Slugging a Barrel

[Iron_Marshal]

I bought some 1/2 inch lead egg sinkers to slug the barrels of my .44 mag pistol and rifle. The reloading guru-guy who is going to help me said he wanted to slug the cylinder bores as well. Waste of time and effort or good idea?

[Borregos]

It is very worth while knowing the throat diameter of the chambers.

[Pisgah]

Knowing the cylinder throat diameters is as important to accuracy as knowing the bore size, if not more so.

[awp101]

Waste of time and effort or good idea?

Neither...it's an excellent idea!

Cylinder throats can be different from not only the bore size but also from each other. I don't remember the cure for oversize throats and an undersized bore but undersized throats can be opened up to match the bore.

That may be clear as mud since I'm posting before coffee....

[Catshooter]

Nope, ya done good.

Them sinkers will work for any bore that they are larger than. Just drive 'em in, if there is much of a difference in size the excess will just shave off at the entrance to the bore.

Measure carefully, gently with the micrometer. Caliper may or may not give you an accurate reading.


Cat

[mikld]

Very important to know those measurements when shooting cast boolits. For clean shooting accurate handloads with cast, the boolits should be .001" or .002" over bore size and a closer fit to the cylinder throats (could be more depending on the firearm and how it shoots cast). I slugged all my revolvers and luckily they were all .0015" to .002" larger than bore dia. I also slugged my Puma .44 and found it to be .431"! Too big for the stuff I shoot in my Ruger SBH.

[Nate Kiowa Jones]

Bore slugging techniques can derive different results. In order to eliminate varialbes it is important to be consistant.

Here's how I like to slug a bore. 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 any high spots or bulges. I like to use a brass or hardwood dowel that is close to bore size. A rod that is too small can deform the soft lead. 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 you a really 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.

[Don McDowell]

If you're having accuracy problems slugging might be a good idea. Chamber cast is probably better.

I've got a handful of those nasty ol Rugers and a Colt that have never had a throat measured, and will shoot 1/2 dollar sized groups at 25 and 50 yds all day long.... 452 or 454 bullets for 45 colts, 430 for 44 special and magnum, and never had a problem.

[Chuck 100 yd]

Try this !! Push your egg sinker through your Lee push through bullet sizing die first.

An egg sinker is sometimes hard to get started into the bore and pounding just makes a mess out of it making it hard to properly measure. If it is just a couple thousandths over to begin with it works a treat.

Sizing in the Lee die also causes it to have a much longer bearing surface preventing tipping like Steve said.