Apparently, the bolt for a .22 rimfire 73 is an item that is very difficult to find. When a part cannot be found, the only choice is to make one, which is what, through photos, I will describe in this post. The original bolt and extractor were "modified" beyond salvage but, luckily, the customer had another rifle that could supply a bolt to use as a model.
The bolt itself was machined from a bar of 1018, while the extractor was made from 1095 and heat treated as any other spring.
The new bolt installed.
This is probably just another job for you but most of us are beyond amazed at your abilities.
ReplyDeleteThank you for the compliment.
DeleteNo heat treat on the original?
ReplyDeleteSince your question wasn't more specific, I'll give the long answer.
DeletePlain steels of such a low carbon content are not, on their own, "hardenable". The only heat treatment options for these steels are: annealing, normalizing and case-hardening. Some small increase in properties can be gained by normalizing, but if a hard surface is required, then carburizing (adding elemental carbon at the surface) followed by case hardening would be necessary. The original bolt is not case hardened. It is, in fact, quite soft. The temperature of the bluing process used at the time would have negated the benefits of any surface hardening treatment.