Ballistic Coefficient Lyman 525 Slug?

[zardoz]

After some searching here, and Google searches, I have come up empty
on this.

Last week I finally got my Lyman 525 grain sabot slug and handles in (after eternity backorder wait), and immediately cast some up. I then loaded them up, and did some initial charges with 41 grains Blue Dot in Remington 2 3/4" hulls.

I had good accuracy at 25 yards, with a 20" fully rifled slug barrel on a Remington 870 gun. Two holes even overlapped, which is a fluke I think, given my myopic, astigmatic vision these days.

This is the slug that looks like the big air rifle pellet. Would anybody here have an idea of what the ballistic coefficient is on this slug?

Thanks.

[yondering]

Should be about the same ballistic coefficient as a brick, give or take a little. [smilie=1:

I like this slug, but it's really not intended for long range use where you would need to know the ballistic coefficient.

Some bench testing should tell you what you need to know, as to trajectory and velocity. You could even measure the velocity out at the 50 yard target, or however far you plan to shoot them, if you feel the need.

[eye shot]

Don't know what the BC is, but that slug can be very accurate out to 100yd. I can get under 3" at 100 and one ragged hole at 50. With a BDC scope I got a 6" three shot group at 176 paces and they hit straite on no key holes. The only thing was getting the wads to stay together in my USH. My Hastings barrel guns did better.

[zardoz]

I tried to run the formula for bullet ballistic coefficient, and kept getting ridiculous numbers.

B.C.= M/(i X (d^2))

M=mass in kilograms
i=drag coefficient
d=caliber (meters diameter)

Used 17.55 millimeters unit converted to .01755 meters as d

Used 525 grains converted to .03402 kilograms as M

i was from a webpage for general Foster type slugs, or drag coefficient of 0.109 which seemed pretty "brick-like". Close enough to estimate I thought.

I'm doing something wrong there, but I note that the Lee 38 caliber full wadcutters have a B.C. of .072, so I was looking for a number between that and .283 which is the B.C. of the 515 grain 50-70 flatnose Lee sells. My numbers were way higher than that from the above formula.

Anybody spot what I doing wrong there?

I found this webpage, which had some interesting statements.

http://www.frfrogspad.com/extbal2.htm#Shotgun

Quoted from that page, "Using a shotgun and slugs with a good set of sights one can completely control their environment with a 125 yard radius."

Sounds pretty ominous. The statements on that page support your assertions there eye shot.

Academic fascination more than anything, but there is an inherent power in magnum loads driving heavy slugs out of the 12 gauge, that seems gut awesome.

[turbo1889]

I just modified the dimensions of a 44-cal hollow-base, full wadcutter in a ballistic calc. program tailored towards big bore revolvers to make it 68-caliber with a weight of 525gr. and the system spit out three different BC for three different velocity ranges:

BC Sub-Sonic ( V <= 1000fps) = 0.11
BC Trans-Sonic ( 1,000fps < V < 1,200fps) = 0.09
BC Super-Sonic ( 1,200fps < V ) = 0.13

Granted that's not a perfect system or comparison (slugs and big bore handgun bullets are about as close as a comparison as it gets though). The fact that the Lyman slug is wasp waisted and the bullet I modified is not that could have thrown the numbers off at least a little but that is what it spit out. Also did a similar modification of an existing short stubby round-nose bullet in the program to estimate some numbers for the Lee 1-oz. slug:

BC Sub-Sonic ( V <= 1000fps) = 0.13
BC Trans-Sonic ( 1,000fps < V < 1,200fps) = 0.12
BC Super-Sonic ( 1,200fps < V ) = 0.10

[zardoz]

Thanks Turbo1889:

Those numbers look reasonably close to what I "guesstimated" they should be.