What size is .62cal?

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There is one thing that todays ML's seem to share with their ancestors and that is inconsistancy/ lots of variance in bore size of a given cal/bals per lb /gauge or gun in the past a gun of (x balls to the lb) which equaled a .562 ball might have a bore size of .577 thru .623 and be acceptable, todays guns are not quite as varied but seem to retain some of the scope allowed in the past for bore tolerance and still be correct for the Cal.
 
Generally, a ball that is at least .015", and better, .020", SMALLER than your actual bore diameter will give you the range of options in choosing the thickness of your fabric patches, so that you can get the best accuracy.

The key to success is to actually MEASURE your bore diameter- and don't trust what the maker says it might be. Rarely will you find any barrel maker actually test firing barrels before they go out the door. And, Gunmakers rarely do that kind of testing for a customer.

"It should be no surprise to any buyer that the bore of that barrel isn't the same as the Nominal diameter the Barrel is SUPPOSE to BE!" It should be no surprise to any buyer that the bore of that barrel isn't the same as the Nominal diameter the Barrel is SUPPOSE to BE! "

Spot On....these jokers don't know the definition of Nominal. my Pedersoli is dead on as advertised .620, True.
 

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I miss Paul Villandigha and his wisdom.

For others interested in this thread, I have a brace of Tower 1777 Sea Service pistols made in Japan stated 62 caliber but one measures 0.615 and the other measures 0.620 they both shoot good with 20 gauge wads and .600 cast pure lead balls or 0.12 linen patches.
 
My TRS M1776 is .62 but haven't shot it yet. Have some commercially made .62 balls, will know more later. Patch size can be adjusted, too. Don't know who made the barrel for the TRS M1776, anyone know? (Early 80's period production). Thx
 
Yes, this is a revived old thread. However, it doesn't really answer the question of what RB diameter to use. Before I reply, keep in mind smoothbores aren't like rifles, where a much smaller range of patch and ball combinations will produce accurate shooting. In my Green River Forge 20ga. NW Trade Gun, the bore diameter is .618" - .619" as best I can determine. It will shoot accurately @ 25 yd. with various patched ~.600" RB's and almost as well with a bore sized (.618") RB with over shot and over powder wads. Tow wads do OK with the bore sized ball, but the powder charge has to be much higher, i.e., in the neighborhood of 90 - 100gr. FFg.

A few weeks ago I read about using a significantly undersized, but patched RB in a 20ga. smoothie. After searching a bit, I found a pristine Lyman .572" RB mould, cleaned it and began casting with it. (It cast perfectly!) At 25 yd. with doubled .014" pillow ticking patches and 70gr. FFg it did surprisingly well. I'm posting two photos of RB results. The first is with three different [nominally] .600" RB's @ 25 yd. with 70gr. FFg. The second photo is with the .572" RB results using tow and doubled pillow ticking patches. If you enlarge photo #2, you can read my handwriting a bit better.


P.S. Even though the Lyman mould is marked .575", it drops a .572" pure lead RB.
 

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I don't shoot much anymore but I got such good results (for me) with a .600" ball and thin patching I actually just stopped looking. I did try a .590" ball with double patching and can't find much to complain about with that load. With the .600" ball powder charge didn't seem to make much difference.
 

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