BP vs Smokeless: What differences are required in the ML?

[ropadop]

What are the required differences between a standard BP ML and a smokeless ML?  Would it be possible to develop a load for 1200 fps 50cal sabot with a 240g 44cal XTP bullet using smokeless powder in a standard Huntsman or a Huntsman with a aftermarket breech plug?  It seems that the barrel could easily withstand the pressure.  Would the unsealed breach prevent ignition or proper burn of the smokeless powder?

[Brewster]

You can get 1700 fps with the same round, using 80 grains of Blackhorn.  Don't tempt fate using smokeless in a Huntsman.

[Busta]

If you want to shoot smokeless powder, you need to get a smokeless muzzleloader. Just not worth the risk in a muzzleloader that is not designed for it. I can get over 2100 FPS with that bullet and 120 gr Blackhorn 209, or over 1900 FPS with 100 gr BH209.
 
 

[Doug B.]

If you want to shoot smokeless powder, you need to get a smokeless muzzleloader. Just not worth the risk in a muzzleloader that is not designed for it. I can get over 2100 FPS with that bullet and 120 gr Blackhorn 209, or over 1900 FPS with 100 gr BH209.

Busta is absolutely right. Don't risk it. My Huntsman is extremely accurate and knocks 'em over just fine with 80-85 grains of Blackhorn 209 under a 240 grain Hornady XTP, and the load doesn't beat me up! Enjoy the Huntsman for what is is.....an extremely fine muzzleloader.

[ropadop]

Let me ask the question this way: Suppose I sent a 45-70 barrel to be converted to a ML.  What key differences enable this barrel to be used with smokeless powder as compared to the standard huntsman? 


What is the difference in the pressure curve between a BP load and a smokeless load that delivers the exact same performance?

[Slufoot]

Hello ropadop,
 
The 45-70 barrel is made with either 4140 Chrome Moly or 416R Rifle Barrel Steel and has been proof tested. There are standards set by SAAMI for centerfire cartridges and barrels.
 
There are no set standards that I'm aware of for muzzleloader barrels.
 
Be safe!
 
GOOD SHOOTING!
Slufoot

[PHATINJUN]

I am sure there are many more here that know way more than I do but when you get into proof testing I do not think many American made ML's are proof tested but the Euorpean makers did considerable proof testing. As far as the Huntsman's go anytime a barrel is marked "Black Powder or Black Powder substitute only" there's your sign . Kurt

[OldSchoolRanger]

Let me ask the question this way: Suppose I sent a 45-70 barrel to be converted to a ML.  What key differences enable this barrel to be used with smokeless powder as compared to the standard huntsman? 


What is the difference in the pressure curve between a BP load and a smokeless load that delivers the exact same performance?

I don't know for sure, but what I think what ropadop is trying to understand, is what changes are needed to the 45-70 barrel to convert it to shoot smokeless powder, in a muzzle loading fashion.

I also am curious, Slufoot was kind enough to give me some insights into the conversion, but I'm not 100% sure that I understand it.  I guess I need to actually see a converted barrel or pictures to completely understand how it was done.

I do have a question tho, if a 45-70 barrel was "converted" to use smokeless powder, does this barrel need to be used on a SB2 frame, or is a SB1/Huntsman frame sufficient? 

[bikerbeans]

OSR,
My converted 45 cal MZ is a converted from a Handi 45-70 barrel.  I put it on an SB1 frame because there isn't any breech thrust as the pressure is only felt by the breech plug not the receiver breech face.  Actually there is a little breech thrust as some pressure is exerted on the 209 primer, but in my experience it is fairly minor. 
The conversion is fairly simple,
The chamber of the barrel is tapped to accept a threaded breech plug, usually a Savage 10ML plug but not necessarily.  The breech plug needs to be headspaced correctly so the 209 primer is in proper  contact with the frame.  The barrel can also be modified for a ramrod thimble and the crown modified to help with starting the plastic sabots.  The foreend will need to be relieved for a ramrod and some type of spring installed to hold the rod tight.  That is pretty much the basics of a conversion.  Also, the extractor/ejector components are removed as they no longer have a purpose.  I see this as a permanent conversion as threading the chamber pretty much prevents you from ever reboring the chamber area for any CF rifle cartridge that would be Handi appropriate.
 
BB

[muznut 54]

The barrel on the huntsman or sidekick is made from heat treated 4140cm this was directly from the factory supervisor before rem took over I called and busted b.... until I got answers he assured me it was the same stuff that their 500sw and all center fires were made from. the breech plug is not up to pare though especially the 7/8 not much meat left around it on the barrel I traded off my huntsman that I bought when they first came out for a new sisekick for that reason.