[Matt VDW]

What could be causing lead fouling at the rear of a barrel, just ahead of the chamber? My load is a Star 185gr LSWC-HP (this is a soft, swaged bullet) over 3.3 grains of Vectan Ba 10 (equal to about 4 grains of Bullseye) in a Kart .45 ACP barrel.

Since it's a low velocity load, I doubt that I'm pushing the bullets too fast. And if I were, wouldn't that result in leading towards the muzzle, not the chamber?

Some causes I've considered:

1) Bullets too narrow (or too wide?) for the bore.

2) Excessively hot-burning powder charge.

3) Insufficient crimp (currently 0.470").

Any ideas?

 

[Ralph]

Could be that the bullet you're using is a little too soft, maybe try a harder cast bullet,even then you'll still have a little,(but not much)lead in the bore, no problem, just run a few copper jacketed bullets throught it and that will clean it out.

 

[shane45-1911]

Not saying it's NOT lead, but could it merely be powder/lube fouling? Lower power loads tend to be a little dirtier, especially in the chamber and rear of the barrel. A lot of powder fouling is deposited there. Just a thought....

 

[bfoster]

If this link Vectan contains similar information to what you are using, I'd note that the Hornady #45100 (this is probably the bullet referred to) is a jacketed projectile, while the bullet produced by the Lyman mould # 452389 is a lead bluff nosed wad cutter (if memory serves).

Note that the listed pressures are the reverse of what is usually the case when testing Jacketed and lead bullets. That is, for a given powder charge, lead bullets usually develop a lower peak pressure than do jacketed bullets. I'd say that it is worth your time to e-mail Vectan with a query as to whether this information is correct.

Your load may not be causing the bullet to fully obturate, hence the leading just ahead of the chamber. Sometimes too low a pressure or a lazy rise time (an insufficently steep ascending node) on the pressure curve can contribute to leading.

You need enough crimp to securely hold the bullet, that is, enough to prevent any chance of setback, and to promote a consistent powder burn, but not so much crimp that you are swaging the bullet.

I'm not really fond of using light charges of very fast burning propellents in the 45 ACP. I have proven to my satisfaction using an Oehler M43 that a heavier charge of a powder having a slower burning rate will often give better consistency.If you wish to stay with Vectan propellents, Ba9 may be a better choice. Or you could try Unique etc...

Bob

[This message has been edited by bfoster (edited 08-14-2001).]

 

[Matt VDW]

Thanks for all the feedback.

I'm fairly sure that's lead, not powder, fouling since it's difficult to remove and I've gotten little silvery flakes out in the process.

I suppose I could bump up the powder charge a bit to see if that would obturate the bullet better. Since the load shoots so well as it is, I'll probably just learn to live with the leading instead.

 

[Walking Point]

Gas is cutting the base of the bullet. It's either undersized or the load is too weak to expand the base of the bullet.

Leading can occur throughout the barrel, or at either end. A barrel that's compeltely leaded usually means the barrel is rough and/or teh load is too hot for the bullet. Leading at teh chamber end usually means gas cutting or the load is hot enough to just melt the base of the bullet, leading at the muzzle tends to indicate the lube is not up to the task or there's not enough of it.

 

[KLN]

The soft lead necessary for commercial swaging machines often results in leading problems with the soft bullets. Cast lead bullets are harder and less prone to leading. However, there are a number of contributing factors, as mentioned above.

A magazine of jacketed rounds will leave the barrel lead free.

 

[CSH]

If the alloy is too soft or the bullet undersized the leading will extend all the way down the barrel. My only 45s that exhibited this sort of leading are Kimbers, and I have heard that Kimber uses Kart barrels. Regardless of barrel manufacturer, the problem was the transition from the chamber to the rifled portion of the barrel. This portion of the barrel is not tapered at all and shaves some lead from bullets, which ends up just forward of the chamber AND on the case mouth (looks almost like nickel plating). This condition also exists in quite a few newly manufactured rifles that shoot jacketed bullets very well. My solution was to fire 10 - 15 bullets coated in lapping compound, which tapered the throat and eliminated the leading problem. This will remove metal from the entire barrel, but most of the effect is just forward of the chamber. The metal removal will become quite noticeable if a lot of rounds (> 30) are fired. Lapping is not a universal cure-all for leading problems but is very helpful in correcting certain bore conditions.

 

[Freespool]

I've noticed with my Kimber that if I don't clean out jacket fouling before shooting lead I get the leading just in front of the chamber. Starting with a clean barrel the same cast bullet load shoots with zero leading. I rarely shoot jacketed bullets anymore. Cast bullets do it all for me - low cost and great accuracy and reliability.

 

[EdGCNM]

Not disagreeing with the above regarding the amount of leading and what causes it, but to clarify, isn't leading just at the beginning of the rifling past the chamber the most common and logical place to have it under "normal" conditions? That is, if leading is going to occur because of a relatively soft bullet and/or relatively hot load. My logic is that the bullet is squeezed into the rifling in order to engage the rifling solidly--in effect, the bullet doesn't actually fit in the barrel to start with. That squeezing occurs where the rifling begins and can cause lead to be deposited. Once fully into the rifling (the bullet now fits the barrel if you like), the bullet will spin down the bore leaving little or no additional lead behind. If the bullet is soft some will be deposited as it engages the rifling, or if it is "pushed" hard the same will occur.

Since we're talking about a light load here, my assumption would be a soft bullet. Then again, I'm often wrong.

 

[Genghis]

Swaged lead bullets are soft. That's one possible cause.

Fast burning powder will "jump" the bullet into the rifling. A soft bullet will strip a bit until it gets engaged and starts to rotate.

45 ACP headspaces on the mouth of the brass. You taper crimp the brass to spec for the headspace. This should also be sufficient to hold the bullet in position in the case.

Swaged bullets are nearly useless. You can dent them with your fingernail. Lead that soft is going to leave fouling in the bore. Go for hard cast lead bullets.

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[Matt VDW]

Swaged bullets are nearly useless.

Perhaps, but they work well for low velocity target loads. The only thing I don't like about the Stars is the leading and I'm learning to live with that.