Stainless Steel Barrel imperfection?

J

JRB

Guest
I have just fitted and run in a new stainless barrel, run in took longer then expected, about 30 shots. Some barrels have cleaned up in less than 10 shots. I cleaned after every shot to remove any powder and copper fouling.
After which not much improvement so i decided to do some groups 6 shots and clean, while i continued for another 30 shots
I inspected the bore prior to running in and saw only light chattering from the rifling process, when i informed the manufacturer, i was told that it would shoot well, and hand lapped by them, so get to it!
When i first inspected the bore after some sighting in and initial load testing, which was a waste of time, with erratic shots, and inconstant groups.
I saw what first looked like some bad copper fouling, a bit relieved, as i wanted to find the gremlin in my groups, i started to clean with JB, and then some sweets to remove any copper. I scoped two or three times to monitor my progress, I was quickly disheartened as the copper color went but what remains, appears like, with the bore scope some pin pitting which looks like rust pits in a neglected CM barrel.
The pitting for need of a better word, was not evident before the break in.
It has shown up in 1 land as small pin pits about 2 inches from the muzzle, and then as a line of pits quite deep about 1/2 inch long and 1/32 wide about 1 1/2 from the muzzle in the groove and again in another groove about 1/32 wide and 3/4 long extending out the muzzle and over the crown as small pits. i now know why the barrel will not group!

I have seem this before in another barrel i have, from about 6 years back, but this is a current stock, new barrel from a leading manufacturer.

Can any one advise what it is, and if there is any hope for this barrel?
I would need to cut off about 2 1/2 inches to remove it from what i can see now. I do not want to do this as i need the length.
Much Appreciated,
Have a Safe and Merry Christmas
Jim
 
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It sounds like what they call inclusions. Here, in the states, a phone call and a send back would be in order and let them decide what they think before insisting on a replacement.
 
I know a barrelmaker that busted up a drill during the deep hole drilling. He decided to section the blank where the drill crumpled and found a ball bearing cast in the steel at that spot....all the steel used today is recycled and there can be some crap in there. I'm sure the maker will make it right.
 
If you can physically see something in there, yes, any reputable barrel maker will send you another barrel.

Barrel makers by barrel stock by the tractor trailor load. And even though the 416 R that most use is by industry standards up to the task, they are still at the mercy of the supplier.

It when you have have one that is just stuck at about a .300 aging capability, but you can't actually see anything wrong, that you are just out of luck.

We will get a bad piece of shafting now and then. Sometimes the flaw will not appear until the material has already been prepped and is in the submerged arc welder for overlay do we find it. The supplier will give us a new piece of shafting, but we eat all of the cost we incurred up to that point, which can be in the thousands of dollars.
 
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I've had similar issues - - -

One of the last barrels I had chambered appears to me has never been finished lapped. I didn't look inside it before I had shot it a bunch, which was a mistake. If it had been looked at prior to chambering, I'm pretty sure it would have gone back. It has been a teaser BUT since I have been lapping it as I do a big clean up after a match, it is shooting better. Makers don't always get em right. I also had a barrel from the same maker years ago that, in spite of it being a laser, had big inclusions, which kept falling out. That barrel set a National Record after I sold it to a lad capable of breaking a record :).

The problem with all of this is, if one does not do their own work, they are into a bunch of money once the barrel has been fitted. I only know of one time a maker sent two barrels to make up for the expense of the chamber job, a number of years ago now but should be a matter of good business practices as far as I am concerned. A barrel doesn't cost that much to a maker.

Pete
 
I recently had a problem with a stainless aerospace part I machine. The parts were required to be tested by mag particle inspection. The inspection failed about 30% of the parts due to “piping” in the material. Think of it as little voids like “pipes” running with the material grain. The material was melted in Italy and previous orders were made from domestic Carpenter material with no issues. I spoke with a metallurgist at Carpenter and the response was they go to great lengths to ensure this condition does not exist within their material but no guarantees could be made against it. Ultimately, some of these material flaws end up being just a really bad deal for the part manufacturer at no fault of their own.
 
Many Thanks,
I will contact the manufacturer and ask for his advise,
So the best guess is that it has an 'inclusion' in the metal grain structure, like air bubbles i guess.
The weird thing is that i closely inspected the last few inches and crown prior to the run in and was nearly perfect from what i could see, apart from a few tool marks. So does the pressure and heat from the bullet open up the imperfection?
Jim
 
A barrel maker explained it to me

A feller I know who makes barrels explained to me how slag gets into the mix that barrels are made from. It's a long explanation but what it amounts to is not enough care taken by the folks who melt down the steel. The end user is saddled with the results. Probably the most critical end user would be us but then what we need from the steel demands perfection, unlike many other uses for the metal.

Pete
 
I was discussing something like this with Greg Tannel a few years ago, and he said that it was probably sulphur inclusions from the added suphur precipitating out. My bore looked like wormwood here & there. Fortunately, it shoots great for a varmint rifle and fouls very little.
 
Regardless of source, what's to complain about?

All barrels are imperfect ... unless they're a "hummer.":)
 
Ok i have been in touch with the barrel maker and he will supply a new barrel, so that is good.
I have shot the barrel a bit more to see if any more inclusions appear, as all looked good at the start, and how they change, now even after cutting 1/2 inch off the barrel and starting again with a fresh crown.
The muzzle inclusion has returned to the muzzle and the other inclusions are changing in shape, getting bigger with in the bore.

At what point do the suppliers to get quality steel!!
Does this come down to cost??
Does the barrel maker get the cost of the steel reimbursed by the supplier?
 
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