Does leading location indicate what the problem is?

[Whiterabbit]

Hi guys,

I can lead my barrel, but it's always the same. Leads up near the muzzle, worst case the front half of the barrel.

Near the forcing cone, a couple solvent patches and I am clean.

This is very very very repeatable. The fact that it leads at the muzzle only, and stays clean near the cylinder and forcing cone, does that indicate what my problem is, or what "knob" I can turn in my recipe to see if I can reduce it?

Folks say #1 issue is sizing, but a bullet too small wouldn't lead like this, would it? could it?

Any thoughts? ditch sizing efforts and experiment with lube?

[Wally]

Hi guys,

I can lead my barrel, but it's always the same. Leads up near the muzzle, worst case the front half of the barrel.

Near the forcing cone, a couple solvent patches and I am clean.

This is very very very repeatable. The fact that it leads at the muzzle only, and stays clean near the cylinder and forcing cone, does that indicate what my problem is, or what "knob" I can turn in my recipe to see if I can reduce it?

Folks say #1 issue is sizing, but a bullet too small wouldn't lead like this, would it? could it?

Any thoughts? ditch sizing efforts and experiment with lube?


I have an Outers Foul Out machine. The cathode rod shows where my gun barrels lead up. IMHO you need to experiment with your bullet lube...try different ones until you find one that leads up the least. I make my own bullet lube--50% lithium grease/50% Cathedral brand candles (51% Beeswax) . I have used the NRA Alox for years...mine is every bit as good.

None of my revolvers lead up in the muzzle area...most lead up in an area 1~2" from the breech.

[sqlbullet]

The conventional wisdom here is that you are 'running out' of lube and should look to a different lube formulation.

But for us to really help we need more details

What gun? Groove diameters for the muzzle, breech. If a revolver, as indicated by the "forcing cone" statement, have you slugged the cylinder throats?

In a revolver you sometimes get combinations that aren't going to work, like small cylinder throats with generous bores.

[cbrick]

Without more info a SWAG would be that you are running out of lube. A cure could be a different (better) lube or a different bullet that carries more lube. Also could be the lube/velocity combination your running, which would also indicate the use of a better/different lube.

Could be a bullet fit issue also, if it's not a good fit from the cylinder throats into the forcing cone it could be simply blowing the lube out ahead of the bullet.

Rick

[Whiterabbit]

The conventional wisdom here is that you are 'running out' of lube and should look to a different lube formulation.

But for us to really help we need more details

What gun? Groove diameters for the muzzle, breech. If a revolver, as indicated by the "forcing cone" statement, have you slugged the cylinder throats?

In a revolver you sometimes get combinations that aren't going to work, like small cylinder throats with generous bores.

BFR, cylinder throat measures .453 (I did not slug it), muzzle groove diameter is .451, I haven't measured the breech.

Bullets sized to .452+ (.4525ish?) do show light when inserted into the cylinder throat and held up to the light. Sizing to .454 is a non-starter.



Without more info a SWAG would be that you are running out of lube. A cure could be a different (better) lube or a different bullet that carries more lube. Also could be the lube/velocity combination your running, which would also indicate the use of a better/different lube.

Could be a bullet fit issue also, if it's not a good fit from the cylinder throats into the forcing cone it could be simply blowing the lube out ahead of the bullet.

Rick

I didn't think about this one :(. I was hoping I could somehow conclude an issue is lube or size related, and put one to bed. Is there anything I can try/test to verify sizing or lube is OK? or do I just have to try everything (complicated, expensive, and time consuming) till I find a magic combo that works?

[Wally]

Can I ask you this..how accurate is the bullet/ load...does the accuarcy significantly deteriorate after 50 or 100 rounds...if it is accurate and stays that way, I'd not be concerned about the leading....

[.357MAN]

Lots of things lead to leading. The main or only thing that dose the actual leading is hot gas blowing by in-between the bullet and barrel. Which melts the lead and depositing the lead on the barrel.
Undersized bullet is the main cause of gas blowby.
Other things that cause blowby are: Bad lube that is not sealing imperfections between the bullet and the barrel. Or exceeding the ability of the current lube to make a seal. A restrictions in the barrel, causing a sizing effect, that then lets gas blowby. Pushing a bullet to fast for the alloy hardness which widens the land markings on the bullet, allowing gas blowby past the extra wide land markings.

Now finding out what is causing the leading is hard. In my experience I can only comment on two of the reasons, and tell you what they looks like.

My biggest problem when I started shooting cast was under sized bullets.
How you can tell its under sized is the leading first happens in the cylinder throat and forcing cone, it looks like you took a gray paste and swabbed the cylinder throat and forcing cone with it. This is easily fixed. Ether do not size the bullet / use them as cast. Or you can open up the sizing die (There are threads on CB that talk about this ).

The second thing I ran into was to soft of an alloy. To tell if your alloy is to soft take about 7-12 1Gal milk jugs full of water. Now line the jugs up along the bullets trajectory, stand 10 yards or further away from them. Now comes the fun part. Line up the sights on the row of jugs and pull the trigger. The result is 6-11 jugs with holes in then and a bullet in the last jug or in the 1-2 before the last jug. Retrieve the bullet from the jug and examine the bullet. You should be able to tell how hard the bullet is for the pressure by how much of the lead that was in the grooves is still there. The most ideal is a slow taper, with the base still the same width as the groves in the barrel.

I can't comment much about lube, yet. My lube is LLA and I am not testing it's ability's at the moment.

My firearm doesn't have any restrictions ether so I can't comment about that as well.

I hope this helps. Good luck with finding the problem, and God bless!

.357MAN

[.357MAN]

Just read what you said. Yes your bullet is under sized for your cylinder, that is your problem.
The bullet is getting gas blowby in the cylinder throat, which is melting the lead and blasting lube away.
Just don't size the bullets or open up the sizing die.

.357MAN

[Bardo]

You may want to read this article.

http://www.lasc.us/Fryxell_Book_Chapter_7_Leading.htm

The guy that wrote this is a member on this site. This website is full of information. I believe cbrick has written a few of the articles over there. So if he says something I listen.

Bardo

[curator]

Possible thread choke where the barrel threads into the frame. Several good revolvers I have measuered up to .002 constriction there. With my Ruger SBH this caused leading in the front half of the barrel no matter what lube or bullet hardness. Once I firelapped it out leading disappeared.

[Whiterabbit]

Can I ask you this..how accurate is the bullet/ load...does the accuarcy significantly deteriorate after 50 or 100 rounds...if it is accurate and stays that way, I'd not be concerned about the leading....

laser beam at 25, a little bigger than i want at 50 yards, maybe 5 inches, and huge at 100 yards. Not good enough. if it were a laser at 100 after 125 rounds (the most I can shoot in one day) I wouldn't care about the leading either.

jury is out on the effect after a few rounds. I'm working on the scope too.

[geargnasher]

[snip]
Could be a bullet fit issue also, if it's not a good fit from the cylinder throats into the forcing cone it could be simply blowing the lube out ahead of the bullet.

Rick


Just read what you said. Yes your bullet is under sized for your cylinder, that is your problem.
The bullet is getting gas blowby in the cylinder throat, which is melting the lead and blasting lube away.
Just don't size the bullets or open up the sizing die.

.357MAN

I believe this is the answer. Had it happen to me, sizing to fit the cylinder throats (ended up being about .003" over groove, had to use a different boolit mould that cast big enough) fixed the issue. I believe in some instances the lube is gone before the boolit moves out of the case. Every time I got leading of this kind, recovered boolits had zero lube on them, there was no lube star at all on the muzzle, but the cylinder gap, frame, and front of the cylinder were positively covered in greasy lube/soot film.

It might only be a little harmless antimony wash though, hard to say without seeing it in person.
Gear

[Boolseye]

Hmmm...I assume we're talkin about a rifle of some sort, here.
+1 on sizing. The gun needs that extra .001 or .002 shooting CBs.
Also +1 on lube–I'm no expert, but with my usual 45-45-10 I get no leading to speak of, as long as my velocities don't get crazy and the bullets are the right size. If there's sigificant leading, chances are it's one of these two things. Good luck,
-jp

[Whiterabbit]

If I were blowing the lube out right away, wouldn't I get leading across the whole barrel?

[.357MAN]

Having no lube doesn't mean you'll get leading through the whole barrel, it would only lead where lube is needed. And lube is needed where gas would blow by the bullet.

.357MAN

[sqlbullet]

I am with 357 and gear. You need to get those boolits up near .454. You might squeak by with .453. But having them under the throat diameter is gonna cause issues.

[Iron Mike Golf]

From boolit to muzzle (boolit, chamber throat, barrel groove at threads, barrel groove mid-barrel, barrel groove under front sight, barrel groove at muzzle) to be the same or slightly decreasing. If at any point the diameter increases compared to "upstream", you have the potential for blow-by. Sometimes, you can prevent that by tweaking lube, charge weight, powder type, or alloy.

You know you have at least one point identified: the throats. It is not uncommon for a barrel to be constricted where it threads into the frame. And, as posted above, sometime affixing a front sight can constrict, too. You may be able to feel constrictions with a tight fitting patch.