COW and 20 ga revisited

[singleshot]

Ok, I've done some testing and found a couple things which has led to some questions.

First, I'll describe what I've done.

I've been developing a load for a .60 roundball in my 20 ga. The balls as-cast will just barely fit into my modified choke which isn't removeable. I'm using Federal hulls, plastic gas checks made for slugs and various fill/buffer/stack height materials. So far, the most consistent load I've tested:

13.5 grains Hodgdon Internaltional Clays
3.4 cc's COW below the gas check
3.4 cc's COW above the gas check
Roundball on top with 8-pt star crimp

Now my questions are:

1) Does the gas check being higher in the stack help?
2) Why does half the COW under the gas check provide more consistency than all above?
3) Would having a tighter fit using a wad with partial petals help? Reasoning: once the roundball enters the barrel, there's .015 slop (unless the COW keeps the ball centered in the barrel)

I didn't test using paper, I was shooting at "exploding objects" like bottles and such so I don't have pretty test results to post. Next time I go out, I'll shoot at paper and take pictures.

BTW, that .60"roundball sure explodes stuff with authority. :-)

[curator]

Singleshot,

Welcome to the wonderful world of cream of wheat shooters! Interesting stuff that COW; both a ballistic improver and breakfast cereal all in one. I assume by the term "gas check" you are referring to the wad column which includes a "gas-seal" on the bottom, a cushion section in the middle, and a shot sleeve on the top. By putting the COW on top of the powder charge, you are in effect, putting a second "gas-seal" in place. The COW upon firing, compresses into a solid mass which is quite effective in sealing off high pressure gas, and preventing the usual blow by, thus creating more efficient, consistent performance. Under the ball, the COW also compresses and conforms to the contours of the slug, helping to center it in the bore. To answer your other questions, your wad column containing COW creates the correct size/length to allow a good crimp--what more can you ask for? As far as using the shot sleeve to act as a sabot for the ball, try and see if it gives better accuracy. If it doesn't, go back to the COW load, or cut all but the last 3/8 inch of the petals off and "patch" the ball with canvas or pillow-ticking cloth to keep the ball centered in the bore. If your balls are pure lead, and not wheel weight alloy or range scrap, they should be soft enough to pass through your choke without damage.

[singleshot]

Curator,

The gas checks I have are simply plastic gas checks, no column with cushioning legs, no shot cup, no petals. I'll see if I can post a picture of one. I picked up a bag of 500 of them for the 20 ga for around $5 so I figured it was worth it for buckshot and slugs.

Thanks for the info, I'm really warming up to cream of wheat, especially since I live in the high desert with very little moisture or humidity.

[singleshot]

Ok, so I modified the amount of COW to reflect what I actually used...it was 6.8cc's total instead of 3.2cc's. However, I've noticed that using 5cc's total and allowing the crimp to fold all the way in...kinda like a roll crimp...is producing more consistent ignition and higher velocity.

So now I've settled on:

13.5 gr International
2.5cc COW on top of powder
plastic gas check
2.5cc COW on top of gas check
.60 cal lead ball
8-star crimp folded all the way in to top of ball

I was getting 3-5" groups at 75 yards yesterday. More testing to follow...