Traditional Firearms > Caplock Long Guns

estimating velocity

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Jim in Wisconsin:
I was shooting my 36 cal. mule ear rifle yesterday and wondered how fast those balls are going. Hornady .350 that weigh about 65.5 grains with 31 grains of 3f black powder and a pretty tight mink oil patch shoots accurate (if I don't wiggle). The barrel is 32 inches long
There is a dead ash tree with the bark off about 50 yards from where I was shooting, so I shot it. The ball made a dent about half it's diameter deep but didn't stick in. That wood is real hard though.
Is there any way to estimate speed without a chronometer? I think that ball is just sort of loafing along.

PetahW:
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IMO,  velocity for a .36, usually used on small game or targets, doesn't really matter because the PRB will usually puncture either for a good effect.    :toast

Ohio Joe:
I would say you're getting close to (possibly) 1457+ FPS at the muzzle... Round ball looses velocity quickly, so at 50 yards you may be in the 978 fps range, and at 100 yards about 786, maybe??? Conditions play a big part in this.

This info is from the; old Lyman Black Powder Handbook... There's probably more up to date information out there. My book is from the 1970's, and I don't know if it was ever updated in later years, and of course the Powder you're using plays a big part...  :shake

Jim in Wisconsin:
Thanks, that sounds about right. Not even close to the "crack" of speed of sound. The old books are still useful, somethings haven't changed since then.

Hanshi:
Unless you have a chronograph it's more of a "guessing game".  I say this because speed per grains of powder isn't always linear.  In my .40 the velocity of a prb was almost predictable until five grains of powder was added to a 35 grn charge causing the velocity to jump 200+ fps.  That anomaly never repeated at any other charge other than the 35 grn that was increased to 40 grains.  Over several sessions it happened every time at that load.

That being said it's possible to be in the ballpark if the following steps are taken.  Using a uniform testing material, wood will work, that has been shot previously and velocity measured.  The penetration has to be measured for the test shot and another shot with 5 grns added.  At least at certain charges the penetration will give a general idea.

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