Printable View
I have a Taylor’s Uberti Low wall in 38-40 which is a sweet little rifle.
I’d like to run a heavier paper patched boolit and am interested in hearing of anyone else’s results or expectations.
I can’t find a published twist but as I measure it, it is 1 in 21” Also will have to see about throat and COL specs.
Just thinking of a bit more of a miniature buffalo gun even if it’s under 1000fps.
http://i251.photobucket.com/albums/g...8B045CC0D5.jpg
that is a very slow twist. You will probably need to stick with traditional .38-40 bullets.
For your bullet weight/twist question ... play with the Greenhill Formula
A smorgasbord of minimum twist/maximum length calculators suggest a bullet between 0.919 and 0.957" for maximum length. Longer than I expected.
I was estimating a velocity of 1200 fps. That is probably too tall for a bullet of that length in that case.
I know where Brent is coming from because he and I were both weaned on the idea that longer (heavier) bullets need faster twists. I occasionally shoot my original 92 Win in 38-40 to 300 yds at our gong matches and it shoots pretty darn well. It has a 1-36" twist and the standard 170 grain bullet is .645" long out of an Accurate mold. I have never figured out twist rates with these old pistol bullet barrels as they seem really slow in the old guns and now much faster in the newer versions yet both seem to work equally well. Your 21" twist is a lot faster than in my 92 Win so why not try a longer bullet and see what it does at the distance you want to shoot. Its all fun no matter what the outcome. Here is a 100 yd target I shot with my rifle using both smokeless and bp loads.
https://www.jpgbox.com/jpg/59793_600x400.jpg
I was typing and measuring while Brent posted and I didn't see his second reply. That is a lot longer than I expected.
Given the velocity constraints of the 38wcf, going to a longer bullet may or may not work worth a flip. The only way to know for sure is to try it.
Very interesting idea Huvius. I played around in QuickLoad to get some ideas. I postulated a 265 grain .398 diameter boolit at .945" length and a 1.79" COAL. QuickLoad thought this would get to 1350 fps with 12 grains of Blue Dot (that would probably be my first choice) or a bit over 1500 fps using 18 grains of Lil'gun. These exceed the SAAMI spec of 16k psi for the old 38/40 but at 20k psi would be pretty mild for a modern-built strong action. I'm not saying these are loads to use but just saying your idea doesn't look too wild when you have a reasonably fast-twist in a rifle.
I think if I was to have another rifle build or a switch barrel for one of my CPA rifles it will be a .38-40. I had a Marlin with that chamber and I let it get away.
That is a great little caliber for having fun swinging and busting bowling pins.