Bore scoping my leaded Mosin barrel

[Wolfdog91]

First time bore scoping so not 100% what I'm seeing, let me know how off I was on my assessment

https://youtu.be/xj6AJDUQieE?si=sGtJehWhxsN54ITb

[Hannibal]

Right now there's so much in the bore it's difficult to tell much except that it's badly leaded.
Check your Chore-Boy with a magnet before you use it. Some appears to be copper or brass but is actually steel with a wash applied. Wrap a few strands around a cleaning brush and scrub the lead out. In the past I used Kroil as well, cleaning solvent would work too.
It'll take some time, elbow grease and quite a bit of effort at first especially. Keep at it until you get the leading out. Then dry patch it a few times and re-evaluate the bore afterwards.
It's quite possible you had copper/powder fouling to begin with which can contribute to fouling issues as well. Your borescope will show you what's in there or not there along with any corrosion damage.

[johnho]

Agree with Hannibal. Way too much lead to determine much of anything about that bore. I shot some cast bullets through my 1903A3 and it was way leaded up in a short time. Took a long time to get it out. I also used a lot of kroil and let it sit overnight and continued brushing the next day. Repeated several times. First time using a borescope is a real eye opener.

[Dusty Bannister]

I agree with the others. It does not help that there appears to be a serious deposit of copper or jacket material in the bore. I also expect to see some pits when you finally get the barrel clean. Solvent, scrub, wipe, wet with solvent, wait and repeat. You may encounter the fouling is in layers and you have to work through each one of them to clean the next. If you use a really aggressive solvent that can attack the iron of the barrel, you will just make the pits bigger.

The second barrel seems to have a lot of chatter marks left after boring the barrel before cutting the rifling. That will likely continue to be a problem for the life of the barrel.

[Hannibal]

Didn't realize there was a second barrel in the video. Gave up looking at all the leading.

The second is fairly typical for a button rifled production barrel so far as the marks running parallel across the lands and grooves. A Savage for instance will often look quite a bit like that. The bore is drilled then the button is pulled through leaving the ridge and groove pattern ironed into the bore surface by the rifling button. It's also pretty common to see that type of corrosion damage on bores that weren't properly cleaned and oiled before storage. That's what the groups of pits and things that look like worm holes are. Corrosion damage. It won't help in the accuracy department or with fouling but on a hunting rifle that shoots 1-2 MOA anyway and doesn't get shot for long strings it won't really have any effect in a practical use sense. You've still got a fair amount of fouling in the corners of the grooves also which is what the black streaks are. It's possible it's even layers of carbon fouling and copper fouling but it's probably primarily carbon based on the appearance of it. If you want to get it all out, wrap a couple of cleaning patches around a worn bore brush and apply either JB Bore Paste or Losso to the patches. Stroke the entire bore a few times, switch to short strokes and concentrate more on the darker areas then stroke the whole bore 3-4 times. Patch it out good with solvent and dry patches. Then check your progress with your bore scope. Repeat as necessary.

[jdgabbard]

Right now there's so much in the bore it's difficult to tell much except that it's badly leaded.
Check your Chore-Boy with a magnet before you use it. Some appears to be copper or brass but is actually steel with a wash applied.

This. It appears that there is a bunch of fouling from copper or brass mixed in there. This barrel needs some elbow grease just to get it down to bare steel to see what you're working with. It may be caused by the copper and brass fouling, or it might be very badly pitted and not be conducive to shooting cast. It's all just a guess until you clean it and get it back down to the metal. Once that is done you'll be able to better tell. It could even be something that could be taken out with some valve seating compound and a jag with a tight patch. You're just not going to know until it is clean.

[405grain]

I would recommend that you use the copper Choir Boy to scrub out the lead fouling as described above, but once you've removed the lead you should do an electrolysis cleaning on your barrel to remove the copper, carbon, and rust fouling that is stripping lead off your bullets like a cheese grater. Get the bulk of the lead out before you try this so you won't die of old age waiting for the lead to come off. Because Mosin's were mostly used during the period of corrosive primers there could be some pitting under all that crud, but cleaning that stuff out of the bore could do nothing but improve it. I tried doing an electrolysis cleaning on an absolute sewer pipe of a Mauser barrel once, just to see how it would work. After two days of scrubbing the barrel was still as dark as a cave. So then I used a TIG rod as the electrode, plugged the chamber, stuffed a small plastic funnel in the muzzle, and filled the barrel with window cleaner (because it contains ammonia). I connected the rod and the barrel to an ordinary 9v battery and the window cleaner started to fizz right away.

I left the barrel like this for 4 hours. I poured out the liquid and it had turned black. When I pulled out the rod it was covered in black slimy crud. I ran some patches through the barrel and the first one was like evicting a slimy black jellyfish. All of the patches were coming out covered with black residue, but each subsequent patch had less and less. The bore was still dark, but it's condition was notably better. I decided to repeat the electrolysis cleaning process again the next day. After the second cleaning I ran patches through the barrel until they were coming out dirty, but dirty like one would expect from an ordinary barrel that requires cleaning. I then cleaned the barrel in the conventional way. Now the bore was bright and shiny. All of the horrible fouling had been completely removed, exposing a perfectly clean steel surface. It was now easy to see that the clean barrel had more pits and craters in it than the face of the Moon, and was completely useless as an actual barrel. Back then a brand new Mauser barrel was way cheaper than doing a re-bore, so that barrel went into the trash. It was a good learning experience though, and since then I've used a trickle charger to electrolysis clean and de-rust many machine parts. Do a Google search on "electrolysis barrel cleaning" and you'll get several pages of information on the process.

[Outer Rondacker]

Well good news! The only kinda fouling that I don’t see is from PC. Get to scrubbing you got a little bit of work ahead of you. You can do it!

[popper]

If the mosin cleans up, the crown should get fixed.

[Wolfdog91]

So that is some heavy lead and copper I'm seeing , mm interesting, will shouldn't be too bad 🥱 been wanting an excuse to try some of that iosso stuff then bench rest guys are always talking about

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[Wolfdog91]

I would recommend that you use the copper Choir Boy to scrub out the lead fouling as described above, but once you've removed the lead you should do an electrolysis cleaning on your barrel to remove the copper, carbon, and rust fouling that is stripping lead off your bullets like a cheese grater. Get the bulk of the lead out before you try this so you won't die of old age waiting for the lead to come off. Because Mosin's were mostly used during the period of corrosive primers there could be some pitting under all that crud, but cleaning that stuff out of the bore could do nothing but improve it. I tried doing an electrolysis cleaning on an absolute sewer pipe of a Mauser barrel once, just to see how it would work. After two days of scrubbing the barrel was still as dark as a cave. So then I used a TIG rod as the electrode, plugged the chamber, stuffed a small plastic funnel in the muzzle, and filled the barrel with window cleaner (because it contains ammonia). I connected the rod and the barrel to an ordinary 9v battery and the window cleaner started to fizz right away.

I left the barrel like this for 4 hours. I poured out the liquid and it had turned black. When I pulled out the rod it was covered in black slimy crud. I ran some patches through the barrel and the first one was like evicting a slimy black jellyfish. All of the patches were coming out covered with black residue, but each subsequent patch had less and less. The bore was still dark, but it's condition was notably better. I decided to repeat the electrolysis cleaning process again the next day. After the second cleaning I ran patches through the barrel until they were coming out dirty, but dirty like one would expect from an ordinary barrel that requires cleaning. I then cleaned the barrel in the conventional way. Now the bore was bright and shiny. All of the horrible fouling had been completely removed, exposing a perfectly clean steel surface. It was now easy to see that the clean barrel had more pits and craters in it than the face of the Moon, and was completely useless as an actual barrel. Back then a brand new Mauser barrel was way cheaper than doing a re-bore, so that barrel went into the trash. It was a good learning experience though, and since then I've used a trickle charger to electrolysis clean and de-rust many machine parts. Do a Google search on "electrolysis barrel cleaning" and you'll get several pages of information on the process.Hasn't been taking out massive chunks like I keep hearing about
https://uploads.tapatalk-cdn.com/20231110/324b36a1c66745f05caaf3461e66ef89.jpg

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[Hannibal]

Hasn't been taking out massive chunks like I keep hearing about
https://uploads.tapatalk-cdn.com/20231110/324b36a1c66745f05caaf3461e66ef89.jpg

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Provide a new borescope image please. Something ain't right. There's enough lead in that barrel to make a 1oz sinker with. Wish I could spend a day with you. I bet we'd both learn some things.

PM me if you want. I've some vacation coming up and I've never seen Mississippi. That might be really cool. :cool:

[405grain]

I use more scrubbing pad than that. I wrapped the brush with the maximum amount that I could force through the barrel. If you can, try at least twice as much as in the photo. Also, some cleaning oil helps to prevent the brush from getting stuck. (Disclaimer: My cleaning rod is made from a 3ft long 1/4" brass rod so I can push pretty hard on it. Use your judgment with that aluminum cleaning rod - you want for the copper to scrape away at the lead, but you don't want to bend the rod either.)

[waksupi]

The Mosin bore is a real sewer. Good example of corrosive primer damage. Powder coating shouldn't be leaving any of that trash in a clean bore. The second rifle looks like last ditch manufacturing, get it out the door! The Mosins I have had all had real good bores, and would shoot into 1.5"

[Wolfdog91]

Provide a new borescope image please. Something ain't right. There's enough lead in that barrel to make a 1oz sinker with. Wish I could spend a day with you. I bet we'd both learn some things.

PM me if you want. I've some vacation coming up and I've never seen Mississippi. That might be really cool. :cool:


https://youtu.be/WUHydSiMj7g?si=Na2zbYg_Ts3X8kr3

[Larry Gibson]

Most here are implying there's something inherently wrong with the bore of your MN but I'm going to stab a sacred cow here. I've shot traditional cast that were lubed and GC'd in some severely pitted/corroded bores including several MNs. I have never, ever gotten any leading close to that. In fact, with a proper alloy, lube, fit and load I've never, ever gotten any leading at all.

I have, however, gotten similar leading in rifles and handguns with excellent bores when testing various PC'd bullets. Not all rifles or handguns but enough that I still am sticking with traditional lube. It's not either rifle that is the problem, it is the PC.

[Hannibal]

https://youtu.be/WUHydSiMj7g?si=Na2zbYg_Ts3X8kr3


So after viewing the latest video, you've made quite a bit of progress but you still have a lot of lead in the last 1/4 to 1/3rd of the bore.

Right now what I'm starting to see is a lot of corrosion damage. Even in the chamber walls. You're going to need to remove that before anything will have any chance to shoot accurately, cast or jacketed.

I'm going to suggest that you finish stripping out the lead first. You can try a brush that fits a bit tighter and the same amount of Chore-Boy or apply at least twice as much Chore-Boy to the same brush.

Once you get that all out you're going to need to get the corrosion removed. I normally don't recommend this but that bore is really corroded. Plug the bore with a foam ear plug and fill it full of CLR. That's Calcium Lime Rust remover. Let it sit for an hour. Brush and patch it out real well. Then do it again.

A word of caution : the CLR will damage any remaining bluing or patina on anything it gets on. Be careful or the outside of the barrel and action will not retain it's current appearance.

You've got a lot of effort ahead of you and it's going to take considerable time and patience also.

Please post another borescope image once you think you're done. Curious to see just how bad that corrosion damage is.

I respectfully disagree with Larry's assessment. I *think* your bore had a considerable amount of exfoliated corrosion in the bore which contributed considerably to the leading issue. No way of knowing for sure unless you happen to have a borescope image before you tried shooting cast. If I am correct about that, it would also make it exponentially more difficult to obtain an accurate bore slug as well.

[M-Tecs]

There are always exceptions to the rules. I have a 30/40 Krag owned by Edward Sherriff Curtis that the only way to describe the bore is it looks like a rattail file turned inside out. Personal I thought it was so bad it was unsafe to fire. The previous owner encouraged me to try his 125 grain Nosler Ballistic Tip load. It is a solid 1 moa for 5 shot groups. I've put a couple hundred rounds thru it and the 1 MOA is an average.

[Hannibal]

There are always exceptions to the rules. I have a 30/40 Krag owned by Edward Sherriff Curtis that the only way to describe the bore is it looks like a rattail file turned inside out. Personal I thought it was so bad it was unsafe to fire. The previous owner encouraged me to try his 125 grain Nosler Ballistic Tip load. It is a solid 1 moa for 5 shot groups. I've put a couple hundred rounds thru it and the 1 MOA is an average.

Well I'd say you won the mil-sup barrel lottery then. Congratulations!

[Hannibal]

Wolfdog, it makes no difference to me if you take my advice, someone else's, or your own. Either way you're gonna learn something you didn't know before.

That's what this forum should be about. Learning.

[405grain]

It's not often that I disagree with Larry Gibson, but in this instance I don't think that the problem is the powder coat. If there's enough crud built up in a barrel that it looks like a horseshoe rasp I think that it wouldn't matter if the bullets were lubed, PC'd, or even jacketed, the bore is going to tear the bullets up. Now I've been wrong before, and I will be again, but in this instance I think it's the bore, not the PC.

In all honesty, the only way any of us are going to really know for sure is for Wolfdog to get the barrel clean and then find out.

[jsizemore]

If a bullet jacketed, lubed, PC'd, HiTek or gas checked is too small for the inside of the barrel, it will gas cut and lay down metal.

[Larry Gibson]

Yup, I stabbed a sacred cow......

One way to find out is now that Wolfdog91 has the bore cleaned is to lube the very same PC'd bullets and try that same load again. Even a normal coat of LLA will tell the tale.

[beemer]

I too think good cleaning to get rid of the corrosion and scale build up will improve things. It will foul quicker than a good bore no matter what you do but smoothing things up a bit will help. I think there is still enough rifling to do it's job.

I had a Mauser with a bore but similar to yours, it shot OK but fouled badly. I actually poured a lap and used some fine compound, just didn't get very aggressive with it. This took the sharp edges off the pits and helped control the fouling, shot better too.

[Gtek]

Clean as clean as it will get, kiss that crown a touch. Paper Patch?

[Hannibal]

Yup, I stabbed a sacred cow......

One way to find out is now that Wolfdog91 has the bore cleaned is to lube the very same PC'd bullets and try that same load again. Even a normal coat of LLA will tell the tale.

Sir, did you view the video? That bore is nowhere near clean.

[405grain]

Larry: There's no cow so sacred that I won't put it on the BBQ. Your last post really hit home because I'm one of those weirdo's that does lube my powder coated bullets. They get a swirl lube of 45-45-10, and there's never a trace of leading. You've got some good advise.

jsizemore has a good point. Wolfdog should slug the bore to make sure he's not shooting under sized bullets.

[TurnipEaterDown]

If you want to knock the high spots off the bore, you can:
Wrap a patch on a tight fitting brush, rub in some lap compound, generously apply oil, stroke from chamber to muzzle (one way) numerous times.
I wouldn't do this on a good bore, but it's not a good bore...

If the chamber itself is badly pitted, I have done:
Piece of scotch brite on a slotted jag, revolve a few times slowly - it Can scratch the chamber but can knock off sharp edges on pits/protrusions.
Follow w/ tight fitted brush w/ patch, compound (like 600) & oil
Follow up w/ JB on a tight fitted brush w/ patch & oil -- much more revolutions that either of the first two.

Worked for me before. Unusable rifle to usable.

[Larry Gibson]

Wolfdog91 already slugged the bore and is using bullets .001 over groove as per his description in https://castboolits.gunloads.com/showthread.php?460976-First-cast-out-my-Mosin

In that thread he states; "Checked this morning and after casting water dropping PC and water dropping again they where around 15bhn if I remember right. Sized and gas checked too .314 ( bore slugged at .313 would have went to .315 but I forgot it order a .315 sizer bushings and since I'm only home for a short amount of time I just said I'll work with this till next month ) powder coated then sized again to make sure it's still a good .314. Expanded my necks with my NOE .315 x .311 expander plug. No crimp"

The bullets BHN is fine and it is not "undersized".

[jsanch03]

I’ll throw my 2 cents in the hat from my experience with a Mosin 91/30 that was doing something similar to what the OP is experiencing. I soaked a patch with kroil and ran the patch through the bore until I felt the oil was lathered into every pore of the bore. I let it sit for about an hour then ran the chore-boy until I stopped feeling resistance. You might have to add a little more chore boy so the copper came grab more surface area between the lands and grooves.

[Dusty Bannister]

I just do not see a powder coated bullet being able to conform to a badly fouled/pitted barrel. Get a bore guide to protect the throat, a couple of TIGHT bronze brushes and some Hoppe's bore solvent and wear out the brushes and get the color out of the barrel. You show jacket fouling and lead fouling and more than likely rust in the pits. Until you get to bare metal, you just are not getting the barrel clean and the fouling will build up much quicker as you have seen. Good luck and let the Hoppe's soak and do the job it is supposed to do.

[jdgabbard]

Larry: There's no cow so sacred that I won't put it on the BBQ. Your last post really hit home because I'm one of those weirdo's that does lube my powder coated bullets. They get a swirl lube of 45-45-10, and there's never a trace of leading. You've got some good advise.

jsizemore has a good point. Wolfdog should slug the bore to make sure he's not shooting under sized bullets.

I too don't mind smearing a lube groove of a PC'd boolit with Lube if I think it's gonna help it out. I swear by PCing since I started it. But sometimes I feel it can use a little help. And there's nothing wrong with it. At best it helps keep lead fouling out. At worst I spend a little time adding some lube to a boolit that don't need it.

[Wolfdog91]

Welp my bornscope crapped out on me for some reason, gotta feeling I wrapped it too right or something when I put it up last welp time to return that and guess I'll order a Ridgid one next

[Hannibal]

Welp my bornscope crapped out on me for some reason, gotta feeling I wrapped it too right or something when I put it up last welp time to return that and guess I'll order a Ridgid one next

Yes, one has to be careful with them. Fiberoptic cable. Any sharp bends or a kink and stick a fork in 'em. They're done.

[405grain]

"Welp my bornscope crapped out on me for some reason"

What?! I'm shocked! Those things are made in sweat shop warehouses in China from the finest child labor that a yuan can buy. How dare they sell you such a piece of junk. [smilie=1:

[Hannibal]

"Welp my bornscope crapped out on me for some reason"

What?! I'm shocked! Those things are made in sweat shop warehouses in China from the finest child labor that a yuan can buy. How dare they sell you such a piece of junk. [smilie=1:

Doesn't matter where fiberoptic cable is made, if you bend it in too tight of a radius or kink it the result is broken fibers and there's no fixing it.

The internet most of us are using right now is predominantly fiberoptic cable and sourced from overseas. Proven technology, but you have to play nice.

Alternatively there's copper cable. Those bundles would be the size of a fuel tanker trailer, outrageously expensive and much more prone to failure. Let alone the army of technicians to install, maintain and repair it.

[popper]

If the fiber is broken you get distortion. If just quit working, a real connection/electronics broke. Evidently CLR is good at removing copper as some precision shooters use it in their rifles. Barrel may be only good for paper patched stuff anymore.

[Wolfdog91]

Just saying this is how the guns been shooting....
https://uploads.tapatalk-cdn.com/20231114/03aa2a4df124a57bdf68da2e074a958c.jpg

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[Wolfdog91]

If the fiber is broken you get distortion. If just quit working, a real connection/electronics broke. Evidently CLR is good at removing copper as some precision shooters use it in their rifles. Barrel may be only good for paper patched stuff anymore.Avoiding CLR right now due to past issues I've had messing with it. It really works.... problem it's it REALLY works . Not off the table but avoiding it for now. But on the subject of the precision guys I took some of their advice and picked up some of this stuff
https://uploads.tapatalk-cdn.com/20231114/51792c1d2545e5f443dc196801f7452b.jpg

Supposed to be the best stuff ever a long with kroil and JB

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[M-Tecs]

IOSSO and JB Bore Paste are about the same. IOSSO seems to be a little more aggressive but not by much. I use and like both.

[405grain]

Wolfdog: That latest target is a huge improvement.

[Forrest r]

Larry: Your last post really hit home because I'm one of those weirdo's that does lube my powder coated bullets. They get a swirl lube of 45-45-10, and there's never a trace of leading.

I do the same thing

[charlie b]

I don't lube my PC bullets. I've been able to do some direct comparisons between lubed (RCBS lubesizer) and PC bullets recently. Both sized the same, just one with Ben's Red lube and the other Smoke's clear PC. The rifle is a well worn Savage model 12 barrel in .308 (over 8000 rounds through it, much more than half cast).

I use Ed's Red (with acetone) for cleaning. The PC bullet fouling is a little harder to get out than lubed fouling. By a 'little' it means I brush and patch the bore two extra cycles (a cycle is wet brush, three wet patches). The lubed bullets take around 5 cycles, the PC around 7. I don't get any sign of leading. Normally shooting 1800-1900fps. FWIW, both are easier to clean than jacketed.

No, don't own a scope, but, a magnifier looking at the rifling in the muzzle shows all the fouling gone. May still be some left in the throat area but it doesn't seem to effect the accuracy.

The only 'rough' bore I've shot PC in is a WWII era Garand. It was no more difficult to clean than my newer bolt gun. But, again, I don't have a borescope so take this with a grain of salt.

Having said all that, I find making lubed bullets to be 'easier' than the effort it takes to make precision PC bullets. Most of my shooting these days is with lubed XCB's.

[Hannibal]

Wolfdog, curious to know what methods to remove the leading and corrosion worked for you?

[Wolfdog91]

Wolfdog, curious to know what methods to remove the leading and corrosion worked for you?

Wore out three 30cal brushes with the chore boys stuff, which I have to say... egh ,I just wasn't seeing the massive chunks coming out like eveyone says . Some with a wet soaked barrel using hoppes #9 some ader it was patched out dry, Little particles sure but that's about it. A lot of wraps a few wraps, dint really seem to matter much as too much would just get pull off the brush . Finally just said whatever it's beat to heck I can't hurt it much worse and wrapped some really fine steel whool ( 0000 I think ) around the brush and sent it a few times just because and ....egh seemed to shine up a little.
Was temped to do some stuff I've been told from bench rest guys involving a drill but since my bore scope broke no point IMO since I can't monitor what's happening

[Wolfdog91]

Wolfdog: That latest target is a huge improvement.

Very last group I shot with it and that's before I start trying to clean it and all this stuff

[Wolfdog91]

I mean honestly I wouldn't consider this hard or anything a little tedious but not bad, just put on my music and zone out scrubbing for a bit then check with the scope. The fact I can actually looks and now I know what's what ,no big deal really.

[Hannibal]

I mean honestly I wouldn't consider this hard or anything a little tedious but not bad, just put on my music and zone out scrubbing for a bit then check with the scope. The fact I can actually looks and now I know what's what ,no big deal really.

That's excellent! No matter how this barrel turns out you will have learned a tremendous amount. I acquired a half-dozen take-off barrels from a gunsmith and a bore scope and set about experimenting for myself. I chose to do this because there is entirely too much contradictory information on barrel cleaning and there's no way to know who is speaking from direct experience, who's repeating what they've read somewhere that sounded good or even who is just reading cleaning patches like they are tea leaves.

I consider the time and money very well spent.

[jsizemore]

The camera is all well and good, I use one myself. It doesn't tell you where there's tight and loose spots in the barrel. Don't need a camera to tell where the carbon is in my 6br barrel.

[HamGunner]

I have found that copper jacket fouling and cast lead shooting do not go together very well. I do best if I really aggressively scrub the copper out before shooting cast lead.

I have never shot a powder coated bullet as the traditional ways of shooting properly sized and lubed cast bullets of the proper hardness for the pressure of the load have worked for me. Lead fouling is certainly no more of a problem than copper fouling for me, even in rough bores.

[charlie b]

And I've shot less than MOA groups with PC cast bullets immediately after shooting jacketed. FWIW, the reverse did not work as well, but, I expect closer to 1/2MOA with my jacketed loads.

A somewhat less than scientific observation was the copper fouling was reduced after shooting PC cast bullets with gas checks. Made cleaning a bit easier.

[Wolfdog91]

The camera is all well and good, I use one myself. It doesn't tell you where there's tight and loose spots in the barrel. Don't need a camera to tell where the carbon is in my 6br barrel.

Definitely told me where there really big crap deposits where lol,and when you whole barrel looks and feels like a average Mississippi back road logging trail....helps to see what's goin on

[jsizemore]

I bet a patch feels interesting going down the bore.

[Ruts]

That bore looks pretty good where I can see it. No reason it can't shoot good once you get the lead out of it. Not sure what other posters think an old barrel should look like but that barrel looks pretty good. I have had better success with lead removal cloth. Very tight in the bore. You can also use steel wool I didn't find the chore boy works any better than a bronze brush.

[Elpatoloco]

Definitely told me where there really big crap deposits where lol,and when you whole barrel looks and feels like a average Mississippi back road logging trail....helps to see what's goin on


When I first started shooting cast and leaded up bores on the regular, someone told me the chore boy trick. I found out that I had to wrap about 4x what I though wad needed on a worn out brush and then PULL it through the bore. I thought I'd have to hook the truck through it to get it through. Then the big chunks came.
Ive never messed with cast in a high powered rifle, much less an old war horse. As you know, your slugs seem to be fine. Good luck and keep posting about it.