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Gunsmithing How smooth should the bore be if it was hand lapped at the factory?

J

johnny_boy

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Minuteman
May 2, 2013
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Washington State
I am new at this, so please ignore my ignorance. :) I bought a short chambered "match" grade barrel for my Remington 700 Varmint 308 in Stainless Steel that was supposed to be hand lapped at the barrel factory. How smooth should the inside be? I thought it would be mirror like finish?

(Looking through a bore scope) I see a bunch of tool marks in the last 10 inches or so near the muzzle, while the rest is free of any tooling marks. It does look like the burrs and edges were cleaned up all the way through though. Is this normal? Does hand lapped means free of tooling marks or it just means it sanded down smooth? It looks like it was sanded down smooth, but If the tool cut too deep in certain sections, obviously the lapping process will not take out enough metal to make that area flat, which is what I think I am seeing.

Do I keep this, or send it back? Since this is my first barrel, I would like to know what to expect.
 
Have you notified the barrel manufacture? If a barrel is lapped too smooth it will actually be a copper catcher. More friction.
 
You just found one of the major problems with a bore scope...trying to find an issue that probably isn't there. I'd just shoot it and see how it does with fouling after a couple hundred rounds.
 
+1 on seanh' s comment....by the time you factor in the magnification of the bore scope there's no telling how small the marks actually are. They may look like 6 miles of gravel road through the bore scope but in reality aren't an issue. There are also different definitions of "match grade" barrels. Barrels may also be lapped after drilling and reaming but before rifling, or after rifling....some makers do both. Put the barrel on your action and go shooting. Next time you want to rebarrel, have a competent smith fit and chamber a barrel specifically to YOUR receiver.
 
Thanks for the reply so far. I just got the barrel tonight, so I have not had a chance to call up the manufaturer. I will do that monday morning.

So, I took the picture of the bore. So you are saying this is normal?

Below is what I think is good. 2/3 of the barrel is like this from the chamber to the 2/3 way into the bore.
_MG_4370.jpg

Last 1/3 of the bore to the muzzle look like this
_MG_4380.jpg

So that second part is perfectly normal for a match barrel from a well known shop?
 
I dont want to see tool marks like those in the second picture in a true match grade barrel. I would contact the manufacturer and send the pictures you have and put the ball in their court.
 
I don't have a clue either way on what it should or shouldn't look like but I am curious as to what the transition area looks like if you can get a pic of that.

L
 
I am not a "smith", but have used barrels from several different makers during the past 40 years or so.

My preference is to have the bore slightly tighter for the last several inches, so if it is lapped a little less in that last 1/3 of the length it might be because the barrel maker has been there/done that before.
 
Layton said:
I don't have a clue either way on what it should or shouldn't look like but I am curious as to what the transition area looks like if you can get a pic of that.

L
Click to expand...

When you sy transition area, what do you mean? You mean the throat area, or the area from where the good part ends and bad part starts? If latter, it just suddenly start having those hash/tooling marks. I will see if I can grab another picture of that in the evening.
 
Diablo said:
I am not a "smith", but have used barrels from several different makers during the past 40 years or so.

My preference is to have the bore slightly tighter for the last several inches, so if it is lapped a little less in that last 1/3 of the length it might be because the barrel maker has been there/done that before.
Click to expand...

That could be totally true. but I think the tool marks are too deep for the lapping process to remove them?

Part of the reasons why I decided to upgrade my barrel is that my factory barrel, while it shoots well at 3/4 MOA average with handload and FGMM, it has severe fouling problem and after about 40 rounds it opens up to 1.5 MOA. It also takes about 5 shots to stabilize the fouling once completely cleaned. So I only have about 20-30 shots where I can group well. I was told that the aftermarket match barrels have far less fouling problem.

I can see why that would be since it is so much smoother. Except for that 1/3 part of the barrel. I was a bit concerned that I would have copper fouling problem in that area.
 
Transition area where it goes from smooth to rough. You've indicated it's an abrupt transition which is what I was wondering. Looking to see if there is a small groove, ridge or tool mark circling the bore in that area.

L
 
Last edited:
Send it back, that is not acceptable in a factory barrel, let alone a "match" grade one.
 
well, so I emailed the manufacturer with the photos. The response that I got is that since this is the "Regular/Standard" Match and not "super/select/premium" Match grade, some tooling marks are expected. Shoot and see what happens.

Also called the distributor. They didn't think it looked right, so they are sending me another one. I should get that in a couple days. I will compare it and see if they are basically the same or not.
 
Jim B in CO said:
Care to say who made it?
Click to expand...

I know...I've been intentionally vague about the maker because I wanted to give the benefit of the doubt for the manufacturer first. I also wanted to shoot it and see how it does as well as how much fouling problem it will have. If it shoots tighter than my factory and has much less fouling problem, I will be happy with it regardless of the tooling marks.

Sometimes the hardest customers to please are the ones that don't know much about the industry. I was expecting a "perfect" barrel based on the Lilja borescope video below
- Lilja BoreScope Video - YouTube

, but I am thinking maybe that is not the norm. My factory barrel looks better than video's factory barrel, but my new match barrel does not look as clean as the Lilja's video either.
 
Just a general question. The fact that the tooling marks are both on the land and the groove at the same spot (ladder rungs, as it were, level with each other), does that indicate a button-rifled barrel?

That is my assumption. I see similar marks inside the muzzle of my 1953 made M1 Garand barrel (button rifling). You also see them in the factory remington 700 barrel in the vid above. So I'm guessing it's a by-product of the button either slipping or "chattering" if that's the correct term, but I've never seen a tube rifled and can only guess. Does anyone know?
 
The tooling marks are from the reamer used before the final rifling. Some manufacturers lap the bore after reaming and before rifling. This was evidently NOT done with this barrel.
 
I am guessing it is a shilen barrel, i have heard some reports of rough barrels from them in the "standard" match barrels.
 
To answer others question about who the manufacturer is - it is Shilen standard match barrel sold via Brownells as short chambered barrel for Remington 700. I double checked with Shilen tech again this morning and I was told it is normal for the standard match grade.

Per their description on the website the standard match barrel should be "The price of Match Grade stainless steel barrels includes hand lapping to a beautifully smooth surface". So I expected 100% of the bore, or at least 90% of the bore to have the beautiful smooth surface. In my case only 65% (17" out of 26") of my barrel is the smooth surface.

I will receive a replacement for it on Monday from Brownells. We will see if that is better. I hope they are shooters regardless of the marks, but I am not sure what the relationship between the two would be.
 
Ledzep said:
Just a general question. The fact that the tooling marks are both on the land and the groove at the same spot (ladder rungs, as it were, level with each other), does that indicate a button-rifled barrel?
Click to expand...

Yes, it is button rifled barrel, since it is by Shilen. I am assuming these are either button chattering while it is being pulled or reamer mark where they didn't flush it fast enough to get all the shavings out and it got caught.
 
OK, I got the replacement barrel today from Brownells. The new one is perfect! Very smooth finish throughout the entire bore. Almost no tooling marks whatsoever. 99.5% of the bore surface is smooth with no tooling marks. Whatever tooling mark there is, it is very faint. Not like the last one where it showed heavy lines.

The outside surface finish seems to be slightly more rough compared to the last one (300 grit finish instead of 400?), so I might polish it up just a bit. But I am not worried about that as it has no effect on the accuracy.
 
johnny_boy said:
OK, I got the replacement barrel today from Brownells. The new one is perfect! Very smooth finish throughout the entire bore. Almost no tooling marks whatsoever. 99.5% of the bore surface is smooth with no tooling marks. Whatever tooling mark there is, it is very faint. Not like the last one where it showed heavy lines.

The outside surface finish seems to be slightly more rough compared to the last one (300 grit finish instead of 400?), so I might polish it up just a bit. But I am not worried about that as it has no effect on the accuracy.
Click to expand...
What borescope do you have? I have been looking at one but i am very unsure of what to look for. Thanks
 
OK, so to wrap this up, here is my range report with the new barrel. I was able to finally get it installed myself this week and go shoot it tonight.

Overall I am very happy, it reduced my group size to about 30-50% of what it used to be. Also, it seems to be a lot more consistent, and much less fouling.

My best was (5 shot group at 100 yards)
1. Varget 45.0 gr - 168 SMK - Lapua Brass - Federal 210M primer - 2.800" ==> About 0.28" if I don't count the flyer. If I count the flyer 0.52" (bottom right of the image)
2. RL15 42.0 gr - 168 SMK - Lapua Brass - Federal 210M primer - 2.800" ==> About 0.55" (top left of the image)

The worst groups came from my test load of Berger VLDs with 8208 XBR. I can't seem to get the VLDs to shoot any decent size group (it was about ~1.0" to ~1.5"). The test load that I made was touching the lands.

Even my crappy factory plinking rounds that shoots 1.6" to 2.0" group on my old barrel was shooting 1.1" group.
 
Glad it worked out for you. Jam the VLDs at least 0.005" and work forward from there (longer) they can be picky, just watch your pressure. On the bore of the 1st barrel, I have seen some real QC issues from Shilen in the last 8 years or so. So much so I would not ever consider a barrel from them again, and they were one of the best for a long time... As far as the comment of it being a Douglas, they are the true sleeper of all barrels, they have been doing it right for a very long time.
 
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