Boolit sized, lubed/coated etc properly- why am I still getting leading?

Rifle is a Marlin 336, originally a 30-30 that shot well. Unfortunately 30-30 is not kosher for hunting here so had it re-bored to 38-55 by JES. Barrel now slugs .377, have tried a number of different combinations- .379-.381, different lubes, gas checked and not- and most recently been using .380 Hi-Tek coated boolits @ 1300 fps and still seeing definite leading.

My understanding was that leading is caused by an improperly sized boolit, poor lube or excess speed. Having eliminated all of these issues I am still scrubbing lead out of the barrel after barely 50 rounds.

Thoughts?

Rough bore?

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Man I hope not. I had JES do the rebore mostly from recommendations on this site, everyone seems to love their work.

I don't have decades of experience like some folks here but I've been shooting cast for a few years in multiple caliber/cartridge/platform set ups and this is the worst I've ever seen.

Before I cast my own and powdercoated them I bought some Hitek coated bullets and I had horrible leading, I figured out it was very hard slightly undersized bullet that was the culprit. When I jacked it up to max loads it got better but still leaded so I started casting and coating my own and the bore life got much easier.

Thanks for the reply! Hi-Teks are .380 which doesn't seem underbore for a .377 barrel

How hard is your bullet?

Have tried everything from 12-20BHN nothing seems to help.

Try a traditional lube w/GC says the PC/HT.

Boolits have been lubed and gas checked, no help.

Where is the leading? Toward the muzzle, or through the entire barrel?

1. Are these your cast bullets, or store bought ?
2. Are you doing the PC-ing, or someone else?
3. What powder ?

As to hardness...at 1,300fps, you want soft -- 30-1/BHN 6 or so -- and a fairly fast powder.

What groove, twist was it rebored to?

Where are you located? A member here might be close and might be inclined to help in person.

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Originally Posted by mattri

Boolits have been lubed and gas checked, no help.

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Lubed with what?

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Originally Posted by mehavey

As to hardness...at 1,300fps, you want soft -- 30-1/BHN 6 or so.

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I don't know about BHN6, that's near pure lead.

I would suggest soft enough to scratch with a thumbnail, which 20:1 is still too hard for that, and soft lube. 50/50+1% or 2% should be perfect and that will scratch with a thumbnail. I have good results with RandyRat's TAC1, I have excellent results with SPG! Felix is probably the best lube on the planet but you should be able to hit a working combo with several of the soft lubes.

Every cast boolit success story is a combination of factors. Miss one and you miss the combo. Too hard? Won't obturate.

Also, post some of your loads. What powder?

My JES rebored Marlin runs a little under .376 groove dia. I size to .377 and run mostly 13 and 1400 fps loads. I've been up to 1700 with no leading. Bullet is the NOE 38-250B, I had the mold built for a plain flat based bullet, no gc. Alloy has been anywhere from 1Sn, 1.5Sb up to ww, all air cooled. Lubed with Winds Wonder Wax or powder coated, shoots great and no leading. One thing I would check is your neck size before seating bullets. If the neck is too small it can size the bullet down.

For 1300 fps you need around 11 Bn.

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Originally Posted by mattri

Rifle is a Marlin 336, originally a 30-30 that shot well. Unfortunately 30-30 is not kosher for hunting here so had it re-bored to 38-55 by JES. Barrel now slugs .377, have tried a number of different combinations- .379-.381, different lubes, gas checked and not- and most recently been using .380 Hi-Tek coated boolits @ 1300 fps and still seeing definite leading.

My understanding was that leading is caused by an improperly sized boolit, poor lube or excess speed. Having eliminated all of these issues I am still scrubbing lead out of the barrel after barely 50 rounds.

Thoughts?

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I've gotta ask since you did not specify your .377 slugging.
Was that groove diameter or bore diameter?

Had you even googled 38-55 you wouldn't have had to ask such a question. it is impossible for 38-55 caliber to have a .377" bore.

Don't be afraid to google, Wikipedia is stunningly accurate for almost any firearm related question (and is usually the first hit returned in a search). All of the specs are there, development history, everything you would want to know about any given caliber is right there at the click of a mouse or a verbal command on a phone.

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I don't know about BHN6, that's near pure lead

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For 1300 fps you need around 11 Bn

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1) I'm running 30-1 for a HiWall/38-55/plain base/ACC 38-320gr (standard 50-50 lube), 1310fps

2) Please note tested hardness of 30-1
https://castboolits.gunloads.com/sho...=1#post4437398

Bottom line: With rare exception, lead alloy "mixes" "as reported on the internet" are much softer than advertised.
Think about it: Pure lead is 4.5- 5.0, and all you've done is add 3% tin.
Not much more effect that ease of fill-out has occurred.




Added thoughts on soft lead and PC
https://castboolits.gunloads.com/sho...=1#post5001471

For loads have been using Unique and more recently IMR4227 from 20-22grains.

Leading seems worse about 6-8" from muzzle.

mattri: Are you doing the casting and PC, or someone else ?
(and if you, what is your PC process/temp, etc?)

I don't know if burn rate is part of the problem, Unique is 32 and 4227 is 65 on the burn rate chart, Hodgdon data suggests 4895 which is 94 which is much slower, I get my best out of 308 with H4895.

By comparison H110 is 63 and Lil Gun 62, AA#9 is 57 and 2400 is 54. These 4 I think are most associated with large bore straight wall heavy boolit pistol calibers, and the 38-55, just looking at the round, is a straight walled cartridge that makes me think it might respond well to any of these slower pistol powders. 4227 at 65 is right there with the infamous four, and it has been noted that 4227 can be temperature sensitive, so there is that.

If there is any logic to the burn rate in 38-55, and I had to strike out blindly I'd probably pick 2400, find some load data for it and see where that got me.

So far have been using commercial cast boolits. No reason to believe the BHN is off, the HI-Tek seems in tact and boolits measure appropriate diameter.

There is no reason that a properly PC'd / 0.380" / 1300-1500fps bullet should even think about leading -- no matter how soft
In fact, soft is good. (Again see bottom of Post #20)

I'm thinking PC-QC* is at the root of your problem.




* (Honest, I don't make these catchy phrases up. :veryconfu )

That certainly could be part of the issue but other boolits leaded badly too, not just these.

Ha! Commercial cast, unless you specifically order a softer alloy, is usually BHN22 and that hard crayon lube = guaranteed leading regardless of diameter or fitment.

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Originally Posted by mattri

...........Leading seems worse about 6-8" from muzzle.

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That is a classic indicator the lube is failing or there's not enough of it.

What lube?

Are you using actual measured .380 bullets or are you trying to use .380 bullets? .380 bullets are .355 dia.

Various, including Hi-Tek coating.

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Originally Posted by jim147

What groove, twist was it rebored to?

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Originally Posted by sigep1764

Where are you located? A member here might be close and might be inclined to help in person.

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Originally Posted by Larry Gibson

Lubed with what?

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Originally Posted by Rizzo

I've gotta ask since you did not specify your .377 slugging.
Was that groove diameter or bore diameter?

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Originally Posted by Larry Gibson

That is a classic indicator the lube is failing or there's not enough of it.

What lube?

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Originally Posted by jimb16

Are you using actual measured .380 bullets or are you trying to use .380 bullets? .380 bullets are .355 dia.

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OP,
Folks here are trying to help you but you seem to be ignoring their questions.
Just sayin'.

This is probably a bad gun. It should be sold or thrown away as there is no solution for this problem. You you could just let it lead and fire a Jacketed bullet thru it about every 5 shots that would clean it out for sure..

In fact since nobody said anything about breaking that barrel in, maybe fire a hundred or so j words thru it, clean all the copper fouling out of the barrel and try your boolits again.

I have never seen a PC'd Boolit transfer Lead to the bore of any gun. It is a Polymer coating .002-.003 thick and there is no Lead contact with the bore. Therefore it can't lead the bore.

Kind of wonder what's going on here? Unsolvable problems always seem to be knowledge related, and solved by increasing the understanding of the subject. Not some Miracle Fix.

Randy

To catch up-

Rebore is a 3 groove 1:16, using 245-265gr boolits.

I am in Iowa.

Multiple commercially cast/lubed boolits have been shot through this rifle, all with the same results, I do not know the exact lube composition of each. As noted coated boolits lead just as badly.

Barrel was slugged in the standard way, pure lead lubed and driven through barrel then mic'd.

As noted boolits used so far have been .379-.381, no 357 boolits were harmed in the making of this post :)

No copper has been down this bore, intention all along was to use cast boolits.

Originally I had planned to order a mold from Tom but wanted to send a little lead down range and experiment with a few different boolits to see how they fed, whether it seemed to like a particular weight etc- which is why I ended up with a selection of various "store bought" boolits. Was planning to use the info from these loadings to help select the mold I would order but would like to sort the leading out before I pull the trigger on a mold.

Not saying this couldn't be the first but have never heard of anyone having trouble with a JES rebore before, everyone seems to love them.

Do you suppose that a pound cast of the neck and throat area would give you a better idea of the size of the bullet needed to correctly fit this firearm? If the neck area is too large, the ignition will blow the lube off the bullet before it seals the bore and this could be the problem with leading the last part of the barrel. Also with powder coated bullets, the hot gas may be cutting the coating and not protecting the sides of the bullet from contacting the barrel. What does the muzzle look like after firing PC bullets. Obviously, you more than likely have a silver star with lubed bullets. Have you checked to determine the cartridge OAL with the largest bullet you can cast? If the free bore is a little too long or your bullet is a little small or short, that might also be part of your problem. There is a very old and proven method used to verify that is not the problem.

If a tight patch does not pass smoothly down the bore, you might consider a bit of lapping might improve things.

Possible, but maybe not likely. An oversized boolit or more to the point a case with the "long" brass will not chamber so fit doesn't seem to be the main issue.
JES recommends short brass and say they cut to .376-.377 which seems to match actual field measurements.

Unfortunately it looks as though boolits sized correctly and with various types of lube/coating just leave a nasty amount of lead in the barrel.

Are the lead streaks always in the same place?

Try a different powder.

IF a rough bore is suspected, the $46 Teslong bore scope will tell the story. Compatible with any laptop and most phones (but not an iPhone). Just do a search for Teslong and the Bezos outfit has them on their site.

It sounds like your still dealing with some unknowns (exact chamber dimensions, etc)... treat this like a science experiment and identify as many specifics as you can.
Shooting a box of J’d boolets will not ruin a gun you want to dedicate to cast... it will just speed up the process of smoothing out any microscopic burrs left in the barrel. Fire a box, swabbing the barrel really good every 3 rounds, letting the barrel cool between shot group.

Then, start collecting your data on a spreadsheet. (#1 to 3 are header/benchmark data and set the stage for 4 to 7, which is the test data)
1. Slugged bore
2. Chamber cast
3. Barrel/bore surface photos
4. Bullets of known alloy composition, hardness, and exact diameter
5. Lubes and PC of known mixture/hardness
6. Various powders and charge weights
7. Photos of the chamber and barrel and leading at: clean; 5 shots; 10 shots; 25 shots; 50 shots...

It is critical you only change one thing at a time so you can pinpoint the culprit. If you change lube and powder charge and a change occurs... what caused it - the new powder or the new lube mix?

Once you have a few hundred rounds through the barrel you can start to make decisions based on data and not guesses.

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Originally Posted by mattri

........Multiple commercially cast/lubed boolits have been shot through this rifle, all with the same results, I do not know the exact lube composition of each. As noted coated boolits lead just as badly. .

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The leading with the commercial lubed bullets you are experiencing is typical. The hard wax used is not the best to prevent leading. If you have or can get some Lee's liquid alox then lightly coat the commercial cast bullets as per Lee's instructions letting dry thoroughly before loading. Or if you have some softer traditional alox based lube remove the hard wax lube from, say, 10 bullets then hand smear the lube into the grooves, load and shoot them. If no leading the there's nothing wrong with the rifle, barrel and Jes's usual excellent work. The solution, which it most often is, ito not getting leading s simply the to use a proper lube.

As to the PC'd bullets leading or leaving a PC fouling in my experience with such is some guns just foul with it and some don't. In my tests of the same bullet/load in multiple guns some foul, some don't. Its one of the reasons I haven't gone to the dark side....