Trapdoor keyholing with 405 gr .459" with lub bands 15 gr Unique

[Clark]

http://i757.photobucket.com/albums/xx220/ClarkM/Paulspicoftrapdoorwithgammacorrection.jpg

This is at 50 yards.

I am posting for him 900 miles away, but he can read this.

[MtGun44]

Not at all unusual. Get a Lee 405 HB design mold, cast from pure lead and your
troubles will be solved with that same load.

Bill

[Larry Gibson]

Bullet cast to hard(?) and sized too much. What bullet is being used on the TD "scout"?

Most TDs have a groove diameter of .460 +. They were made that way as the barrel specification called for a bore of .45 caliber with grooves .005 deep. Best to have a softer cast bullet of 20-1 or a BHN of 8 +/- at .460 - .462+.

Larry Gibson

[Janoosh]

+1 on Lee HB 405 and soft boolit. Also...dont crimp boolit....just let the brass kiss the boolit to hold it in place. It's a single shot...no need to crimp...especially with the holy black...
with smokeless, a minor crimp is best.

[Clark]

Thanks for the response.
He is sending me email about this thread.

​Paul wrote : I used .458 dia bullets . MTGUN 44 said to use The Lee HB 405 gr mold . I have one. But why pure lead ?

[35remington]

The blackpowder trapdoor was intended to use soft bullets, and the softer lead lets the hollowbase function as intended. The mould also usually casts at .462-.463" depending upon alloy composition, which is what you want and need.

[TNsailorman]

I had a similar problem with a Remington Rolling Block in .43 Spanish. I changed lead to a softer lead and quit sizing my bullets. I just shot them as they came from the mold. Keyholing stopped, and accuracy improved dramatically. While the book says .439" for the .43 Spanish, my barrel evidently is larger than the book calls for. I cannot do the math for a 5 groove bullet so I am up the creek on the measuring for the proper diameter. I guess I will just shoot and enjoy her the way she is now. I think Larry is right, a bigger bullet with soft lead may also be your answer. james

[13Echo]

In my 1884 I find the Lee 405hb shot as cast from 30:1 alloy does fine with black powder. I haven't tried it with smokeless. Unlike my Sharps I did find that my trapdoor preferred a firm crimp over the base of the ogive of the bullet for best accuracy. I think it let the charge build pressure enough for a complete burn and helped bump the bullet up to fill the grooves. The 500gr SAECO 1881 bullet only required a light crimp. The reason to use soft lead is so the bullet can bump up to fill the rifling grooves.

If you haven't got a copy get Wolfe's book on loading for the Trapdoor Springfield. It is a rambler and disorganized but it will answer your questions about the old soldier.

Jerry Liles

[fouronesix]

It's no secret here or in other sources that TDs generally have large groove diameters and prefer soft bullets. Likely something .461-2" diameter in 400-500 grain soft lead. Not necessarily pure lead. The BP ammo of the day was normally loaded with bullets of 16-20:1 or similar alloy. Bullets don't have to be hollow base. Undersized hollow base bullets attempt to make up for the small diameter by having a hollow base.

[WILCO]

I learned something new today. Thank you.

[MtGun44]

Wolf's book explains this in great detail. He is the one that got Lee to make
that mold (405 HB) specifically for the trapdoors. I works perfectly in my one with
a huge and very worn bore that was slinging all the harder and solid base boolits
every where - at least as bad as the pic. I think I used 14 gr of Unique, but you
are right there with the powder choice and quantity.

35 Rem is right on with his comments.

"undersized hollow base is attempting to make up for the undersize.. . . ."

Well, actually - this is how the original ammo was made, and how the rifle
was designed to work, not a bandaid. TDs were never intended to have groove
diam boolits - that was essentially not done in those days, but HBs were the
norm - remember they were just barely out of the Minie ball stage by 5-10
years - so they pretty much thought a HB was normal.

Bill

[fouronesix]

The original TDs were designed to use blackpowder and soft alloys that would obturate the bullet. The shallow hollow base can't aid much in inertial obturation to fill the grooves. At most, the shallow hollow base will flare a little to better seal the bore. There is a difference between obturation due to inertia of a major length of the shank of a bullet and the expansion via pressure swell of the bullet's base surrounding a shallow hollow cavity. The 500 grain soft lead bullet with a full load of BP will obturate more fully than a 400 grain soft lead bullet no matter hollow base or not.

Sometimes I wonder if the shallow hollow base of those bullets (and the current iterations for that matter) were more a carry over of design from the shallow hollow base of the paper patch bullets for tail tucking or even a residual artifact of the hollow base Minié form??

Or as has been suggested for the OP.... get an inexpensive Lee hollow base 405 grainer, use whatever lead alloy, use whatever powder, hope it shoots accurately, doesn't keyhole or require bore "lead mining" after shooting :)

[Larry Gibson]

The hollow bases were actually called a "dished cavity" and were there to regulate the weight of the bullet while maintaining the same external dimensions. Never was there (the "hollow base") to aid in obturation.....says so in the Springfield Rifle manuals.

Larry Gibson

[webfoot10]

Clark: Drop your unique charge down to 10 or 11 grains and fill your case with rice krispies to the top. Seat a unsized cast boolit and give it
a try. The cereal will crush down when seating the boolit. Got my trapdoor shooting down to 3 in groups at 100yds from 12 in groups with
the filler. Hope this helps.
webfoot10

[fouronesix]

The hollow bases were actually called a "dished cavity" and were there to regulate the weight of the bullet while maintaining the same external dimensions. Never was there (the "hollow base") to aid in obturation.....says so in the Springfield Rifle manuals.

Larry Gibson

I'll buy that. If Springfield printed it, I'd consider that pretty much from the "horse's mouth" so to speak. Not sure how that fits with the current Lee HB 405 gr bullet theory.... but then again the modern designs need not fit into the original reasons of 130 or so years ago when much of the modern "ideas" need only to sell.

[arjacobson]

Plus one on the lee mold.. I use 27 gn of 4198. Lees bullet and an over powder wad.. great load.

[40-82 hiker]

Bullet cast to hard(?) and sized too much. What bullet is being used on the TD "scout"?

Most TDs have a groove diameter of .460 +. They were made that way as the barrel specification called for a bore of .45 caliber with grooves .005 deep. Best to have a softer cast bullet of 20-1 or a BHN of 8 +/- at .460 - .462+.

Larry Gibson

Absolutely need 20:1 or softer. I size .459", but my TD groove diam. slugs between .457" and .458". Make sure your load is in the 1100 to 1300 fps range for good obturation (I use 24.3grs. of 5744 (suggested start load for TD - don't see any need to exceed that) and a guy let me shoot one through his chrony at 1240 fps recently). I don't have any experience with the HB boolit, but use extensively the 405gr. Lyman 457124 (I had to open it up some). I barely crimp. Use Lyman Moly lube, as my TD seems to love it, with no leading.

I also seat the boolit out a bit. Must not be too far, though, as the same boolit combo is working great in my newly rebored '86 Win. with nothing changed.

Sorry I can't add anymore than the others. Hope some of this helps. Can't help but think others are right to say that your lead is not soft enough. Also, slug the bore and size accordingly.

[MtGun44]

I'd suggest Wolf's book on the subject, lots of good info there and if you follow what
he says, your TD will shoot well.

Bill

[Larry Gibson]

I'll buy that. If Springfield printed it, I'd consider that pretty much from the "horse's mouth" so to speak. Not sure how that fits with the current Lee HB 405 gr bullet theory.... but then again the modern designs need not fit into the original reasons of 130 or so years ago when much of the modern "ideas" need only to sell.

Spence Wolf, who designed the Lee 405HB bullet, made it as close to the dimensions of the original M1873 HB'd 405 gr bullet as he could and as close as a nose pour HB mould would allow (the original M1873 bullets were swaged). Thus the design is to replicate original loads for the TDs. Also the HB goes back even further to pre Civil War with the advent and adoption of the Minie' style HB (which again the Lee 405HB design is not). Nothing "more modern" about either design. The "more Modern" design which still works better in the TD is the 500 gr M82 bullet, also with a "dished cavity" to keep the external dimensions constant.

However, the Lee 405HB is an excellent bullet in it's own right, especially when used "as cast" or sized to fit the groove diameter of a TD. Actually when cast, sized and loaded as per Spence Wolf's instructions it also is a good bullet that does replicate the accuracy of the original 45-70 M1873 loads.

Larry Gibson

[fouronesix]

The 405 Lee of soft alloy would be fine if it casts large enough to fill the grooves. If not, then back to the problem of trying to get an undersized bullet to shoot well in the often largish groove diameter TDs. Of course one person's definition of accurate or "shore shoots good" is not the same as another person's definition.

Heavy charge of BP with fiber wad can help... but only to a certain point as the bullet's inertial mass drops. That's probably one of the reasons the soft alloy 500 gr Govt usually works pretty well over BP in the trapdoor. With smokeless, it becomes more problematic. I dinked with the available factory molds/bullets for my TDs, including following some of Wolf's details- some worked OK, some didn't. I woke up one day and decided I have a brain and pretty much know what makes a BPCR type rifle shoot. Pitched in the towel on the baling wire, duct tape, cheap molds, internet "wisdom" and used my brain to design a custom mold for the purpose .... problem over. Both my TDs now shoot really well... probably well above their "pay grade".

[Larry Gibson]

To bad Rapine closed shop. They made excellent moulds designed and sized perfectly for TDs. I have the 460210HB, the 460500 and 2 of the 460250s. All are excellent in my own original and replica TDs. They are the 1st and 2nd from left and 2nd from right. The Lee 405HB is the middle bullet.

Larry Gibson

107947107948

[jonk]

Oddly enough, I've never gotten the Lee 405 to shoot worth spit in my TD. Switched to the Lee 500 gr, spg lube, 40 gr of 3F black powder and 2 overpowder wads (bullet seated to the wads/charge- which isn't as deep as you'd think) and I have a very mild, accurate load. 1" out to 100 yards, 3" at 200 from a bench.

I agree, back down your load and soften up your lead; then you can see if that boolit/powder will do anything for you.

[Clark]

My brother has the mold and has the book, but reading this thread got him to finally read the book.
A few years back he bought the book, read the first and last 15 pages and could not get anything out of it.
But now he read it.

He has been cleaning and cleaning his trapdoor, and really enjoyed this thread.

[Larry Gibson]

You or he has any questions about the TD or Spence's book don't hesitate to ask.

Larry Gibson