Buddy of mine had a new prefit Shilen .300 RUM spun up for his Savage and brought it to me to install. He did not have them thread it for a brake, and upon delivery took it to a local gunsmith (never heard of the fella, but what do I know) to be threaded. That fella talked him into paying him to hand lap the throat. I told him I'd never heard of anyone doing this to a new custom and asked him why would anyone need a hand lapped barrel's throat to be re-lapped. My buddy isn't experienced at all with rifles and this is his first build, I obviously do not know everything about the shrimping business...but this seems odd to me. My instinct was he wasted $75 and possibly a portion of the already short barrel (throat) life. If I'm wrong then please set me straight!
Lapping throat of custom barrel
- Thread starter Bravo 4
- Start date
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$75 to 'lap' a Shilen barrel? Well...seems like a waste to me, but what do I know? If I felt it needed 'lapped', I would have bought the Tubb FinalFinish bullets and did it that way. Hopefully the 'smith did no harm and your friend never needs to "know" his $75 would have been better spent on ammo. Watching this thread though to see if someone 'smart' tells us how this was the best $75 ever spent...
shortgrass
Well-Known Member
On a freshly chambered , hand lapped, barrel the is a very small amount of "fluff" from where the throat was cut. You usually just shoot it to it "break-in". No real need to lap it.
shortgrass
Well-Known Member
A solid pilot reamer will leave some 'marks' sometimes, too. If, further up the barrel, there are "marks" that collect copper, they didn't do a good job of lapping in the first place.
Hey Shortgrass, looks like there are some "possible reasons" to spend the $75 after all. Glad you chimed in.
shooter7
Well-Known Member
The smith I've used in the past recommended that I shoot and clean for the first 5 shots to smooth out the small burrs left over from cutting the chamber. He's done a Lilja and Krieger and both shoot very well.
dok7mm
Well-Known Member
A good borescope examination of chamber neck/shoulder junction and throat after chambering will reveal any burrs. As @shortgrass said, most will smooth out, with proper break-in.
Larger burrs or "curls" seem easier to remove prior to breaking in barrel. A maroon pad, properly sized brush and an abrasive paste, work well for this.
Personally, I've seen the most irritating burrs show up at neck/shoulder or shoulder/body junctions. I don't believe I've seen anything in throat that firing wouldn't take care of.
Larger burrs or "curls" seem easier to remove prior to breaking in barrel. A maroon pad, properly sized brush and an abrasive paste, work well for this.
Personally, I've seen the most irritating burrs show up at neck/shoulder or shoulder/body junctions. I don't believe I've seen anything in throat that firing wouldn't take care of.
shortgrass
Well-Known Member
Those will "shoot out" with barrel break-in. The marks a solid pilot reamer can leave behind are another good reason to use live pilot reamers. The David Tubbs bullets will remove those marks, but they'll lengthen the throat, too,,,,,, but lapping might, also....
shortgrass
Well-Known Member
And on target, too!Thanks for the responses. I will do a break in of sort on any of them and believe them to smooth out in doing such.
$75 in ammo could have gotten him a break in, some load development and initial data collection.
TwoMore
Well-Known Member
If the reamer used was dull and there are burrs on the lands or even paddle shaped burrs in the freebore (the reason I don't like rented reamers) I would definitely lap rather than shoot those pieces of metal embedded in the bullet down the length of a nice barrel. This happened to me on a 6mm creed I built and I made the huge mistake of renting a uni throater to extend the throat when I looked up in there with my hawkeye I was pis--d so I built a leather lap (hob) with some ISSO and cleaned it up and I also tried it with some 600 on a mandrel , the Isso gave it a nice finish and the barrel shot great and minimal copper fouling during break in
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J E Custom
Well-Known Member
I am one of those that Believe in letting the reamer cut the chamber, set the throat, lead, freebore and even place the proper finish on everything. If everything is done right, (A dull reamer or on with an improper fitting pilot is not consistent with quality) Nothing in the chamber needs to be touched by anything except a Bullet.
Don't polish, de burr, shoot abrasive bullets or mes with the throat unless you want to reduce barrel life and accuracy potential. Throating can be used by an expert without damage but it is best done with the chamber reamer with the right/desired throat dimensions to prevent any slight misalignment.
If the throat needed to be lapped, the smith should have just chased the chamber enough to clean it up before he set the head space. Not trying to second guess the smith But something sounds wrong with lapping a throat to me.
J E CUSTOM
Don't polish, de burr, shoot abrasive bullets or mes with the throat unless you want to reduce barrel life and accuracy potential. Throating can be used by an expert without damage but it is best done with the chamber reamer with the right/desired throat dimensions to prevent any slight misalignment.
If the throat needed to be lapped, the smith should have just chased the chamber enough to clean it up before he set the head space. Not trying to second guess the smith But something sounds wrong with lapping a throat to me.
J E CUSTOM
TwoMore
Well-Known Member
I agree , I learned a good lesson that day
crkckr
Well-Known Member
I don't know if Schilen hand laps their pre-fit barrels but I'd be willing to bet they at least scope them before they get shipped. They do have a reputation to maintain! It sounds to me that the 'smith took advantage of a customer that simply didn't know any better.
Lapping a factory barrel might be something worthwhile but it would *have* to be scoped first to find out. A buddy bought a Rem. 700 and the barrel looked as good as any custom barrel I've ever scoped! It shoots like it, too. That's rare, of course, but clearly happens sometimes. My R700 .308 barrel looked like 20 miles of gravel road and also shot like it. It was so bad I didn't even bother fire lapping it, I just had my 'smith put a nice Hart 5.5 barrel on it.
I'll usually scope a factory barrel first thing and more often than not it will get fire lapped (NECO process). Anything that shoots lead bullets usually gets fire lapped as well. It really helps in that respect.
Custom barrels shold never be lapped, even after scoping it. If it's that bad send it back! My custom barrels never even see the JB Bore cleaner I use for removing lead & carbon (although I now use Bore Tech carbon remover so the JB may be reduced to just hand guns).
The truth is mist barrels are not shot out but "cleaned" out using poor cleaning methods & tools. Dewey rods, chamber guides & new chemicals will give you the most out of your barrel these days. Personally, on my custom guns, patches go one way, once. I never try to pull them back thru the barrel. But that's me, you'll figure out what works best for you.
Cheers,
crkckr
Lapping a factory barrel might be something worthwhile but it would *have* to be scoped first to find out. A buddy bought a Rem. 700 and the barrel looked as good as any custom barrel I've ever scoped! It shoots like it, too. That's rare, of course, but clearly happens sometimes. My R700 .308 barrel looked like 20 miles of gravel road and also shot like it. It was so bad I didn't even bother fire lapping it, I just had my 'smith put a nice Hart 5.5 barrel on it.
I'll usually scope a factory barrel first thing and more often than not it will get fire lapped (NECO process). Anything that shoots lead bullets usually gets fire lapped as well. It really helps in that respect.
Custom barrels shold never be lapped, even after scoping it. If it's that bad send it back! My custom barrels never even see the JB Bore cleaner I use for removing lead & carbon (although I now use Bore Tech carbon remover so the JB may be reduced to just hand guns).
The truth is mist barrels are not shot out but "cleaned" out using poor cleaning methods & tools. Dewey rods, chamber guides & new chemicals will give you the most out of your barrel these days. Personally, on my custom guns, patches go one way, once. I never try to pull them back thru the barrel. But that's me, you'll figure out what works best for you.
Cheers,
crkckr
