barrel question for matchlock musket project

[powder und ball]

Ive just cut out a stock on the band saw for a 16th century replica of a english pattern matchlock musket.  Of what ive been reading on this forum lots of people are using seamless steel high grade tube for cannon and mortar barrels im looking for a strong seamless tube for the barrel of 43'' long and 5/8'' inside dia or .62 caliber.  And want a wall thickness of 3/16.  Does anyone no of a good grade of steel that would safe handle a charge of 70 grains of 1f black powder with a .62 patched round ball.  Ive have a breech plug not yet machined but im planns on threading the barrel and plug and having it doen at a local cnc shop.

[Double D]

P&B,

I have been out of town for a few days and just got back and noticed your post.  

Take a look at our Cannon Resource list at the top of the forum.  Under materiels you will find two sources for small lots of metal.  Give them a call and see if they can help you.  

You may have to buy something and turn it down.

You might also post your request over on the Regular muzzleloader board here on Graybeards.  There is tremendous amount of knowledge over there.

[Cat Whisperer]

Does anyone no of a good grade of steel that would safe handle a charge of ....    

You really need to do some REAL engineering (like figuring hoop strength) for the given charge, plus a generous safety factor.

But, having said that, most smokeless rifle barrels are made of 4140 or 4130 steel.  It turns well, is available in DOM (drawn over mandrel) tubing which is stronger than just 'seamless'.  You do have to do some special things to weld it so it won't have a tendency to crack - heating it to several hundered degrees fahrenheight (700?).

Look to see what others (with GOOD safety records) are using - what type of steel, what type of breach plug and what types of pressures.  That will give you a good estimate of where you'll end up.