bore polishing (just say no)

[Jay Christopherson]

I bought a new-but-used rifle for my daughter to shoot. It was mostly stock, except for the barrel which was a nice .224 Brux 1:8 twist at 29", setup to shoot 80-ish grain bullets. The same smith had chambered another barrel (the same barrel) at the same time that shoots lights out at mid-range. The barrel has minimal use (I would bet maybe a couple hundred, max).

But... for some reason (I'm told it was spontaneous), the smith decided to "polish" the bore to a mirror shine. The only way to do that is to remove metal. :-/

I took it out to see how it shoots - with a known load, it shoots 100-120 fps slower than it should and I could have produced better groups with a slingshot at 600. In fact, I've actually shot FAR better groups using a sling and an AR service rifle, even though I've only done that a few times.

The moral of the story is - just say no to f-ing with the bore. Shoot it like the maker intended... as it comes from the shop. IMO, the only thing you can do by "lapping" or "polishing" a custom barrel bore is f-ck it up.

EDIT: I don't know the smith who did the work personally, so I don't know what the thought process was. Maybe it was an experiment... I don't know and it really doesn't matter at this point. I mostly just wanted to point out what I think are the results of a poor decision. I'll have another barrel chambered up shortly... if it had worked out to use the barrel that it came with, great, but it was still a good deal so I'm not particularly unhappy. More like non-plussed that someone would think polishing the bore to a mirror shine was a good idea.

 

[LA50SHOOTER]

I bought a new-but-used rifle for my daughter to shoot. It was mostly stock, except for the barrel which was a nice .224 Brux 1:8 twist at 29", setup to shoot 80-ish grain bullets. The same smith had chambered another barrel (the same barrel) at the same time that shoots lights out at mid-range. The barrel has minimal use (I would bet maybe a couple hundred, max).

But... for some reason (I'm told it was spontaneous), the smith decided to "polish" the bore to a mirror shine. The only way to do that is to remove metal. :-/

I took it out to see how it shoots - with a known load, it shoots 100-120 fps slower than it should and I could have produced better groups with a slingshot at 600. In fact, I've actually shot FAR better groups using a sling and an AR service rifle, even though I've only done that a few times.

The moral of the story is - just say no to f-ing with the bore. Shoot it like the maker intended... as it comes from the shop. IMO, the only thing you can do by "lapping" or "polishing" a custom barrel bore is f-ck it up.

EDIT: I don't know the smith who did the work personally, so I don't know what the thought process was. Maybe it was an experiment... I don't know and it really doesn't matter at this point. I mostly just wanted to point out what I think are the results of a poor decision. I'll have another barrel chambered up shortly... if it had worked out to use the barrel that it came with, great, but it was still a good deal so I'm not particularly unhappy. More like non-plussed that someone would think polishing the bore to a mirror shine was a good idea.

Jay,

Did it copper foul bad as well ? - I've heard about this same thing, someone "thinking" they can make something better than it already is.
Barrel fouled bad & accuracy went to $hit on it.

- Ron -

 

[Jay Christopherson]

Jay,

Did it copper foul bad as well ? - I've heard about this same thing, someone "thinking" they can make something better than it already is.
Barrel fouled bad & accuracy went to $hit on it.

- Ron -

Yep. I cleaned it up after only 22 shots and it was fouled quite a bit more than it should have been, for a low round count barrel.

 

[dskogman]

Assuming it’s a 223/5.56 shoot a few boxes of steel ammo thru it. Take that shine right off and maybe start shooting.

 

[LA50SHOOTER]

Assuming it’s a 223/5.56 shoot a few boxes of steel ammo thru it. Take that shine right off and maybe start shooting.

But I doubt that it will ever have that same Hand Lapped finish that it did when it was sent out the door. - Myself personally, I'd send it back & have it re-lapped.

- R -

 

[Jay Christopherson]

The overall deal was friendly enough that I'm just considering the barrel to be a sunk cost and I'll chamber a new one for it. I'd rather have one that I've done myself anyhow. If it ends up sucking, I'll know who to blame (and so will my daughter)... ;-)

 

[SBS]

If this barrel was lapped after it was finished, it bell mouthed the muzzle end. Try cutting an inch or so off the muzzle. Can't lose anything but a little time.

 

[joshb]

I just bought a gun off the sale board that has a Blackstar barrel on it. I summed up the parts, as I always do, and used a zero $ value for the barrel. It was a fair price so I sealed the deal. If the "electro polished barrel" doesn't shoot, I'll save up and put a Krieger on it. Polished barrels seem to be a problem. Maybe that's why Savages shoot pretty well with all those humps and valleys from the rifling process?

 

[zeke06]

Slug it and see what you have for bore dimensions. If it’s decant lap it with 220 aluminum oxide lapping compound (no finer). It will take you longer to set it up and cast a lap then to actually lap it. Re-crown it when your done. Worst thing that’ll happen is you’ll be out about a hour of your time.

 

[mikecr]

Your 'smith' is an idiot

 

[Dusty Stevens]

i've never heard of such. i bet a polished bore is a copper mine.

 

[Raythemanroe]

Fireforming barrel


Ray

 

[500Stroker]

Everything looks good on paper, the proof is on a paper target.

 

[Alex Wheeler]

Jay, maybe it will come back if lapped? I'll lap it if you want to see.

 

[johnfred1965]

I read an article by Dan Lilja I believe, about bore finish. At a certain point the barrel gets so smooth that the copper jacket smears in the bore, fouling badly and ruining accuacy. Don't remember if he recommended a solution, but roughing it back up a little couldn't hurt.

 

[butchlambert]

Isn't a 1 in 8 a little slow for a 80grn. VLD. Yes a polished bore will foul. Spit on your finger, wipe it off and see how it sticks to glass when pushing your finger across it.

 

[onelastshot]

My basic rule when it comes to barrels is that less is more. If you have excessive fouling, copper or lead build up that's affecting accuracy, remove it. The nonsense of hand lapping or polishing a barrel makes no sense to me. Some people think they can always improve something that doesn't need attention. Again, less is more.

 

[Jay Christopherson]

Jay, maybe it will come back if lapped? I'll lap it if you want to see.

That might be interesting to try. I've never lapped anything myself, but if you wanted to give it a try as an experiment, I can send it to you for sure. I also thought it would be interesting to slug it and see if the bore was opened up.

EDIT: @butchlambert, if the barrel was shorter than 29" I'd say 1:8 was marginal for 80 grain. My 20" SR is 1:7.7 shooting the same bullet (100+ fps slower) and it's more accurate than this barrel is. I shot an identical rig with an identical (though non-polished) chamber/barrel with the same load and it might be the most accurate .223 I've ever shot at mid-range distances.

 

[Jdne5b]

What is the difference between lapping, polishing, and cleaning with JB/Iosso?

 

[mikecr]

What is the difference between lapping, polishing,

Different surface profiles. The best barrel makers provide a profile that reduces copper fouling to near nothing. If you change this, one way or another, copper fouling rate increases.

and cleaning with JB/Iosso?

This is to abrade/manage fouling constrictions.