BL-C(2) for .308 AR loads

[golfnutrlv]

Maybe this has come up before, but I cannot find any good information out there regarding BL-C(2) in an .308 AR....

Hodgdon's description of the powder seems to state it was meant for 308/7.62, and probably for a gas operated gun.

Is this powder even feasible for my needs? Is the burn rate a little too slow for a .308 Carbine?

Thoughts?

Rifle is a Sig Sauer 716 GAS PISTON rifle 16 inch barrel. Primary bullet wil be 150 FMJ-BT or similar.

Thanks all!!!

[golfnutrlv]

Does anyone have any info???

[Unclenick]

BL-(C)2 is cannister grade WC846, which has been the U.S. military's standard 7.62 NATO powder for decades. If your gun can shoot standard NATO ammunition, it will work with this powder.

Note that this powder is an older spherical powder formulation. The deterrent coatings used do not light as easily as some of the more modern sphericals, like Ramshot TAC. You will therefore want to use a magnum primer with it. CCI reformulated their magnum primers specifically for this older type of spherical propellant in 1989, and that is the priming mix they use in their #34 military sensitivity spec primer, which would be my choice for use with this powder in a gun with a floating firing pin.

Unclenick's Powder Matches from 2009 MSDS sheets (some newer ones lack the information).
This is current as of (04AUG12) as far as I know.  I'll add data as I encounter it and change the information ast need be.  Note that bulk grade versions have sloppier burn rate specs and can vary significantly from the cannister grades which are controlled for burn rate by blending with held back fast or slow lots, as needed to bring them in line.

    Cannister      | Bulk Grade |      Cannister         |Cannister |     Cannister        |
      Grade        |            |        Grade           |  Grade   |       Grade          |
                   | St. Marks  |                        |          |                      |
     Hodgdon       | Mil & OEM  |      Winchester        | Thales   |        IMR           |
___________________|__Numbers___|________________________|__(ADI)___|______________________|_
                   |            |                        |          |                      |
HP-38--------------|-- OBP231 --|- 231 ------------------|----------|----------------------|-
                   |   OBP124   |  AALite (WFL)          |          |                      |
Titewad            |   OBP132   |                        |          |                      |
Tightgroup --------|-- OBP242 --|------------------------|----------|----------------------|-
                   |   OBP465   |  Super-Handicap (WSH)  |          |                      |
Longshot           |   OBP473   |                        |          |                      |
Lil' Gun ----------|-- OBP516 --|------------------------|----------|----------------------|-
Hybrid 100V        |   SHP771   |                        |          |                      |
                   |   SMP224   |  AutoComp              |          |                      |
-------------------|--- WAA90 --|- WST ------------------|----------|----------------------|-
H110               |    WC296   |  296                   |          |                      |
HS-6               |    WC540   |  540                   |          |                      |
-------------------|--- WC748 --|- 748 ------------------|----------|----------------------|-
H414               |    WC760   |  760                   |          |                      |
H335               |    WC844   |                        |          |                      |
BL-C(2)------------|--- WC846 --|------------------------|----------|----------------------|-
H380               |    WC852   |                        |          |                      |
US869              |    WC869   |                        |          |                      |
-------------------|-- WMR780 --|- Supreme 780 ----------|----------|----------------------|-
                   |   WXC170   |  WSF                   |          |                      |
Clays              |            |                        |  AS30N   |                      |
International Clays|------------|------------------------|- AS50N --|----------------------|-
Universal Clays    |            |                        |  AP70N   |                      |
H4227              |            |                        |  AR2205  |IMR 4227 second source|
H4198 -------------|------------|------------------------|- AR2207 -|----------------------|-
Benchmark          |            |                        |   BM2    |                      |
H322               |            |                        |  AR2219  |                      |
-------------------|------------|------------------------|- AR2210 -|- IMR 8208 XBR -------|-
H4895              |            |                        |  AR2206H |                      |
Varget             |            |                        |  AR2208  |                      |
H4350 -------------|------------|------------------------|- AR2209 -|----------------------|-
H4831              |            |                        |  AR2213  |                      |
H4831SC            |            |                        | AR2213SC |                      |
H1000 -------------|------------|------------------------|- AR2217 -|----------------------|-
Retumbo            |            |                        |  AR2225  |                      |
H50BMG             |            |                        |  AR2218  |                      |
-------------------|------------|------------------------|- AR2215 -|IMR 4198 second source|
                   |            |                        |  AS25BP  |IMR Trail Boss        |

[Jimro]

This is a "similar" bullet.

150 GR. NOS BT
Hodgdon BL-C(2) .308" 2.800"
45.0 2661 40,200 CUP
48.0 2839 50,000 CUP

This is a less similar bullet.

150 GR. NOS E-TIP
Hodgdon BL-C(2) .308" 2.800"
43.7 2654 47,800 PSI
47.0 2868 60,100 PSI

Data source Hodgdon.

Mil spec for M59 Ball:

Bullet: 150.5 grain FMJ
Powder: 46 grains WC846 or 41 grains IMR 4475
Velocity = 2750 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton or clip pack - 5" mean radius @ 600 yards.

Mil spec for M80 Ball:

Bullet: 149 grain FMJ
Powder: 46 grains WC846, 41 grains IMR 4475, or 41.5 grains IMR 8138
Velocity = 2750 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton or clip pack - 5" mean radius @ 600 yards, link pack - 7.52" mean radius, max average at 600 yards.

Hope this helps.

Jimro

[golfnutrlv]

Thanks guys! I was more worried about the gas operated aspect, and whether it would be a kind choice for my rifle.

[Jimro]

A lot of M59 and M80 ball ammo has been fired through M14/M1As over the years. The burn rate is fine for those, plus the Garand as well.

I don't know it will work with your gas piston carbine, but if your carbine shoots milsurp M80 ball then I wouldn't worry about it. I don't see Sig putting out a rifle that wouldn't work well with milspec ammo.

Jimro

[Unclenick]

Jimro,

I'd be careful about citing the "military loads" that come from tech manuals as legitimate data. In this case it's OK, but only because they are in the middle of the Hodgdon load range for the canister grade of the powder. Since Hodgdon uses Winchester brass, which is roomy in .308, and the military uses Lake City brass, which is not roomy, the two grain difference is probably close to right for achieving Hodgdon's maximum load pressure in the military case. So it should still be safe.

Just be aware the tech manuals are merely reporting loads they think was one particular real lot, but these are not meant to be load recipe manuals, so that charge weight specification isn't edited very carefully.

For example, if you look at TM-43-0001-27, you find on page 5-9 that it says the M2 Ball cartridge (152 +0.0/-3.0 grain bullet) used 50 grains of IMR4895. Then on page 5-21 it says M72 Match ammo (174.5 +0.0/-3.0 grain bullet) also uses 50 grains of IMR4895. I have the actual M72 National Match lot loads for several years from a published table, and they were:

.30-06 National Match Ammunition
Year, IMR 4895 charge, manufacturer, velocity, and designation:

1957 48.0 grains FA 2640 fps (T291)
1958 48.0 grains FA 2640 fps (T291 switching to M72 in mid-year)
1959 48.0 grains FA 2640 fps (M72)
1960 48.0 grains FA 2640 fps (M72)
1961 48.5 grains FA 2640 fps (M72)
1962 48.1 grains LC 2685 fps (M72)
1963 46.7 grains LC 2695 fps (M72)
1964 46.0 grains LC 2669 fps (M72)
1965 46.5 grains LC 2708 fps (M72)
1966 47.2 grains LC 2711 fps (M72)

The FA ammunition apparently all used the same lot of 4895 except for 1961. The LC ammunition had different powder lots each year. They retuned the loads for pressure and accuracy each year the powder changed, and though the boxes all had "2640 fps" printed on them for all years of production, that number only held true for the FA ammunition. The LC ammo produced the velocities listed and note that the next-to-smallest charge weight (1965) produced the next-to-highest velocity. This indicates how the burn rate of the powder was changing by year. Using QuickLOAD to estimate burn rate difference, as compared to the IMR4895 default model in QuickLOAD which is close to what we buy off the shelf, the bulk grade IMR4895 in those loads appears to range from -2% slower to +13% faster.

If you ignore 1957 through 1959 (to avoid counting the same lot of powder more than once), the average charge for M72 was 47.3 grains, and not 50 grains, which it never was, and which is given by TM-43-0001-27. The canister grade powder sold to handloaders goes through extra process steps to keep its burn rate withing ±3%, so you can see the military load information represents data from lots too dissimilar to our own for load data developed with canister grade powder to be counted on to work reliably with it.

[Jimro]

That is excellent advice. I've heard that warning a couple times now, but so far for the 308 data it has all worked out to align quite reasonably with Hodgdon's data (when I started trying to replicate 118 Special Ball). I know that there errors happen, and that specifications change with time (as evidenced by all the primer, brass, powder, projectile changes over the course of 118 development).

Still good to bring up, and good to load to match velocities stated instead of matching a powder charge.

Jimro

[Unclenick]

Yikes! I forgot about your load duplication project. I started to compose a reply there that I never finished to give you some added bullet information. I'll find the thread and put it in.

Keep in mind with the TM loads what I mentioned about Hodgdon using Winchester brass for .308 testing, with its larger-than-military case capacity (in that chambering). At Hodgdon's site you click on the "Print" button to see what case, primer, barrel length and twist were used in their load development.

For more information on how the tech manuals editors messed with things, like substituting "psi" for their test lab's "CUP" units, take a read through board member FALPhil's article.

[Bart B.]

Other things about .30-06 and 7.62 match ammo's velocity. . . . .

First, the average velocity (at 78 feet) has to be 2640 fps for the '06 and 2550 for the 7.62. Both plus or minus 30 fps. This makes the loads have virtually the same ballistics down range so the sights on M1 and M14 service rifles will be able to use the same come ups from short to long range and be within 1/2 MOA of exact. I've heard that some issued lots' velocity was out of this range as Unclenick's post showed; why is beyond me.

Second, peak pressure has to be 50,000 CUP +/- about 2,500 CUP. As bullet, case, powder and primer lots vary a bit, the actual average charge weigh for different lots of loaded ammo may vary up to about grain or more across many lots of ammo. With the high speed powder measures used, it's amazing they hold charge weight spreads of 4895 to 4/10ths grain max; much less when they used ball powder in 7.62 ammo.

Third, accuracy specs for both call for a mean radius of the test groups' shot holes be no larger than 3.5 inches; about 10 inches extreme spread at 600 yards. National Match lots tyically were about 6 inches extreme spread and sometimes about 5 inches. They shoot a couple hundred bullets into a single group then plot and measure each shot hole's radius from group center. One lot of 7.62 NATO M118 match ammo (1966 LC12064) I and some others were issued would drop 2 or 3 bullets from a box of 20 about 2 feet low at 600 yards. How that lot got issued to the troops is obviously a boo-boo in Lake City's quality control. But humans work there and such animals have been known to make mistakes.

=========================

That article Unclenick linked to on the PSI versus CUP numbers for the .308/7.62 rounds by FALPhil is interesting to me. I was deeply involved in a discussion on that in the old rec.guns forum back in 1996.

[Jimro]

Unclenick,

Those magic CUP to PSI label changes have probably started more "308 Win isn't safe in a rifle marked 7.62" than any other reason.

It's like the old decimal error on the iron content of spinach. Spinach isn't rich in iron at all, but one guy publishes one mistake and people still believe it a century later.

Jimro

[golfnutrlv]

Thanks all for the replies. My plan is to try BL-C(2), Reloader 15, and CFE 223. I have a couple other powders to try as well.

Hopefully I can get a reliable and economical load out of one of them.

[Bart B.]

golfnutrlv, if you test each powder in loads with good techniques, betcha an ice cream cone that RE15 will give the best accuracy.

[Jimro]

Bart B.

I don't think his 16" upper is really designed for accuracy work. At least not at the ranges where an accuracy difference of fractions of an MOA would have meaningful use.

Jimro

[golfnutrlv]

For the record, this is a carbine, I am not looking for top accuracy. Just function, and economy.

[ncrypt]

Hi Gulfnut...I have the same rifle and had to pick up a can of BLC2. What load did you end up using for those 150 FMJ's ? I didn't find the minimum all that accurate.

[totalloser]

Work up the load per book description. If you aren't using a collet style crimper, I suggest using one, it helps in gas guns in general. I have found accuracy in all but one of my gas guns to be best with the loads a little towards the high side with my batch of blc-2.

I used BLC-2 for a few years before I sold my Socom (m1a) pushing 150 grain pills. I bought surplus BLC-2 to do double duty in .223/.308 and was very pleased with it. No scientific tests with the .308 loads, but seat of the pants says it was shooting more accurately than the open sight 2" groups I was getting out of my mini 14 in *ideal* circumstances.

Also, I was volume loading using mixed brass (7.62 nato and commercial .308) and so to keep it safe I was loading ALL for heavy military brass to prevent overpressure, so obviously significant improvement was possible.

Two last things: In my minis I found periodically cleaning the piston/op rod of gunk improved accuracy significantly, and my experience is much less than scientific. I mostly was blasting rocks apart at the range rather than scribbling in notebooks and reading chronographs, so keep that in context for my advice.