SLugging the barrel

[newcastle]

Ok I've seen this mentioned left right center and really need to know exactly what is involved to a) do this and b) ensure that i get the right measurements to be able to use the information.
I ASSUME that the purpose being to measure the diameter of the barrel you have to use a soft something or other which will mould to the rifling much as a bullet does?
I ASSUME that one needs a micrometer to measure the OD of the item which has been pushed through the bore, and thats about as far as I get.

What do you use? What do you push it though with? Do you have to oil it? Do you measure the bit that has been in the groove or on the lands etc etc? plus of course once you've done this what is the formula for max accuracy in reloading. if one gets a dia of .310 does one use .311 bullets for instance.

Information

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[browningautorifle]

I use a lead ball(buckshot) as close to diameter as possible. I drive it in from the rear if possible. No oil. Use a rod that matches the bore as close as possible. Flat end to the lead and tap tap tap until it falls out the front. Measure the outside and you have your bore diameter. You generally want one over your outside diameter. .310 uses .311. There are other ways so hang on a minute.

[Parashooter]

[newcastle]

SO you can either drive all the way through or just do the 4 inches nearest the muzzle? IF you go through the whole barrel is there ANY way of telling if there's a tighter bit in the barrel or if it's not consistent all the way through. Also what is the size that people generally use for .303 barrels?

[browningautorifle]

That's why you slug your 303 is to find out what YOU need to use. I think .311 is what you find for jackets. They can vary vastly. You would feel the ball move easily through a loose spot. Yes, as he points out you can slug both ways.

[newcastle]

No i meant what size buckshot shoudl I use? is there a standard size for 303s.?

[browningautorifle]

You only have so many sizes so I guess .31 or .32. .32 should swage down ok.

[vintage hunter]

There are 7 pellet sizes available in the US, #4 thru 000. Sizes are as follows, #4 = .24 in., #3 = .25 in., #2 = .27 in., #1 = .30 in., 0= .31 in., 00 = .33 in and 000 = .36 in. The 00 size is most common and the easiest to find. Midway has all sizes available in 5 lb. bags last time I looked.

[newcastle]

Do most people use 00 or 0 for 303 barrels thne? I'll go with the majority. Also I forgot one question. Does one have to do any cleaning after wards? does pushing lead through slowly leave any bits that shooting lead through fast doesan"t?

[Parashooter]

Since buckshot are pretty soft, either the 00 or 000 size works fine for the typical .303 with groove diameter somewhere in the .311"-.318" neighborhood. Size 0, being ~.320" diameter, is marginal. One way to get a few is to open up a loaded buckshot round, commonly sold in 5-pack for about $5 (cheaper than ~$25 for a 5-pound bag or even the ~$8 for 100 .350" Hornady round balls). Some folks recommend fishing sinkers, but it's seldom certain what these are made of or how clean the metal is.

If you're curious about uniformity, do one slug near the muzzle and do another from the breech end, about 3" past the throat. Usually, there's not much difference and it isn't worth the trouble of making the soft metal or hard wood drift needed to drive one from the breech (or to upset one near the breech after driving from the muzzle). Feeling for loose or tight spots while pushing the slug from the muzzle end gives a good idea of uniformity - or amount of metal fouling if the barrel wasn't thoroughly clean before slugging.

Unless your barrel is really raggedy, slugging won't leave behind any bits whatsoever.