8mm Lebel to .41 Swiss Cartridge Conversion

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If you own a Swiss Vetterli than you’ve most certainly discovered the unique rimfire cartridge it was designed to fire – and it’s been obsolete since around 1942.  That is unless you either purchase from a vendor converted .348 Winchester or 8mm Lebel brass converted to 10.4×38 (41 Swiss) or you manufacture it yourself.  Similarly, you’ve probably discovered that the bolt itself must be converted from rimfire to centerfire.  While this is not a tutorial on bolt conversion, it is however a method that will work to convert 8mm Lebel brass cases to 41 Swiss with relatively little effort. A great link concerning this rifle can be found here: Click me.

For starters however, a few years ago I purchased from an online vendor some already converted 8mm Lebel brass cases when I purchased my first Swiss Vetterli.  At the time I thought it was great – I’ll get this ole’ girl shooting again.  I acquired all the tools needed to reload the cartridge such as Lee Precision reloading dies, bullet mold and even converted the bolt from rimfire to center-fire.  However, when I received the brass from the vendor I discovered that the vendor, through the conversion process, over flared the case mouth to point of which there were splits in the neck and the brass itself was too short to feed through the feeding tube and into the chamber with any reliability.  OK, I figured I’ll just single feed it into the chamber just to get it shooting – but that got old and the brass quickly wore out due to the split necks.  Well, it’s time to make my own and develop a way to avoid the split necks and have reliable feeding cartridges.

As I’ve mentioned in previous cartridge conversions, we can go into detail about the cartridge specifications and the history – but why.  That information is well available on the web and in books and can readily be researched without me reiterating it to try and look all “technical”.  Let’s again just say – this will work; so enough of the “technical” stuff – lets convert some brass.

Let me start by advising you that if you’ve purchased the Lee Precision 41 Swiss Die Set you may be experiencing some issues with the seating of your bullets.   I found out the hard way that the bullet seating die is too narrow; that is – where the bullet rises through the milled hole inside the die.  Lee Precision likely milled it to ~.425″ since the original 41 Swiss bullet was .425″; and if you’re loading bullets larger than .425″ you may find the bullet being seated prematurely as it will catch on the rim of the hole inside the seating die.  To resolve this problem simply use emery cloth wrapped around a wooden dowel chucked into a handheld drill and lap out the hole until your bullet passes through the hole without obstruction.  Another issue with the bullet seating die is trying to seat the bullet to the required 2.2″ overall length while obtaining a taper crimp high enough on the bullet to ensure a deep enough seat and provide good bullet tension, at the same time.  To resolve this issue, remove the bullet seating knurled knob and inside will be the seating stem – somewhat cone shaped.  File the larger round end off a few millimeters which will allow the knurled seating knob to be screwed in deeper before it contacts the nose of the bullet (this is particularly useful if you are loading a flat-nosed bullet versus a round-nosed).  Also, you’ll need a #17 Lee Precision Shell Holder.

The first step is to trim the 8mm Lebel case down to the proper length.  The original 41 Swiss case length was 1.5″ (38 mm), however the Vetterli’s chamber throat is rather long and we want to leave some extra on the case length if we need to later shorten the case later – after fire-forming.  Therefore, I chose to trim the case anywhere from 44.9 mm to 45.0 mm.  This should give me some play room for the final case length; in addition as we fire form the case the overall length will shorten as the case is fire-formed to the chamber (we’ll lose approximately .3 mm).

The second step is to remove the decapping pin from your 41 Swiss sizing die.  Failure to do so will destroy the case since the 8mm Lebel case mouth is simply too small to expand to the 41 Swiss without destroying the case with the decapping pin.  Once the decapping pin is removed, raise the ram of your press and screw your seating die in until it touches the shell holder.  Next, lube your case (I use RCBS case lube) and insert your case into the shell holder and run the 8mm Lebel case up into 41 Swiss sizing die to begin forming the neck of the 41 Swiss brass.  To the left, you see the case prepared to enter the sizing die with the decapping pin removed, on the table.

Trimmed and Sized

Here you see the case after it has been trimmed, chamferred, deburred and sized in the 41 Swiss sizing die.  Notice the new neck started for the 41 Swiss – the small, upper part of the neck will be later expanded through fire-forming.






Next, we’ll need to anneal the case to allow the brass to expand inside the chamber when Annealingfire-formed.  Failure to anneal the case will most certainly result in a destroyed or split case.  The annealing process is simple.  Using a propane torch, evenly heat the case neck and shoulder to the point the brass begins to glow a dull red.  Do not over anneal the case.  Once the brass begins to glow red simply drop the case into water to cool it off.  I use a hand drill with a socket attached to hold the case as it rotates in the flame of the propane torch.  This allows the brass to heat relatively evenly, and then simply tilt the drill to drop the case into cool water.   We then need to either let the cases dry overnight or place them in an oven at a low temperature (ex. 150 degrees F) for about a half hour to dry any water that is inside the case (otherwise we’ll get a pfftt instead of a bang when we pull the trigger).

To load the case for fire-forming, seat a large rifle primer in the case and load 12 grains of Alliant Red Dot.  Next, fill the remainder of the case with Cream of Wheat (or other filler) leaving approximately 1/4″ space on top.  Lightly pack the corn meal with a pencil or wooden dowel.  Cover the Cream of Wheat with wax (either by melting it – which is messy or pushing wax or bullet lube into the case mouth to make a seal) or Elmer’s Glue and let dry overnight.  We simply want to keep the Cream of Wheat in place as we fire the case – otherwise we’ll have a mess in the chamber.  Load it up and fire it off.  It should result in a nicely formed 41 Swiss case and no splits if done correctly.  Below is the result of fire-forming the case – perfectly formed to your rifle’s chamber.



Now that the case is formed we need to load the case.  I have chosen to cast my Vetterli bullets from the Lee Precision Mold C430-310-RF using soft lead (BHN approximately 5).  Softer lead will obturate as it’s fired (hopefully) enough to seal the bore of my rifle which slugged at .433″.  Note: After fire-forming the case length went from 44.95 mm to an average of 44.63 mm (as mentioned earlier – we’ll lose about .3 mm length fire-forming).  So, my new cartridge is not really 10.4 x 38, but rather 10.4 x 44.6.  Each person may wish to experiment with their own rifle to determine what case length works best in their own rifle.





Ironically, this length worked well in my rifle once I seated the bullet and tested it in the chamber.  It worked well in respect it allows me to seat the bullet at the 2nd crimp groove from the top, allows for a deep enough seating which allows the case neck to grip the bullet well after it’s crimped, and gives me the necessary overall length of 2.2″.   Now THAT is what I wanted to see, no splits and long enough to seat the bullet and still chamber without any problems!


I know there are many ways to “skin a cat” – but this is how I’ve chosen to convert 8mm Lebel Brass to 41 Swiss Vetterli.  It works good for me and I’m happy with the results.  I hope you find this information valuable and maybe you can get that ole’ war-horse shooting again.


Safe Shooting!


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