Why Lead Builds Up in a Barrel, and What a Bore Coating Changes

If you shoot lead bullets, you've seen it. You run a patch through the bore after a range session and it comes out gray, or you hold the muzzle up to a light and the rifling looks dull and smeared instead of sharp. That's lead fouling, and it's one of the oldest annoyances in shooting. It's also easy to misread, so it helps to know what's happening inside the barrel before you decide what to do about it.

Where the lead comes from

A lead bullet is soft metal pushed down a steel tube under a lot of pressure. The rifling cuts into the bullet's surface, and the bullet drags along the steel for the whole length of the bore. Friction and heat shear off a thin film of lead, and some of it stays behind. One shot leaves almost nothing. A few hundred shots leave a layer you can see.

Where it collects isn't random. The throat just ahead of the chamber, the first few inches of rifling and the area behind the muzzle crown are the usual spots. Gas cutting makes it worse: if a bullet is too soft for the load, or slightly undersized, hot gas slips past the bullet and melts its surface, smearing lead onto the steel. Hard cast bullets, the right lube and a properly sized bullet all help, but none of them end the problem. Plenty of shooters run cast bullets through pistols, Glocks included, because it's far cheaper than jacketed ammunition, and then give the savings back in cleaning time.

Why a leaded bore is worth caring about

Lead isn't only a mess. A fouled bore behaves like a different barrel, and that shows up in a few ways.

• Groups open up as the lead builds unevenly and nudges the bullet on its way out.
• The bore narrows in spots, which can push pressure up. That's a good reason to take heavy leading seriously instead of shooting through it.
• Every later cleaning takes longer, because old layers get harder to shift the longer they sit.
• Lead packed into the rifling is easy to miss by eye and easy to scratch the steel trying to remove.

Copper and plastic do the same thing in their own way

Jacketed bullets leave copper, usually as a thinner and more even smear. Shotgun wads and some polymer-coated bullets can leave plastic behind. Different material, same result: something that isn't steel is sitting where the bullet needs a clean, slick path. Solvents that attack copper don't always touch lead, and the reverse is true too, which is why a shooter with a mixed safe often ends up with three bottles under the sink.

What a bore coating changes

A coating works on a simple idea: put a thin, slick layer between the steel and the bullet, so less metal transfers and what does transfer has less to hold onto. Pb Blocker is a product built around that idea. According to its product page, it was originally formulated to combat lead build-up in the barrels of Glock pistols. After extensive testing, the same coating turned out to be useful on lead, plastic and copper alike. This article won't guess at the chemistry, because the product page doesn't describe it.

What the page does list is straightforward. It reduces all build-up, it's easier to clean afterward, it works in all firearms, and it allows hotter loads. "Hotter" is a relative word, so stay inside published load data for your cartridge and bullet. A coating is not permission to go past the book.

The customers quoted on the site describe it in practical terms. J.B. Holcomb, a big game hunter, says: "With the use of PbBlocker, I have cut my cleaning time by 90%". Cope Reynolds, owner of Southwest Shooting Authority and host of The Shooting Bench, says: "We fired 1000 hard cast bullets through a Glock 22 without cleaning and the amount of lead in the barrel was virtually undetectable." Those are their experiences with their guns. Yours will depend on your load, your bullet and your barrel.

What it does not do

A coating doesn't replace common sense. It doesn't make a badly sized bullet right, it doesn't excuse loads past the manual, and it doesn't mean you never look at your bore again. The claim is smaller and more useful than that: less build-up, and an easier, shorter cleaning when you do get to it. Check the bore now and then, keep your gear clean, and treat a sudden change in group size or recoil as a reason to stop and look.

Pb Blocker is $16.95 a bottle and ships from Farmington, NM. If you'd like to talk through a particular gun or load before you order, call 214-274-4321, Monday through Saturday, 8am to 6pm, or email hayes@pbblocker.com. The 100% satisfaction guarantee applies to all purchases, and the product itself is on the /klaudius/pbblocker/product/pb-blocker page.