How to make a sulphur chamber cast


Beginners guide on how to make a .303 chamber cast

I hope that this is of some use or help to anyone who is wondering how to make their own chamber cast for their .303.

Read all of this first, as I’ve included some hints you may want to prep for in advance.

I still have the first chamber cast that a good friend of made for me a while back. The whole technique and method seemed extremely clever and masterful.  Well, that was because the bloke who did it was, and is. This however this was in slight contrast to my first attempt.  I made a couple of small mistakes of which I hope to spare you from and show you that anyone can successfully make their own chamber cast as well as another option to consider.

Things that you will need

Sulphur, go to your local hardware or garden store. I bought a 600g packet of “Flowers of Sulphur”, it cost me I think around 7-8 dollars. This should last you for ages, as when you have finished with a cast you can break it down and use it again!


A heat source, I used a propane gas torch, you could and should use any GENTLE heat source. In the future I will use a gas ring cooker that I melt my lead with.

A small pot for melting the sulphur in. Make sure it has spout from which to pour from, it needs to be able to accurately pour into the chamber. I made my pot out of a simple can, works rather nicely actually, I will add a handle later but I used a pair of slip jaw pliers. The handy thing is once you have finished pouring the mix you simply put it aside, let it cool and set. So next time you want to make another cast you already have it ready to reheat!


1st hint, make a lid that will fit over the top of the can to form as good as possible seal. Should the sulphur catch fire, then simply cover with lid, the ensuing smoke will extinguish the fire. Then let it sit for a minute and resume.

You will also need an appropriate cleaning rod, patch(s) and oil, and also a mallet.

Ensure you have an uncluttered space to work in. When working with lead or items like this I’ve got into the good habit of wearing leather gloves and safety eyewear, also suitable clothing including footwear. Also VENTILATE the area, if in a garage open all the doors (leading outside! If you have a garage that has internal access to your home, close that door,) If you have kids or dogs about make sure they are not likely to get in your way!

Remove the bolt from the rifle and oil the barrel. Not excessively mind you, but run an oiled patch through as this will make extraction so much easier and save damaging the cast. Also oil in the chamber where the case sits as well. Afterwards dry patch this area as you do not want oil in this area.

With that oiled patch, place it say an inch past where the end of the projectile would end when a round is chambered in the rifle. Make sure that you have a good portion of the area you want to make a cast from, but don’t overdo it.


Place the rifle aside. Remove the jag from the cleaning rod so that you have the end of your cleaning rod exposed. It has an even surface that will nicely distribute the impact from the gentle tapping as we push the cast out.

Pour in some sulphur powder, say a ¾ of a cup into your pot and gently expose it to heat, you can use a butane gas torch, but again like I said, next time I will use the gas cooker.


The good thing about using the cooker is it that it allows you have a hand free, as you’re not holding both items. But, if you do use a torch, don’t hold it in one spot too long as it will easily burn and catch on fire! If that occurs, simply get the lid and place on top! Again let it sit and cool to a safer level and resume.

Soon you will notice some of the sulphur will bind or clump. Continue moving the can with a circular or rocking motion as this will allow even heat distribution & soon the sulphur will completely melt. It may be a bit grainy, you can stir it a bit to help break up any lumps. You are ready to pour.

2nd Hint, don’t over fill the chamber so that you fill the channel on the side of the barrel where the extraction claw goes into when the bolt is closed. You don’t need to go that far as it will form a seal that you will have to break in order to remove the cast. You will see in the image below that at the rear of the cast another small piece of sulphur, thats the result of too much mix in the chamber.


3rd hint if you can, get someone to hold the rifle whilst you pour. The rifle needs to be muzzle down butt up. If you are unable to get someone, then put the tip of the barrel on some rags on the ground to protect the crown and use a vice or similar to hold the stock of the rifle, I have some cork tiles that I have made into blocks to protect the wood. You can hold the rifle and pour the mix yourself, but it’s always easier to have it held in place.

Pour the mix into the chamber filling just below where the case rim would sit. Put aside the pot and turn off the gas to the cooker.The mix will set very quickly.

Change the position of rifle in the vice from the vertical to the horizontal. Now gently insert the cleaning rod into the rifle from the muzzle end, you will feel it come into contact with the patch. See if the cast will come out with a bit of firm pressure. DONT force it, it can be brittle and after all this effort you don’t want to break the cast! If it is hard to remove, a gentle series of taps with a mallet will do the job, but again carefully. You will just need to be careful with the trigger sear that it doesn’t get caught against that as you remove the cast.


Depending on the groove number it can be awkward to gauge, however, do your best, it will give you a very good indication as to what is going on in that barrel.

Tips, Sulphur will shrink around 0.002 – 0.003, you can halve that by adding graphite

What I didn’t like and would change.

I would add graphite so to reduce the shrinkage and to help see what I’m looking at, the yellow visually to me was a tad awkward and the graphite turns it to a far better grey colour.

I’m also toying with a lead cast version which I will “how to” in the next few days.

Also for demonstration purposes I will use something other than an AGP ball burnished P14 barrel, doesn’t really show what I was intending so I have included an image of a casts we did some time ago.