Concave flats: Normal?

[Canute Rex]

Hi All,

I've just started draw filing a Rice barrel. It's a 38" .50 caliber B weight Traditions swamped. What I'm seeing is a consistent concavity to the flats. I mean, "flats." I'll do a few passes and there will be filed areas on the edges and a trough down the middle. I thought I would be just doing some smoothing but I'm really removing some material. I've done three flats so far with the same pattern.

Also, there are two rings of extra low spots around the barrel, centered in each flat. One ring is about 6" from the muzzle and the other is about 9" from the breech.

Is this normal?

Thanks!

[Ky-Flinter]

Is this normal?

No, and I've never heard of such.  If it was me, I would stop filing and call Jason at Rice to discuss it.  He's a good guy and stands behind his work.

Ron

[rich pierce]

I have seen some slight concavity when I was draw filing one of their barrels recently.  Must be the cutters. In my experience it might be 0.002” or so; files away pretty quickly.

[PEARL DRUMS]

Any chance you’re flexing your file a bit?

[rich pierce]

Any chance you’re flexing your file a bit?

First thing that came to mind for me, too. I reduced downward pressure and held hands close to the flat as possible. Same result - took several passes to get the middle of the flat to file. No biggie for me.

[alacran]

I will take concave over convex any day. All the original barrels I have seen are less than perfect.

[rich pierce]

I will take concave over convex any day. All the original barrels I have seen are less than perfect.

We sure do have it good nowadays. The new smoothbore profiles from Rice are outstanding.

[Clowdis]

I've seen the same things before when draw filing a barrel. I think you're either not exactly even with the flat or you're flexing the file. Either way the error is very small and shouldn't effect the fit of your barrel to the stock.

[Canute Rex]

Any chance you’re flexing your file a bit?

I'm holding the file close in, about half an inch either side of the barrel. I have reasonable arm strength, but no S on my chest.

I'm wondering whether the rings of low spots have to do with the fixtures for holding the barrel in place while machining. Academic curiosity - they aren't that deep. Just the last areas to flatten out.

Here's what the concavity looks like:

[Bob Roller]

Unacceptable additional work to an already labor intensive endevour.I planed a lot of barrels in Bill Large's shop in years past and never heard or saw of this condition and he made his barrels from 1144 also called "Stressproof.I used it for lock tumblers because it's easy to work with and hardens in oil like drill rod.are ALL 8 flats like this???
Bob Roller

[Tumbledown]

If I had to guess, the milling head's shaft was not quite perpendicular to the barrel but tilting ever so slightly towardsthe muzzleor breech. This would cause such a scooping effect.

[Bob Roller]

Is this being done on a vertical milling machine. or maybe a modified planer WITH a milling attachment. I remember hearing about them but don't remember ever seeing one. Thank you for the reminder.
Bob Roller

[Canute Rex]

Unacceptable additional work to an already labor intensive endevour.I planed a lot of barrels in Bill Large's shop in years past and never heard or saw of this condition and he made his barrels from 1144 also called "Stressproof.I used it for lock tumblers because it's easy to work with and hardens in oil like drill rod.are ALL 8 flats like this???
Bob Roller

I started on the hidden flats to get some practice in but once I encountered the concavity I stopped at three. I sent a message to Rice to ask about it.

Hand planed Japanese matchlock barrels from the 19th c and before had concave flats. Maybe Rice was just going for a traditional look.

I wonder if it's from a resharpened cutter that didn't end up square.

[Birddog6]

Any chance you’re flexing your file a bit?

I'm holding the file close in, about half an inch either side of the barrel. I have reasonable arm strength, but no S on my chest.

I'm wondering whether the rings of low spots have to do with the fixtures for holding the barrel in place while machining. Academic curiosity - they aren't that deep. Just the last areas to flatten out.

Here's what the concavity looks like:

I have never seen a Rice barrel that bad.  I would have stopped long ago on the filing.  Sure the gunmakers barrels need some work, but I think that one slipped by them.  I have bought dozens
of barrels from them & never received anything like that.

Call Jason at Rice & send him a photo. He has always been more than fair with me.

[Scota4570]

I came across this exact thing with a barrel from a kit last month.  Also Rice.   I do the initial striking with a 14" mill file, it only took a few extra swipes. 

The machine marks indicate a horizontal mill to my eye. 

[Ky-Flinter]

It would be interesting to lay a straight edge across one of the unfiled flats to get an idea of how deep the concavity is.

Ron

[Scota4570]

In my case about 0.001" .  Insignificant, but it does show when you are draw filing. 

[P.W.Berkuta]

To me that barrel is totally unacceptable especially for the price that they are charging for them. If I paid half price for that barrel I would not complain and just file it flat. That workmanship is terrible, and I would complain.

[bama]

I have draw filed a couple hundred or more barrels over the years and I have never encountered one that had perfectly flat flats. All of the flats were slightly concave to some degree. Nothing that a good smooth cut bastard file couldn’t take care of in short order. I always draw file as part of the finishing process. Never has draw filing caused enough metal removal to cause a fit problem. When Green Mountain started making swamped barrels there were definite hard breaks in the profile changes in the barrel. I have used several of Jason’s barrels and the swamping profiles were smooth.

The reason I save the draw filing to do during the finishing process because here in the south a good clean barrel will rust while you’re looking at it. So I do it once and don’t sweat the surface rust, inletting black and file marks until I get ready to finish.

[Bob Roller]

I have never heard of a file flexing and used a long angle lathe file on the few I draw filed in my shop.They leave a better finish and a new one makes the task much easier.Files are a bench craftsman's friends if used properly and with a variety of shapes and cuts a lot can be done with them.The people who made the fine locks seen on English guns were called "Lock Filers".Not long after I came on this forum I bought the file inventory of a local industrial supply business that they had ordered for someone who never came to get them and I sold all except the ones I kept in this forum and I think all of them were made in the USA.

Bob Roller

[Bill Madden]

In recent years, swamped  octagon barrels from Rice have not been finished like they once were with the octagon profile milled dead flat and the milling marks removed by sanding with 120 grit or so.  All of the Rice barrels that I have seen in the last 3-5 years or so, whether mine or those ordered by others, have noticable concave flats with swirled milling marks that have not been removed.Put a square on the barrel and some chalk on a flat. You will see what I have described.
To avoid a gap between the barrel wall and barrel channel, the side flats have to be draw filed and sanded smooth before attempting to inlet the barrel.  Although the top flat and oblique side flats can be dressed later, I prefer to draw file and sand the entire barrel to 320 grit with no scratches before sending it off to Rase for inletting.  It takes me about 8 hours, i.e. an hour a flat.
The barrels are still good barrels. They are just not being finished to the same quality that they were in the past.

[whetrock]

It's reasonable to talk with Jason. But at the same time, I don't see it as poor craftsmanship on his part. Cleaning up a barrel is just part of gun building.

[Canute Rex]

If I had to guess, the milling head's shaft was not quite perpendicular to the barrel but tilting ever so slightly towardsthe muzzleor breech. This would cause such a scooping effect.

Given that it's a swamped barrel, there's only one possible point on the barrel that it could be perpendicular. In all other places it will always be gouging a little, either with the leading or trailing side of the cutter. That's probably it.

I tried to measure the concavity, but I just don't have the right tool for it.

[hudson]

The last barrel I got from Rice was just machine finished with visible mill marks and took little clean up. I usually make brass plugs and fit in both ends of the barrel with a tap fit, I dial both ends in on the bore when in the lathe. I found one top flat off .018 from the centered bore. When spinning the barrel there was run out toward one end not excessive I believe but left me a bit uncomfortable. Not an expert in deep whole drilling but thinking the drill dulled or was being pushed too hard. Rumor has it that Rise Is behind in orders and pushing there machinery to the limit. With all the barrels I have had from Rice I never had one like this before.

[David Rase]

Just draw file the barrel and move on.  It's what we do.
David