Not for the old Trapdoor warhorse with three grooves needing .515"-sized bullets, this is for building new muskets:



A "new" standard for .510-grooved/.500-bored barrels.
Now the barrels are same caliber as the 50 BMG, 500 Jeffery, etc.
I like that .200"-long freebore of .512" diameter.
The new 50-70 Musket has been "Weatherby-ized."
Maybe I can hang a grease groove out in front of the case mouth.
maybe semi-paper-patch, wrap that grease groove with a single layer of thinnest paper.
Or not.



http://www.singleshotexchange....the-50-70-for-a.html

Croft Barker hangs a grease groove out of his case with 600-grainers and excellent accuracy in his .512-grooved, 1:26" twist barrel.

My dummies:

Looking good, RIP. I still haven't cast any slugs from the 600-grain Creedmoor mould I bought from Buffalo Arms. Need to fix that.

Bill,
You and Croft Barker are using similar ~600-grain bullet and barrel with .512" groove and 1:26" twist, eh?
His article (linked above) does not get specific on the weight of black powder in his ~1-MOA, 5-shot, 200-yard load for silouhette and paper punching.
The secret seems to be in getting a uniform amount that requires, after drop-tubing, about 0.090" compression of BP,
with a primary wad of 0.030" to 0.060" thickness over that compressed powder,
then two pieces of newsprint paper "wads" between the primary wad and the bullet to make sure the wad does not stick to the lubed bullet base.

Start with 70 grains of FFg and see how much of it fits to meet the above parameters?
Croft Barker says GOEX 2F is good.

I am thinking a lot of folks shoot only 65 grains of FFg with their 425-grain bullets!

Barker uses Winchester Large Rifle Magnum primers:
"These are very hot primers that promote fast ignition and lessen fouling."

I am wondering if Croft Barker's BP loads are within the MAP of 22,500 PSI listed in the Wikipedia blurb on the .50-70 Government?

A smokeless load with 650-grainer at +1400 fps in a 28" barrel could be easily done at 22,500 psi, according to QuickLOAD.
That would make a smokeless 50-70 beat a BP 50-90.

RIP, you know I need to slug my barrel. It is a Green Mountain, but I had in mind it was a .500/.508. Hope so, as my mold is a .510. You'd think I would pay closer attention.
The action is a re-heat treated Husqvarna with block replaced that was rebarreled to 8X58R, so I am sure it will stand up to however much Olde Eynsford I can drop-tube into the case.

Bill,
Forgive me, I got confused, was thinking Badger and .512-grooved for yours, not Green Mountain and .508-grooved, as you said before.
I have trouble enough keeping up with what I am doing myself.

As you were.

Whether your barrel is .508 or .510, your .510-diameter-bullet-throwing mould will work for BP loads.

That great authority Croft Barker says about the proper bullet diameter to be used:

"It depends. If the charge is black powder and bullet alloy is 1:30 tin/lead or softer then I would select a bullet of groove diameter or .001" to .002" SMALLER." (emphasis added by Rip)

He continues:

"Although black powder 'bumps' bullets up more than smokeless, I would not shoot any bullet (except a Minie or paper patched) that was more than .002" under groove diameter. When firing smokeless rounds I would choose a bullet of .001" over groove diameter to prevent leading and enhance accuracy."
(emphasis added by Rip)

And furthermore he adds:

"The above (with Minie and paper patched exceptions noted) applies to naked lead or soft alloy lubricated bullets. If the bore is deeply pitted, firing a .004" to .006" under-diameter bullet that is then paper patched will result in zero leading."

That about covers it for whatever groove diameter, even Lucretia Borgia's twin sister born 150 years ago,
like this Model 1866 Springfield 2nd Allin Conversion Trapdoor, 50-70 Government, made from an 1864 percussion musket,
relined from .58-cal to three-grooved .515-groove, best I can tell:



Some gunsmith converted it to short rifle with two bands instead of three. Maybe that improved the civilian sales appeal for the surplus warhorses. Sporterized!

Then someone stuck "decorative" brass tacks into the fine, original, walnut stock and added the human hair wind guage hanging on the cleaning rod.

I am saying the latter culprit was Crazy Horse himself. Fine provenance, eh?

No proof, but that is my story and I am sticking to it!

Well, for the "Crazy Horse Trapdoor" with .515" groove and 1:42 twist,
I need to size some soft lead 450-grainers down to .510" diameter and paper-patch them to .515" diameter?

Now I gotta learn to paper patch?

Or just go with soft lead .514"/450gr slugs and BP of 65 grains.
What I tried before, and they did not keyhole, though accuracy could have been better,
was .512"-lubrisized and relatively hard 1:20 tin/lead, with hard lube.
I am slowly learning about these things.

I love this picture of the 3-grooved, relined barrel that we recrowned after I got her, making the short rifle a wee bit shorter, and thus sportier:



The cracked stock was also repaired. She's still a shooter!

Here is the bullet from NEI that Croft Barker does so well with in his 50-70 Govt. with a 1:26" Twist, .512-grooved barrel,
it is 1.26" long and weighs 598 grains in 1:30 tin/lead, add some SPG lube and call it a 600-grainer:



Croft Barker sizes it down to .511" for use with BP in his "MOA" silhouette-hammer.
It is the 4th one down from the top on the far left of page 14 of the NEI catalog: ".512-600 #378E Gunn 50"



And here is a "sample" drawing of one of the Hoch Custom (nose pour) bullets, meant for a .510-groove/.500-bore,
it is 1.20" long and ought to weigh somewhere around 575 grains in 1:30 (weight is my guess):



They seem to think that 1:36" twist is fast enough for a 1.2"-long bullet.

I am adding both of these moulds to my wish list.

BTW, I picked up a used Pedersoli Sharps 1874 "Long Range" model 50-70 Govt with a 34"-long, heavy barrel, 1/3 octagon and 2/3 round.
Twist is 1:26", 6-groove, .512"-groove/.504"-bore.
I am wondering if the 1.4"-long Hoch .512/"650" grainer will stabilize in it?
If not, Mr. Barker's bullet ought to be the cat's meow in it.