WC872 in 308 Report

M

Marco Califo

New member
CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

Actually, there is no published load data for WC872 in 308. But given certain known and published parameters, "I was able to get there from here."

More than one on-line reloading supplier carries WC872 at prices starting as low as $39 for 8 pounds - that is under $4.90 a pound! Wideners carries brand new, never loaded WC872 at that price. WC872's specific application is 20mm Vulcan Cannon. AA8700 data can be used, and I found it to be spot on when using Lee's PPM and volumetric data, checked with a scale.

All loads were in once-fired, sized and trimmed WRA 68 brass, with CCI #34 primers.

Load data was adapted from here: http://www.castpics.net/LoadData/Surplus/Datapages/308.htm

I understand that I am not allowed to post specific duplex loads data here, so I won't. Message me if you want specifics. Ambient Temp was 88 F.

First load tested was straight WC872 49 grains (moderately compressed) under 190 gr SP (blemished Hornadys I got from Midway). Five rounds all fired, somewhat shotgun boomish. Point of impact was 5" low at 50 yards in windy conditions (moving target). The point of these rounds was to identify a baseline for unburned powder and any residue. Yes, there was a trail of granules down the bore, but not what I would call sooty or messy.

Next, referencing the above link, I tested duplex loads. All remaining loads were with 175 grn FMJ. The link called for IMR 3031; I substituted 844, and tested 3 steps -0.5 grn., 0.0 grn delta, and +0.5 grn. All shot well with increasing accuracy (point of impact normalized by the last stage) with slightly less bore granules at each step. No signs of excess pressure.

Conclusions: Nope.
Observations and speculation:
1. Barrel temp remained very manageable. Reverting to standard 844 loads, barrel heated up.
2. Accuracy? Too early to say, but I think it was predictable.
3. No ka-booms were experienced.
4. Seems like WC872 could be used to extend conventional rifle powders, more economically, and at cooler barrel temps. I plan further tests in this direction.
 
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CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I've got quite a bit of WC872 in my basement right now. I've been using it in 6.5x55, 51 grains under a Nosler 140gr HPBT.

With the 308 case I'd expect that you wouldn't start seeing any signs of pressure until you got well north of 210 grain bullets, but I'd like to see someone's quickload calculations before I gave it a shot. The AA8700 data showed compressed loads for 30-06 with cast bullets, but I've run into limited data for jacketed.

Jimro
 
That is right. I did not find any info for jacket bullets. It is the cast bullets guys who had the only load data I could find. I am using jacketed and assuming it is close. I plan to try 220 grn RN, but have not bought any yet. Big bullet, moderate velocity seems like what 872 should be good for. That is also why 175 is the lightest bullet I am testing.

Jimro, Thanks! I found that in the 1999 Accurate 8700 load data.

I have also decided to try this with 223/5.56mm and 75 grn Hornady BTHP. Same drill.
 
Well, I found a copy of the 2003 Accurate Data for AA8700 which shows compressed loads in 30-06 for 220gr jacketed Sierra Round Nose bullets.

8700 (C) 55.8 1995 62.0 2168

The caveat is to reduce max charge by 2 grains for the 220gr HPBT Sierras.

Seems to me that since the 308's powder column is the same diameter as the 30-06 that a max charge of WC872 under a 220gr bullet would be relatively safe. Honestly I've been thinking about trying to swage down some 160gr 270 caliber bullets to 6.5mm to see if I can't get better ballistics from my swede (maybe even match the old sight ladder).

Jimro
 
Military BALL POWDER® Propellants listed in order of burn rate

From St. Marks Powders website:
"7121 Coastal Highway - Crawfordville, FL 32327 - (850)-577-2264 - Fax (850)-577-2263 - www.gd-ots.com - Approved for public release 5/21/1998
Powder Designation Cartridge
SPI Igniter Artillery
OBP® 126 .50 Cal. Blank M1A1
WC 814 5.56mm Blank M200
WC 818 7.62mm Blank M82
WC 815 60mm Mortar
WC 819 81mm Mortar
WPR® 260 5.56mm SRTA M862
WPR® 270 9mm NATO HPT
WPR® 289 9mm NATO M882
WPR® 293 9mm Subsonic
WC 687 7.62 X 39mm Ball
WC 815 60mm Mortar
WC 816 120mm Mortar Igniter Propellant
WC 864 MACS Igniter
WC 827 7.62mm SLAP M948, SLAP-Tracer M959
SMP® 842 5.56mm Non–toxic
WC 844 5.56mm Ball M193 & M855, Tracer M196
WC 844T 5.56mm Tracer M856
WCR® 845 5.56mm Ball M855, Tracer M856, M995
WC 846 7.62mm Ball M80, Tracer M62
WC 846S 7.62mm Ball M80, Tracer M62
WC 846 + CaCO3 7.62mm Ball M80
WC 750 7.62mm Match M118 & M82
WC 855 30mm AAH TP M788, HEDP M789
WC 856 .50 Cal. SLAP M903, SLAP-Tracer M962
WC 857 .50 Cal. Tracer M17
WC 858 20mm HPT M54
WC 859 20mm Phalanx MK149
WC 860 .50 Cal. Ball M33
WC 860 + CaCO3 .50 Cal. Ball M33
WC 863 120mm Mortar Main Charge
WC 866 20mm PIVAD M940
WC 867 20mm MPC PGU 28/B
WC 868 20mm Improved PGU 28/B
WC 869 25mm M910 TPDS-T
WC 872 20mm TP M55, HEI M56
WC 886 25mm M791 APDS-T
WC 886L 25mm M919
WC 890 25mm HEI-T M792, TP-T M793
WC 891 25mm API PGU 20/U
WC 895 30mm GAU/8A TP PGU15, API PGU14, AIPGU13
SMP® 992 155mm MACS Decoppering"

Curiously, they do not list WC 820 available at http://www.gibrass.com/gunpowder.html
WC820 Orignal application is for the U.S. Cal. .30 Carbine Ball M1 round. This lot loads at 13.5gr with 110gr FMJ projectile. This is a ball powder
which can be loaded using Accurate #9 data; be sure to begin with starting loads. Ideal for .410 shotgun and .357 & .44 Magnums. This is pulldown ball powder. $80/8# jug.

WC820n Brand new, virgin powder. Orignal application is for the U.S. Cal. .30 Carbine Ball M1 round. This lot loads at 14gr with 110gr FMJ projectile. A ball powder which can be loaded using Hodgdon H110 data.
This is new ball powder. $100/8# jug.
 
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I am pretty familiar with reloading terminology but am amiss as to what the term duplex loads means?
 
A duplex load is one where two powders are loaded into the case, generally a slow powder is loaded first, with a faster powder on top (at least that is how I remember Ackley writing about it). The theory is that the slow powder will push the bullet down the bore a bit and expand the effective case capacity for combustion when the fast powder kicks in and keeps pressures high for a bit longer. This method was designed to get past the "performance plateau" of "more isn't always better" when it comes to powder charges (sometimes adding powder does not add to velocity in a linear pattern, sometimes it tapers off or "plateaus").

With an ultra slow powder like 872, some folks are going the opposite route and using a fast powder to augment the primer in building initial pressure. I haven't found any "hard and fast" rules with how they do this, but reports go anywhere from a few grains, to 5% of the total charge weight. So it ends up fast powder on the bottom, slow powder on top.

In theory, a compressed load will prevent the powders from mixing due to normal handling.

Jimro
 
WC872 in 223

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

Once again, just as with 308, there is no published data for 872 in 223.
Today I loaded and tested some 223 using WC872 surplus powder. Once-fired LC brass, CCI #41 primers, Hornady 75 gr HPBT. This test started with WC872 at 100% case capacity, not compressed. Then each successive step was one less grain 872 and one additional grain WC844 (at the primer). I used my scale for the 844 portions, and Lee PPM for the 872, measured by volume using the AA8700 factor I found to be useable. I loaded ten of these steps until I was at 38% 844 underneath 62% 872. I only loaded one of each step, and two of straight 872. My intention was to start with the straight 872, examine each fired case carefully, and abort the test at the first clear sign of excess pressure. I was looking for where a pressure spike would happen. I do know what excess pressure looks like in this bullet and cartridge, and I had some of these fired cases (flattened and micro perforated) for comparison, and also 10 more live of that same load.
So, I fired all 10, slowly and examining the case each time. Step #9 flattened the primer but #10 did not. I think #9 may have been loader error (might have had a little more powder, I caught my self muffing a couple I had to dump out and remeasure). I also grabbed the barrel after each shot, because my 844 loads heat the barrel more quickly than I like. Heat was not a problem with these loads.
This test appears to indicate that up to 25% 844, underneath 872 is safe. Steps 7-10 will be repeated, at 1/2 grain increments to recreate or disprove the #9 issue.

My next question/test will be mixing, rather than stacking these two powders, and see how/if that behaves differently, and if I can find an accurate load that uses mostly 872 and burns cooler than 844.

I should add that these tests (308 & 223) were all using Savage bolt action rifles and I do NOT think 872 will have application in gas operated guns, due to the slow burning speed granules of partially burned powder could get into the gas system. Also gas systems work best within a specific pressure band at the gas port.
 
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WC 872 is to slow for the 308. I can load a case full in the 6-284 with 70 gr. bullets and get lower velocities than with faster burnning powders. I bought 96 lbs. of it, and while it does a fairly good job in my 224 TTH, I going to build a 6mm - 300 WSM with a 30 in barrel to make full use of this slow powder.
 
Catfish, You are correct that WC872 (by itself) is not suitable for 308, because it burns too slowly. I don't know if you noticed in the previous posts, but this thread is about using Duplex loads: more than one powder in the same load. Hence the obligatory warning in bold.

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

The theory and proven practice involves, for example, two powders, one main charge and a smaller igniter charge (at the primer). Then full case capacity is used to minimize mixing. This has made these very slow powders useful for cast bullet shooters http://www.castpics.net/default.html who have published certain data there.
I am performing some experiments based on published practice to try to identify other useful uses for this very slow, very cool burning, and very inexpensive powder. Specifically, I have tested duplex loads in 308 and 223. I have not found a perfect load yet for either, so far a heavy igniter of WC844 under WC872 in 223 with 75 grn bullets has worked best by far.
 
Interesting..........

Thanks Marco.............please keep posting your reports. I am very curious about duplex loads also, particularly with WC872
 
WC 872

Any further tests and reports yet Marco? I am working away from home for several months but intend to start on similar tests myself when i make it home. I have 48# of this ready to go!
 
I have been busy, too. I hope to post an update by the end of this month on 308 190 grn JSP and varying proportion stacks of WC844 under WC872.
 
"Shooting duplex loads is Russian Roulette on the shooting range."

The above's a quote I got years ago from a Remington/DuPont rep regarding their IMR powders. He said he first heard it from a Winchester/Western rep at a firearms and ammo convention.
 
WC892

I have been using WC872 now for a year or so....in 308, 7.62x54R and 303 Brit. I have been using a kicker of either Red Dot, or IMR4227 or Unique with the balance of a compressed load of WC872. This works very well, leaves NO unburned granules and is also VERY accurate with a Lee Cast boolit (185gr) at 100yds. I went up to 7gr of kicker but finally settled at 5gr as best. I still have 47lbs of WC872 to burn through yet!
 
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