coning

[holstil]

I ordered my lathe last week so I could learn how to chamber my own barrels. It'll be a while til I get the power to it. Now I'm trying to better justify this purchase by finding things to fix. One thing that really bothers me is a Cooper chambered in 6br that doesn't like to eat. I'm curious if I can give her some table manners with a cone job? I figure it would only take a couple .030 to .060. If this can be done, how would I do the bolt? Make a fixture of some sort and chuck the bolt in the tail or steady and spin a cutting tool? Anybody coned a factory rig outside of buying an after market bolt? Oh yeah, it's a three lug, sako style ejector.
Jim

 

[mps5949]

Give Neil Jones a call at 814-763-2769. He is the smith that took my factory remington action and converted it to a sako style with coning on the bolt face and the chamber. Feeds well.

Mike

 

[holstil]

I appreciate the heads up.

 

[Preacher]

Neil Jones did the same thing on a 40X I have thats chambered for a 22/284, one of these days I'll get around to shooting it if I don't sell it first.......
Coning the bolt is easy enough to do if you have a threaded mandrel for the entry, and support it with the tail stock......

 

[rayjay]

You need to be making stuff like the bolt mandrel. Great practice for doing threading and shoulders, etc. Midway has a book called The Gunsmith Machinist. IMO a lot of the content is a waste of space but the on topic content makes the book worthwhile. In it is most of the info you need for working on the bolt.

I have gotten into the habit of sliding my cartridges all the way into the chamber instead of just sitting them on the loading ramp [ talking single shots here ]. This way when I close the bolt I know it's not going to stop. Even the coned bolts have a small part of the bolt face that is flat.

ETA: I don't recommend using a live center in the firing pin hole. Use the steady rest.

 

[rayjay]

Here is a pic of my bolt mandrel that I made after reading that book. In the second pic is a tool I made for lapping the locking lug abutments in the rec. It also can be used as a coarse check to see how straight a rec is. I found this out when I went to make these pics. I had already assembled the 40x that I lapped with the tool so I used a 700 rec that I had on the bench. This rec is so crooked that the tool won't go down beyond the rec face !!!

 

[holstil]

rayjay, thank you for the pics and info. I can see now the difference between a bolt mandrel, threaded into the back of the bolt and a bolt fixture, clamping to the side of the bolt,as seen in the Brownells catalog). Please correct me if I have something wrong.
I think I will enjoy making these items.
It is fun to learn a new trade. I have a little experience with a lathe and Bridgeport, but my training is layout and fabrication of steel with a little welding and optics thrown in the mix. I think this will be an excellent addition to make things. My 4yr. old daughter says we're tinkers.
May I pm you you with questions that arise?
Thanks Jim

 

[rayjay]

If you post questions here on the forum everyone can participate, both those with the knowledge and those seeking it

 

[gamma]

Rayjay,whats the thread pitch on that bolt lug truing fixture and are they standard 60 degree.
Thanks.

 

[rayjay]

Remington's and clones use 1/2x13 60 degree threads. You have to turn the mandrel each time you use it. I would suggest getting the book mentioned earlier. It has step by step instructions on truing an action including the proper use of the bolt mandrel. The mandrel is used in conjunction with the steady rest.

When turning a bolt in a lathe be very careful. The bolt handle at the very least could hit the tool post or carriage possibly destroying the bolt. At worst it could hit the lathe operator.

 

[Stoner25mkiv]

I would suggest getting the book 'The Complete Illustrated Guide to Precision Rifle Barrel Fitting' by John Hinnant, also offered by Midway. It has just about everything you'd want to know on the subject, along with detailed prints for machining all the neccessary tooling you'll need.