Barrel slugging

[DShortt]

New lapped barrels are normally going to be looser at both ends, that's why they recommend cutting an inch off both ends. Probably not necessary at the chamber end but definitely necessary on the muzzle end.

Yes, agree with that. That's why I insert the slug an inch into the barrel to get past the extreme end.

 

[Road_Clam]

So for my knowledge , by slugging are you trying to identify bore imperfections or the rifling dia ? Typically in any through hole making machining process you have entry and exit "bell mouth" to a certain degree, its just the nature of applied cutting forces.

 

[LVLAaron]

So for my knowledge , by slugging are you trying to identify bore imperfections or the rifling dia ? Typically in any through hole making machining process you have entry and exit "bell mouth" to a certain degree, its just the nature of applied cutting forces.

Diameter problems. Looking for tight/loose spots.

 

[DShortt]

So for those of you who do slug barrel blanks, have you found many that you consider out of spec/rejected? Please don't call out suppliers, that's not what my intention is with this thread. I've just been surprised by my personal experience and wanted to know if I have company or just have bad luck buying blanks.

 

[jackieschmidt]

Yes, agree with that. That's why I insert the slug an inch into the barrel to get past the extreme end.

The barrels in the OP’s initial post is are already chambered and tested.

 

[DShortt]

The barrels in the OP’s initial post is are already chambered and tested.

Sir, I'm the OP. I've found abnormalities with both chambered and crowned barrels as well as blanks. The insert the slug an inch into the bore comment refers to blanks.

I apologize for not being clear about that.

 

[STS]

I slug blanks as soon as I get them. I've sent back 2 in all the ones I've slugged. Both from the same manufacturer, and both very obviously loose in the last 3 to 4 inches of the blank. There is no point in spending any more time with a blank like that. I'll echo what Dusty said about the technique of slugging. If you sense a tight spot, you have to bump the slug back up to size once you get past the tight spot to do the job correctly. In fact, I will start the slug and advance it down the barrel and see if it has the right feel. If it needs to be bumped up to get the right resistance you need to expand the slug between 2 rods. Lube the bore and slug with oil and run it back and forth a few times and defects will be obvious. If you want some entertainment slug a bunch of factory barrels. You'll dislocate your shoulder when you hit some of those loose spots.

 

[DShortt]

I slug blanks as soon as I get them. I've sent back 2 in all the ones I've slugged. Both from the same manufacturer, and both very obviously loose in the last 3 to 4 inches of the blank. There is no point in spending any more time with a blank like that. I'll echo what Dusty said about the technique of slugging. If you sense a tight spot, you have to bump the slug back up to size once you get past the tight spot to do the job correctly. In fact, I will start the slug and advance it down the barrel and see if it has the right feel. If it needs to be bumped up to get the right resistance you need to expand the slug between 2 rods. Lube the bore and slug with oil and run it back and forth a few times and defects will be obvious. If you want some entertainment slug a bunch of factory barrels. You'll dislocate your shoulder when you hit some of those loose spots.

Yep. You ain't kiddin' there even a little bit. There seems to be no end to the way rifle manufacturers can manage to mess up a barrel. The only reason I mentioned them in my opening post is that's the reason I started checking all barrels. If we're paying a premium for an aftermarket product it should be a premium product in my way of thinking. Otherwise why bother?

 

[jackieschmidt]

To be exact, I have slugged maybe 10 barrels in 20 years. Mainly just for curiosity.

I have never found one that felt anything but normal.

But then, for the past 25 years I have shot nothing but Kriegers and Bartliens on my 6PPC and 30BR Competition Rifles. I I see no reason to try anything else.

 

[Tad_Earhart]

There is quite a bit of good info here on slugging and what to look for. I would like to add a few things myself with the preface that 95% of my barrel work is typically for rimfires where usually the barrel lives and dies by how it slugs (lead bullets) and where the chamber and crown is located on the blank. It is pretty well known that the rimfire blanks of quality are taper lapped from the manufacturer because of this but a person still cannot just blindly pick a spot to cut and crown. I have and will likely always continue to do my CF barrels the same as I outline below.

I think the idea posted earlier of "mapping the bore" best applies to what I am doing when I am slugging either a new blank or a fitted barrel. On a new blank, I will typically use about 15 slugs to get a complete picture, with measurements, of what the bore is doing. I will push 2 slugs through the bore, breech end to crown end to get an idea of the bore to start, then I will push individual slugs in from the breech end, incrementally in steps, and then push them back out of the breech end to preserve the diameter at that spot for measurement. My increments are 1", 2", 3", 6", 9", 12", 16", 20" from breech, then 3", 2", 1" from the crown end. I will mark all of these increments on my slugging rods and push the slug from the breech end up to the desired mark, then push the slug backwards out the breech again. My opinion, pushing the slug backwards can almost tell you more about the bore than pushing it forward based on how easily and quickly it will release the bullet, if at all. While I am pushing all these slugs, I am marking the spots that I feel something funny or odd to see if a pattern comes up. I have done many barrels in the past that on the reversal of the slug back out of the breech end, I detected some sort of odd spot in the bore, usually roughness, that I never felt pushing the slug forward. Then the final two slugs are used to feel for any of the anomalies I may have felt during the process and either confirm or deny them. After all of this, I will mark the OD of the blank at my increments and measure each slug and record the measurement at each spot of the bore. When you finish up, it gives an easy visual up and down the blank how it tapers, if it does, and what places may be best to establish the throat/leade of the chamber and most importantly here the crown.

I am not suggesting that my practices are the best for everyone, it is a ton of sorta aggravating work, but I will not fit a barrel without doing it. I use pulled bullets from cheap lead rimfire rounds. They have worked fine for me with .22CF barrels as well, occasionally having to bump them a tick bigger to fit the bore better. Cheap lead bullets that are not coated or full of lube will work fine for the larger calibers as well once they get started in the bore. One thing that I do differently is that I do not lube the bore or slug. This post has gotten entirely to long to explain it further but I did want to note it.

 

[rwj]

Do any barrel manufacturers specify ID tolerances against which the results of slugging can be compared and become a basis for return?

 

[LVLAaron]

I'm gonna make an educated guess that zero barrel manufacturers want you slugging their barrels.

 

[Mark Buettgen]

I'm gonna make an educated guess that zero barrel manufacturers want you slugging their barrels.

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

 

[rwj]

I'm gonna make an educated guess that zero barrel manufacturers want you slugging their barrels.

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

Exactly!

 

[Dusty Stevens]

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

I use the bones. I done ate the chicken.

 

[DaveTooley]

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

Mark's a specialist when it comes to Vudoo chickens.

 

[DShortt]

I got mine from The Viper.

 

[Brady W]

Mark's a specialist when it comes to Vudoo chickens.

He's a crazy person. Just ask him, he'll tell you!

 

[Brady W]

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

+1

 

[Tad_Earhart]

Vudoo, live or dead chickens, flying pigs, etc how else are you to determine the place to cut the barrel to finish it? Maybe I am unaware of some new tech that gives the same info as slugging? I know I would sure enjoy barrel fitting more if I did not have to go through the process. I'll admit the better the quality of blank (lapping), the less that needs to be done in terms of slugging for determination of spots to cut but who wants to blindly fit a blank to find out many rounds and time later, if it would have been slugged they would have found a bad spot 1/4" back from where it was originally crowned? Way to many stories like that come about and no telling how many barrels have been give up on because of something like that.