Art it's funny that you say that.  I recently bought a Lyman Postell mold but it was machined terribly.  It has huge vent lines so it makes terrible whiskers when casting with it.  I'm going to try it out soon, although I do want a heavier bullet to take advantage of the fast twist.

Chris.

I haven't played with enough different angles to really know for sure.  I know that a lot of what I read isn't necessarily true.  Dan's leade angle for the 38-50 chamber is 3 degrees per side.  I know that my best shooting black powder rifles are Shiloh's that use 2.5 degrees per side.  They are pretty accurate.  I have shot a 245-5c from an NRA legal prone position using BP with them, and a number of 10 shot sub moa groups at 300 prone.  But I also have a number of rifles with 1.5 degree that are great, and I even have some 45 cal paper patch rifles using Dan's chambers, with 25 degree leades.  I haven't shot those for a few years, but last time out one of those 25 degree Dan T 45-70 PP rifles held better vertical at 500m than anything I've ever shot.

Even freebore I'm not 100% sure on.  If it's up to me, I'd pick zero, or something small like 0.050", just enough to hold a grease groove.  That's how a lot of my rifles are.  One 38-55 highwall that Steven Durren built for me is set up that way also with 1.5 degree per side as per his recommendation and it's my best 38 cal rifle to date ( with smokeless ).   

But I also have a Borchardt long range rifle   built by Curt Hardcastle some time ago.   45-90 with an enormously long freebore of 0.475" long.  You'd think that'd be bad, at least based on what I've read on the internet, but it is machined very very well.  As close as I can measure, the freebore is 0.4585" and the grove diameter is 0.458" so the bullets are held in very good alignment with little distortion.  I once shot the same score on a 1000 yard target as Dave Gullo did on the same relay  .  It's a very 
good gun, and in addition to the long freebore has a 1.5 degree per side leade. 

So I don't really know.  I suspect it all comes down to who is doing the machining on the gun. 

My most accurate cast bullet rifle seems to be a Cody 1885 in 32-40.  I have only had it out twice, but on the second time with it ( and the first time shooting breach seated with it ), I shot 2 well centered ten shot groups in a row that I believe would score 250.  I was just shooting at orange pasters, I wish it was on the official target.  I'll try that this winter.  Each target used different bullets too. I'll have to chamber cast that one to see what the chamber looks like, but my guess is that it's mostly that a high degree of skill was used to make it, and the barrel just worked out well.      

Chris.

Chris et.al.

RE: Prior Post on the 35-40 Maynard NASA bullet design

I found Dr. Gunn's comments on my NASA style bullet design which I have copied below. For those who like this sort of analysis I hope you find it interesting.


"Bob;
To minimize transonic drag, you want to use an ogive radius of at least four calibers, preferably five.
Your present design has an ogive radius of only 6866" which is slightly less than two calibers. This means the form factor of your present bullet is no better than that of the Gavre/Krupp G1 bullet. With an estimated weight of 345 grains when cast from 1/20 alloy, your present bullet design wil produce a G1 Bc of about 0.4.
The 0.10" diameter meplat is in the right ball park for good transonic performance. fI you want your bullet to have a tangent ogive, you can get a four caliber 1.5" ogive radius by extending the nose length to 0.5995". Or even better you could use a 3 degree secant ogive and a 0.525" long nose to produce the same 1.5" ogive radius. This wil reduce the bullet's weight to 325 grains while improving its transonic G1 Bc to about 0.5.
The forward grooves in the bore ride section and just behind the forward centering band are both pretty shallow. Neither is deep enough ot function properly as a dirt scraper.
After catching numerous bullets in sawdust, I did not see a big problem with base finning. fI you do make the base band slightly under groove diameter, you wil probably get leading problems and inaccuracy with smokeless loads. While you may not intend to use any smokeless loads, there's no sense dialing ni a potential problem fi there is no apparent gain.
If you really want ot minimize any possibility of finning, use the 19th century trick of estimating the average bore diameter and then using that as your bullet's base diameter. For example, fi the lands and grooves are equally wide, the bore diameter is .350" and the groove diameter is 358", a bullet diameter of .354" wil split the difference. If the lands are very narrow and the grooves occupy 3/4's of the rifling area, the effective bore diameter would then be .356".
The forepart of the bullet shank should be the same diameter as the cylindrical ball seat, less an amount sufficient to allow for the build up of BP fouling.
I don't know if any of the original BP bullets used just one large lube groove. What with all that bumping up that occurs when BP hits an undersized base band, I suspect that the shank must need a certain amount of intermediate sup"