Annealing

[17 squirrel]

Saw this post on the excellent saubier .com and with the permission of tilleyman ( cheers Graeme) have reposted it here on the excellent UKV. Full kudos to RWS for taking the time to look and reply, i can think of a couple of companies that could learn from that. The ozzys love the .17s

 

I had problems with shoulder splits on some RWS cases to reformed to 17 Hornet, so I sent them off to RUAG Ammotec GmbH Technical Laboratory at their request.

 

They performed a series of detailed tests and determined my annealing technique was faulty, leaving the case too hard:

 

 

When we anneal our cases for the last time the color of the brass turns into a cherry red (approx. 600°C). We reach that color by annealing with a induction heated coil. We also anneal the cases between every forming step to make them soft enough to prevent a split in the case when they get formed again. Then we just let them cool down in the air. We control our annealing process directly by measuring the material hardness.

 

I spoke with our master of case production today.

He told me that your rotating of the case when you heat them, is a good idea. He also thinks that you should warm them until they are cherry red and don´t cool them down in water immediately. You should try to cool them down in the air just as they are. It is no problem when you can´t hold the case with your hands at the bottom during the annealing process. A sign that the bottom gets too hot is when the body of the case changes the color. It is important that the annealing happens quite fast (hot flame), precise (just the shoulder) and constant around the whole shoulder (turning of the case).

So there you have it from RWS direct... I modified my annealing technique and haven't suffered a single split case since.

[17 squirrel]

Hope you find it interesting. For some reason this disappeared from the bottom of my last post.

[phaedra1106uk]

600c (1112F)?, if the cases are visibly glowing red they're way over temperature and will be over-annealed resulting in weakened brass.

 

Annealing should be applied to the case neck not the shoulder at around 750-800F.

[JSC]

Why were you quenching them in water?

[VarmLR]

I didn't think where brass was concerned that quenching in water hurt the annealing process, as it would with other metals, where quenching hardens them? I also anneal by turning the brass (in a cordless drill) and use a hot flame applied to the neck only until the colour changes to a dark blue (they don't all seem to darken, in which case I only hold the case in the flame for the same length of time as for the cases where it does) and I immediately remove the case from the heat and quench. Not yet suffered a split case, but am I then doing something wrong here? I appreciate that there's no need to quench. I do it to reduce risk of burns!

[JSC]

OK, NP it's just that some people think quenching is necessary for case brass because it is for other types of brass with different ratios of Cu/Zn.

 

You really need to get hold of some Tempilaq indicator paint so you can estimate more accurately the temperature you're getting the brass to.

 

Too much guesswork at the moment IMO.

 

Also, someone is getting their °C mixed up with their °F! Target temperature for a quick anneal (so you don't heat up the lower part of the case too much) is around 750°F (400°C).

[Tenex]

Hello lads. Just been reading though this post and thought you may find this interesting.

He anneals them too much but the idea is brilliant.

[1066]

Hello lads. Just been reading though this post and thought you may find this interesting.

He anneals them too much but the idea is brilliant.

 

 

The originator of this idea was a Swedish chap who's youtube handle is "Mr Longrange". The basic idea was developed into a good working machine by an Australian guy "Skippy". Skippy published drawings and parts lists and called his machine Black Betty. Dozens, maybe hundreds of Black Betty's have been made. The design has continued to evolve into quite a slick simple machine.

 

Here's a later version:

.https://www.youtube.com/watch?v=tBUBOdxHgho

[Tenex]

Ya just got to have a go at making one haven't you

[Martin52]

FWIW, my timing for .308 Lapua brass is 6 seconds using a single bernzomatic torch with Mapp gas, not propane. The 450 deg tempilaq melts to about 1/4 inch below the neck shoulder junction. Some cases change colour and a blue ring is evident, but sometimes not. I do not find the colour change to be a reliable indicator. Testing for springback on the case mouth using mole grips and very light tension, just enough to deform the case mouth, suggests 9 seconds but at that point the neck is clearly a cherry red and the tempilaq has melted to about 1/2 inch above the case head. At 6 seconds the case mouth can still spring back so the case may well be under-annealed however the tempilaq indicates the case body is still OK. More work to do !

 

Martin