Bought a M1879 Argentine RB in 43 Spanish. Other than a few spots of corrosion in the first couple of inches forward of the chamber, the bore is bright and sharp. Ordered some custom ammo from a Gun Broker seller so I'd at least have that brass (brass has a JBA headstamp and looks real nice). Have other brass on back order. Figured if the custom ammo worked well, I could duplicate it. As best I could measure, the groove diameter of my bore is .442"
Custom ammo: 27.0gr 5744, bullets .439" with some type of dark grey slick coating on them (PC?) and no visible lube in the grooves. Per my thumbnail, the bullets were not soft. Bullets seated to crimp groove.
1st 5 shot group not bad, but not great. Next 5 shots worse. Next 5 more worse. Next 5 even more worse. Run patch down bore and look. Bore leaded up, especially the first 8" or so from the chamber. Using Chore Boy pure copper pad strands (hard to find, I finally order them via amazon) wrapped around bore brush, I finally got the lead out. Polished bore with fine to extra fine to super fine polish. Bore shines more and the spots of corrosion look better, but still can be seen if you take more than a quick glance.
From reading old posts on the forum, it seems there could be 3 problems, so I decide to tackle them at the same time: 1) Bullets too hard. 2) Bullets too small. 3) Lube insufficient.
As-cast, my Lyman 439186 comes out at .443" at the widest point. Order a custom .443" sizing/lube die from BA to basically just lube them. I've been successfully casting for my Danish RB in 11.7x51R using the Lee hollow base 405gr mould. My Danish RB has a groove diameter of .462". I pan lube the Danish bullets which leaves them at .462", and I use 25 lead to 1 tin so they're on the softer side. Nice accuracy and no leading in hundreds of rounds fired (Danish has essentially a perfect bore).
Cast the 439186 using my 25/1 alloy that works good in the Danish. Run through .443" lube die (easy as there is little to no sizing being done). Old fashioned, I like and use NRA type 50/50 lube. First test is simply does the bore still lead up and only loaded 5 rounds. I used what I felt was a light charge of 11.0gr Unique. Might as well get the bullet nearer the rifling, so I make the oal 3.15". My roller easily chambered the fatter bullets. 5 shots and NO LEADING...I am happy. Bonus: the accuracy is MUCH MUCH better than the custom ammo, as in converted to approximate a 100yd group (I was shooting closer to accommodate my old eyes) it was 1.45" and the windage was right on. I had fully intended to go in future groups higher in charge weight and use other powders, such as 5744 until I found an accurate load, but decided to reload my 20 empties with the same 11.0gr Unique and shoot some more due to the nice accuracy shown with the one 5 shot group. The load felt mild, certainly not with the thump the custom loads had (maker said they give 1300fps); have not choreographed my load yet; guessing between 1000 and 1100fps. Today fired the 20 rounds of my load. Could not see any leading and hit the targets...I'm really happy.
Loaded up 20 more of the same load. Did find that after 3 firings that the brass needed a minor neck resizing (looked like the Lee sizing die sized down about 1/16" from the case mouth; decapping pin didn't even punch the fired primer out) to better hold the bullet. Deprimed with Lee decapping die. Had bought RCBS #22 shell holder as the Lee one is suppose to be too tight for some Spanish brass, but the JBA brass fit in the Lee holder just fine...oh well, leave one holder in the press and the other in my priming tool.
Ladies and Gentlemen, I've learned so much from this forum, and I thank you all. Hope my story helps a future 43 Spanish reloader.
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Originally Posted by Der Gebirgsjager
