Barrel wear

[KNeilson]

While cleaning my rifle after sundays shoot, I detected a couple spots in the barrel that felt more "slippery" than the rest. Using several different jags and patch thicknesses, carefully checking, I could find them repeatably at the same spots. The closer fitting combos made the detection easier. They are about 3/4 long, and they all coincide with the points that the under lugs are installed. Its a Rice .54 cal transitional swamped in "C" weight...I can see it happening closer to the waist of the swamp where the bbl wall is quite thin, and this spot  is a little "looser" than the one closer to the breech.  Never was a problem yet as I have been looking for this, and so far I have not noticed a large accuracy decrease either. But am just wondering if there is a fix (like freshing), or maybe I am doing something wrong or just have worn the barrel out? For the last 500 rounds or so I have been using pure soft lead .535 balls, 10 oz denim patching, and 80-105 g 3F charges... The barrel itself has about 3000 rnds thru it now......  thx.  Kerry
A pic of the lug installation..
 

[Roger Fisher]

I'll stick my neck out; but you did ask! You will get better answers than mine; but have you checked (with a short straight edge) for a buldge on outside flat/flats at those loose spots??

[KNeilson]

Thx Roger, no I havent yet, but will as soon as I get home tonite. I will mike to get a precise number......Thx for the suggestion... Kerry

[bob in the woods]

Exactly what I was thinking.

[smylee grouch]

I dont think 3000 rounds would even come close to wearing out a round ball barrel under normal conditions. It will be interesting to find out what exactly is causing your barrels condition. Good luck in your search for answers.    Gary

[bgf]

How deep is that dovetail -- it looks pretty deep?  Figure out the depth of your dovetails and then see how much barrel you have between the dovetail base and the bottom of the grooves.   I would check it out and try to be sure there is sufficient metal there before shooting again. 

[KNeilson]

bgf, the dovetail is as deep as the lug you can see. As a guess, no more than .050. I will give exact measurements later. They were a good push fit with a finger, then staked very lightly with a sharp prick punch and a chasers hammer. Positively no forcing involved. ...Kerry

[Acer Saccharum]

I would think a bulged lug would be a very short loose spot in the barrel, like 1/2" long, not a 6" or 10" long loose spot.

Barrels will often have tight and loose spots from the factory, but we don't often look for them until we really try to get the gun shooting properly.

I am going to guess that most of these loose spots come from the manufacturing process, not from shooting. But they are not discovered until loading/cleaning procedures.

It is a good rule to run a tightly patched ball down a barrel BEFORE you make any cuts on it. Then you may be more likely to return it to the MFR without a problem. Once a cut has been made, it's yours.

While you have the breech out, it's a good time to make any adjustments to the plug-barrel fit. Easier done now than when it's already stocked up.

[bob in the woods]

Acer, unless Ihave it wrong, the loose spots are only 3/4 in long, and line up with the lugs.
Looks bad to me.

[Ian Pratt]

  I think what's being suggested is that you may have cut your dovetails too deep and don't have adequate barrel wall left in those spots, not that you used too much force in installing your lugs.
  Here's how I figure it - if Rice makes their Transitional C weight the same as everybody else, the barrel is .772 wide at the waist.  Subtract your bore size of .540, gives you .232. This is the total wall thickness, you need to divide this by 2 to give you a single wall thickness, which is the thickness of steel between your bottom flat and the bore. In this case it's .116. It's possible a rifling groove may fall across that area so I always include that depth too, so assuming the bore is truly centered you're down to around .100 wall thickness.
   Barrel makers generally caution against dovetailing lugs in the thinner sections of a barrel. I often use underlugs with a very thin base in cases like this or more often solder them on without dovetailing, then inlet the lug base into the barrel channel.

[KNeilson]

Acer,Bob, Pratt et all thx....

I would think a bulged lug would be a very short loose spot in the barrel, like 1/2" long, not a 6" or 10" long loose spot.

Acer, Bob is correct. The bulges are about 3/4 or so long, and the term youve used (bulged lug) would describe them or where they are quite well. 

Barrels will often have tight and loose spots from the factory, but we don't often look for them until we really try to get the gun shooting properly.

I read other posts that describe checking as you say and previously had tried this with out finding the "spots" that are there now.  When I put it together, I used 3 lugs as opposed to 4 to keep the center lug as far from the swamp waist as I could(because of the thin wall). My guess atm is that where I put the lugs, the barrel wall has moved enough for me to feel..  Kerry

Pratt, you posted while I was replying... This is my first build, I used the lugs supplied with the component set, and knowing what I do now soldering the centre one would have been a far better option. Your calculations are similar to mine, as in the wall being about .100, but the lug thats close to the breech has a similar feel also. And the barrel is over an in. there for a wall of 1.025-.054= .485/2 -.012= .2305 .
Here its not as bad but it still has moved or worn enough to feel.....Kerry

[Don Getz]

Strange that you would get noteicable "dimples" at all of the underlug spots, even the one toward the breech end of the
barrel where you have a lot of barrel wall.   I have cut dovetails into many barrels, even B weight barrels in 50 cal. which
has a thin wall at the small part of the barrel.   I would pull the breech plug, clean the barrel real well, and look thru it.
If there are dimples at those spots, it will show up as a dark shadow at that spot.   Did you by any chance shoot a heavy
proof load in the barrel before you actually started shooting it?    You state that you shoot 100 grains of FFF.   While I
personally would prefer FF, I don't think that load of FFF should affect the barrel.   You have created an unusual situation,
not sure if I have an answer.   Your dovetailing looks good, neat, and assuming it is not too deep, should not have caused
the problem.   I think if it were mine, I would switch to FF powder, hold my loads down to 80-90 grains, and continue shooting it.   If the problem gets worse after more shooting, I would then probably replace it.............Don

[keweenaw]

It's not necessary to seat the lugs the entire thickness of the base.  I cut mine to recesses 0.025 - 0.030" deep and then tip up the dovetails but even if you file the dovetails at 0.020 - 0.030" the lug won't pull out.  It only takes a few minutes to cut a bit of recess along the bottom flat of the stock where the lugs are below the surface of the barrel to get clearance.  

As to how much it's bulged, you can feel the difference in bore diameter with a tight patch at amounts that are less than 0.001" so the bulges might be very, very slight.  Of course the wall thickness at the rear lug will be considerably thicker than the calculations for the waist so having a bulge there surprises me.

There is no fix for this if the barrel is bulged as removing metal from the bore by freshing out will only result in a still thinner wall.  Also because the bulges are likely to be very slight the approach to even out the feel of the bore would be to lap it rather than recut it.

BTW 105 gr. of 3F is a pretty stiff load.  You didn't say what brand of powder you're using but if that were Swiss, it would be a really stiff load.

Personally, and I'm not advising that this is what you should do, I would only worry about these if I could see them in the clean bore with the breech out or my bore light shining up from the bottom.  And I would limit my load to 100 gr. of 2F Goez.  If I could see the bulges, the barrel would be scrapped.

Tom

[JTR]

You say the barrel has 3000 rounds through it?
And it hasn't blown up yet.
I'd think if it was going to blown up, it already would have.

But,,,, now you know there's some sort of bulge going on in there.
Maybe it's been there since the very first shot?
But then again, maybe it's just been there only since the last shot.
You don't know and there's no way to tell.

Chances are that you could shoot this barrel for another 3000 shots with nothing exciting happening. No smoke and fire, no parts blowing everywhere.

But now, absolutely, positively, since you know they are there, every time you concentrate on pulling the trigger your mind will be toying with thoughts of those bulge spots. Like a devil on one shoulder and an angel on the other, one will be saying go for it, it's okay! while the other is saying watch out, maybe this time!

So at some point you might find you move your grip on the fore end just a little,,, not to get your hand away from the bulge, not really, but because, well, for some reason it feels better to grip the fore end in the new spot.
 
Then you might start to flinch a little..... Certainly not because of the bulge spots,,,, but probably because of that new flint you put in there, or maybe a new brand of priming powder you started to use...

And then your groups might to start to open up just a bit on the targets..... Certainly not because of those bulgy spots, or your new grip on the fore end, or that little flinch,,, naw, none of that,,,, probably just some wind you hadn't noticed,,,,, but certainly not because every time you start your finger pulling back on the trigger your mind starts thinking about those dang little bulging spots!!!

So you might as well just get a new barrel and put it in there,,,,
because your going to do it sooner or later.

John

[Acer Saccharum]

I'd replace the barrel. Life is short enough already.

[KNeilson]

Don, Tom, thx for the replys , its the kind of information I am looking for. To continue my 2nd post, I went home and took the barrel out of the stock and measured it. The depth of the dovetails is .055,so the wall thickness will be what we figured earlier. I then took a small machinists square, and laid it along the barrel at the lugs location. There is no discernable "bulge" in the 7 flats surrounding the any of the lugs, and across the lugs I cannot detect anything that concerns me. Then I measured it, first with a screw mic, but I found this difficult to be accurate because of the barrels taper. I then drew a felt pen line around the barrel and used the thin section of a digital caliper and could not get more than .005 difference no matter where I measured. Nothing to suggest an "egg" or "oval" shape. The depth of the dovetails is .055 I draw filed the barrel when finishing which may cause some variance, and I would suppose this would be within the manufactures tolerances. I looked down the bore from the muzzle end, using a single LED on a flexible stalk and can see a slight difference in the reflection by the middle lug, but it looks more like a surface variance or tool chatter, rather than a shadow that would suggest depth.

To answer the last couple posts..
 It has never had a "proof" load or anything greater than 120 g of Goex thru it. The first 2500 rounds or so were fired using 50-70 3F or 60-80 of 2F while I was trying to find what worked best. With these charges I was getting from 1400-1600 fps. The shots grouped well, but I had difficulty finding out how much sight to hold at 75+ yds. I had told some of the local fellows I was planning to hunt, and it was suggested I used greater charges. This is when I went to the 80-105 charges. Measured velocity went to 1700-1800 fps,the trajectory flattened to about 3" in 100 yds, and my ability to hit what I wanted to across changing distance improved greatly. I was quite happy which is why I stuck with these numbers. I know now this is considered "stiff" as you suggest Tom, but no-one as of yet has suggested dangerous. I was paying more attention to MV than the granulation of powder I was using to get that, but I do feel my rifle is "faster" using 3F as opposed to 2F. This being the main reason I was/am using it, also I went and bought a case and am still working on the tail end of it.

To summarize,
 imho the spots are less than .001 as has been suggested, I tried again this am and a you need a tight fit with a stiff patch material to feel them. The barrel still shoots well, and as I have planned to use it hunting I think I`ll use it for only that, and get another to fit to the stock for "club" target shooting. I do more of this anyways, and would rather use a smaller caliber to save on powder and lead.. so far roughly 100# of lead and 30# powder this year. But I have been a bit maniacal in my new addiction.......thx for all the informed responces...     Kerry
John, Acer, you posted while I was typing,
John,

But now, absolutely, positively, since you know they are there, every time you concentrate on pulling the trigger your mind will be toying with thoughts of those bulge spots. Like a devil on one shoulder and an angel on the other, one will be saying go for it, it's okay! while the other is saying watch out, maybe this time!

Somehow I think you know me, my thoughts to a T....... Acer

Life is short enough already.

Why I`m doing this now....     Kerry

[Dphariss]

If the barrel has loose spots its junk.

Dan

[bob in the woods]

Life is short, but it would seem longer without fingers

[Don Getz]

If it were mine I would shoot it................Don

[Gaeckle]

I wonder if the hole for your pins is just but a hole in the barrel lugs....not slotted in any way or somewhat oversized for the pin. I would think that when shooting the barrel is flexing somewhat. Perhaps the stock is swelling and shrinking and combined with some flexing from the barrel you've created smooth spots directly in line with your lugs....

just a guess....

[keweenaw]

The only way to "see" a bulge will be to pull the breech or put a good light in the bottom of the barrel and have it coming up. The light has to be coming toward your eye. The first is better, a bore pointed toward a clear northern sky is ideal.  For the second, one of those single AAA minimag lights works great for a bore light for anything 50 cal or larger.  Our eyes are very good at seeing discontinuity in smooth surfaces.  When I take dents out of shotgun barrels with my English dent raiser I work at them until  I can no longer feel them but even then I can see them until I flex hone the bore.  As Don said, bulges will look like dark spots.

The loads you've given are certainly not at the level of unsafe loads.  My all around 54 cal loads in a B weight barrel are on the order of 80-90 gr. 2F, just never felt the need for anything hotter for our shooting which is all inside of 100 yds except for the odd shot at the monthly club shoots where there might be one long shot.  105 of 3F would be getting to the level of unpleasant for routine shooting.

Tom

[Ky-Flinter]

If it were mine I would shoot it................Don

Me too.


BTW, on the topic of bore lights.... Stonewall Creek Outfitters sells a tiny light that is a shade over an 1/8" in diameter and about an inch long.  Very handy and not expensive.

-Ron

[keweenaw]

Those tiny bore lights are bobber lights for fishing and have an LED for a bulb.  Buy them on a card at fishing stores very cheaply.  They work great in small bores but don't make nearly as much light as the minimags.

[JTR]

Hmmm, If you can't measure any discernable difference other than between .001" and .005" between the 'bulged' area and a non bulged area, then you don't have a bulged area. Like you said, a .001" to .005" can be the difference from draw filing.
I wonder if what you're feeling inside the bore isn't a loose spot, but instead, a slick spot?
You've shot it 3000 times more or less, so maybe the patches have just polished the bore in some areas? Let's see, add a little black powder residue from the previous shot, add a little lubricant from the patched ball,,, shot the works down the barrel with a good bit of force and speed,,, enough times,,,, the patch polishing the bore doesn't sound impossible?

If this is the case, knock those angles off your shoulders, and shoot the thing!

John 

[Dave Faletti]

Could the barrel have had internal stresses that cutting the dovetail relieved?  If you are getting good enough accuracy I would shoot it.