Any simple fix for a barrel crown at the workbench?

[GrocMax]

An appropriately sized steel ball glued on the end of a small tube and a dab of good lapping compound does wonders for crowns with a chamfer. Start ~220 grit work up to 400+.

[MrMajestic]

PTG makes crowning tool with appropriate brass mandrels. I have shorten many barrels and re-crowned with it, by hand, and have even bettered accuracy on many with never a loss. Just my humble experience...

[ben lurkin]

https://4drentals.com/product/muzzle-facing-tools/

I used this to fix up a miscut crown on a Cz527 Varmint model I owned. Use plenty of cutting oil and clean the barrel often so you don't scratch up the rifling with the cuttings and it works very well!

[Centerfire]

I don't understand how I can use any kind of a tool with a pilot that fits inside the bore. I figure a snug spinning pilot is going to wear down or scratch the bore lands.

Probably any kind of a screw with a round head on it (brass or steel) with lapping compound would do the trick if I drill and spin it on the end of the bore for a long enough time.

[GrocMax]

Pilot bushing doesn't rotate in the bore, reamer or tool rotates in the pilot bushing. They don't scratch unless you pick one that is too tight, and that is from going in and out.

[Bill K]

Originally Posted by Centerfire

I don't understand how I can use any kind of a tool with a pilot that fits inside the bore. I figure a snug spinning pilot is going to wear down or scratch the bore lands.

Probably any kind of a screw with a round head on it (brass or steel) with lapping compound would do the trick if I drill and spin it on the end of the bore for a long enough time.

You can save yourself a lot of worry and see what is needed, plus view some of the videos available, showing what and how to service the crown on a barrel, Centerfire. Brownell's, for one, has the tools and instructions, which are not at all complicated. Bill K

[Centerfire]

Originally Posted by GrocMax

Pilot bushing doesn't rotate in the bore, reamer or tool rotates in the pilot bushing. They don't scratch unless you pick one that is too tight, and that is from going in and out.

Ahhh....ok that makes sense. By just looking at a picture of the reamer, I couldn't tell that the whole thing wasn't one solid piece that spins. Now I got it. Thanks.

[rick w.]

For crowning, I have a lot of faith in the nice lathe and proper cutter. That said, gotta have access to such in some form or another. Lathes and experience can get expensive to the user.

Next, one might consider a piloted specialty reamer. Bushings can be had in any size you wish. Knowing the right size bushing to order for most is the issue if kinda sensitive to such. Not overly inexpensive, but do a nice job with patience.

The grease with fine grit is an old method. I have never done it myself; as a lathe sits in the garage; just the way it happened here. It would be hard for me to put a steel screw head to a crown, remembering that barrel steel is pretty soft. Any burr on the harder surface will mark thru the compound I am fairly sure.

All in all, one might consider shooting the rifle as is and see the results. Does it allow a q-tip to pass without fliers off the q-tip?. Think I would still shoot it first and rely on research if it does not shoot up to expectations.

[Alan in GA]

have you shot this rifle yet and tested for accuracy? Scratches inside bore don't always affect accuracy unless possibly at the crown itself.
Shoot it first.

[Centerfire]

Originally Posted by Alan in GA

have you shot this rifle yet and tested for accuracy? Scratches inside bore don't always affect accuracy unless possibly at the crown itself.
Shoot it first.

The advice by George, Hal, Danny and now you, is proly correct. It's a superficial machine mark below the surface that likely means nothing. Bore is whistle clean otherwise. No, I haven't fired it yet, and decided not to. Heart's just not into a 221Fireball. I'll put time & money into this stock & action later by making it a 20Vartarg I've always wanted. Thanks again guys.