Trapdoor Springfields Bullet Size?

[Niederlander]

Gentlemen,  For any of you who shoot original trapdoors with smokeless powder, what bullet diameter do you use?  I know they have what are today oversize bores.  When I had one, .457 bullets were a joke.  Will .459 do it, or do they need to go even bigger?

[Snake Oil]

I know in mine that when I cast 457 and pan lube things are bad (keyhole and such), but when I powder coat them (the main body comes up to .459) they shoot pretty well in my 1884 have not tried them in my 1873 yet... but I also used black powder (pyrodex) ... I've not had enough time to truly "develop" the load, these are initial investigation results.  Not sure if this is helpful at all in retrospect, but trying to be helpful 

[Drydock]

.459s have shot well in mine.

[RattlesnakeJack]

I have achieved fairly decent success with .457 bullets for 405gr GAF-legal loads for the Martini-Henry ... which actually should have a bullet in the .468 to .470 diameter range ... by casting them very soft (even pure lead) to ensure maximum diameter bump-up for effective rifling engagement, and using them "as cast" rather than sizing them down.  Pretty much any time I have shot a Martini-Henry in main match skirmishes at Muster, that is what I was using.  Not so effective for long-range accuracy, of course, but I load the proper larger diameter bullets of the full standard 480gr weight for that.)

For shorter-range use, at least, maybe give the soft-cast, not-sized route a try ...

As another possible alternative, the original, lsmaller than bore diameter, Martini-Henry bullet was paper patched, up to the necessary diameter, and Know of a number of present-day M-H shooters who paper-patch their bullets (even ones with annular grease grooves) for very effective accuracy.  (I'v personally never been a fan of fussing with that, but it is another possibility to consider ...

[Snake Oil]

Oooooo... paper-patching sounds fun to try!

[RattlesnakeJack]

A few random links, related to the .45-70 -

- https://castboolits.gunloads.com/showthread.php?443501-paper-patching-45-70-bullets

- https://www.go2gbo.com/threads/paper-patching-45-70.172328/

- https://forum.castbulletassoc.org/thread/1905-paper-patch-45-70/

- http://www.blackpowdergang.com/pdf/ppb.pdf

I'm sure Gen. Google could supply more ...

[LongWalker]

I tend to not shoot much smokeless in original trapdoors, but all of my shooters over the years have experienced at least some smokeless.  Tolerable accuracy--the basic 4-5 MOA that most trapdoors in good condition will do with the equivalent of BP issue ammo--can usually be reached with bullets sized to .459.  Remember though, when you work up a load with a .457" bullet and decide to increase the diameter, it is a good idea to drop back to starting loads and work up your load to match the desired velocity.

The next step up in accuracy from here is to select a bullet with a nose that fits the bore.  Take one of your bullets and press the nose into the muzzle.  If it drops in, it is too small.  If the nose of the bullet slides in easily, it is still too small.  You want a bullet that you can force in by hand, and when removed shows 3 lightly engraved markings from the lands. 

The third step up is to size the bullets to the largest diameter that will chamber.  Make up dummy rounds with bullets sized .459", .460", .461", and larger if you can.  Chamber the dummy rounds til you find the one that won't chamber, then go to the next smaller diameter. 

I'm still testing loads in my current rifle (Model 1873 with 1879 sights).  I've only got about 400 rounds of smokeless through it, all smokeless equivalents of the M1882 Rifle loads (500gr bullet at ~1,300 fps).  When testing I prefer to shoot 10-shot groups at 300 yards.  My averages so far:

.459" bullets: just under 14" (eight 10-shot groups)
.459" bullets, nose fit to bore:  11" (ten 10-shot groups)
.461" bullets, nose fit to bore: 10" (ten 10-shot groups)

I haven't tested the rifle with duplicates of the M1898 Rifle loads (original smokeless loads, 500 gr bullet at ~1400 fps).  If I were going to shoot smokeless loads in the long range match, this is the load I'd use.  My aged and decrepit carcass much prefers BP carbine loads!

[cpt dan blodgett]

Probably the softer the alloy 20 or 30 to 1 will help any thing in the .458 range to expand to fill the bore.  While not a trap door I do have an overbored rossi 44 mag .434-.435 bore when slugged.  Key holed at 25 yards with hard cast.  Switched to deparado bullets (soft alloy) shots round holes and decent groups at 100.  Getting bullet soft enough to upset is the key.  Down side if you run soft bullets to fast they can strip out.  Not a problem at trapdoor velocities

[Niederlander]

So far I've tried it with .460 bullets over 13 grains of Trail Boss.  All of them hit point on and about an inch at twenty five yards.  Considering the jury rigged sights, that was pretty good.  The .459 hollow base bullets seemed to work okay, too, but I've got to attach a front sight to know for sure.

[Drydock]

.459-460 should work well.  Frankford arsenal loaded .459.  Something to remember: The lands of Springfields 3 groove rifling are wide and tall, fully 50% of bore diameter.  Most other rifling the lands are 10% or less of bore diameter.  The modern rule of .001 over does not apply here, the lead displaced by those lands needs somewhere to go, and where it should go is into the grooves. 

The alloy used by the Army was 16-1 lead tin, FWIW.

[Niederlander]

I'm thinking I may just pan lube them and then run them through a Lee .460 bullet sizing die.  A bit cumbersome, but it's not like I need thousands of them.

[Dave Fox]

My bestest load for an 1891-dated .45-70 trapdoor is a drop tubed, slightly compressed load of FFFg, no wad, under a 520 grain hard unsized .459 SPG lubed bullet. Dip the bullet nose in Udderly Smooth hand cream before loading. Reamed-out the peep on the Buffington rear sight a little bit and inserted a tall, fine front sight blade. illustrated is best 100 yard benched three shot group. Those late '73s can shoot!