Ghetto style barrel crown lapping

[oafpatroll]

I have two .22 barrels that have gritty crowns so looked at what cutters and bore guide combinations cost some time back and decided to live with them as they are. Then I read something about lapping crowns with a ball bearing and that peaked my interest. Found this writeup which i think sounds like a way of achieving as precise a job as you are likely to get without real tools and tooling.   

[Tripodmvr]

I have seen an article suggesting the use of a de-burring tool.

[oafpatroll]

I have seen an article suggesting the use of a de-burring tool.

Do you mean a cartridge case deburring tool?

[Tripodmvr]

Correct, yes.

[oafpatroll]

Interesting idea. My concern with it would be how to keep it perfectly aligned which cutting. Not sure that i rate myself to get that right by hand.

[Treeman]

when you say gritty, just how bad is that - got a picture perhaps. My old gunsmith Gerry Schults of GS Custom fame, showed me to use some sand paper/water paper and thumb to make old .22 crowns (which seem to always be gritty) shiny again. Mine were just not smooth, clean and the thumb and water paper worked fine.
 NO LOSS OF ACCURACY

[oafpatroll]

The one barrel has a few noticeable gouges and a small burr. The other is just roughly finished. The sandpaper idea doesn't sound like what I'm after because there'd be no way of keeping the dimensional accuracy, i.e. concentricity with the bore and squareness, of the crown unless all I was doing was polishing. Since, at least in the one, I'll need to cut some metal I want something that will allow me to keep it as honest as possible.

[Kola]

Once cut, I use a round head brass screw and lapping compound with the cordless drill to polish.

Cutting precisely if it is rough enough to need that is going to be the challenge.

Edit.
I 'cut' a crown with a Dremel in a jig I made to align the Dremel with the bore, using a round grinding stone.
Then polished as above.
Worked well.

[Treeman]

Bit off subject, but! I seriously doubt the crown on a .22 does much cause and effect, just not enough going on nor enough expectations at play - unless we talking a 200 m type .22

We were shooting 304 m shots with .22 in Aus, 1 lt milk cartons.
They love the long range nonsense hunting, my brother shoots deer at 1 km - 1000 m using a 30 06, the free game allows for this and it is quiet a big following. The one bloke we shot with uses a 243 for the 1000 m ?
 

[Tripodmvr]

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiGsvuO5ISAAxXQX8AKHbUlBtoQtwJ6BAggEAI&url=https%3A%2F%2Fvimeo.com%2F352949469&usg=AOvVaw2CkMKZI7dIcEVz1urKOCMO&opi=89978449

[oafpatroll]

Thanks for all the inputs. I'm not expecting this to make a significant difference to accuracy but if it does that will be a bonus. The worse of the two is already more accurate than I can take advantage of with my level of skill. Main benefits I'm looking for are to learn how to do something with makeshift tools and make the otherwise near perfect guns look that little bit better. I've done lots of valve grinding so the technique looks t=like one I won't struggle to get the hang of and the ability to pick a bearing diameter to achieve a specific crown angle is appealing. If I make a two angle crown I can start with a smaller ball that that will be a closer and hopefully more precise fit in the bore. Once that angle is cut it will in turn help align the bigger ball for the second angle. Will give it a go and report back.

[Treeman]

Thanks for all the inputs. I'm not expecting this to make a significant difference to accuracy but if it does that will be a bonus. The worse of the two is already more accurate than I can take advantage of with my level of skill. Main benefits I'm looking for are to learn how to do something with makeshift tools and make the otherwise near perfect guns look that little bit better. I've done lots of valve grinding so the technique looks t=like one I won't struggle to get the hang of and the ability to pick a bearing diameter to achieve a specific crown angle is appealing. If I make a two angle crown I can start with a smaller ball that that will be a closer and hopefully more precise fit in the bore. Once that angle is cut it will in turn help align the bigger ball for the second angle. Will give it a go and report back.

***************************
Sand paper on thumb boet, it works and is more accurate than your .22 can detect negatively. If I were to do it any other way I would use different diameter grind balls, those round pink, blue etc balls of grind compound on a steel shaft. With the amount you removing it will not run off, the ball will self center and before any drift can accrue you should be past the little bit you want to remove - then thumb and water paper to polish. Its 0.0? you wanting to remove, i do not believe the amount you removing will affect accuracy even on a rifle, its just too little.

[223]

The problem with free-hand crown lapping methods is that there are many opportunities for the process to apply the cut unevenly.  These being any possible unevenness in the thumb, ball or stone used to do the job, as well as things like gravity and the angle the barrel and tool are held at.

To get the lapping perfectly concentric to the bore, it may help to chuck the barrel in a lathe and clock the muzzle up properly.  Then, with the barrel turning at a relatively slow speed, you can apply whatever method you choose.  The centered barrel will ensure all polishing is done evenly and concentrically.  Yes, I know we don't all have access to a suitable lathe, but we all can find someone who has the lathe and is willing to help, even if that may cost you a bottle of anti-freeze or something.

[janfred]

The ball bearing method is for people without access to things like lathes and clock gauges. Not everyone has buddies at a workshop...

Using a hardened steel ball bearing even though it is a poor lapping tool is because, unlike brass/copper balls or round head screws, it is extremely difficult for the ball to be worn out of round. The method described keeps the tool self-centered.

Using a drill to spin the tool (ball bearing) is also advised against as it works too fast and is difficult to keep the force applied in line with the bore.

First prize would always be to have a competent gunsmith do the work, but sometimes needs must.

[oafpatroll]

Janfred sums it up perfectly. The only person I knew with a lathe up to this task passed away years ago and I dont have the budget or a pressing need to justify having it done by a smith. I have time, patience and a range of grits of grinding paste and a box full of ball bearings. The method described in that pdf is essentially the same as that for grinding valve seats and I've done enough of those to be confident that it's doable. As mentioned above achieving bench rest accuracy isn't my expectation here.