Casting a bore lap

[Jim Flinchbaugh]

My searches came up empty so I'm gonna ask. I'd like to cast a lap to get the kinks out of my Redhawk. Can someone point be to a thread about making the lap or describe the procedure? A simple 1,2,3 type of description is sufficient
TIA
Jim

[Wolfer]

My RNV had a tight spot under the threads. I firelaped about 60 rounds but still had it.
I cut most of the bristles off of a bore brush leaving all the bristles on the very end.
Put a patch on the bore and push the brush in until only the threads are sticking out.
With a rag tied around the barrel ( in case of spills ) pour your lead almost to the top.
You can then screw a rod on it and slide it about halfway out and apply lapping compound. It's very easy to feel your tight spots and work on them. As your lap wears out just stick it in the melt till it melts off and repeat as needed.
Good luck, Woody

[leadman]

I've done basically like Wolfer but used a jag, plugged the bore below it with a tight patch. Pull the lead part way out and cut some rings in it to hold a little more lapping compound.
Think I read this was the way Harry Pope lapped his barrels.

Probably many different ways to get the same results. Good Luck.

[looseprojectile]

of experimenting will get you a pound of experience.
You are working with a larger caliber. That is good.
I heat the barrel and make sure that there is no oil on anything. It don't hurt for the lap to have a few wrinkles in it. [holds the compound] Burn the oil off the bronze brush with a propane torch. Use the same torch to heat the lead in your ladle.
I like longer laps, such as four inches. Gives you a longer stroke without it comming out of the barrel.
The smaller bores like seventeens are a bugger to deal with. Did a 17 caliber pellet rifle the other day, PITA. Helped enormously! Was rusty.
All I have and use is #280 grit compound and it is all I need.
I use a ball of aluminum foil for a plug.
Be sure to report how it went.

Life is good

[looseprojectile]

You haven't reported how it went yet.
So, how did it go?

Life is good

[Arctic Blues]

Good thread!

Thanks fellers :)

[Big Rack]

If you can try Gunsmithing Tips and Projects by Wolfe publishing I have a 1989 copy page 263 is the start of a article by Veral Smith "Correcting the revolvers critical dimensions" has that and a lot more. I'd scan it but my wonderful all in one printer won't do squat when the ink runs out.

[B R Shooter]

There has to be a secret to casting a lap, getting the compound on the lap, then getting the lap back in the bore. The lead will only shrink down but so much, not much clearance there.

[calaloo]

You don't pull the lap completely out of the bore. Cast it about 4 to 5 inches long. There will in all probability be wrinkles in the casting. Carefully pull the lap out leaving about an inch in the bore, butter it with the compound and have at it. Put a stop on the rod so it doesn't come out the other end. It's a Hillary to get back in.

[B R Shooter]

Well, OK. So you're saying there will be enough imperfections to get compound in? You ave to use a fairly rough compound grit. It has been said that a bore that is too smooth will copper foul. (I'm talking target grade barrels here). One maker I have talked with says to stay around 180 grit, no finer.

We certainly know, a finer compound takes less space and therefore could be used in the tight space. Perhaps a start with a finer compound then go rougher.

[Sensai]

I just use Kerrosafe. It shrinks enough to get started with the abrasive of your choice and wears down by the time it would get back up to full diameter. It's also a lot easier working with low melting point alloy than 450+ degrees. Maybe not the best way, but it's the way I do it.

[nanuk]

I read that when your lap wears, instead of melting another, just put a brass rod in and tap on it to expand it and continue....

IIRC, you load the lap, work it till it is loose, re apply grit, pull into the bore, and tap it some to enlarge it, if it feels too loose, tap it again...

I've not tried it, but have some barrels to practice on, just need the time. Cerrosafe is an interesting alternative.

[uscra112]

I just use Kerrosafe. It shrinks enough to get started with the abrasive of your choice and wears down by the time it would get back up to full diameter. It's also a lot easier working with low melting point alloy than 450+ degrees. Maybe not the best way, but it's the way I do it.

+1 on Cerrosafe. Haven't even thought about using lead since I first tried it.

[deymorin]

Does hand lapping distort the shape of the lands?