Winchester 55 FMJ's

[D.Hayden]

I'm trying to find out what the Ballistics Coefficient is for the Winchester cheap stuff. They list it for the loaded ammo, but not the components. Anybody know it?

Just trying to see what to plug into the calculator.

Winchester (55 FMJBT)

From thier loaded ammo:

Product Symbol: USA223R1F

Ballistic Coefficient: 0.255

From Midway:

Sectional Density: .157

Ballistic Coefficient: .148

.148 seems pretty low for this bullet, compared to the Hornady. At 100 yards, it shoot great, I just want to calculate drops at 300-500.

As a check, Midway matches Hornady's site

Hornady (55 FMJBT)

From Hornady:

Ballistics Coefficient 0.243

Sectional Density 0.157

From Midway:

Sectional Density:.157

Ballistic Coefficient:.243

Thanks.. Dave

[ErikW]

I always used .255 (G1 model).

[George]

Anything from .225 to .255 is gonna be close enough for government work. Most 55 grain FMJ’s are about .240 to .250 for the G1 BC

If it is a flat base projectile, use the G1 data as is. If it’s a boat tail convert it to G5 which will take a .255 BC down to .160

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Regards,

[D.Hayden]

Thanks!

I don't understand the G-1 vs G5, but I have the books out. Pistols are so much easier...

[George]

Basically, if it’s a 55gr FMJ with a flat base, then plug in .255 as the BC and if it’s a boat tail then plug in .160 as the BC and you will be good enough to go.

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Regards,

[ErikW]

Hmm, I don't know about mixing and matching ballistic coefficients with different drag models. Doesn't the ballistic calculator use a specific model? Like I said, I don't know, it's above my head.

[George]

Whatever BC you plug into a calculator, the result “should” be correct if the drag model is correct for the projectile. G1 for flat base and G5 for boat tail.

Most FMJ ball and a lot of 52 and 55 gr match projectiles are flat base so the G1 BC drag model generally available is correct there. Projectiles like match grade SMK 69 through 80’s and even the Hornady bulk FMJ’s with the boat tail and the exposed lead base are best modeled with G5 corrected BC data. G5 corrected BC’s are generally around 30-35% lower than the G1 BC. I do not know why mfgr’s even publish G1 BC’s for boat tail projectiles, but they do.

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Regards,

[D.Hayden]

I don't understand it, but works out close enough..

G1 @ .243 drop at 500yds: 66.8

G5 @ .170 drop at 500yds: 62.0 (~60% of .243)

G5 @ .160 drop at 500yds: 65.0 (~65% of .243)

Thanks George...

[D.Hayden]

I emailed Winchester... got this back:

The BC is .255.

[George]

yeah, it is, but that will not work out on the target face anywhere beyond 250 yards. At 300 plus the G5 data is what will pan out closer, or right on. Guaranteed!

Example, 135gr .277“ diameter Sierra Match King in my MOR rifle. Sighted in at 200 yards at sea level. Took the G5 drag model corrected BC, ran it and compared it to the G1. It was over 22 inches different at 600 yards. Used the G5 data at 7000 feet elevation in Raton last year and got a 1st round hit on a 640 yard steel plate. G1 would have been a first round mike. Nuff said.

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Regards,

[D.Hayden]

Just posted that as an FYI...

My plan is to use them for < 200yd stuff... I'm just too cheap to use the good stuff... I need to get over that.

At A2 I used the Hornady 55's maybe not much better, but worked all the way out for me..

[George]

I use the Hornady’s too for my 1:9 Limited/backup AR. They are absolutely fine for 3 gunning out to 350+ and they should hold MOA in most well setup AR’s. I tried a couple hundred of the WW 55gr FMJBT’s a while back and they were pretty much the same as the Hornady for me over WW 748 (27.5gr @ 2.225” OAL).

I think the bulk Hornady/WW 55gr FMJBT are a fine choice as primary 3 gun AR ammo if your barrel prints them MOA. I wouldn’t push them real, real hot (over say 3100 fps) and with the exposed lead base they do shoot a little grungier than a match grade HP with the jacketing wrapped from the rear.

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Regards,