Your most accurate .43 Spanish smokeless powder loads?

[Rapidrob]

I'm wanting an accurate load for the .43 Spanish using the Lyman 370 grain bullet using smokeless powders. I am not interested in Black powder loads.
I'm holding a 200 meter Off Hand match next Saturday and would like you most accurate load data. I do not have access to Australian brands or Norma powders.
The rifle is like new and is very accurate with the loads I have tried but there is very little posted data on the web for other powders.
Thank you for any helpful info.

[cwtebay]

I've used H4198 a lot in my 1880's rolling block. Mine is the BOTTLENECK version of the 43 Spanish. My best accuracy has been achieved in the 60-75% range of max loads.

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[ascast]

I have used Unique and SR4759. I do not remember the charges.

[steveu]

I have had good luck with 4227, 4759 & trailboss. All of these loads are around 1200 fps. I have to hold about 1 foot low at 200 with the rear sight at the lowest setting. You will also have to seat the bullet out as far as possible. Mine are only in the case .10” to compensate for the long throat.

[TNsailorman]

The best accuracy I have gotten out of my rolling block .43 Spanish is from TrailBoss. james

[Rapidrob]

What is the load for Trailboss and other powders? I'm not a suing Snowflake.

[Whole Bunches]

Here's my load:

11.0GR UNIQUE, LYMAN 439186 SIZED WITH .443” DIE, WW LR, 3.15” OAL

My Argentine RB has a .443" groove diameter. Leading is terrible and swift if bullets are under size. No leading and fine accuracy with this load in my RB. Don't recall the velocity or if I even measured it, so it may be too slow for your needs. I only need to resize a small portion of the neck to hold the next bullet. My lead mix is 20/1 lead/tin. Buffalo Arms made my .443" sizing die. My Lyman 439186 bullets come out of the mold at .443".

[steveu]

What is the load for Trailboss and other powders? I'm not a suing Snowflake.

I use 18 grains of trailboss.

[TNsailorman]

I have used two loads for TrailBoss in the .43 Spanish. Both using a Lyman .439 mold that was altered to .440. I was getting very light lead with the bullets at .439 and the .440 cured that. One load was with 13.0 grains TB and the other with 16.0 TB. The 13.0 grain load was just a hair more accurate at 100 yards but not by enough to matter. They were very close in accuracy and surprisingly very close in point of impact. The 16.0 grain load hitting about 1/2 inch lower. Both loads were also very mild in the recoil department. I don't need speed as I will only be shooting the .43 RB at paper and paper is not that tough to kill. I never tried any penetration tests either. james

[Rapidrob]

Thanks for the Trail boss info...shame there isn't any for sale.
I shot the rifle at 200 and 385 meters a couple of weekends ago. It has potential for some decent long rang accuracy.
I found the Bertram Brass was not up to pat and I lost several to case splits 1/2 way up the brass.
I resized .348 Winchester blown out to the .43 Spanish length. That brass seems to be doing well.
So far I have tried IMR 3031, 4350, 7828 and AA5744. The latter left unburned powder in the barrel.
The .50 Spotter surplus powder shows potential but I'm not sure if when the load leaves the bore clean of powder grains that it is too high a pressure, I need to do some number crunching.

[brstevns]

Have been using 24gr 5744 with the same bullet you are using.

[TNsailorman]

Back some years ago I bought a bunch of Bertram .43 Spanish brass and almost have of it split on the first firing. Unless they have changed since then, they did not anneal their brass and it was very thin brass to boot. Mr. Huntington (the old man himself) helped me with loading the .43 Spanish and even made me a custom .43 Spanish neck sizing die from a couple of fired cases I supplied to him. At a very reasonable price too. He was a great old gentleman to talk to and was very, very helpful to me in my early black powder cartridge endeavors. Not only with information but He replace every Bertram case that split. my experience anyway, james

[Rapidrob]

During the 500 meter practice, ten out of twenty Bertram case split in half. No other makers brass had any problems at all.
I've contacted Bertram U.S.A to see what if anything they will do to replace the failed cases or replace the whole 100 cases purchased.

[steveu]

I had a box of Bertram that I never had a split neck because I annealed the necks first thing.

[cwtebay]

Back some years ago I bought a bunch of Bertram .43 Spanish brass and almost have of it split on the first firing. Unless they have changed since then, they did not anneal their brass and it was very thin brass to boot. Mr. Huntington (the old man himself) helped me with loading the .43 Spanish and even made me a custom .43 Spanish neck sizing die from a couple of fired cases I supplied to him. At a very reasonable price too. He was a great old gentleman to talk to and was very, very helpful to me in my early black powder cartridge endeavors. Not only with information but He replace every Bertram case that split. my experience anyway, james

I have quite a few random boxes of Bertram brass. I have to say I have no luck with it at all. I have annealed multiple ways - induced, spun, annealeaz....all the same result - splitting and damaged cases. Even with relatively tame rounds like 43 Spanish, 35 WSL, 35 WCF, 310 Cadet - I'm keeping it for rainy day use, but I'm fortunate not to have to rely on it. Ironically - their 577 3 1/4" is top notch!

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[Bent Ramrod]

My first box of Bertram .43 Spanish cracked 8 of 20 cases in the body at the first firing. Annealing the rest and subsequently purchased cases well down the body slowed the splitting some, but I'd still lose a case or two every time I ran them through the reloading sequence. It was especially distressing with .25-25s; the splits were always too far down the body to simply trim them to .25-21s and soldier on. And of course, they were always expensive.

Later batches I purchased, in the .25s, the .405 Basic and a few others, once annealed, gave a lot less trouble and good service. Somewhere in there, Bertram seems to have gotten the metallurgy right, anyway. They still haven't done anything, as far as I can see, with reproducible lengths, rim thicknesses or diameters, but, hey, nobody else is producing the stuff. Credit where credit is due.

My Peabody rifle has too small a chamber for full size grease groove boolits. It needs the black powder impulse to slug them up. It'll shoot about 4-1/2" for 5 shots at 100 yards with the Ideal 451112 with the base bands sized 0.439" and the boolit well seated in the shell.

[Rapidrob]

This is the second caliber to cause problems. The first was .310 Cadet. The cases were so thin and soft you could not seat a bullet. Bertram replaced all of the cases at that time.
Failed .43 Spanish

.348 Winchester with lathe thinned rims. They hold up very well with the same loads as well as smokeless powder loads.

[Rockindaddy]

SR 4759 and 5744 in the 24~25 grain charge range should shoot accurately. IMR 4198, Reloader No. 7, and 4227 will also work well.

[Rapidrob]

No reply. They don't care.