Slugging a Barrel - A Primer with Pics

[j8064]

There are many "how to" instructions out there on slugging barrels. The first time I decided to slug one it seemed a little out of my comfort zone. But it's really very easy. And it's a good thing to do on many rifles - especially old mil-surps. Slugging the barrel is a great way to know what the bore diameter is like and what your reloads may or may not do for you at the range.

Today I pulled my 6.5 Carcano cavalry carbine out for a range trip. The bores in Carcanos can vary a lot. Most modern 6.5 Carcano factory ammo (like Prvi) is loaded with .264 bullets. Many (but not all) Carcanos would be much more accurate if they were fed .268 bullets. But a bullet too big for the bore is a bad event waiting to happen. Best way to know if the reloads I built with .268 bullets can be fired in the ol' gal is slug the bore. Here's how to do it.

Tools you'll need:

• Some soft lead like fishing sinkers or BP balls in a slightly larger diameter than the rifle's bore.
• Several short pieces of hardwood dowel.
• A rubber mallet.
• A caliper or micrometer.

Below is a series of pics on how to put those tools to good use:

1. Select a lead sinker or ball that is slightly oversized. It's kinda like loading lead balls in BP guns. You want the muzzel to shave a ring as you start the lead down the barrel.
   
2. Start the slug you selected with a rubber mallet and a short piece of dowel. I like to use the conical sinkers with a hollow base and a piece of dowel that fits in the base of the lead.
   
3. Tap the slug in with the mallet and dowel to get it started down the bore.
   
4. Slowly start driving the slug down the barrel with the mallet using short pieces of dowel.
   
5. The muzzel should shave a ring for you. Then you know you'll have a good slug to measure.
   
6. If you use the right diameter dowel, sometimes your slug will stick to the end of it!
   
7. Measure the bore's lands and grooves. In this case, the grooves of the rifle are .2675. No wonder .264 diameter bullets are not very accurate!
   
8. After spending 5 minutes slugging the barrel, I have no qualms about shooting the .268 bullets in the loads on the left through this ol' gal tomorrow.

So there you have it. Slugging a bore is about as easy as it gets. The same method works on pretty much any caliber.

AND it's always a good thing to have an idea how your reloads are likely to perform in the rifle once you pull that trigger.

 

[pilgrim]

Congrats and thanks for posting it. It is something I have thinking of trying.

 

[IndispensableDestiny]

Make sure your sinkers are all lead and not modern environmentally friendly junk. You can also take a cast of your bore using Cerrosafe alloy. While you are at it, take a cast of the chamber and throat.

 

[ineoin]

Great post, Thanks

 

[j8064]

To come full circle, the cavalry carbine liked the .268 loads much better than the factory .264. They shot about a 6" group a foot high at 50 yards. Nobody said this rifle was a tack driver. But firing the .264 bullets at 50 yards, getting on paper at all is a major challenge.

A agree, Cerrosafe works well too. But a lead slug through the bore will tell you a lot about your rifle in only a few minutes with little prep and cleanup.