BC of slugs and RB

[nitro450exp]

Hello again.

I am working up loads for my 12 ga Paradox.
I have a neat external balistics calculator to calculate near/far zero max ordinate etc.
Does anyone know the BC of 0.735" round balls and the four groove foster type slugs 0.730" sold by 1899Turbo ?

Thanks
In advance

Nitro450exp

[wiljen]

I think all of them have roughly the same BC as a cinder block.

RBs are generally .045-.055
Foster type Slug is only marginally better at roughly .07

[nitro450exp]

Hello again.

I have seen the foster type slug listed at 0.107 BC , doesn't specify rifled or not.
What makes you say it is around 0.07 ?
I am amazed the RB are so low.
I would have thought a sphere would be more efficient than that.
But I don't know that is why I asked.

Nitro450exp

[turbo1889]

The best info I can find on your particular question without having to take the time to re-write it all myself is contained here:

http://www.shotgunworld.com/bbs/viewtopic.php?f=118&t=199698&start=28

That link will take you directly to a very informative but rather long winded post on another less friendly competitor of this forum by tommygirlMT, my GF, who is also an active poster on this forum as well.

I should warn you that she was in the middle of a rather heated internet forum argument when she made that post and that she has a significantly more aggressive personality then I do and does not shy away from a fight like I do so take what she says with a grain of salt. I will also make a very clear disclaimer that I cannot control her nor do I make any attempt to do so and will not be held responsible for her actions.

The basic information, analytical methodology, and mathematical formulas she uses in that post are however spot on "dead nuts" accurate and correct as far as I can tell and does indeed specifically address the questions you are raising; thus why I linked to her post in this case. She does some of her best writing when she is confronting someone who in her mind is spreading misinformation and in her mind needs to be called to the carpet. Personally, I wish she would just simmer down a little and make good informative and well written posts without all of her usual spelling and grammar errors along with the continual use of three dashes to connect continual sentence fragments as a regular habit and not just when someone pushes one of her buttons and gets her all bent out of shape. (Yah, I know if she sees this post she is probably going to mention it to me. Oh, well, I can’t behave myself all the time.)

As to the exact B.C. for the slugs that I cast from my custom mold; I do not have that information but since sectional density and form factor are the two input values for the B.C. formula an increase in weight and thus section density should lead to a proportional increase in B.C. for slugs with the same exact form factor. The form factor for my slugs is not the same as it is for the Lyman foster slugs since it is a round nose slug shape and mine have a hammer head nose shape (shallow 40-degree nose angle SWC with a 50% Meplat).

I would imagine from my general knowledge of how various projectile shapes behave in flight that my slugs have a form factor which produces slightly higher drag then the round nose shape that the Lyman foster slug uses. I would think, however, that their higher weight and thus greater sectional density would offset this factor.

In conclusion, I would guess that my slugs have about the same B.C. as the Lyman foster slug for the lightest weight 1-1/4oz. version. The heavier weight versions (1-3/8oz., 1-11/16oz., & 1-3/4oz.) would have B.C. values greater then the Lyman foster. I do not know for sure though, next time I find the time to spend a whole day at the range I might risk setting my Crony up at various downrange distances at and beyond 50 yards to measure the flight velocity differences at various distances down range and then use that information to calculate the slugs true B.C. from the experimental data so collected. Since my purpose and intent when I drew up the design for those custom slug molds was to build a slug that hit like the proverbial "bag of hammers" and knocked stuff over right where it stood and not to make a long range flat shooting slug the exact B.C. of that design has never been a huge concern to me personally.

[longbow]

According to the Lyman Black Powder Handbook, a 0.735" round ball has a BC of .104.

I found a Winchester Foster slug ballistics table on the internet but can't seem to access it now. If memory serves, the Foster slug was considerably lower ballistic coefficient than the ball.

That's the best I got for now.

Longbow

[nitro450exp]

Hello All,

Thanks for the info so far, Turbo I am sorry I butchered your screen name.
I was typing without aide of brain.

I was just hoping to have a rough number to plug into the calculator,
since I will be hunting in tight wooded conditions with a SXS and express iron sights, I will not be taking long shots.

I do like setting up all my guns and loads with a Max ordinate based on a 6" circle
I like to know near and far zero and well as max range, the calculator gets me close, as long as the inputs are close, then I follow up with an actual test with targets set up at the actual ranges.
For this experiment we are probably in the range of 70 ~ 100 yds.

Thanks
Nitro450exp