Ok, so I'm building the trapdoor springfield with a green mountain barrel. I loaded .45-70 cases with 62 gr of ffg. I have molded my own lee 500gr bullets. Using a home made bullet lube recepe I got from venturinos primer book. Using cut out tablet circles for bullet backing. 1st shot ever and it hits 1" right at 25 yards. The next shot goes into the target sideways at 25 yards. It leaves a perfect siloette of the bullet. I swab out the barrel as good as I can that is until the patch comes out clean. Fire next shot and again 1" at 25 yds. next shot again enters target sideways. What is happening? Is my lead too soft?

I would say that your rate of twist is too slow for that bullet. Your not stabilizing the bullet properly. What is your rate ow twist? The bullet that was intended for the trap door rifle was the Lee 459-405-HB. Here is a link to it. It talks about if your bullets are key holling you need this mould. Ron

http://www.trackofthewolf.com/...22&partNum=LEE-90268

If it is a keyhole the like Idaho said the bullet is not stabilizing. Too slow a twist too long a bullet. Or maybe a bullet to small in diameter.

it is a green mountain .45 cal 1:18" twist designed for plack powder cartridge sharps rifles.

Several other possibilities; The bullet diameter is too small and the bullet isn't engaging the rifling, or the alloy is too soft and the nose is slumping making the bullet unstable, or the alloy is too hard and the bullet isn't bumping up to properly engage the rifling. Your bullet for that barrel should be .458. For the round nose bullet 30:1 lead tin alloy is suggested though wheel weights will work if the bullet is correct diameter. If the bullet is small then a soft alloy may allow it to bump up and engage the rifling. The pointed nose bullet will have a tendency to slump under acceleration if the alloy is too soft. Things to consider.

Jerry Liles

OOOOOPS!!!
I sized my bullets to .457"

Try pan lubing and shooting as cast.

Jerry Liles

That is the plan. Thanks for not laughing out loud.

So, I cast new bullets and load them up and shoot one round. Still getting keyholed bullets. So I measured the bullets from the mold and they are .459" to .460" then I try to force a lubricated bullet down the bore and it is very tight. It would require a hammer to accomplish this. Next, I make a chamber casting and something appears very wrong. the chamber has no throat and is cut a full 1/8" short. So I was seating my brass into the rifling and basically extruding the lead bullet into the barrel. When I went back and retreived the fired bullets there were no rifling marks on the bullet at all. Boy am I glad I did nit use jacketed bullets in this gun. I think things could have gone very badly.

Ouch! When you get the chamber corrected why not make a Long Range Rifle like Springfield made and use a 45-90 reamer? Those rifles had the faster twist, 6 grooves, and a 2.4" chamber and used the 500gr bullet with 80grs powder.

Jerry Liles

will that case fit in the trapdoor springfield?

Springfield made a series of trapdoors for long range competition that used the 2.4" case with the 500gr bullet. It was considered for adoption as the standard but they finally decided to stay with the 45-70-500. The 2.4" case (45-90) will fit very nicely in a trapdoor and the action is fully capable of handling the round. Recoil may be another matter.

Jerry Liles

I like what you are thinking there jerry. After the deer season I will start working on it. thanks.

Ok, only eight months later..... unscrewed barrel and ran a reamer up the chamber and brought her to correct chambering length for a standard .45-70. Checked with go no-go gauges. I thought about doing the .45-90 but I already have dies and brass and I know a guy with the reamer so there ya go. Real sweet shooter, three rounds nice 2" group at 50 yards just test firing so groups will get better with more time to shoot.

This is still in the works so try not to laugh and point too much. 1884 action and lock from my grampas gun. Green mountain tapered barrel, trigger gaurd and sights from a T/C Renegade, the stock I wittled from a 4"x10"x4' piece of straight grain walnut and the butt plate is a chunk of stainless steel plate. the wood requires final sanding. it's still pretty rough but shoots very nice. The metal finish has not been decided on yet, the action and lock is original and the barrel is rustolium flat black for now. I am leaning to duracoat brown but have yet to make the final decsision.

Loading with 2F black and 500 gr bullets from lee mold, I cut disks from tablet backing with 7/16" hole punch. the lube is home made from soy wax and crisco and lanolin.... I think. Remingtom brass and 215 rifle primers.

And that is my drop tube. the counter weight is a section of shotgun barrel filled with lead to it don't tip over.