Good DIY For Bad Forcing Cones

[Good Cheer]

Without a lathe to make tooling, anyone have a good DIY design for regrinding the forcing cones on revolvers?

So far I'm plotting on an all thread spindle, copper tubing to protect the bore, still cogitating on rigging up something to hold the grinding surface.

[rintinglen]

I bought the 11 degree, forcing cone, cutter tool from Brownells--not cheap, but use it twice and it'll pay for itself versus hiring a gunsmith. No need to have a lathe or a mill, it's a hand tool but precision results are readily achievable. I would think twice before attempting to improvise a means of doing this sort of work, for fear of creating an oblong or eccentric funnel and making things worse.

[Nueces]

A cutter is far better than a grinding stone for this job, as the cutter retains it's shape during use, and a stone will tend to wear to match the metal. The only way to make grinding work well for a forcing cone would be to rotate the barrel breech in a lathe and use a tool post grinder. Since that requires pulling the barrel, the cutter system is the way to go.

[charlie b]

If I were doing it myself I would send off for a reamer made for this job.

Using a stone in such a situation can easily lead to a ruined barrel. You would need to basically make a long shaft in a tube that closely fits the barrel, with as short a shank as possible for the grinding tool. Kinda like a mini version of a valve seat grinder that will fit inside a barrel. FWIW, I have seen many ruined valve seats from DIY types, and that is considered an 'easy' job.

Best---> send it to DougGuy.

[Bazoo]

I have a brownells 11 cutter, shaft, handle, bore guide, and brass lap. I use stickyback sandpaper on the lap to smooth the FC and it works great. 38-45 caliber. Anyways. If you want to borrow it I’m glad to loan, just pay return shipping.

[Good Cheer]

Gents, using a stone has never been considered.
Hopefully someone has been through the DIY creating process on this.

By the way (and not as though it really matters) the revolver I'm reworking is a Pietta 1858.
The way the factory cut the forcing cone, the top corners of the lands are actually moved a wee bit over into one side of the grooves. An eleven degree cutter would be wonderful if I had one.

[Good Cheer]

I have a brownells 11 cutter, shaft, handle, bore guide, and brass lap. I use stickyback sandpaper on the lap to smooth the FC and it works great. 38-45 caliber. Anyways. If you want to borrow it I’m glad to loan, just pay return shipping.

Bazoo, just saw your kind offer.
Yes, I'd love to.
Will send you a PM.

[charlie b]

...regrinding...grinding surface.


Gents, using a stone has never been considered....

Sorry, we just read your post and went from those two words.

Glad it sounds like there is a good solution for you.

[Jtarm]

You can rent the Brownells cutter from 4D Rentals.

[Bazoo]

I learned from over on Rugerforums.net it is pretty straight forward. You put the shaft down the bore, screw the cutter on from in the frame opening, oil on the cutter, I did a drop on each of the three cutter teeth. Then you slide the muzzle guide down the shaft, and then attach the handle. Put your muzzle guide in the bore and pull the handle which pulls the cutter into the forcing cone. Turn it with a light pressure. It cuts. Every half dozen turns you back the cutter out of the FC and check progress and remove chips from the cutter with a toothbrush, reoil and continue. When you get it where you want, stop. You want to remove all of the old angle so you don’t have a compound angle. But you also don’t want to open the breech end up so much that it’s thin. The 5 degree cutter would be better if it already had a 5 degree, so it will clean it up with minimal widening at the breech end.

I attached sticky back 600 grit paper to the lap, and use that to smooth the cutter marks.

[Martin Luber]

What is 4D rentals? Thanks

[MrWolf]

What is 4D rentals? Thanks

Rental place
https://4drentals.com/

[Jtarm]

In addition to what Bazoo said: check progress with a SIZED case. Stop when the case mouth will just barely enter the forcing cone.

Go too deep and you might have to get the barrel set back. Don’t ask how I know this.

[Good Cheer]

The first revolver in question (with bent over edges on the rifling lands) had the forcing cone beyond groove diameter so no question as to what needed to be done... Fix the lands and call it done.

Fixed a rough Pietta .36 caliber 1858 also. Polished the Walker. Checked the Dragoon. Going through all the forcing cones and seeing if anything needs doing.

Bazoo, thanks again. Will be back to you soon.

[Good Cheer]

Sorry, we just read your post and went from those two words.

Glad it sounds like there is a good solution for you.

I've used a formed wooden cone or conical stone covered with emery paper to adjust chamfers. I thought I might end up doing that sort of thing again. Having the cutter the accomplish the initial metal removal is much quicker, much better.

[Bazoo]

Glad to be of help.