Mould selection 43 span RB

[Marvin S]

Been doing some more measuring and thinking about which mould to buy for the ol RB and would like some opinions. Do I just buy the lyman that advertises 370gr .439 dia that is supposed to be for the 43 span or maybe buy the one they say is for a 43 mauser @ 340gr .446 dia. I can build my own sizer die to what ever size I want as my bore measures .442 at the front end and at the chamber end.

I just measured the neck/ throat with a telescoping bore gauge and got .463. That would leave me about .010 for case neck thickness. I dont have any cases yet to go by so what do you think. If I did just get the supposedly .439 blocks what do you think the actual as cast dia with pure lead would be.

I know im fighting the same problem that everyone does with these guns just trying to make a good choice from the start. Thanks to all.

[405]

These type guns, chambers, throats, bores are almost always a crap shoot.
Unless you get something really unusual the Lyman mold that claims to drop .439 diameter bullets will not drop bullets any larger than that. Chances are that it will drop something less than .439.... and that is going the wrong way. The diameters claimed are based on something like a Lyman #2 alloy. Pure lead or even a 20:1 alloy usually drop at smaller diameter than the Lyman #2. At least the Lyman mold I have that is listed for the 43 Spanish and at .439 doesn't even come close with my softer alloy. In the end I just "bit the bullet" and ordered a custom mold for my 43 Span. RB.

I have no experience with the fatter "Mauser" mold but it would surely drop at large enough diameter. The down side to the "Mauser" mold is the profile. Since the 43 Spanish RB is a single shot no need to go with such a large meplat profile unless you want to use it primarily for hunting and shorter range shooting. I imagine the ballistic coefficient suffers from the large meplat but.... hey... if your plans are for 100+/- yard shooting the accuracy could be very good!

[Don McDowell]

The RCBS mold I have drops from 20-1 at .446. I'ld recommend going with the .446 diameter and sizing down to .444
But just for kicks before you order a mold get a hold of some cerrosafe and do a chamber cast that takes in about the first inch of the rifling, so you can get a good measurement.

PS you might want to order a couple of boxes of different sized/styled bullets from Montana Bullet works before you order a mold. Sometimes 50$ for some bullets you can melt down later is a bunch cheaper than a 60 $ mold that won't work nuthin you've ever seen.

[Buckshot]

"my bore measures .442 at the front end and at the chamber end."

...........You mean groove, right? :-) Since you can make your own size dies, I'd get the Lyman mould. Once you've got the throat ID down you can size the Lyman down and then paper patch it back up. This is the boolit originally fired from it anyway. Via paper patching and sizing before or after patching (if required) you can match whatever you need.

You can paper patch while watching TV if you're so afflicted, as it would then make it productive time :-)

..............Buckshot

[missionary5155]

Good morning
MY RB measures right there also. I use a Rapine 400 grain RN that drops at .444+ with near pure lead. Also have the Lyman .446 which I size to .443 . Also have an origonal Lyman .439 lapped out to .442. All these shoot well cast with near pure . I had to turn my case necks thin to get the FAT bullets to seat. BUT it WORKS Nicely.
3" at 100 yards is about as good as either of my rifles will do. The HUge case gives ample space for 75 grains compressed 2F. I leave my boolits seated out about 1/8" and push fit the boolit into the chamber.
I do all my shooting off cross sticks with these shoulder mashers. Steel butplates and 155 pounds of bony body needs all the recoil help it can find.
The 43´s are bad mouthed by alot of people shooting small boolits in big throats. BUT the 43 was a military cartrige designed to be fired rapidly with BP under adverse conditions without stopping to wipe the bore every 5 shots. That it will do !
Mike in Peru

[Marvin S]

Yes bottom of the bore/groove. Do you suppose that the original cases had thinner necks? Ive done a search for Rapine moulds and find next to nothing.About what is the thickness of the modern case necks before and after turning. When you guys use the for instance 12-13 gr unique load do you use any filler? Many thanks guys.

[Buckshot]

http://www.fototime.com/23E5560C8BB6BF7/standard.jpg

Two powders (SR4759, H4198) and two boolit's (Lyman & RCBS) @ 50 yards.

http://www.fototime.com/7CD7CAD02940F78/standard.jpg

From my M1879 Argentine contract Remington RB.

The original load was about 70.0grs of black powder and a roundnosed 370gr paper patched slug. Like many other black powder cartridge rifles, the boolit was bore (land) size, or a few thousandths short of the groove diameter. The explosion of the BP charge would upset the soft lead slug to fill the grooves. Since smokless powder is progressive in it's burning, no sane load of smokless is going to upset the slug as BP did.

...............Buckshot

[76bronco]

Buckshot, are you paper patching these?

[Buckshot]

Buckshot, are you paper patching these?

...............Nope, never paper patched for the Argentine. Those fired in the targets above were the stock Lyman and RCBS grease groove slugs.

...............Buckshot

[Jeff7mm]

I also have recently aquired a 43 Argentine Rolling Block and will offer my experiances. If you can, do a chamber cast first. The reason for this is the variable throat diameter. I will discuss this firther below.

Another poster has already mentioned the folded head case and its effect on headspace. Correct brass can be obtained from Buffalo Arms and Track of the Wolf and both offer the advantage of buying only a single case if you wish. Track of the Wolf offers brass with two different rim thicknesses as well. It is reformed from .348 Winchester brass but dont get the idea as I did that if they can reform it, why should I pay $2 plus per case for something I can do myself.

They must be using some sort of arbor press which creates a raised portion on the rim to increase the rim thickness and radically resizing the base diameter which cant be done on ANY reloading press. If you dont break the press trying, you will split the sizing die, even if it did work you still have a case with a rim too thin to headspace.

I mentioned Track of the Wolf having two different rim thicknesses. A 43 Spanish case is identical to a .44-77 Remington/Sharps except the bullet diameter is supposed to be .446 for the .44-77 and .439 for the 43 Spanish with of course slight differences in case neck diameter. Track lists two diameters of rim thickness for the .44-77 as well as the 43 Spanish case. I ordered the 43 Spanish cases which are designed for original rifles and they were a perfect fit. If they are out of one order the other, both are made from .348 brass and one pass through the sizing die makes a 43 out of a .44-77.

Lee makes a die set at normal prices so dont pay the $100 plus others charge.

Now we discuss the neck diameter of the chamber. I found Grafs had some Jamison Brand 43 Spanish cases which were surprisingly considerably cheaper than the reformed brass. They are beautiful, thick, properly headspamped, and I was very happy until I loaded them and none would chamber. The bullets were sized .439 but the case neck wall thickness would not allow the round to chamber with a bullet seated. And you cant buy a case neck reamer in .43 caliber anywhere. Before spending the money on the Jamison brass be sure your rifles chamber will allow you to use them.

My bore diameter is .440 and I have been using a Lyman 370 grain mold as it is the only one listed near .439-.440 the mold has been a nightmare as the designer put a very thin base on the bullet with a tapered edge which refuses to fill out properly. Im getting 80% rejects despite 40 years of avid casting experiance. Temperature has been tried up and down, harder and softer allows tried, the mold revented, and the pour hole in the spue plate enlarged. Nothing has fixed that problem.

I have another Rolling Block in .45-70 which outshoots most of my scoped hunting rifles with it using iron sights and paper patched bullets. The 43 Argentine was built with paper patched bullets in mind and Im getting a slight edge with paper patched in it as well. I suspect the poor sights as compared to the .45-70 may limit my attempts to determine the potential accuracy of this rifle. It appeared unissued and I cant bring myself to drill it for a tang sight or cut a dovetail for a new front globe sight.

With the sight limitations in mind, Im not getting any difference in accuracy using black, pyrodex, or smokeleess, about 4 inch groups at 100 yards. Paper patching does reduce groups about one minute of angle.

The bullet mold problem was finally solved by honing out a Lee push through .430 sizing die to .434 which sizes out the base imperfections and allows a 9lb onion skin paper patch to .440 diameter. This rifle will not chamber a larger diameter bullet.

Smokeless data can be used from listed 45-70 data. When using smokeless bear in mind this was an 1879 contract rifle and while I consider it stronger than a Trap Door I wont use any smokeless load other than one listed as suitable for a trap door. Double check that listed load with at least one other source.

The factory specs listed this round as 1450 fps with that bullet weight and that is confirmed by my chronograph. A safe equivelent load is 26-26.5 grains of Alliant #2400.

[Marvin S]

Just curious as to why every one thinks I need to do a chamber cast when I have measured the neck area and I know this is an accurate measurement. What is the neck thickness of these different cases you speak of. Thanks to all.

[Jeff7mm]

It was a simple matter to determine that with the bullet seated it would not fully enter the chamber and a comparison of neck diameters with bullets seated revealed the thicker case necks. Im sorry I did not record the measurements.

[Marvin S]

I just got my cases in today from TOW, also a set of Lee dies and a small bar of cerosafe. I measured one neck and it was .012 wall. This will be probably cutting it to close for a proper boolit. Ive been working on building a mold, so far I have made one form cutter for lathe boreing and one cherry type from w-1 tool steel but have not heat treated them yet. I have made one set of mold block blanks and vented them but have not cut anything yet. Might work might be a disaster.