80:1 Alloy for Trapdoor Springfield "Gallery Load"?

[broken-mold]

On page 145 in his excellent book, "Loading Cartridges for the Original .45-70 Springfield Rifle and Carbine" (3d Edition), Spence Wolf says to cast a 460210 Rapine bullet from 80:1 alloy to use in a gallery load for 50-100 yard ranges. I don't have that exact mold but one that is very close made by Tom at Accurate which is his 46-210RN. My question is in regards to the alloy that Spence says to use, namely an 80:1 (or "1 in 80"?). I've never seen that alloy listed anywhere else. Is it basically the same as a 40:1 alloy with half the amount of tin?

Also, why 80:1? Is that to keep the hollow base bullet soft to insure complete obturation of that hollow base? If so, would not an alloy like 40:1 or even 20:1 be adequate for complete obturation as long as the alloy contains only tin and lead and no antimony? The powder charge for this "Gallery Load" is 20, 25, or 30 grains of FFFG or 5 grains of Bullseye. Could the boolit alloy be so soft due to the very low pressure charges used to propel it?

If the very soft 80:1 .460" boolit is seated into a case that has been expanded to .460" and the case is even slightly taper crimped wouldn't that squeeze the boolit down to less/much less than .460" thereby negating the use of a .460" boolit vs .457"? Spence repeats several times throughout his book that a .460" diameter (20:1) is required for the Trapdoors, both the 420gr and the 500gr. When I figure out how to measure a three rifling pound cast I'll verify that in my two TDs.

Note: The 46-210RN boolits pictured are cast from 20:1 to test their diameter which is .460". I hope a softer alloy would not reduce the diameter appreciably.

[rmark]

Soft alloy to allow the hollow base to expand with low pressure loads would be correct. At 80-1 the tin probably helps the hollow base fill out with not much hardness gain.

[Larry Gibson]

I have the Rapine 460210 mould and use the bullets cast in it in my H&R TDs and my original TD. I've never tried an BP with that bullet but have thoroughly tested it with Bullseye. I found the 80-1 alloy spence mentions to be a bit to soft for my use. The very low % of tin also caused a lot of reject bullets which had a lot of wrinkles, especially on the bottom of the skirt. I found an alloy of 20-1 to be much better. I load those over 6 gr of Bullseye fo 950 - 1000 fps depending on the barrel length used. More than 6 gr of Bullseye and the accuracy is lost as the skirts begin blowing out on exit from the muzzle.

I sized and lube my 460210s with my beeswax/olive oil lube at .4615. I made an expander to fit the Wolf special Lee 45-70 dies which expands the inside of the necks to .460 which works well with my .4615 sized bullets.

My original TD has a .461 groove and my H&Rs have .458/.459 groove barrels. I use the thin shim method to measure slugs from odd groove numbered bore slugs.

[Rockindaddy]

Yeah! Trapdoor Springfields have a groove dia of .461 to .462" Should have called the new 1873 US Government cartridge 46-70 The only way to get the old trapdoors to shoot is with big boolits. I mean large diameter .002 over groove dia. boolits. Lee makes a 45-70 mould around 400 gr with a hollow base. If I cast em soft they shoot pretty well with 24 grs of SR4759. Never loaded gallery loads. Good luck with them. Show us some targets!!!

[Nobade]

I have found that by paper patching 45 caliber pistol bullets I can get them to fit my trapdoor and shoot quite well with light loads like these. Since I didn't have the right mold it seemed like the expedient way to go.

[country gent]

Another reason for the low ration of tin to lead is to keep the bullet as soft as possible and flow well casting. The reason to keep soft is so the hollow base expands under light loads and less wear on the indoor back stop.
With the pure lead minnies loads were kept down so the skirts didnt "blow out" destroying accuracy

[Larry Gibson]

Bullet on the left is the Rapine 460210

[Larry Gibson]

The specification for the M873 Springfield rifle was a bore of .45 [hence the "45" in 45-70] with groove depths of not less than .005".

The "hollow base' in the Lee 405 gr cast bullet designed by Spence Wolf to replicate the original M1873 bullet is actually a "dish" [as per the original platte drawings of the bullet] intended simply to keep the external dimensions of the bullet the same. It was not there to aid in obturation as per a Mine' bullet.

The skirt on the Rapine 460210 is very thin with the cone shaped hollow extending well up into the bullet. If cast too soft such as with 80-1 alloys the skirt blows out on muzzle exit at velocities much above 600 - 700 fps with accuracy going south.

[Chill Wills]

If the very soft 80:1 .460" boolit is seated into a case that has been expanded to .460" and the case is even slightly taper crimped wouldn't that squeeze the boolit down to less/much less than .460" thereby negating the use of a .460" boolit vs .457"?

If the rifle the ammo is loaded for is a singleshot, there really is no need for a crimp and you may find the accuracy could be better without.

[broken-mold]

I have the Rapine 460210 mould and use the bullets cast in it in my H&R TDs and my original TD. I've never tried an BP with that bullet but have thoroughly tested it with Bullseye. I found the 80-1 alloy spence mentions to be a bit to soft for my use. The very low % of tin also caused a lot of reject bullets which had a lot of wrinkles, especially on the bottom of the skirt. I found an alloy of 20-1 to be much better. I load those over 6 gr of Bullseye fo 950 - 1000 fps depending on the barrel length used. More than 6 gr of Bullseye and the accuracy is lost as the skirts begin blowing out on exit from the muzzle.

I sized and lube my 460210s with my beeswax/olive oil lube at .4615. I made an expander to fit the Wolf special Lee 45-70 dies which expands the inside of the necks to .460 which works well with my .4615 sized bullets.

My original TD has a .461 groove and my H&Rs have .458/.459 groove barrels. I use the thin shim method to measure slugs from odd groove numbered bore slugs.

When I turned the hollowing pin for my Accurate 46-210 mold I turned it to make the skirt thickness about .100", way thicker than they appeared in the pics of the Rapine 460210 which you posted. Also, the hollow only extends into the base 0.282" which is about the depth of the second bearing band. I saw your pics a year or so ago when I was unsucessfully searching for a Rapine 46210 and found the Accurate 46-210. I wish I would have had a couple of your 46210 boolits to measure when I was turning my pin.

Coming from a background of muzzleloaders I plan to experiment with BP, but I sure would like to hear more about the light smokeless loads you mentioned. Spence recommends a filler which I am uncomfortable using due to danger of a ringed barrel. He also recommends drilling the flash hole to 0.096" and using Fed 215 Magnum or Win WLRM primers. I'll PM you and maybe we can talk about some of those details which are not the subject of this thread regarding alloys.

[broken-mold]

The specification for the M873 Springfield rifle was a bore of .45 [hence the "45" in 45-70] with groove depths of not less than .005".

The "hollow base' in the Lee 405 gr cast bullet designed by Spence Wolf to replicate the original M1873 bullet is actually a "dish" [as per the original platte drawings of the bullet] intended simply to keep the external dimensions of the bullet the same. It was not there to aid in obturation as per a Mine' bullet.

The skirt on the Rapine 460210 is very thin with the cone shaped hollow extending well up into the bullet. If cast too soft such as with 80-1 alloys the skirt blows out on muzzle exit at velocities much above 600 - 700 fps with accuracy going south.

I have both Lee moulds that Spence had them to manufacture according to his research. One is a ~420gr hollow-base and the other is a flat base 500gr, both with round noses. They both drop boolits at .460" using 1:20 alloy. My hollowing pin for my Accurate 46-210 was turned to make a hollow like the hollow base of the Lee 420 boolit. I'll post pics of the moulds ASAP.

[broken-mold]

If the rifle the ammo is loaded for is a singleshot, there really is no need for a crimp and you may find the accuracy could be better without.

I know with most loads in this cartridge that is usually the case but I understand that loads in these Trapdoors are supposed to do better when crimped. Could that be due to a need for the pressure to spike to a certain point before the boolit heads out? If so, why would that be true for Trapdoors when other rifles, like my 1971 Buff Classic or my '74 Sharps (both .45-70) do just fine with light crimps that only straighten out the case wall or even with no crimp at all and with a belled case mouth remaining?

[Chill Wills]

I doubt you will need a crimp with the BP loads.The Bulls Eye load may or not too. It would be worth testing to see which trade-off works out best. If you do, I would be interested in your results.

[Larry Gibson]

I don't crimp the smokeless loads other than the just straight the case mouth flare out.

broken-mold, no problem on PMing me.

[fredj338]

I used to load 800fps load with 300gr bullets for CAS when the 45-70 was allowed. I just used straight lead. At that vel, no leading. I never shot it past 50y but it was quite accurate out of my 1886 rep.

[broken-mold]

I have found that by paper patching 45 caliber pistol bullets I can get them to fit my trapdoor and shoot quite well with light loads like these. Since I didn't have the right mold it seemed like the expedient way to go.

That is very interesting. I considered that but assumed PP wouldn't work too good with the short throat in Trapdoors. What kind of accuracy did you get and at what range? Did you patch to bore or groove diameter?

[Bigslug]

The skirt on the Rapine 460210 is very thin with the cone shaped hollow extending well up into the bullet. If cast too soft such as with 80-1 alloys the skirt blows out on muzzle exit at velocities much above 600 - 700 fps with accuracy going south.

My experience with hollow bases is almost exclusive with MP Molds copies of the .455 Webley MKII and MKIV bullets, but they fall into the above skirt and velocity parameters exactly. The Webley MKVI revolver is a bit of an odd duck in that the cylinder throats were deliberately milled smaller than the groove diameter of the barrel. British alloy seems to have run from as hard as 12-1 (at least for the earlier guns - I'd guess that was just because it was what the Martini and Cadet rifles were using, and they had plenty of it) to nearly pure lead with trace antimony under the press of WWI. I cast mine out of reclaimed shotgun slugs (trace antimony) with tin added for fillout for a bullet in roughly the 40-1 /20-1 range. Tumble lube only with 3.2 grains of Bullseye shoots them accurately and clean through the weird throat arrangement, so I have to conclude they are obturating just fine. I agree with Larry in that 80-1 is needlessly soft.

V-anvil micrometers are the ticket for measuring slugs out of offset land/groove patterns. I never could make the shim wrap method work.

[Nobade]

That is very interesting. I considered that but assumed PP wouldn't work too good with the short throat in Trapdoors. What kind of accuracy did you get and at what range? Did you patch to bore or groove diameter?

Works great. Accuracy was pretty much limited by my eyesight, 50 yds is almost one hole, 100 yds maybe 1.5 - 2.0 inches. I patch them to groove or more. I try to get a nice slip fit in a fired case, usually about .462" or so. This reminds me to play with that again. It's been a while. The nice thing about doing this is 45 caliber pistol bullets are the perfect size to patch up without needing any sizing first. This works well in my Marlin 1895 as well. The only drawback is the light bullets hit way low, easy to fix with the TD's ladder sight but not so much with the Marlin.