Slugging barrels.... don't do this!!!!

[FrankG]

To all.... I will come right out and say it.... slugging barrels I don't agree with for multiple reasons. Argue with us all you want.

Customer feels his gun wasn't shooting good enough. So he makes his own steel bushing to slug the bore and threads it on to a cleaning rod and pushes it down the bore. He feels there are tight spots in it. I'll guarantee the barrels bore/lands are all scored and the barrel is junk! No warranty!!!!!!

No information on how he's cleaning it, caliber, how many rounds on it etc....I told him flat out.... not going to warranty the barrel. Not to mention no information given as to the actual diameter to the .xxxx" place the bushing was made to and what equipment was used to measure the bushing.

We had a gun manufacturer without even talking to us.... decided they were going to check the bore size of the barrels.... yes they pushed gauge pins down the bores of not one... not two but around a couple of hundred of our barrels.... every barrel the lands were scored and damaged!

Not to mention any lint or debris in the bore or any type of fouling... it's just going to amplify making something to go sour.

Don't even argue, lead slugging isn't any better or won't cause any issues. It will not give you accurate measurements.

Even Mark has gone off on guys saying they slugged a bore with a lead slug and tried to measure the grooves.

There are maybe two guys.... that I/we know that will tell you they have slugged/checked bores and they are honest in saying they can get close to the size but even what they come up with is subjective.

Later, Frank
Bartlein Barrels

 

[LVLAaron]

Steel bushings? Damn.

 

[SKWERLZ]

Ooopsies

 

[chester999]

Wouldn't a tight patch give as much info as slugging a barrel?

 

[Will Henry]

Slugging a barrel, with a lead slug, can give you some information, but not necessarily the information you think you are getting. If you push a slug through a barrel, it will reflect the diameter of the smallest place in the barrel. You will be able to feel variations in the bore, but you may not be able to tell what those variations are. In other words, what feels like a tight spot may be tight in the bore, in the grooves or both. It may also be an indicator of a variation in land width. The important thing is, you can feel very minute variations. Minute enough that you would have trouble finding the source.
Recently, I had occasion to slug a barrel in an attempt to find out why it shot so poorly (NOT a Bartlein barrel, by the way) The barrel seemed tighter at the muzzle (by a barely measurable amount) and felt tight at the throat. The thing was, it wasn't tight at the throat. Instead, what I was feeling was the deformation of the lands caused by a dull throater or poor technique, or a combination of the two.
Another barrel I slugged in an attempt to gauge the variations in diameter. This was possible because this particular barrel varied a LOT. A 7mm, it varied from .2836 to .285+ (as close as I could measure) with a place in the middle which was larger than that. The tight part was at the breech, the looser part at the muzzle. Not surprisingly, accuracy sucked! (6moa) I lapped it out to .286 and quit. The loose place was still there. Accuracy had improved to around 2 moa. This was an Austrian barrel, hammer forged, half octagon, with a full-length rib. The gunmaker was satisfied with the accuracy after lapping.
Anyway, I think slugging can be a useful diagnostic tool and can even be useful to gauge a barrel, if one has some idea of what he is seeing and feeling. I don't know that one can measure to within a tenth, but you can measure and feel a tenth in variation. The barrel needs to be absolutely clean and lightly oiled.
It is probably important to note, while I have fit and chambered many barrels, over the last fifty years, varying in quality from piss-poor to superb, I have never made a single barrel. WH

 

[338 Mollett]

The ONLY time I slug a barrel is when I'm drilling a hole for an AR barrel to reduce the burr in the bore . And that's with lead .

 

[tobnpr]

Never slugged a barrel other than Mosin-Nagant milsurps to see if .311 or .313 was the best choice.

Why anyone, would slug a brand-new- and top tier- barrel is absolutely beyond me.
One would obviously need to be an idiot to use steel instead of lead anyway- but I have no clue as to what could be done with any information gleaned.

I think getting into tenths with this process is a fool's errand anyway. And you're certainly not going to see deviation in the thousandths. So WHY??

 

[pcmacd]

To all.... I will come right out and say it.... slugging barrels I don't agree with for multiple reasons. Argue with us all you want.

Customer feels his gun wasn't shooting good enough. So he makes his own steel bushing to slug the bore and threads it on to a cleaning rod and pushes it down the bore. He feels there are tight spots in it. I'll guarantee the barrels bore/lands are all scored and the barrel is junk! No warranty!!!!!!

No information on how he's cleaning it, caliber, how many rounds on it etc....I told him flat out.... not going to warranty the barrel. Not to mention no information given as to the actual diameter to the .xxxx" place the bushing was made to and what equipment was used to measure the bushing.

We had a gun manufacturer without even talking to us.... decided they were going to check the bore size of the barrels.... yes they pushed gauge pins down the bores of not one... not two but around a couple of hundred of our barrels.... every barrel the lands were scored and damaged!

Not to mention any lint or debris in the bore or any type of fouling... it's just going to amplify making something to go sour.

Don't even argue, lead slugging isn't any better or won't cause any issues. It will not give you accurate measurements.

Even Mark has gone off on guys saying they slugged a bore with a lead slug and tried to measure the grooves.

There are maybe two guys.... that I/we know that will tell you they have slugged/checked bores and they are honest in saying they can get close to the size but even what they come up with is subjective.

Later, Frank
Bartlein Barrels

Barrels are spodabe probed with a DEAD SOFT LEAD BULLET. Lead will never harm a barrel when used this way.

I have slugged a dozen barrels w/o issue in this manner. I have a Teslong bore scope, and I promise that all is good.

Who in their right freaking mind would shove tight fitting steel down a bore? Duh? Duh? And Duh again?

This ain't ROCKET SCIENCE, dudes. Just fundamental common sense?

_Anybody that clueless probably should not own a firearm!!!_

 

[Dkk37058]

Had a friend slug his barrel trying to find a tight spot forgot to take the slug out fired the rifle and the barrel split like a peeled banana. Luckily he wasn’t hurt except in his wallet.

 

[pcmacd]

Slugging a barrel, with a lead slug, can give you some information, but not necessarily the information you think you are getting. If you push a slug through a barrel, it will reflect the diameter of the smallest place in the barrel. You will be able to feel variations in the bore, but you may not be able to tell what those variations are. In other words, what feels like a tight spot may be tight in the bore, in the grooves or both. It may also be an indicator of a variation in land width. The important thing is, you can feel very minute variations. Minute enough that you would have trouble finding the source.
Recently, I had occasion to slug a barrel in an attempt to find out why it shot so poorly (NOT a Bartlein barrel, by the way) The barrel seemed tighter at the muzzle (by a barely measurable amount) and felt tight at the throat. The thing was, it wasn't tight at the throat. Instead, what I was feeling was the deformation of the lands caused by a dull throater or poor technique, or a combination of the two.
Another barrel I slugged in an attempt to gauge the variations in diameter. This was possible because this particular barrel varied a LOT. A 7mm, it varied from .2836 to .285+ (as close as I could measure) with a place in the middle which was larger than that. The tight part was at the breech, the looser part at the muzzle. Not surprisingly, accuracy sucked! (6moa) I lapped it out to .286 and quit. The loose place was still there. Accuracy had improved to around 2 moa. This was an Austrian barrel, hammer forged, half octagon, with a full-length rib. The gunmaker was satisfied with the accuracy after lapping.
Anyway, I think slugging can be a useful diagnostic tool and can even be useful to gauge a barrel, if one has some idea of what he is seeing and feeling. I don't know that one can measure to within a tenth, but you can measure and feel a tenth in variation. The barrel needs to be absolutely clean and lightly oiled.
It is probably important to note, while I have fit and chambered many barrels, over the last fifty years, varying in quality from piss-poor to superb, I have never made a single barrel. WH

One can often smooth out these tight spots with a "fire lapping" treatment.

NECO sells a kit for this. It is enough material to lap hunderts of barrels.

It takes several hours to prepare the loads and fire them, but I've had it do wonders on several weapons including a USGI 30 carbine. That bore looks like glass and does not require much cleaning after the fire lapping. It's a PITA, but it REALLY DOES work!

It will move your throat out a wee bit, but the positive effects greatly outweigh this.

Four Abrasives Kit

Great way to firelap your muzzle loader. Kit consists of the four abrasives (#220, #400, #800, #1200 grits) in jars. The abrasives are laboratory grade abrasives and in a paste form.

www.neconos.com

They also sell dead soft slugging bullets for nearly all calibers if you don't want to make them yousef.

Best to use jacketed bullets for the fire lapping. See NECO site or call them (they actually answer the freaking phone??? In this day and age?)

PM me if you would like more info, and I will give you my phone number so we can talk if you wish.

mac

 

[pcmacd]

Wouldn't a tight patch give as much info as slugging a barrel?

No. NOT AT ALL.

Sure, you will find gross stuff, but the soft lead slug is by far the best tool for this job.

You can use a micrometer on a lead slug - and NOT on a tight patch.

 

[chester999]

Sounds like the person the OP refers to should have stuck to a tight patch.

 

[coldboreshot]

Thankfully, that individual is not an EOD tech.

 

[DShortt]

Driving a steel 'slug' down a barrel.

Just when you think you've heard everything.

 

[Oldman1950]

I shoot cast bullets almost exclusively. Getting a new to me rifle one of the first things is to use a pin gauge to determine the bore size. Just drop in into the bore and if it doesn't fit then try the next smallest until I find a size that will slide down the barrel with gravity. Next operation is to take a cartridge case and fit a rod (brass or aluminum) cut to length so when slipped into the case it is flush with the mouth of the case. The next step is to chamber the case with the inserted rod and slide a soft lead slug that is close to bore size down the bore. Taking a BRASS rod a little longer than the barrel and slide it down the barrel until it pushes the lead slug to the top of the cartage case. With a small hammer I tap the end of the rod and slowly the lead slug will upset until it fills the lead and about an inch of the rifling. You will know when the slug is 100% upset as the sound of the hammer tapping the brass rod will change to a dull thud. Open the breach and a few more taps on the brass rod and the lead slug will be removed and it will have perfect imprint of the lead and the rifling. Between the pin gauge and my micrometer I now know what I have so fitting a lead bullet to the bore is a lot easier. Usually one shoots cast bullets about .001" over groove size.

A. J. Palik

 

[Will Henry]

One can often smooth out these tight spots with a "fire lapping" treatment.

NECO sells a kit for this. It is enough material to lap hunderts of barrels.

It takes several hours to prepare the loads and fire them, but I've had it do wonders on several weapons including a USGI 30 carbine. That bore looks like glass and does not require much cleaning after the fire lapping. It's a PITA, but it REALLY DOES work!

It will move your throat out a wee bit, but the positive effects greatly outweigh this.

Four Abrasives Kit

Great way to firelap your muzzle loader. Kit consists of the four abrasives (#220, #400, #800, #1200 grits) in jars. The abrasives are laboratory grade abrasives and in a paste form.

www.neconos.com

They also sell dead soft slugging bullets for nearly all calibers if you don't want to make them yousef.

Best to use jacketed bullets for the fire lapping. See NECO site or call them (they actually answer the freaking phone??? In this day and age?)

PM me if you would like more info, and I will give you my phone number so we can talk if you wish.

mac

Fire lapping would likely work well in the one barrel I referenced. In general though, I consider fire-lapping to be a poor substitute for proper use of a cast lead lap. I readily admit this may be simple prejudice on my part! WH

 

[Sniperhandle]

Parker Hale and some other British barrel makers used to drive steel balls down the barrels and it made them shoot better and these "Ball Burnished Barrels" were sought after, So driving steel down a barrel isn't always bad, I can't find the old manuals that had the process written down and illustrated, But I have the information somewhere, Here is a page I found on the interwebs.

 

[1shot]

A hardened gage pin?? Y'all know ya can't fix stoopid!!

 

[Janeau]

Slugging a barrel is a method used by lead bullet caster to determine the proper bullet diameter for that barrel. Nothing else. No other purpose than that.
Some nut decided to use that method for other purpose..it’s just that..a nut case.

 

[Edd]

This is copied from a custom rifle builders website.

When fitting a new barrel the first order of business is to confirm the specification such as profile, twist, rifling count and caliber. The barrel is then cleaned spotless inside. Then a 17" Hawkeye bore scope is used to visually inspect every land and groove from one end to the other to look for uniformity, tool marks and imperfections that can cause unacceptable fouling. Then we use dead soft lead slug oiled up with 20-50 motor oil. It is passed both ways through the bore pushed by a series of brass rods until it can be passed back and forth smoothly. We can feel dimensional changes that cannot be measured. With my eyes closed I can feel things as subtle as external taper changes in the bore, where fluting starts and stops and of course any internal defects that can affect how the bullet rides in the barrel. Depending on what is found it is corrected or if substantial like loose where the crown is going to be then the barrel is rejected and the barrel manufacturer will need to replace it.