plz delete
- Thread starter SigWig
- Start date
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
Eh... to answer your question simply: No. Just no.
Lapping does not make the barrel accurate, not will it improve a factory barrel. Lapping .007" out of a factory barrel will completely remove all the rifling, and if it doesn't, your bore will look like the 100 year old Mauser that served through both wars, was stuffed in a dank closet for 50 years and then cleaned out with valve grinder, a steel brush and CLR. You cannot controllably or accurately lap out .007". It is simply not feasable. Also, lapping is not what makes a barrel accurate. Lapping is similar to filling the gouges in your stock with sawdust and glue: it smoothes out the f*ck-ups and makes it look pretty, but cannot enhance the already poor workmanship hidden from view.
I can tell you that lapping is unnecessary. Having properly sharpened cutting tools (for drilling/reming and single point rifling) is the key to an ultra smooth barrel. By using a single point cutting tool in both the bore and grooves ensures that the lay of the cuts follows the path of the bullet. And if done properly, the grooves should have a slight taper from breech to muzzle, and usually around .0005"
I hope that helps. However, if you are intent on this be my guest. The barrel makers will love you for it.
Lapping does not make the barrel accurate, not will it improve a factory barrel. Lapping .007" out of a factory barrel will completely remove all the rifling, and if it doesn't, your bore will look like the 100 year old Mauser that served through both wars, was stuffed in a dank closet for 50 years and then cleaned out with valve grinder, a steel brush and CLR. You cannot controllably or accurately lap out .007". It is simply not feasable. Also, lapping is not what makes a barrel accurate. Lapping is similar to filling the gouges in your stock with sawdust and glue: it smoothes out the f*ck-ups and makes it look pretty, but cannot enhance the already poor workmanship hidden from view.
I can tell you that lapping is unnecessary. Having properly sharpened cutting tools (for drilling/reming and single point rifling) is the key to an ultra smooth barrel. By using a single point cutting tool in both the bore and grooves ensures that the lay of the cuts follows the path of the bullet. And if done properly, the grooves should have a slight taper from breech to muzzle, and usually around .0005"
I hope that helps. However, if you are intent on this be my guest. The barrel makers will love you for it.
redshooter
CGN Ultra frequent flyer
- Location
- Central Ontario
I'm making some assumptions here...
It's not magic. Think of it this way a Saleen Mustang is still a Mustang. It's so much better because of the care and attention put into some of its assembly. I'd assume a custom barrel maker will produce a tube that has less variation nothing more. That is probably achieved by taking more care when setting up the machines and not letting the cutters get dull/worn. Drill the hole and cut the rifling to tighter tolerances and you get a better barrel. Sure some process may be inherently better, but in the end Cut rifling, button rifling, or hammer forging can produce a superior product. It's all in the attention to detail, do it right or do it fast. Sure you can do both, but if your flinging them out the door your going to have some bad ones.
What do you really need to know. Its a tube with grooves cut into it. If you make the hole a uniform size, the grooves uniform and the twist constant with no variation you get a good product. Have one or more of those things varying beyond a certin tolerance and you get a crap product.
It's not magic. Think of it this way a Saleen Mustang is still a Mustang. It's so much better because of the care and attention put into some of its assembly. I'd assume a custom barrel maker will produce a tube that has less variation nothing more. That is probably achieved by taking more care when setting up the machines and not letting the cutters get dull/worn. Drill the hole and cut the rifling to tighter tolerances and you get a better barrel. Sure some process may be inherently better, but in the end Cut rifling, button rifling, or hammer forging can produce a superior product. It's all in the attention to detail, do it right or do it fast. Sure you can do both, but if your flinging them out the door your going to have some bad ones.
What do you really need to know. Its a tube with grooves cut into it. If you make the hole a uniform size, the grooves uniform and the twist constant with no variation you get a good product. Have one or more of those things varying beyond a certin tolerance and you get a crap product.
ultimate_monkey
CGN Ultra frequent flyer
- Location
- victoria BC
what lapping a barrel actually does - smooths the machine / tool marks from cutting / forming the rifleing so the barrel doesnt copper foul...
an accurate barrel comes from - precise tool set up, sharp bits, tight tolerances, quality martrial to actually make the barrel, and having a good smith assemble every thing for you
the hole "barrel break in" comes form the same things, by shooting and cleaning shooting and cleaning you smooth out the tool marks with out allowing copper to build up essentially lapping with with bullets, a high end barrel doesnt need this
an accurate barrel comes from - precise tool set up, sharp bits, tight tolerances, quality martrial to actually make the barrel, and having a good smith assemble every thing for you
the hole "barrel break in" comes form the same things, by shooting and cleaning shooting and cleaning you smooth out the tool marks with out allowing copper to build up essentially lapping with with bullets, a high end barrel doesnt need this
I would read this and the other articles on the Lilja website for a start...
http://www.riflebarrels.com/articles/barrel_making/details_of_accuracy.htm
http://www.riflebarrels.com/articles/barrel_making/rifle_barrel_accurate.htm
And here
http://bettincustomguns.com/Technical Information/Barrel rifling techniques.htm
http://www.border-barrels.com/articles/bmart.htm
Hope this helps
http://www.riflebarrels.com/articles/barrel_making/details_of_accuracy.htm
http://www.riflebarrels.com/articles/barrel_making/rifle_barrel_accurate.htm
And here
http://bettincustomguns.com/Technical Information/Barrel rifling techniques.htm
http://www.border-barrels.com/articles/bmart.htm
Hope this helps
I think your mis-understanding what lapping the barrel is.
No expert here, but I belive most barrel makers pour molten lead into the barrel to create a plug. This plug then has polishing compounds applied to it and they run it up and down. This works like sand paper to smooth out the bore. The plug follows the rifling and will twist as it runs the length of the barrel.
So to say that you want to hand lap a barrel from 6.5 to a 270 is similar to saying I want to take a wooden 2x6 and use sand paper to change its dimmensions to a 2x4 BY HAND. Not going to work very well.
As was already stated, custom barrels are better than factory for many reasons.
Higher grade metal
Straighter blanks
Straighter holes
Sharper tooling
More time to produce
Less stress in the finished product
lapping a barrel
Zig Wig !
Think about this - how in the world could you hand lap a 4140 ss barrel out to another size caliber over a distance of say 24-28 inches and remove exactly the same amount of metal to keep a consistant diameter over the lenght and be smooth enough after even if you could do it - to actually shoot it and not rip the jackets right off the copper bullets ! I believe its impossible to do such a thing BUT i am not a machinist so maybe coyote or someone can jump in and set me straight !
Cheers RJ
Zig Wig !
Think about this - how in the world could you hand lap a 4140 ss barrel out to another size caliber over a distance of say 24-28 inches and remove exactly the same amount of metal to keep a consistant diameter over the lenght and be smooth enough after even if you could do it - to actually shoot it and not rip the jackets right off the copper bullets ! I believe its impossible to do such a thing BUT i am not a machinist so maybe coyote or someone can jump in and set me straight !
Cheers RJ
I wonder if John at Marstar knows where some Pratt & Whitney B series barrel making machines could be hiding? Maybe if there is anything left of them we could get some of the sold off ones back to North America.
Should we start a list of available cut rifled barrels?
Cooper gets it's barrels from Wilson Arms it looks like, must be button rifled I guess. They would select the best barrels out of the lot.
How does tikka make such a good buttoned barrel?
If there was an old pratt& whitney kicking around in north america I would have found it
A lot of barrels shoot good whether 3, 4 ,5 or 6 groove ask any barrel maker if there is a secret and there isn't it has to do with sharp accurate tooling and a perfectly reamed hole .
The lapping takes the left over minute tooling marks out and the barrel can be lapped to give it a small taper of a few tenths of a thousand at the muzzle or a slight choke.
The secret to an accurate barrel is consistency of the bore straightness of the hole and uniform rifling.
You can add me to the list of cut rifle barrel makers.
I,m not sure exactly what it is you want to do but it is impossible to lap out a barrel to another caliber ,you can rebore an existing caliber to another but not lap to it like I said before there would be no rifling left and your arm would hurt lol.
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