[oldred]

I am about to decide on a barrel blank for an 1885 High Wall project I am working on and I am a bit confused as to what twist rate to use. This thing is to be chambered in 45/90 and the two barrel blanks I have to choose from have either a 1 in 20 twist or a 1 in 18, both 30" in length. Mostly (likely all) I will be using BP and 500 grain cast bullets, I have read up some on this subject but I am still confused as to the best choice for that 500 grain slug which will be my primary load.

 

[crazydave]

Either will spin that bullet. If you want the lightest loads / slowest velocity that's still accurate - spin fast.

If you're NEVER going over 500gr - spin slow....

BTW - my 1886 .45-90 has 1 in 32" twist - 350gr is max before the bullet tumbles. Winchester went to 1 in 20 to spin 500gr bullets (and later the 405s) with equal aplomb. FWIW....

 

[ChrisL]

1-18 is pretty standard these days for .45 cal black powder shooting. Personally I'd go that route for the flexibility of being able to use heavier bullets.

Chris.

 

[boommer]

1-18 hands down!

 

[oldred]

OK, I went with a Green mountain barrels BPC 1-18 at 35" for the blank and will probably settle on 32" inches when finished.


Next project is to turn this 1.270" diameter blank into an octagon barrel!

 

[TexasMac]

Oldred,

You won't be able to "turn" that blank into a octagon barrel, but you could mill it into one. Just having some fun .

Wayne

 

[oldred]

Oldred,

You won't be able to "turn" that blank into a octagon barrel, but you could mill it into one. Just having some fun .Wayne

I guess I wasn't thinking when I said that,

The really funny part is that I am going to do this on my lathe since I don't have a mill (yet!). What I did was to build what might be referred to as a "tool post mill" that is mounted on the tool post with the blank mounted between centers so I can use my lathe to mill the flats on this barrel, I have done a trial piece on some bar stock and it works pretty good. The milling set up was fairly easy but holding that long barrel blank with any rigidity was the problem and was a real head scratcher for a while. What I finally did was to place a piece of 1 1/2"x3" ground stock against the side opposite the cut (this piece is also supported on both ends so the weight is not hanging on the barrel blank) and this adds the necessary rigidity along with a way to hold the piece solidly in position.

 

[TexasMac]

Oldred,

You've sure got my interest. So what will you be cutting the flats with? I could possibly envision using a tool post grinder to grind the flats, but I'm guessing that's not your approach. Since I'm in the same boat as you, lathe but no mill yet, I'm very interested in more details on your technique .

Wayne

 

[MikeG]

It seems to me that you wouldn't have enough travel on the crossfeed to do this without it being a major pain? Let us know how this works out.

 

[oldred]

Cross feed won't be a problem since the blank is mounted between centers and the end mill will be running from the tool post, kind of like reversing jobs since the work will be held stationary and the spinning cutter will be moving along it's length instead of a lathe bit. I know this sounds a bit like a crazy idea but I have milled a flat 18" long on a piece of 1" 1018 stock I had as a test piece and it actually worked quite well after I got the rigidity problem licked. I will be attempting to do the barrel soon but I intend to try a full length run on a piece of heavy wall tube before I try to use this thing on my barrel, so far however the results have been very encouraging. The "mill" attachment was actually quite simple and involves nothing more than a shaft mounted in bearings in a simple, but fairly heavy, bracket fastened to the compound in place of the tool post. This is then powered through one end with a pulley/belt connection to a 3/4 HP 110 volt motor and the other end of the shaft holds the end mill. If this thing works out ok I could post some pics if anyone might be interested but I would want to make for sure it actually is a workable idea first, so far however it has worked quite well.

 

[MikeG]

I gotcha. Sounds neat, post some pics.

 

[TexasMac]

I'd also like to see some photos. I mentioned a tool post grinder earlier and have considered modifying the grinding wheel end to hold a end mill, which sounds similar to your setup.

Wayne

 

[oldred]

I'd also like to see some photos. I mentioned a tool post grinder earlier and have considered modifying the grinding wheel end to hold a end mill, which sounds similar to your setup.Wayne

That's the idea and I too considered modifying a tool post grinder but the rig I came up with was simple and cheap so I went that route, I can also see a couple of other uses for this "milling" attachment. As I mentioned the milling part was easy but holding that long shaft rigid turned out to be harder than it might seem and rigging up the necessary support without interfering with the carriage travel was actually a bigger problem. That has been solved now but I need to experiment some with different tooling, feed rates, DOC, etc to see what this rig can handle.



I will post some pics after I make some chips and know for sure this thing works ok.