Lapping Compound
- Thread starter Nick B
- Start date
Register to hide this ad
Sorry, but this post begs me to ask this.......
why would you want to do that, especially since your question is an indication that you don't even know where to start?
why would you want to do that, especially since your question is an indication that you don't even know where to start?
I'd suggest the 600. I got their 320 grit. which was a little too coarse, IMO.
Kuhnhausen's shop manual says to start with 320 & finish with 500. If you have a new cutter I think 600 will work with a good brass lapping head.
.
Kuhnhausen's shop manual says to start with 320 & finish with 500. If you have a new cutter I think 600 will work with a good brass lapping head.
.
I used 320, 600 and 800 but only because I had them. The 600 finish is probably sufficient, you need to go slow and check often. 5 micron is around 2800 grit, no real point going for a mirror finish since it will be etched by hot gases the first time you fire it.
It's a shame Brownells don't make a lap to match the S&W FC angle (8 degrees I believe) as this way you wouldn't need the cutter and would have more chance of keeping the FC opening in spec. Because the only option is 11 degrees you need to cut first other wise you will end up with a compound angle. If I had to do another I'd consider having a toolmaker turn up a brass lap to match the existing FC angle and just polish the tool marks out rather than change the angle then polish.
It's a shame Brownells don't make a lap to match the S&W FC angle (8 degrees I believe) as this way you wouldn't need the cutter and would have more chance of keeping the FC opening in spec. Because the only option is 11 degrees you need to cut first other wise you will end up with a compound angle. If I had to do another I'd consider having a toolmaker turn up a brass lap to match the existing FC angle and just polish the tool marks out rather than change the angle then polish.
Last edited:
Nemo288
Member
The Beartooth bullets lapping kit seems to be the best thought out kit around for cast bullet fire lapping.
It includes their tech manual which is chock full of cast bullet goodness.
They recommend and supply only one lapping compound.
They also explain why.
Firelapping Bullets
Veral Smith's company also offers the proper advice and slugs for slugging (you should do this first) and lapping.
Lead Bullets Technology
Veral invented the WFN bullet and IMHO is the modern Elmer Keith when it comes to cast bullet design.
Unfortunately, he is not as eloquent as Elmer but his data and ideas are more rigorous.
Get both books, read them, slug your barrel(s).
Only then think about lapping a barrel.
There are 2 methods.
Fire lapping with live (very low power) rounds.
And manually with a rod and jag.
Properly, this jag is cast of lead in the bore.
Big hassle but you can do it with a tight fitting normal jag and patches.
Lapping A Rifle Barrel
Lapping (Doug White; Kelly McMillan; Norman F. Johnson; Russ Kepler; Gale McMillan)
I have read all kinds of this stuff on lapping, have the Beartooth kit, but have yet to muster the courage to actually do it.
It includes their tech manual which is chock full of cast bullet goodness.
They recommend and supply only one lapping compound.
They also explain why.
Firelapping Bullets
Veral Smith's company also offers the proper advice and slugs for slugging (you should do this first) and lapping.
Lead Bullets Technology
Veral invented the WFN bullet and IMHO is the modern Elmer Keith when it comes to cast bullet design.
Unfortunately, he is not as eloquent as Elmer but his data and ideas are more rigorous.
Get both books, read them, slug your barrel(s).
Only then think about lapping a barrel.
There are 2 methods.
Fire lapping with live (very low power) rounds.
And manually with a rod and jag.
Properly, this jag is cast of lead in the bore.
Big hassle but you can do it with a tight fitting normal jag and patches.
Lapping A Rifle Barrel
Lapping (Doug White; Kelly McMillan; Norman F. Johnson; Russ Kepler; Gale McMillan)
I have read all kinds of this stuff on lapping, have the Beartooth kit, but have yet to muster the courage to actually do it.
Last edited:
ohioseabee
US Veteran
Having worked..
in the carbide cutting tool industry for many, many years, I used to use the "swarf" (which contains both the tungsten carbide and diamond particles removed during the grinding process). Unlike steel cutters which have their flutes milled before hardening, carbide can't be milled - it has to be ground with large diamond impregnated wheels.
in the carbide cutting tool industry for many, many years, I used to use the "swarf" (which contains both the tungsten carbide and diamond particles removed during the grinding process). Unlike steel cutters which have their flutes milled before hardening, carbide can't be milled - it has to be ground with large diamond impregnated wheels.
Similar threads
