What I am wondering about is the apparent pitting in the photo on the right.
This barrel was taken off of a rifle that I had built years ago, .338 Jamison.
I recently purchase a borescope and the pictures are of this barrel.
What am I looking at??
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What I am wondering about is the apparent pitting in the photo on the right.
This barrel was taken off of a rifle that I had built years ago, .338 Jamison.
I recently purchase a borescope and the pictures are of this barrel.
cohunt
Well-Known Member
Looks like tool chatter marks to me, but I'm definately not a pro
yoteslayer
Well-Known Member
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- Feb 4, 2013
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Not sure but looks a lot like fire cracking what barrel mfg and how many rounds
BallisticsGuy
Well-Known Member
This. Circumferential grooves are tool marks. It'll probably make it take a while to get copper equilibrium but no worse than most off the shelf rifles. Good bore scope pic quality!
Hand Skills
Well-Known Member
Looks like galling to me. Galling is defined as adhesive wear. In truth it's likely a combination or abrasive wear and adhesive wear.
Very much exacerbated by the machining marks left behind by tooling.
The mechanism at play here is material getting stuck in the machining marks and taking barrel steel with it when it leaves. Under intense heat and pressure it's not an easy thing to model, but that's what happens in a rifle barrel.
Lapping is a very effective means of reducing such tool marks, which in turn reduces fouling. It also can reduce the fouling shots required to reach the equilibrium @BallisticsGuy mentioned.
I understand you're asking about the pitting, does that answer your question?
Very much exacerbated by the machining marks left behind by tooling.
The mechanism at play here is material getting stuck in the machining marks and taking barrel steel with it when it leaves. Under intense heat and pressure it's not an easy thing to model, but that's what happens in a rifle barrel.
Lapping is a very effective means of reducing such tool marks, which in turn reduces fouling. It also can reduce the fouling shots required to reach the equilibrium @BallisticsGuy mentioned.
I understand you're asking about the pitting, does that answer your question?
Yes, and I was a little surprised to see machine marks like that.
My other thought is that I used to use Sweets until I learned here on these forums that it was not recommended by some. Was wondering maybe some of the Sweets was not removed by dry patches and left in the machine marks and possibly initiating the pitting.
Thank you all for the replies
By the way the rifle this barrel was on has since gotten a 270wsm barrel(pacnor) that shoots very well!
Gary
My other thought is that I used to use Sweets until I learned here on these forums that it was not recommended by some. Was wondering maybe some of the Sweets was not removed by dry patches and left in the machine marks and possibly initiating the pitting.
Thank you all for the replies
By the way the rifle this barrel was on has since gotten a 270wsm barrel(pacnor) that shoots very well!
Gary
Hand Skills
Well-Known Member
By the two pictures it appears pitting is localized to the lands only. If you are seeing pitting in the grooves also, maybe a solvent has an effect. But on only the lands I don't think so.
Ok, good information.
I recently got the bore scope and have taken a look at most of my barrels.
This particular barrel is the worst of the bunch which is surprising to me since this was suppose to be a custom barrel at the time. The pacnor for example doesn't have near the machine marks that this one does.
Anyway just asked for my own information, probably not going to use this barrel any longer! Thanks again for all the replies!!
Gary
I recently got the bore scope and have taken a look at most of my barrels.
This particular barrel is the worst of the bunch which is surprising to me since this was suppose to be a custom barrel at the time. The pacnor for example doesn't have near the machine marks that this one does.
Anyway just asked for my own information, probably not going to use this barrel any longer! Thanks again for all the replies!!
Gary
BallisticsGuy
Well-Known Member
Why not keep using it? The lands are still sharp and there's no alligator skin. I would assume the throat is in similarly good condition. If the gun still shoots well, use it till it stops shooting well.
Many of my students have asked me if they should get a borescope. I always tell them no. Anything they learn from looking in the pipe is unlikely to be well understood by non-experts and will only cause them to needlessly second guess themselves.
Many of my students have asked me if they should get a borescope. I always tell them no. Anything they learn from looking in the pipe is unlikely to be well understood by non-experts and will only cause them to needlessly second guess themselves.
B23
Well-Known Member
That's about how most factory barrels look when they're brand new, I'm a little surprised a custom barrel looks that bad though as they nearly always look much better than that.
J E Custom
Well-Known Member
What you are looking at is a very poor Quality barrel !!!
The annular marks are from the drilling process. It was bored to large for the reaming (If reamed) to remove it. Reaming is a very important part of the rifling process and is done to true up the drilled hole and size it for rifling.
It also looks like the rifling process was not proper to get the annular drill marks off the top of the lands. The top of the lands should be smooth and free of any machine marks. in addition to all of the problems with the bore, The billet had some problems as well that caused Delamination. (the missing square chunks are not indicative of piting) this normally occurs when a sufficient amount of the billet is not removed before forming/rolling and the billet still has some slag
or defects in it and when rolled they leave cold joints/lamination's.
Attached is a link to a barrel makers video inspection and what the bore should look like when finished. that may give you an idea of what a bore should look like if done correctly.
http://riflebarrels.com/video-inspection-machine/
This looks like a buttoned rifle barrel Because of the lack of machine marks on the edges of the lands where the barrel material is forged into shape and size, and with the improper bore size there was not enough material to displace the defects. This can also occur in a cut rifled barrel if the proper process is not used. I have a brand new cut rifled barrel that has some major problems and has been rejected for use.
Chances are that you cant see any defects with a bore lite, but when you look with a good bore scope, what appears to be fine, suddenly
is shockingly bad.
J E CUSTOM
B23
Well-Known Member
It won't surprise me if it shoots really well for you. The barrels on my CZ 527's look about like that and they still shoot amazingly well.
