barrel question

[Robby]

I have a .32 cal., 3/4" across the flats, GM barrel, 42"long. After shooting it yesterday I noticed a slight, but noticeable, easing of the patch at one place as I cleaned the bore, by measurement it is 5-1/2 inches from the breech. I don't shoot the gun often and don't remember this from before. I have never fired more than 40gr. 3f through it. I pulled the barrel and B/P, and, held to the light, there is a visible ring, faint, but you can see it. It looks almost like a dent. I miked the outside, and there is no bulge on there. I have heard the term "ring the barrel" used here and that is what I am wondering has happened (if I understand the term correctly). I never noticed any difference in loading, seating or shooting. I made this gun for my wife and certainly don't want to use, or let someone else use it, if there is a safety issue, but I don't really understand what is going on. Any thoughts and suggestions on this would be greatly appreciated.
Robby

[Acer Saccharum]

There are two possibilities that come to mind for me.

One possibility this ring was in there from manufacture, and you never noticed it until you had a tight ball and patch combination.

The other possibility is that a ball may have not been fully seated. Sometimes the ball gets stuck on the fouling, and won't go down anymore, so it feels like it's on top of the powder. But it's not. This airspace between powder and ball is what can cause a barrel to get a ring in it, from the shockwave of pressure suddenly hitting a stationary object(the ball).

I doubt the barrel is compromised from a strength issue, judging from the healthy wall thickness. Will it still shoot OK? You will have to bench it to find out. My guess is that it will shoot fine, as long as the ring is down at the breech end.

Acer

[JCKelly]

I would urge you to cut off and discard that section of the barrel. It is unlikely to cause problems, I think, but if it does it will be a very, very bad problem. Barrels are cheaper than body parts.

If there is a ring in the bore that means the metal was dented, or moved around a bit. There is only so much that you can stretch or move these steels without potential for some damage. Don't believe there is any way to find or measure that damage, except that if the barrel has a ring, which I would think of as a 360 degree local dent, it has been cold worked a bit.

I suppose it is obvious, but I should say that whatever caused that ring was an extremely high local pressure. That Green Mountain barrel is made of 1137Mod, GM can be more definite but the yield strength is somewhere above 70,000 psi. Again a good mechanical engineer might be able to tell you better, but to me that means the local pressure probably exceeded 70,000 psim That is unusual with black powder but it surely does happen.

I've done metallurgical investigation of a number of failed barrels in the past, acted as expert witness for a couple of guys who got severely injured and just plain looked at one ringed barrel.

Of course, the most common and we would like to believe only reason for a ringed barrel is not seating the ball on the powder.

I think other things can happen now & again that are in no way due to the shooter's error in loading. Well, that's just my opinion, although I think I've a gov't paper on cannon that says the same thing in language I don't understand. I am a mere metallurgist, not a great mechanical engineer.

Anyway, cut off & throw that part of the barrel away.

[P.W.Berkuta]

You can try and get a Green Mountian to have a look at it and let them give you their expert advise ---- 

[J Shingler]

You sure this might not be a reamer chatter mark that you just noticed? I think you would have noticed you're rammer sticking out an extra 5''. And even then not good but you are talking about a 32 cal. What kind of load do you shoot? Maybe some slight corrosion in the breach area making it feel tight and the clean slick area above it feel looser? Just hate to see you scrap a barrel if it really is not hurt. I have only seen two ringed barrels and they were both close to the muzzle.   

[omark]

if it is truly ringed, you should be able to find it on the outside with a micrometer.     i had a 22 barrel with 3 rings in it once, and you could run your fingers up and down the barrel and could feel each one.     mark

[Jerry V Lape]

I won't disagree with JCKelly.  However, if there isn't a corresponding ring on the exterior of the barrel I would doubt the barrel has been damages.  I  suspect you have either not noticed it before or you have smoothed up the barrel in usage in that area.  Measure that barrel/s exterior carefully with a quality micrometer as a first step to determining whether it is actually damaged or not.  You might also go so far as to find someone with a laproscope to let you take a good close up look at the area on the inside. 

[Robby]

Wow, A lot of good information. Thank you all so much. I decided to err on the side of caution, not something I would ever be accused of when concerning myself, but, Other people will shoot this gun, and down the road who knows. I would not want to think I caused someone else harm from something I did or neglected to do. I have just ordered a new barrel, After a good deal of phone work from leads given to me by G/M, I found one.
       I remeasured the barrel with a good micrometer and can find no deformation for three inches either side of the ring, there is a lot of steel there, I cannot remember it ever being there before, and cannot think of anything I might have done to cause such a thing to happen, but, I just cut it off, so I can't change my mind. Besides I have made a lot of guns built around a barrel, now I get to build a barrel around an existing gun, that's different, just trying to create a bright side. Anyway, thank you for the thoughtful answers, I did consider everything you folks offered, thank you.

[Birddog6]

Being it is a .32 cal & you are fairly sure you didn't short start it, My guess is it is a chattermark from the reamer.  If the power fluctuates much at all while they ream the barrel, it makes the reamer chatter from the speed change of the maching going off & then surge coming back on & it will cause this.  I have had 4 barrels that had this at dif. times in the past 10 years, and they were brand new barrels.......  Which is why when I buy a barrel now, be it one of 6 at a time. EVERY one is debreeched & checked for breechface/plug fit, then swabbed with a Tight jag/patch to insure the barrel is as perfect as I can feel & see.

And it could have a ring in it & it not be visible or measurable on the outside of the barrel, IF  this was caused by the reamer, because the reamer deflection would not show on the outside of the barrel.

That being said, you have 3 options.

1: Shoot it as is & take your chances.  It is a .32 cal & IMHO, light charges will never be an issue.
2: Send it to Green Mtn. and let them check it & get their opinion. They may replace it & then you get to rebarrel the rifle & fit it to the rifle.  Not fun sometimes.
3: Send it to Bobby Hoyt & let him check it & if he finds it OK, let him recut the rifling & he can make that puppy slick & smooth as a whistle...... I sent him a couple barrels a while back & they came back like brand new.  Not a round bottom cut like they had, but very nice job & saved the barrels at a reasonable price..

 

PS:   IF  you are loading with a vent pick in the vent while loading, you could have short started it.  One time I was shooting a .40 cal & loaded it as such & leaned the rifle against the bench with the range rod in it sicking up out of the barrel & while standing there, the rangerod rose out of the barrel about 5-6" !!!!  I thought I was seeing things. So I asked the guy I was talking to if he saw that.  He said Yes, but I thought I was nuts.  I checked & pushed it back down & it came up 2". Took the tight  tapered vent pick vent pick out &
then pushed the ball down. Shot it, tried it again.... same thing.  Keep in mind this was a really tight ball/patch combo with grease, but it happened.And that was the last time I put a vent pick in tight when loading also.      You CAN compress a load & air into a sealed space & the compression move the ball..........  The same way a CO2 discharger works..........

Oh well........ Sorry... Couldn't type it fast enough.  You did a 4th option ! 

[caliber45]

Hey, Robby -- Since I build "carbines" (21-inch barrels, so I can get TWO out of a GM 42-incher) and derringers, I could make use of that barrel if you'd rather sell it than build a shorter rifle than you're accustomed to building. I'd have to order a 3/4ths barrel channel cutting tool (been meaning to, anyway . . .), since I normally use 13/16ths GM barrels. If you want to sell, let me know (eallen10@cox.net) the price, and I'll consider it. Sorry for your problem; I HATE to have to cut up a finished rifle. -- paulallen, tuc. az

[David Price]

A friend of mine  fired his 40 cal rifle when it was only short started and ringed the barrel.  There was no ring on the outside of the barrel.  He new that he did not drive the ball home so we knew what caused the problem.  That was thirty five years ago and he is still shooting the rifle today, and it lost no accuracy.

Put your short starter down the barrel and see if the bulge is at the end of the starter.  If it is I would have to guess that you fired it with the ball only short started.  It can easily happen.

[Kermit]

Good enough reason not to use short starters. 

[smallpatch]

Robby,

I have a 20ga Colerain smoothbore barrel that is ringed about 6" from the breech.  Barrel was dirty, fowling hard, nitro card got stuck, assumed it was seated.  Barrel has no ring on the outside.
When it happened, I called Colerain.  Their explanation is that as an obstruction, the super heated gases will cause that ring, before the ball begins to move.


Long story short, I've been shooting it for about 8 years.  Shoots like a champ.  Both shot and ball.  I sure don't use the hard cards anymore.


Especially in a .32.... I'd shoot the crud out of it.

[Dphariss]

Being ringed inrenally does not alway mean its ringed externally on a thick wall
There is also the possibility of a FLAW of some sort.
Replace the barrel if GM won't. The risks are too high.
If you keep the ringed barrel just cut it off 6" from the breech and proof it well before any future use.

Dan

[Robby]

Like I stated previously, the deed is done, I cut the barrel off. If it were me and me alone, I probably would have kept on using it, but, down the road one of my grand kids will have this gun, and if there is a one in a billion chance that it would hurt one of them, I won't take it, besides, if any of my genetic make-up has been passed on to them, they will find plenty of ways to hurt themselves, you can't do everything for them.
Thanks again,
Robby

[J.D.]

if any of my genetic make-up has been passed on to them, they will find plenty of ways to hurt themselves, you can't do everything for them.
Thanks again,
Robby

Now that is funny. Sad, true, and funny. And unfortunately the same can probably be said for everyone who reads this forum. 

All in all, I think you did the right thing by removing a potentially dangerous area from that barrel.

God bless,
J.D.