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Molten Salt Annealing Rig

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Here's my molten salt bath annealing rig.  Shameless rip-off of a great idea from Ballistic Recreations 😁.  I needed a set up to fit my Lyman pot so I set about making one for .338Lap cases.  About £8 in stainless from eBay and salts from APC Pure for about £24.  (It helps to have a lathe).

Early development yet but looking good.  5sec at 520deg C at 20mm depth of salt is too long.  I found 3 sec seems to give the desired affect for a .338 Lap case.  A lot better than gas burners I think (I built one of those too).

I must admit it puts the willies up me a bit having half a litre of 520deg C salt in front of me. 😟  When melting the salt mix for the first time there's a bit of scum and fizzing as impurities are burnt off, the second melt was much cleaner.

Pics of results soon

Anneal 1.jpg

Anneal 2.jpg

Anneal 3.jpg

Anneal 4.jpg

Anneal 5.jpg

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Reading about exploding salts from moisture etc worries me!

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It should worry any sensible person!  However if you're sensible why not consider it.  After all water in the chip pan is a bad idea too 😁

 

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Interesting, my gunsmith is in the process of assembling the components for one. The salts are arriving today I think. I like the idea that you have exact control of the temperature.

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2 hours ago, Chris-NZ said:

Interesting, my gunsmith is in the process of assembling the components for one. The salts are arriving today I think. I like the idea that you have exact control of the temperature.

Yep, the temperature control is near perfect. Once you have the right depth of insertion for the case set, the only variable is the time and that's easy to manage.

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Hi,

got the salts from APC in hyde. Got the thermometer from eBay at a fraction of the company selling the complete kit. Just fancy not paying through my nose for the privilege. 

Only now need the plate to take my cases. Again don’t fancy paying $47.00 shipping to uk. Final option is to make one !

 Nick 

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36 minutes ago, Nick 53 said:

Hi,

got the salts from APC in hyde. Got the thermometer from eBay at a fraction of the company selling the complete kit. Just fancy not paying through my nose for the privilege. 

Only now need the plate to take my cases. Again don’t fancy paying $47.00 shipping to uk. Final option is to make one !

 Nick 

Yep, I got some stainless discs from eBay including stainless pop rivets and screws.  Setting the case depth is a matter of suck it and see.  Don't be surprised the salt mix is really scummy as it melts, it does get clearer as it heats to the final temperature.  PS, the case in my pictures was just for setting up, the cases must be de-capped before processing.

Good luck

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Here's some .338 trial cases compared to a brand new Lapua out of the box. The black line is to show the colour change as the pic is a bit poor in that respect.

3 sec seems to give sufficient heating to anneal and moderate heat transfer up towards the head. 5sec seems a touch too long.  The neck 'springiness' seems to be the same as the new case and definitely softer than the fired cases I have to compare with so I conclude (admittedly in a less than scientific case study) that molten salts at 520C work very well and are very repeatable.

Not bad for under £100 for the metal, new Lyman lead pot and chemicals (including safety equipment😀)

 

IMG_2184.jpeg

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Are you dropping them into water as you go?

Pete

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Apparently after salt annealing the cases need to be dropped into water,I have seen the salt annealing been done a fellow shooter has this set up.

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12 minutes ago, Re-Pete said:

Are you dropping them into water as you go?

Pete

Yes, straight into a bucket full, kept well away from the salt pot as a splash of water into the salt would be unpleasant indeed!  Water cooling has no relevance to the annealing process, it's just to clean off the salt carry-over. It's also convenient to have somewhere to put the hot brass.

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How much salt did you buy? I have the same Lyman pot and I've been trying to guess how much I'd need to get a decent depth once melted.

Pete

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4 minutes ago, Re-Pete said:

How much salt did you buy? I have the same Lyman pot and I've been trying to guess how much I'd need to get a decent depth once melted.

Pete

I find a total mix of 500g to be about right.  I did buy extra because it was economic and useful to have top-up as some is lost due to carry-over.

When you do your first melt the salts combine in a eutectic mixture and solidify in one hard 'puck'.  I suggest not leaving the jig in the pot, remove while the salt is still hot.  When everything is cold I take the pot out of the heating element and knock the 'puck' out into a plastic bag for storage as the salts are hydroscopic.

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There is an article on salt annealing on a web site Target sport shooting? Bloody brain can’t remember the correct title! It gives the amount of salt required to be mixed. Article is by a Paul Parkinson cracking read.

 Nick 

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1 hour ago, Nick 53 said:

There is an article on salt annealing on a web site Target sport shooting? Bloody brain can’t remember the correct title! It gives the amount of salt required to be mixed. Article is by a Paul Parkinson cracking read.

 Nick 

I use 50% potassium nitrate;  45% sodium nitrite;  5% sodium nitrate -  by weight.  At 500C there is no fuming I can detect.   Be careful about going over 550C things start to get 'exciting'.

I accept no liability for the correct mixture🤔

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Thanks.

Since Paul lives around the corner me we will mix the salt together.

( Preferably not in the kitchen) !!

 

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