doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Barrel Bulge - How much is unsafe?

Dear Mr Beretta,
If I get one of your authorised dealers to hone the bores of my SO-5 by two thousands of an inch, because that is what I like, and whilst he is doing that he fixes the loose rib that you were incapable of fixing when you made this expensive piece of crap.Will it be still covered by your factory warranty as obviously the bores will still be in proof.
Yours sincerely,
John Moses Browning

With all due respect, I disagree completely with the statement that "When steel undergoes inelastic deformation, the tensile strenght decreases and may fail subsequently catastrophically."

First, steels that are of low hardness like barrels, can be "cold worked" ("inelastic deformation" or commonly known as plastic deformation) safely and in most cases this enhances hardness and strength, and often increases fatigue strength. Heck, we do plastic deformation of parts specifically to enhance strength properties on airplanes all the time.

Dents as well as bulges are examples of plastic deformation. Both are safely fix by cold forming almost routinely, because barrel steels are very mallable. So mallable in fact, that the manufacturers routinely roll mark barrels, another form of plastic deformation.

So, I believe the notion that a little ol' .001" bulge reduces strength or is dangerous, is not only false in my estimation, but outlandish as well to this engineer.

"So, I believe the notion that a little ol' .001" bulge reduces strength or is dangerous, is not only false in my estimation, but outlandish as well to this engineer."

This Engineer has degrees in Nuclear Engineering, Graduate study and research in Metalurgy from the University of Wisconsin all which can verified by calling the Department Chair of what is now called Engineering Physics, Michael Corradini http://www.engr.wisc.edu/ep/faculty/ . Mike used to work for me.
Rebut my Post about Metalurgy and steel but don't personally attack me as 'outlandish'!
There is nothing incorrect in what I Posted.
Beretta is correct in that "He advised that this rendered the gun unsafe".
Engineers do not deal in 'estimation' and you should be glad that they are trained not to.
You on the other hand are quick to dismiss and quick to personnaly attack what you don't agree with, unfortuneatly a trait that shows up more and more frequently on the Internet.
I really don't care if you don't agree with me but I do care about your attack on myself. If you want to keep things civil, then an apology is in order, if not, then so be it.-Richard Budowle

Dear Sirs,

This is a very interesting interchange of information and as tone and nuances cannot be conveyed adequately while posting I'd be a little more "thick skinned".

Outlandish (as in bizarre or unfamiliar) doesn't sound as needing apologies, but...

Anyway, I am far from being an engineer, but the example of dents and their repair does seem to grant the fact that the barrel's safety won't necessarily suffer from an "outwards dent".

Am I very out of touch here? If I need correcting go ahead, I am humble enough in my ignorance.

JC

JayCee, I agree on all three counts. Can't begin to imagine how a .001 bulge can render a barrel unsafe!! After all what is the difference between a "bulge" and a "dent"? Dents have been routinely removed from barrels many times greater than .001 and used every season with no problems. JMTC

Gentlemen,

I am new here and aside from the fact there is truly a "gold mine" of information here I am a little disapointed with some of the bantering found here. However, in regards to the question at hand will the 0.001" bulge create an unsafe condition - it is very unlikely. This is assuming no other part of the shotgun was compromised when the bulge occured. No one here other than the owner has personally seen the gun, right ? As previously mentioned the so called bulge is a result of the steel stress exceeding the yield point of the steel (plastic range) resulting in permanent deformation. However, this will not necessarily result in weakening of the barrels or we have many weakened barrels due to dents that have seen regular service for many years. Has anybody ever tried to accurately measure 0.001" repeatedly? Unless you are very experienced and careful with your measuring technique you could very easily exceed 0.001" in measurement error. All else being OK the barrels will be fine.

Hard for me to imagine that .001 inch bulge would have even caused the rib solder to turn loose. I was under the impression that soft solder jobs were much more elastic than that. I have been removing a bulge midway up a set of 30" Utica Fox ejector barrels. This bulge was much, much more than .001", though my memory fails me as to the exact amount right now. Anyway, when the bulge was nearly removed all the way around the barrel except for between the ribs, which required maybe two hours of peening with a specially filed brass punch while a bore plug was inside, one rib finally popped loose at the site. This is no great problem. I will have the ribs removed, after which I will finish removing the rest of the bulge between the ribs, then I will have the ribs relaid and the barrels reblued. I will then shoot the barrels as I do my other Foxes.

I have found that steel, as well as other metals, will work harden. Have no idea whether or not this strengthens the area, but it darn sure gets harder. I am not surprised at Beretta's response, however.

As a student we conducted tensile tests on steel specimens. The purpose of one test was to demonstrate that the yield point of steel can increased by reversal of stress. The experiment showed that if a steel specimen is stressed to the yield point and the load is removed and then a load is reapplied the yield strength increases.At the same time elongation is slightly reduced but the ultimate strength is not changed.You can demonstrate this phenomenon by taking a paper clip and bending it back and forth. You will note that it gets progressively stiffer to bend the clip untill it finally fractures. This is the point when yield and ultimate strength are one and the same.It follows that the elongation is zero at fracture.
My understanding of the British rules of proof is that barrels submitted for proof that are rejected due to small bulge, may be repaired by hammering down the bulge. After reboring these barrels may be submitted for reproof. Provided they pass proof,they are approved for use by the gun maker.

I think you are all a little right, and all a bit wrong too. .001 inch isn't at all dangerous. I'll bet that there is more variation in barrel diameter over the length of the barrel than that. I'm sure that Beretta is as lawsuit-shy as any other company in this litigious society and would naturally advise not to shoot the gun. Mild gun barrel steel will work harden and that is not a good thing in barrel steel. Taken to extreme, work-hardened steel in a single spot on a barrel wall is a recipe for catastrop failure if subjected to sufficient pressure. Non-hardened steel barrel walls would probably just bulge. But in my opinion the cold work to take out .001 isn't going to increase the hardness of the spot to such a degree that there is any risk to anyone.

I think that this is now getting off topic.I do not wish to read about people falling out over THEIR personal opinions.
I believe my tongue in cheek John Moses letter gets to the point of the original query.
Get in touch with Beretta and get them to sort it pronto.
It is very obvious to me that this gun had quality issues before it was released from the factory, and the factory rep who gave his opinion and cause of the bulge needs to be retrained or perhaps even trained.There are Gunsmiths and Gunsalesmen.I don't deal with salesmen.