As I have decided to put an over size bolt knob on my Remmy 700 foxing rifle I thought I would post a few pictures of how to do this as I know a few of you may want to do this? This method is a much better method than 'chopping off 'the original bolt knob and the drilling abd brazing a threaded stud into the bolt handle as much stronger.
The first thing to do is grind one side off the original bolt, I use my knife grinding machine but an upturned belt sander in a vice will be ok, just remember to try and keep the ground surface flat as this will help you later and to keep COOLING the hot metal in water as you dont want to soften the area you are grinding. As the belts will be 'eaten' by the bolt you could use a grinding disc to take the lions share of the metal stock off the bolt and finish with the belt, I used 40 grit but anything below 120 will surfice.
Next once side one is flat you want to do the same to side two
Then mark a right angle from the side of the bolt, this will be the mark you will be threading up to and dont want to go beyond and is your point of reference.
After this is done measure the width of the bolt and find the centre and mark.
Now colour the shiny ground surface you have take the stock from and mark two lines taken from the edges of the bolt handle sides, they dont have to be super accurate it just to show you where your grinding to.
The next stage is to measure the thread size on your bolt know. So if the thead is say 6 mm you dont want to go any smaller than 8mm. This will then leave you with a square section of metal at the end of the bolt which is the old bolt knob which you ground away. Note that I made the mistake of attempting to round that section of metal then realised it needed to be square. The reason for this is when you are using the tap and die to thread the section it will need to be completely square as the threads you will be cutting will 'follow' this perfectly and so the bolt knob will screw onto the bolt straight and square, if it isnt the threads will 'wander'. This is important and I will need to square the bolt in the picture to do this. There is still enough 'stock' there to achieve this and so will post another picture when all is complete.
Ok thats it for now and I will post more pics when the job is done...hope that helps if your going to attempt this job..