.62 cal. underhammer rifle.

[twotoescharlie]

finished building this rifle, need starting loads, have .600 balls,any thickness patches needed, any type lube necessary, don't shoot nothing but real black powder. any of you fellers got a starting point for a rifle with a bore of this size?
  been shooting black powder for over 50 years, but I don't like to waste my good powder.

  TTC

[Longknife 76]

Twist and groove depth are two of the most important items that I need to know before making an opinion. That .600 ball in a .620 bore is going to need a THICK patch, say .025 at least. With a SLOW twist that this barrel should have, say 1/72 you will be able to use a much stouter charge and retain good accuracy. Another thing to consider, if you are just "paper punchin" out to 50 yards a light load of 60  to 80 grains will do. If you want to shoot 100 or more then a larger charge will get you a flatter trajectory. The most fun of a new gun is "tweaking" it to get the utmost accuracy!!!! IMHO...LN

[coyotejoe]

I'm real fond of patching from old blue jean legs which mic .030-.035" thickness and that should work well with your .600" ball. The advantage in using such thick material is that it will not blow out or burn through so that is one thing you don't have to be concerned about, also there is plenty of material to bunch up in the grooves if your barrel is a deep groove bore. Anything from 50 to 150 grains of 2f should be good.

[Winter Hawk]

A good starting load in grains is 1 1/2 times the caliber.  So for 62 x 1.5 = 93 grains, then work up or down from that point.  I find it interesting that the .45-70 cartridge is right there (45 x 1.5 = 67.5 grains almost 70).

-WH-

[Forestclimber]

Can you post a picture of the rifle?

[StrawHat]

Another option is to double patch the round ball.  I've done this with a couple of my hunting rifles.  I also use a bit of hornets nest betewen powder and patch on rifles where I am concerened with the patch burning.  Not sure why but the nesting works as a "gas check" and protects the PRB.

The powder charge would depend on how you want touse the rifle.  Target or hunting.  Makes a big difference when I pour powder.

Good luck.

[twotoescharlie]

don't have access to camera to post photos, this is a longhammock barrel and wallyworld ticking is pretty tight, have to use a short starter. it mikes at .014 and is lubed with moose snot. used 70 grains 3fg and was shooting 1 1/2  inch groups @ 50 yards. which is pretty good for myself.  (almost 72 years old and failing vision)

  TTC

[S.S.]

A half inch group at 50 yards with a .62 caliber should
do anything you need it to just fine.