What causes "donut holing" in a shot pattern?

[Stormrider51]

Been giving this subject some consideration lately and thought I'd toss it out to get your ideas.  What causes the shot pattern from a muzzle loading smoothie to sometimes form a ring with a "donut hole" in the middle?  I've seen the video evidence that says this happens.  But why?  I could understand it if the shot column were being rotated as from a rifled bore.  Centrifugal force would fling the individual pellets outward from the line of flight.  But from a smoothbore?  I've heard it opined that it is the over powder and cushion wad "blowing through" the shot.  That doesn't make sense.  In fact it would seem to defy the laws of physics.  The wads have less weight than the shot column and a large frontal area.  The wads should fall behind very quickly thanks to aerodynamic drag.  Could the over shot wad cause this much disruption of the shot pattern as the shot passes it?  It doesn't seem likely either.  Is it possible that it is the powder gas blow-by disrupting the column?  What do you think?  Just idle speculation on a Friday night.

John

[ridjrunr]

smoothies are a different animal, at least for me, still learning.
With my 12 ga. @ 20 yrds, my cushion wad goes right through thin plastic type corrigated cardboard. My pattern is ok, just not what I am used to in a shotgun. It patterned ok on turkey, head/ neck silhouettes.

[mario]

 I've heard it opined that it is the over powder and cushion wad "blowing through" the shot.  That doesn't make sense.  In fact it would seem to defy the laws of physics.  The wads have less weight than the shot column and a large frontal area.  The wads should fall behind very quickly thanks to aerodynamic drag.

One must remember that, initially, they are traveling at the same rate of speed. 10 ft from the muzzle, that's a different story, but right out of the muzzle, the over powder wad is pushing against the shot. I think that it starts a chain of events right at the beginning that just magnifies with distance.

In my guns, the simple fact is, cushion wad=doughnut, no cushion wad=no doughnut.


Mario

[No Rod]

Mario is right, I had the same problem and went to an unlubed light felt cushion wad and my pattern closed right up.

[Captchee]

yep . i fid the same thing .  to much powder and  it will blow the pattern wide  and the wad will take out the center of the patern . some where i have some early photos  that greener took showing this happening as well as  photos of  cups throwing shot as they tumble

[Stormrider51]

Thanks guys.  I appreciate the insight.  I was leaning toward the idea that it had to be gas blow-by but it would appear to be the use of a cushion wad.

John

[Feltwad]

One of the main causes of  a holed pattern is with a felt wad with no card on top .With minus a card shot embeds in the felt wad  which leaves the muzzle like a bullet and blows the pattern.
Feltwad
A flint lock will not secure a chicken house door

[Stormrider51]

Thanks guys.  I was cursed with a mind that worries at a subject I'm interested in but don't understand.  In my life I've been a pistol or rifle shooter.  A shotgun was always something kept in a patrol car or beside the bed for those more serious social occasions when I needed to administer a large dose of valium to a situation.  Usually the sound of a 12 gauge pump being racked was enough to get folks attention.  Now I'm exploring the muzzleloading smoothbore and finding that things don't match up with my old Remington 870 so I'm wondering why.  Hey, it keeps me interested.

Thanks again,
John

[Ironhand]

You might try reducing the ratio of powder to shot. Either less powder or more shot. Probably less powder.

Used to do this to tighten patterns when I competed in BP trap.

Ironhand

[Feltwad]

If your gun is a 12 bore{gauge] then use a volume load I always find that 2.3/4 drms of FFg to 1.1/8 oz of shot  5 for game 7 for clays is the best, one drm  = 27.5 grains.
Feltwad
A Flint Lock will not secure a chicken house door

[Buzzard]

I've found the same thing to be true. A cushion wad, made heavier by soaking with a lube, will easily blow through a shot column early in the down range travel of said column. I've taken to breaking the cushion wads in two, loading 1/2 wad per shot. It did eliminate the holey patterns, in both my smoothbores, 20 & 28ga. BTW, loading a half of a wad also eliminated blown patches when using PRB.

[pathfinder]

If your in the Michigan area on July 28th, the Lansing M/L gun club is having a Flintlock ONLY trap shoot and clinic. I'll be there as my Bess. and I need some help in the bird dept!

 Their website;  http://www.lansingmuzzleloadinggunclub.com

[Captchee]

You might try reducing the ratio of powder to shot. Either less powder or more shot. Probably less powder.

Used to do this to tighten patterns when I competed in BP trap.

Ironhand

 yep i have found the same thing .
 more powder to shot will open the patern . less powder to shot will help tighten  it up

[Feltwad]

Do you really need a cushion wad? I have shot muzzle loading shotguns now for many decades in all bore {Gauge } sizes from the big 4 to the small 32 and I always find that a volume load with two 1/8 over powder wads then the shot the a 1/16 over shot wad will do the job .If the gun becomes a bit coked then a bit of spittle in the bore followed by a wad will do the job .To be honest I find a small amount of coke in the bore makes a gun shoot better.
Feltwad
A Flint Lock will not secure a chicken house door

[Captchee]

i have to say it depends . i have shot smoothies that shot best with no wads  and just a heavy over the powder card .  others that shot best with just an over the shot card  inplace of the powder card . still others that wanted wads and all cards . it just all depends on what works