44 1/2 actions? It appears that the splashing occurs under the firing pin - as the firing pin hole is a bit of an oval shape (not oversize) - since the firing pin is at an upward angle from the hammer to the chamber.
Any input appreciated.
oldsingleshots.