Accuracy relationship of round ball dia vs wad thickness

[borderdogs]

Hi Guys,
I have a question to the forum about the relationship of the diameter of a round ball to the thickness of the wad and how it relate to accuracy.

Its certainly known that a tight fitting round ball & patch will limit gas leakage. But is there a relationship to accuracy if you use a wider diameter round ball and thinner wad verse a smaller diameter ball and a thicker patch. For example has anyone seen a difference in accuracy using say a .490" ball with say .015" wad verses a .495" ball with a .010" wad? I have used patch material like scrap bed sheets, etc and either cut them as I shoot with a patch knife or pre cut patches with a shop made wad cutter. I have purchased wads before but I never really thought too much about wad thickness and ball diameter as it relates to accuracy. I just wanted a tight fit.

So any thoughts on this out there? I would really like to know.
Thanks,
Rob

[Kermit]

I'm confused. Are you using a patch AND a wad? I'm sort of thinking you are saying "wad" when you mean "patch."

[LH]

seems like every gun has its own preference.  Over the years in a dozen or so guns,  I'd say my best accuracy has usually come with close to bore diameter balls and patch cloth in the .012 to .015 thickness range.  "Usually" being the key word.  I know some people who get excellent accuracy with bore sized balls and .020 patch too. If I'm trying to find the best accuracy for any given barrel,  I will try everything available to me if necessary.  I'm not a bench shooter though,  so for offhand guns,  anything that will produce 2 or 3 moa consistently when the wind aint blowing is fine for me. 

[Standing Bear]

My RB barrels have .012" rifling or deeper. A .495 ball and .018 - .022 patch works well.

Shooting .490 and .015 or thinner patch in one of those barrels will exit the barrel and look ok at 25 yds.  At 50 the knuckle ball is starting to act up and it gets worse past that.

If you are shooting a button rifled barrel the grooves are .004 deep or less so a .490/.015 combination probably will work.
TC

[hanshi]

My Rice barrel has very deep rifling and shoots excellently with a .490" ball and a .024" patch.  Haven't yet tried a .495" ball.

[borderdogs]

I probably should have said patch instead of using patch and wad to mean the same thing. I reload black powder cartidge rifles too and cut my own "wads" for them. I also cut my own "patches" with a wad cutting die I made. They are both cut and they are both round. Unless I have patch material I cut with a patch knife. Sorry for any confusion. Thanks for the responses they are very helpful!
Rob

[SCLoyalist]

Differences in groove shape, groove width, and groove depth between rifles of the same nominal caliber probably mean you're going to have to resort to shooting and taking good notes to see what gives best results.    There are two patch thickness measurements that come into play:  thickness with the calipers touching the material lightly, and a compressed thickness with your fingers applying substantial pressure to the caliper jaws.   It appears to me that the compressed thickness tells you something about taking up space between the ball and the lands;  the uncompressed tells you something about how the patching will fill the grooves.  One example out of the old Lyman BP Manual says suppose you had a barrel with a .503 bore diameter land to land, and a .526 groove to groove diameter.   A reasonable starting point would be a ball  0.005 under bore,   in this case a .498RB, and a patch at least as thick as  (groove diameter - ball diameter)/2, or  (0.526 - .498)/2  = 0.014"    And, it's better to go with a thicker patch than a thinner one. 

Probably the best advice is to do several shooting sessions with an open mind,  retrieve fired patches and look for signs of cutting or burn-through,  and see what ball/patch combo you and your rifle are happy with in regards to accuracy and ease of loading.    If you can lay hands on the old Dutch Schoultz package on working up a load, he describes a systematic approach to working up a load, including finding a good patch/ball/patch lube combination.   Eric Bye's new book on Flintlocks also  has a page or two devoted to patch thickness selection, as does the old first edition Lyman Black Powder Handbook.

[Daryl]

The only .010" to .015" material I have, is a cotton handkerchief for blowing my nose into. For me, patch material for round balls starts at .020" and gets thicker from there.

Lyman's Black Powder Handbook has an excellent set of drawings showing a ball that was introduced into a bore with it's patch.  One shows only marks from the lands - too thin a patch.  One of the balls has the patch's weave imprinted on it all over, from the lands and from the bottom of the grooves as well.

In order to get the cloth's weave impression into the lead from the bottom of the grooves, the ball and patch combination must produce considerable compression in the bottom of the grooves - yes - the bottom of the grooves, not just the high spots, the lands.

As with your BP Ctg. guns shooting best with a bullet being .001" to .003" LARGER than the groove diameter, so too does the muzzleloading rifle, but in my own and other's experience, .002" to .003" is a mere start for compression for the ball and patch combination in the bottom of the grooves.

The heavier the load, as in the rifle's most accurate 50 to 100 yard load (generally also a heavy 'hunting' load when suing oiled patches) the tighter that combination must be to contain the pressure behind it and continue to seal the bore.  If the ball and patch combination is too small in diameter compared to the groove diameter, gas cutting will occur and 'throw' shots with heavy loads. Squib loads will sometimes shoot well with thin patches, but that load will not provide the rifle's best accuracy at 50 yards or further out, in my experience.