Hello,I have been interested in a rolling block to build a hunting rifle in.I would like something in 45-70,but from the info I gather from this and other sites is the rolling block should be loaded to black powder pressures only say 300gr bullet @ 1400?better safe than sorry right, But then I see numerous rolling blocks with numrich barrel conversions in calibers such as .444 marlin(see martini/hagn site)An example of a .444 marlin load could be a 275gr@2250,so why wouldnt it be safe to fire a 400gr 45-70 @ say 1800 with a rolling block rebarreled with modern barrel(RB in good condition obviously) both loads(according to my cartriges of the world book)generate approx. the same energy.I'm pretty sure numrich didnt sell the .444 barrel kit with the intentions of the owner loading to B.P. pressures nor do I think they would sell a dangerous item,then again they no longer sell these conversions...maby I just answered my own question!!I should mention martini/hagn said the rolling block was built like a vault and could handle the .444 marlin safley. With there experience, I tend to belive what they say.Basicaly,I would like to buy a remington made rolling block and re-barrel it with a modern barrel chambered in 45-70,and would like to load a 300gr@ about 1800fps.Is this safe to do or not???PS please excuse any mistakes in load info,I have NO experience in reloading and why I am asking here!
rolling block pressures?
- Thread starter chris wilson
- Start date
Some, like the 1902 Remington can take pressures like you are asking about as it was chambered in 7mm Mauser and up to 44,000 Cup. It was made when smokeless and higher pressures where std. The older Rolling Blocks, that were made before the advent of smokeless are the ones that should be limited to "Trapdoor pressures", and the easiest way to do that is with real Black Powder.
If you like the old single shots or copies and you want to load them warmer, I would suggest the 1885 or "Highwall" or the modern Ruger #1 for those loads above Rolling Block levels.
If you like the old single shots or copies and you want to load them warmer, I would suggest the 1885 or "Highwall" or the modern Ruger #1 for those loads above Rolling Block levels.
300 grain Remington and Winchester factory loads are pushing 1880 fps and are safe in all guns, including trapdoors. Hornady reloading manual, 7th ed. lists max loads for 300 gr. hollowpoint, safe for all guns at arround 1900 fps with 4 different powders, and 1800 fps with 4 more.
the real issue is not how heavy a bullet nor pressure (other than relative to firing pin diameter) ---- it is thrust on the breach face. For any gun, you can multiply the original operating pressure times the square of the base diameter of the cartridge and come up with a number to compare proposed conversions with. Again ignoring the need to bush large firing pins, a high pressure small diameter base cartridge may have the same or less thrust on the breach than a much larger diameter base cartridge with a lower operating pressure.
As an example people sporadically propose making a double rifle out of a hammer shotgun. A 12 guage in black powder probably operates around 6 or 7000 psi with a base diameter of roughly .8". That gives a factor of 4480. A 30-06 has a base diameter of .466 and a pressure of 50000 gives a factor of 10857 or over double what the gun was designed to take. A 22 hornet with a base diameter of .294 and loaded to 50,000 psi would give a factor of 4321 or about the same thrust as the original shotgun loads.
Some guns have strong designs and will withstand well in excess of the cartridges that they were originally designed for but in the absence of a lot of engineering and metalurgical knowledge, comparing a factor related to the thrust of the original loading with that of the proposed loading gives you a basis to start with.
cheers mooncoon
cheers mooncoon
As an example people sporadically propose making a double rifle out of a hammer shotgun. A 12 guage in black powder probably operates around 6 or 7000 psi with a base diameter of roughly .8". That gives a factor of 4480. A 30-06 has a base diameter of .466 and a pressure of 50000 gives a factor of 10857 or over double what the gun was designed to take. A 22 hornet with a base diameter of .294 and loaded to 50,000 psi would give a factor of 4321 or about the same thrust as the original shotgun loads.
Some guns have strong designs and will withstand well in excess of the cartridges that they were originally designed for but in the absence of a lot of engineering and metalurgical knowledge, comparing a factor related to the thrust of the original loading with that of the proposed loading gives you a basis to start with.
cheers mooncoon
cheers mooncoon
Thats what I needed to know.A formula to compare original loads to modern,in a more accurate way than with cartrige pressures.I'm just getting into reloading,so this will give me a way to figure out what I could do with a rolling block.It has been advised to me before to go with a high wall.If I could find one I could afford I would but for $250 you cant beat a rolling block!I live and work in grizzley country and was thinking of building a rolling block to take a bear next fall.Hey if the old 45-70 can drop a buffalo past 400 yards,it can drop a grizz.its all in where you put the bullet.Could anyone reccomend a sutable load??I was surprized to see the loads sutable for the trap door.I kinda thought it was to weak to shoot any more than target loads.I have NO experience shooting blackpowder rifles so trying to figure out how powerfull they are is rather difficult exept for comparisons with loads I do shoot.as I can see I should be able to get all the power I need out of the 45-70.
Thank you for your response fellas!
Thank you for your response fellas!
vagrantviking
CGN Ultra frequent flyer
- Location
- Southern Alberta
I believe that you can get 1200-1400 fps out of the 45-70 using 500gr bullets and black powder. That adds up to some pretty serious knockdown.
For faster lighter bullets a lever gun or break open action might be a better way to go as far as keeping costs down. Its about whats going to put a grin on you though.
For faster lighter bullets a lever gun or break open action might be a better way to go as far as keeping costs down. Its about whats going to put a grin on you though.
