The mystery of the 1884 Trapdoor

[Carrie450]

Gentlemen, I have a mighty strange case here. I have an 1884 Springfield Trapdoor. It's getting some really strange groups but I'll explain my load details first.
I've tried two bullets so far. Both Lee moulds, 405 grain. I have tried hollow base and solid, hard lead and soft lead, 70 grains of Schutzen powder. I have tried with and without an over powder card.
Here's the weird bit. I keep getting the strangest groupings. Reliably, I get two bullet holes touching each other and that's it. I get numerous such groups fairly widely dispersed. If I could get rid of the dispersion this would be a tack driver of a rifle. However it only seems to like having two holes touch at a time.
I don't suppose anyone here has any wisdom to share on this topic? I'd love to make the rifle reach its full potential.

[Tatume]

I'm really surprised you can get 70 grains of black powder (2f?) in a modern 45-70 case. Do you do any cleaning between shots? At what range are you shooting?

Try using whatever amount of powder fills the case to the base of the bullet with only slight compression, and let us know your groups then.

[Tatume]

P.s. You might want to move this to the Black Powder Cartridge forum.

[Carrie450]

I figured it's more of a gunsmithing matter than anything else, an issue with the rifle requiring correction. Like something is moving that isn't supposed to be.



Is it not supposed to be 70 grains ffg? The powder compresses quite tightly.
I don't clean between every shot, as I see no reason that would be needed for a military rifle. The US army has, at that time, rejected designs for less.
This is a consistent phenomenon at any range.

[cwtebay]

Just to clarify - you'll shoot 2 that are touching, then several scattered across the target, then another 2 touching later? Are the first two from a clean bore always in the close group? One would have to surnise a change in headspace or other breech /chamber / barrel tolerances are happening if it's really that random and you are very consistent with reloading. Are these older cases you're using? I have tried hard to get even close to 70 grains and still seat a bullet in modern brass with little success.

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[Deadeye Bly]

Check the tang screw, make sure it is tight. Make sure the bands fit properly without excess looseness. If these are good then it is an ammo issue. The 1884 will probably shoot best with a 500 grain bullet. Most groove diameters are oversize. A .462 diameter bullet will generally do best in trapdoors. If you don't have an oversize bullet then you must shoot soft lead so it bumps up to fit the barrel. 405 grain bullets will not bump up properly unless they are heavily crimped. Use a good black powder lube such as SPG and use a blow tube between shots to keep the fouling soft. These tips should help. They can be accurate. This is how mine shoots at 100 yards. 535 grain bullet from BACO mold .462" diameter. 60 grains 1 1/2 Swiss, SPG lube, blow tubed between shots.
254410

[waksupi]

I'm also puzzled how you got 70 gr. in a modern case. Also, the diameter of your bullet. I have four trapdoors, all shoot .461. All will shoot into 1.5" at 100 yards. Your 405 gr. bullet should shoot well in it.

[Carrie450]

Just to clarify - you'll shoot 2 that are touching, then several scattered across the target, then another 2 touching later? Are the first two from a clean bore always in the close group? One would have to surnise a change in headspace or other breech /chamber / barrel tolerances are happening if it's really that random and you are very consistent with reloading. Are these older cases you're using? I have tried hard to get even close to 70 grains and still seat a bullet in modern brass with little success.

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So far you and everyone else is seeing my exact confusion.
So to clarify to you though, I have numerous groups of 2, 2, 2, 2, etc all around my target.
It's newish brass, Winchester variety. As for the 70 grains, it just compresses down enough. I've later pulled bullets and found the powder compressed into almost a solid tube.

[Carrie450]

Check the tang screw, make sure it is tight. Make sure the bands fit properly without excess looseness. If these are good then it is an ammo issue. The 1884 will probably shoot best with a 500 grain bullet. Most groove diameters are oversize. A .462 diameter bullet will generally do best in trapdoors. If you don't have an oversize bullet then you must shoot soft lead so it bumps up to fit the barrel. 405 grain bullets will not bump up properly unless they are heavily crimped. Use a good black powder lube such as SPG and use a blow tube between shots to keep the fouling soft. These tips should help. They can be accurate. This is how mine shoots at 100 yards. 535 grain bullet from BACO mold .462" diameter. 60 grains 1 1/2 Swiss, SPG lube, blow tubed between shots.
254410

I'm a little financially tight at the moment so new moulds are out of the question for now. However I can at the very least try fiddling around with resizing bullets for my Martini Henry. 480 grains should do it, I imagine.
Though with both barrel bands tight, and the tang screw tight, it doesn't look like anything I'd blame on ammunition. That's the strangest part. How predictable and unpredictable the groups are.

[country gent]

Are you doing anything to control fouling? Blow tube, wiping between shots? when you clean is the fouling soft or hard and gritty? I believe the original carbine load was around 55grns under a 405 grn bullet. The extra was made up with a cardboard tube in the case. a thicker wad stack would work also. Most of these rounds were loaded to around 1200 fps and the original rifles were built around this. How does Extreme Spread and Standard deviation numbers look? What manufacturers Black Powder and granulation are you using in this rifle?

As to the rifle mechanics, Checking the tang action screws is a good idea. If holes are large then a little bedding might help. Check the action mortise for solid firm contact. play here will have affects. Any barrel bands or studs need to checked also.

These rifles had lighter barrels so bench technique is going to be important, Varying down pressure on the stock wrist forearm will affect groups also. Try to hold the rifle firm resting on the bags and pulling straight back. Keep the rifle "square" canting differently will cause groups to open. Most of the BPCR shooters use a spirit level on the barrel or front sight for controlling this. Last is to pay close attention to the trigger pull

[fgd135]

Fwiw, I had an 1884 recently that would not hold a zero, no matter the load. The rifle appeared to be in great shape, not abused, a shiney bore, too. Screws were appropriately snug, etc. After some close examination by a gunsmith, it turned out the barrel was bent...I ended up replacing the barreled action with one in the same general sn range, from ebay, of all places. Used my original block and rear sight. Now it shoots very well.
It was my gunsmith that suggested replacing the barreled action. The original sn did not show any special provenance.

[Carrie450]

I've been using both Goex and Schutzen powder, both FFG granulation.
Cleaning the rifle, I find that after a patch I get usually powderized fouling.
As I lack a chronograph, I am unable to measure the spread of velocity...
Mechanically everything is tight. The action is bedded, the barrel is tightly fit. Really nothing seems to move.

[mazo kid]

What lube are you using?

[RedlegEd]

Hi. Does your trapdoor have a traditional ramrod, or bayonet ramrod? If you have the traditional ramrod, check the ramrod catch at the front of the stock. Sometimes, they'll break and push on the barrel causing inaccuracy/inconsistent groups. Ed
254438

[cwtebay]

Hi. Does your trapdoor have a traditional ramrod, or bayonet ramrod? If you have the traditional ramrod, check the ramrod catch at the front of the stock. Sometimes, they'll break and push on the barrel causing inaccuracy/inconsistent groups. Ed
254438Nice! Good thought!

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[Carrie450]

Hi. Does your trapdoor have a traditional ramrod, or bayonet ramrod? If you have the traditional ramrod, check the ramrod catch at the front of the stock. Sometimes, they'll break and push on the barrel causing inaccuracy/inconsistent groups. Ed
254438

It has a traditional ramrod catch. No, it's not broken. It's actually set pretty solid in the stock.

As for lube, Lyman Alox bullet lube.

[Carrie450]

Forgot to say. I wasn't able to test my 60 grain loads yet today. I'll try as soon as I can tomorrow likely.

[RobertS]

I've heard that trapdoors tend to shoot better groups with the ramrod removed from the stock, as it tends to vibrate when shooting.

[cwtebay]

Mine shoots a 3" group with 61grains of 2f goex and a 405 grain hollow based bullet I can't use solid based projectiles because of a skip in the rifling just ahead of the chamber. I've always pulled my cleaning rod before shooting at paper - because the sound is annoying, but I'll bet that it does affect accuracy.

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[kootne]

If you are using Lyman Alox lube, I would start by switching to a Black Powder friendly lube such as SPG. Get a copy of the book, "Loading cartridges for the original 45/70 Springfield" by Spence Wolfe.

https://www.shopspg.net/Lube-Bricks_c9.htm
https://www.amazon.com/gp/offer-listing/157579019X/ref=tmm_pap_new_olp_sr?ie=UTF8&condition=new&qid=&sr=

[doulos]

For those who are wondering how you can get 70 grains of black powder in a a 45-70. You use one of these https://www.buffaloarms.com/45-cal-rifle-compression-plug-for-lyman-rcbs-expander-die-body-van45rcp
I had no problem putting 70 grains in 45-70 cases. But its pretty tough without a compression die. I first used a drop tube , then an over powder wad then compressed it with one of these dies. It made the compression very uniform for every cartridge. I havent shot BPCR guns in a long time. But my Shiloh loaded this way was very accurate.