What does it mean to "slug the barrel"?

ursavus.elemensis · Post by **ursavus.elemensis** » Sun Apr 06, 2008 4:06 pm

What does it mean to "slug the barrel"?

and

how does one go about doing that?

Old Ironsights · Post by **Old Ironsights** » Sun Apr 06, 2008 4:15 pm

Easy (ish).

Get a soft lead Round Ball or fishing sinker sightly larger than the diameter of your bore. Say, .500 for a .457.

Put it into the crown and hammer it down the bore until it comes out the other side (obviously, use a non-marring/mild rod to drive it with...).

You now have a "slug" you can measure with calipers to determine the exact dimensions of your bore - both lands and grooves.

That's all there is to it.

Pete44ru · Post by **Pete44ru** » Sun Apr 06, 2008 4:52 pm

Or..........You can have your wife fire a bullet past your head, catch it in your teeth, and then measure it !

Tycer · Post by **Tycer** » Sun Apr 06, 2008 5:45 pm

I do one like OI said, then I put a heavy length of something (brass rod, bullets of smaller diameter...) in the barrel and drive one slug 2" down the barrel and use the heavy something to drive it back out, and I fill a case almost full with lead or bullets and drive enough lead down the barrel to get a good cast of the chamber and leade in front of the case.

The first slug all the way through gives you the minimum diameter.
The second will show you if the muzzle end is the same size.
The third will show the diameter of the chamber end, and give you a great idea of how far out to seat bullets and what to expect from cast bullets. No leade is not great, a gentle leade is great. Seating cast bullets to just engrave on the rifling and jacketed to come up .002" short of the rifling can help accuracy.

Use plenty of slick lube down the barrel to preventing a stick and use a heavy hammer. If you use wood to drive the slugs, use 6" sections instead of one long one.

Iron_Marshal · Post by **Iron_Marshal** » Sun Apr 06, 2008 6:07 pm

I am relatively new here and this is WAY OT, but I love the picture of your K-9. I was a K-9 officer in the USAF for about five years and love the working class K-9. I have handled German Shepherds and Belgian Malinois (not so affectionately referred to as Belgian Maligators).

I have no idea about slugging a barrel, but I had to comment on your fine looking partner. Sorry to bog down the topic.

Post by **Chuck 100 yd** » Sun Apr 06, 2008 6:36 pm

One can also take a cast of the chamber/bore using Brownells Cerosafe (an alloy of metal that melts at about 160 deg. and shrinks as is cools and then swells back to the exact size of the mold/bore after 1hr.)
Plug the bore using a tight fitting patch on a cleaning rod, pour in the molten Cerosafe,it will solidify almost instantly,push it out and measure after 1 hr. using a good mic.
A cast bullet sized 1-2 thousandths larger than groove diameter should be accurate and if of proper alloy and lubed with good lube will not lead the bore.
have fun!

BenT · Post by **BenT** » Sun Apr 06, 2008 9:18 pm

Make sure you oil the barrel first. I use 6 inch pieces of hardwood dowels that way I don't have to start hammering one long piece, just keep adding another piece when your flush with the muzzle.

AJMD429 · Post by **AJMD429** » Sun Apr 06, 2008 9:32 pm

Tycer wrote:If you use wood to drive the slugs, use 6" sections instead of one long one.

Why is that? I would think that would increase the chance of one splitting and wedging into the barrel?

JReed · Post by **JReed** » Sun Apr 06, 2008 11:13 pm

AJMD429 wrote:
Tycer wrote:If you use wood to drive the slugs, use 6" sections instead of one long one.
Why is that? I would think that would increase the chance of one splitting and wedging into the barrel?

The shorter peices are easier to deal with. They shouldnt break if you oil the bore first. Nice even taps with a rubber mallet is what I do. No need to be He-Man.

Nate Kiowa Jones · Post by **Nate Kiowa Jones** » Sun Apr 06, 2008 11:47 pm

Here's how I do it. I like to use a slug of soft lead that is at least 1 1/2 times long than the bore that's being slugged. This extra length assure that the slug doesn't wobble or try to turn in the bore as it's hammered through. This can be verified with short slugs. Measurements will vary depending on where you measure it. The longer slug yields more consistent results. Make sure the bore is clean lead free and lightly oiled, as in an oiled patch pushed though it.
You can drive the slug in from the muzzle if you use a leather or rubber mallet so as not to damage the crown. I like to drive it all the way through to feel and high spots or bulges. Next if it's a levergun I use two wooden dowels just smaller than the bore and cut to the cartridge OAL. These are inserted into the chamber end and the action closed. Next the slug is re inserted in the muzzle end and driven to the wood dowel then bumped up so it's now tight. Now, open the action, remove the dowels and gently tap the slug on out. This will give a real true picture of the bore just in front of the chamber or farther out depending on how many dowels are used.
To measure I like to use a zero-ed Starret micrometer. I don't think most dial calipers are accurate enough.

Leverluver · Post by **Leverluver** » Mon Apr 07, 2008 12:26 pm

Ditto about everything NKJ said, but I made brass pins to take the place of the wooden dowels. I've had too many of them break. I do use an under sized slug and only bump it up when they contact the brass dowels. I have another longer brass rod of bore diameter that smacks the slug agains the short dowels.

Triple ditto on the calipers.

Old Ironsights · Post by **Old Ironsights** » Mon Apr 07, 2008 1:09 pm

AJMD429 wrote:
Tycer wrote:If you use wood to drive the slugs, use 6" sections instead of one long one.
Why is that? I would think that would increase the chance of one splitting and wedging into the barrel?

IMEX the opposite is true. A ful length dowel will try to flex then split, where the shorter dowels seem to align within the bore and run "cross grain" to each other.