What to do with BLC-2?

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BarrelBurns

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CAUTION: The following post includes loading data beyond or not covered by 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.

Hey guys, looking for a bit of insight on a 55gr 5.56 load, here's the short version; Can't come by varget easily, though I'd still like to try it. I bought 4lbs of blc-2, started at 25gr, worked up to 28 (hornady 9th states 28.1 max for .223) 28.0gr produced considerably tighter groups with a small amount of flattening, no other signs of excessive pressure. It's cold here now, and I know blc-2 is temp sensitive. Should I chance loading more now, or work up again in summer? Here are the details-

55gr fmj bt w/c pulls (unknown make, weight and dimensions seem consistent)
FC brass, trimmed at 1.745"
S&B primer
28.0 BLC-2
1.255 oal (mid cannelure)
Light crimp

Shot from Sig 556 16"bbl 5.56 NATO chamber 7" twist

First time poster, lurked awhile. Thanks to those with more knowledge than me who have helped in the past.
 
It won't matter when you load it, just when you shoot it. If you develop the load for cold temperatures, then leave it for cold temperatures. This article on temperature affects is interesting. It concludes barrel temperature is actually more important than powder temperature.

A little primer flattening is normal for a maximum load. Be aware that in 1989, CCI reformulated their magnum SR primers specifically for the WCxxx line of St. Marks powders, which H335 and BL-C(2) are part of. The surface coatings on these old formulations from the 1960's are hard to light, so they heated them up and added some metal dust to make more sparks and so on. Nowadays I think most primers have hotter sparks, but note that the Russian made ones do not. I don't know about the Czech primers.

You can buy military sensitivity spec primers for added slamfire protection from CCI as CCI#41, which have that same magnum mix formulation, and Tulammo sells a NATO spec primer as KVB556M, which is magnum. There is also the newer Federal GM205MAR primer with military sensitivity spec for target loads, but it is not magnum and meant more for summer use with the usual array of stick powders, I think.

BL-C(2) is canister grade WC846, developed for 7.62 NATO ball ammo. When the military tried it in .223 with the 55 grain bullet, they didn't like the pressure characteristics for the gas gun. They found they needed something faster, so they tried a set-aside lot of WC846 that had proved to burn too fast for 7.62, and found it to be just right for the 5.56. They asked St. Marks to make them some more of the fast version on purpose (it was an accident of process the first time), but St. Marks didn't want to catalog two different burn rate powders with the same number, so they gave the faster version the designation WC844. H335 is canister grade WC844.

So, if you want best AR performance, you might want to switch to H335 for your current bullet weight and use the BL-C(2) for heavier bullets in the 223. You'll save almost 5 grains of powder per shot doing that. I've used BL-C(2) with 75 and 7 grain bullets and found it did fine with them.

62 grain FMJ's should like the slower powder better than the 55 does, too. They seem to be sold fairly frequently in bulk.
 
Wow. That's encyclopedic. Great info thanks. I will be working up a load with blc-2 and hornady 75gr bthp match. Good to know I have a decent powder. So the S&B primers may not ignite as well as others? I took to them after I found they cut my SD down. I should've mentioned I did warm up my barrel nicely before testing. And I let each round camp in the chamber for 15seconds or so. I'll just make up a few and re work in the summer.
 
I believe that a new powder is made for the 223. It is called Benchmark and it is suppose to be very temperature stable.
 
I didn't know until recently that benchmark was one of their "Xtreme" powders. Serves me right for not doing the footwork huh. I think I'll buy a pound, really like h4198 for 300blk.
 
I've been using BL-C(2) with 55gr bullets for a few years in the AR, seems to work well for me plus I've been able to find it over the last couple of years. H335 has just lately re-appeared on local shelves; I have had a couple of lbs on hand but not enough to support changing over. BL-C(2) is also usually a couple bucks cheaper per lb. I'm also shooting a 20" rifle if that matters. Most accurate loads are more in the 26.5 to 27.0 gr range for me, which also leaves room for temperature concerns if you have them.

I have only noticed temperature sensitivity with BL-C(2) in one load, the .204 Ruger which is loaded right at the maximum. In very hot weather, or with a round sitting in a hot chamber for a several minutes it can get a little sticky.
 
Good to know thanks. Is your chamber .223? I think I'll re evaluate the load keeping 27.5 my max. I ran it on quick load and at 28gr and 105* it starts to over pressure. Barrels are spendy for the Sig too, so I'm trying to keep that in mind as well, I try to keep my fun and funds in good balance
 
I believe that a new powder is made for the 223. It is called Benchmark and it is suppose to be very temperature stable.
Click to expand...

I have been using Benchmark for .223 for a few years now. It has given the best accuracy of any other powders I've tried in temperatures from 100F to -10F.

I also use it in .45/70.
 
The load I posted are for my 5.56 NATO chambers....I do have a .223 match chambered AR and that a bit too hot for it. One big clue with the AR for a hot load is a noticeable round ejector imprint on the base of fired brass, especially if it also shows brass wiping (from the bolt turning while the pressure is still high). Primer isn't always a reliable indicator as there is some variation in cup thickness between manufacturers.
 
I figured yours was 5.56 I know about the ejector impression, but haven't heard of brass wiping before. Is it noticed on the bolt face? Or does it smear the lettering on the headstamp?
 
Well both really, but I pay most attention to the headstamp of the brass. It starts with the round ejector impression and swipes a short arc on the base from there. The steel ejector can also have brass transfer on it.
 
I have not tried it in my AR but in my bolt action 1-9" 27gr of BLC2 with a 55gr hornady and Sierra Bullet it will put 5 rounds in a dime @100 yds. The 223 is not picky as far as I can tell. I have had awesome results with W748, Benchmark, H335, Varget, BLC2, CFE223, and 3031. My favorite so far for accuracy has been the BLC2, and Benchmark. My lever action 223 has a 1-12" twist that shoots 55gr bullets with 3031 avereges .70" 5 shot groups. I love my 223's they are fun to shoot for me and my kids and very accurate. Good luck with your loads!
 
Good to hear, thanks for the info. I loaded up a few 27.5 at different oal's to see if I can duplicate the 28.0 load. Thanks and good luck to you as well.
 
I'm using 27.5 grains of BL-C(2) under the Hornady 55 grain soft point in both my AR-15 (Colt 6920) and Mini-14. Out of the 16" barrel of the Colt this load chronographs at approximately 2950 FPS. I have no excess pressure signs from either rifle.
 
Nice! Your the closest to my load so far, how hot are your summers? I'll still be testing the 27.5, but man 28 was sweet. And I need all the help I can get. Thanks for taking the time.
 
Computer says that IF your cases are 1.759" long AND IF your cases hold 28.8 grains of water, AND IF the Hornady 55-gr FMJBT matches your bullets,


it's almost 1,000 PSI over SAAMI spec pressure

IF giving a velocity of about 3,030 fps.

Me, I'd never exceed that speed out of a 16" barrel with that powder/bullet combo.

All of my cases hold more than 28.8...

Using the above data, to stay within 98% of maximum pressure (which I believe no ammo plant does, not enough safety margin for the open market), you would have to back off to 27.7 gr and settle for 2,990 fps. See what a difference .3 gr of powder makes here? 40 fps.

That's at 60 F. It's predicted to bump up against the max pressure spec at 80 degrees, giving 3012 fps.

YMMV, of course.

I think you meant the OAL is 2.255 inch...
 
Thanks grump. You must have ran ql for .223. Run it again for 5.56 NATO. 58060psi at 28.0. (62366psi max) at 70* Yes 2.255oal. Sorry. My cases are 1.745" and hold 31.3gr h2o to overflow. Quick loads default temperature is 70* did you set yours to default at 60*? Id like to change my default to 90* for when I forget.
 
Our summers hit 100 degrees with a few days above that. My loads were developed and tested in 90+ degree weather for that reason. The largest increase I have seen in pressures was when ammo was left out in direct sun on hot days then fired. The jump in velocities (thus pressures) was pretty dramatic. But then that applies to all rounds, not just to BL-C(2) loads.
 
Over the years, I have used BLC2 with practically every .224 bullet weight and many different rifles and never could get really great groups.

With larger cases, I have found BLC2 is a great choice for accuracy.

I fully understand the issues with finding 335 and other great 223 powders thus like they say in the military; "Do the best with what you got" .
 
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