So I have been working hard to find a good load with BL-C(2) and 39 BK's, and havn't had much luck. For one thing, I get definite signs of pressure (sticky bolt, cratered primers) if I load much above minimum (28 grains). I tested a bunch of loads at 28 grains this weekend with various seating depths and tightened my groups from all over the paper to nice neat vertical strings, some longer than others depending on when I shot them. At one point today I started seeing pressure signs with my loads even though they are at the minimum charge . I have been keeping my rounds in the shade, but thought I would try puting them in an ice-filled cooler as it has been in the 80's and sunny here in VT. The next 10 shot groups I shot actually GROUPED! I didn't measure, but they were under 2 inches and NOT vertically strung. And my rounds showed no pressure signs. my question is are all powders this sensitive? should I try a different powder? This gun can shoot factory ammo into half an inch usually, so I know I can find a good load. I am fairly new to rifle reloading so any help would be greatly appreciated.
I haven't used BL-C (2) with Sie 39gr BKs,but I have loaded a good bit with the 32 gr Sie in my 204 ruger,with good results ,up to 30grs.For temperature considerations I switched to IMR 8208 XBR (the least sensitive powder available)with the 32 gr Sie and 28.5 gr of the XBR I have sub 1/2" groups without excessive pressure,out of my G2 Contender(4000fps).I intend to load it for my 39gr Sie as well.Pours great,and burns clean.
Neil, I have used about 2/3 pound of BLC 2 for 204 loads and haven't had any pressure signs yet. I have loaded all of the way to max recommended load, and even went over by .1 grain. All of the loads used either CCI-450, CCI BR4, or Rem. 7-1/2 primers. Any load in my Savage model 12 will show some cratering around the firing pin because the firing pin hole in the bolt is large creating extra clearance, but so far even with published maximum+ loads the primer flattening is very minimal. In fact, I'm not sure the case will hold enough BLC 2 or 8208 powder to flatten a good primer, although I'm not going to keep working up high enough to find out. My brother has a Rugger M77 that will flatten them at high charges. I haven't worked with the BLC 2 enough yet to say I have found the absolute best recipe yet, but what I did see is it had good potential as I shot some groups where 4 were in the .1xx" range with a small flier.
Mostly I too have been working with the IMR 8208 XBR powder, and it shows good accuracy potential as well. Any of the good powders for a 204 type cartridge should be capable of decent accuracy, some may be better if you are shooting for the absolute best groups, but I doubt changing to a different powder will make large improvements. Having said that, it wouldn't hurt to try another powder. To find the best load with any powder and bullet combination takes some work and cost money for components, so if you have several powders and bullets, the possible combinations get to be large and you could just get lost if you don't methodically work through each powder for the best charge.
You say you are fairly new to reloading, so I'll offer some general advise. First, consistency in your process is vital. Be absolutely sure your scale is calibrated and your powder charges in each test batch is accurate. Do you have a standard for your scale? If not, the bullets have are most likely within + or - .1 grain of 32 or 39 grains, and could help to determine if your scale is off. The neck tension needs to be consistent, so your sizing routine can affect accuracy. Be sure the primers are seated completely. I don't know how deep you are seating you bullets in the case, but for now I would recommend seating them between 2.25" - 2.3" and when you get a good basic load down you can play with seating depth to fine tune it.
If you would describe your process and equipment used it would help for other people to see where you might need improvement. Also, some good clear pictures of the primers would help a lot. The cratered primers alone may not be so bad, and the sticky bolt could be because the case should needs to be bumped back further. Of course, it could be because the pressure is too high, and since there is a safety concern it pays to be careful. What primers are you using? I doubt that a minimum load of BLC 2 would be so sensitive to heat it would show such a wide swing. I would venture to say either the powder charge is higher than you think, the pressure signs aren't really too excessive, or there is something unusual with the chamber/barrel. You need to get your pressure issues worked out, and then you can concentrate on loads and methods to meet your accuracy goal. Your rifle should shoot pretty well if you can get 1/2" groups already with factory ammo.
M_D, thanks for the detailed input. I'll give some more info on my equipment and methods. The rifle is a savage 12 fv, with about 150 rounds through it. I have been tumbling hornady brass in corn cob media, neck sizing with a lee neck sizing die (using the recommended double size method for best concentricity ), trim to length of shortest cartridge and chamfer + debur (only did this once), clean primer pockets, then gently wash the brass in soapy water to remove any oil or dirt and let dry overnight with a fan. primers are Remington 7 1/2, seated at or just below flush. I have two scales, a lyman balance and a cheap Frankford Arsenal digital. Tested against each other they show almost the exact same load, but I have been using the balance type because it just seems more reliable and I trickle every charge with a redding powder trickler. I then seat the bullets with a lee seater and they appear to be seating true. I have tried a few seating depths, but now I believe that should be a last step? Also, I have fired this brass 3-4 times now and am going to try full length sizing then annealing tonight. You could be right that the sticky bolt may be due to the shoulder needing to be bumped back. Do you have any suggestions? I really try to load the most consistent rounds I can but I do lack experience so any help would be great.
There was a thread not too long ago with pictures of primers that might be informative for you, it needs to be determined if your pressure signs are real or false alarms. The cases grow with each shot and will start to get tight, some sooner than others. Also, full length sizing dies sometimes will not bump the shoulder back quite as far as others. Then you have different chambers. So, occassionaly due to tolerances it may be that a "full length" size will be just a tad snug yet. If a cartridge chambers with some drag and then after it is fired has similar drag when opening the bolt it is different than a cartridge that chambers easily and is significantly tighter after firing. Although extreme, some times I have seen bolts that had to be pounded open (not good usually). Neil, I don't have much time at the moment so I'll post a little more latter.
Neil, I have a Savage 12 VL. All the .204 12s have a tendency to crater primers at "normal" pressures. It's because the firing pin hole in the bolt face is excessively large in relation to the firing pin. In my gun, even factory loads crater. I WS2-coat my .204 bullets, which reduces chamber pressure about 2K psi and I still get cratering a full grain below published max loads. Basically, you have to use primer flattening as a gauge. If the shoulders are still rounded and there's no sticky bolt, you're probably all right.
BL-C(2) is known to be pretty temperature sensitive, moreso than most. My original .204 load was BL-C(2) but I picked up a little accuracy by switching to RL-10X.
But 10x also is a touch temperature sensitive, too. When it's 90°-ish, my RL-10x loads were picking up ~150 fps and the groups ballooned to about double their usual size. They probably also had dangerously high pressures. On hot days, now I carry my bullets in a soft-sided lunch bucket with a couple of packets of blue ice. I have to wipe the sweat off the bullets first but they shoot much better that way.
FWIW, I do load development by Optimum Barrel Time. I'll skip the long-winded OBT explanation but if your barrel is 26", OBT says your best accuracy will be at 28.0 grains. That should give you about 3765 fps and a shade over 57K psi PMax. That's at 70°F so if your bullets get 90°-ish, they'll be too hot in more ways than one.
well I checked some of my brass today in my chamber and they indeed went in tight. I took out my new redding full length sizer and ran 10 pieces through with Imperial sizing wax as far as they could go. I have never full length sized rifle brass and I had some dents form in the shoulder (too much lube?) and had one neck crack (time to anneal?). the brass went into my chamber just as easy as factory ammo. I was short on time but I loaded one round with 28.4 grains of BL-C(2) and fired it. It showed no pressure signs or cracking. I will do more testing this weekend. Thank you for your replies and keep the suggestions coming .
. I have been keeping my rounds in the shade, but thought I would try puting them in an ice-filled cooler as it has been in the 80's and sunny here in VT. The next 10 shot groups I shot actually GROUPED! I didn't measure, but they were under 2 inches and NOT vertically strung. And my rounds showed no pressure signs. my question is are all powders this sensitive? should I try a different powder? This gun can shoot factory ammo into half an inch usually, so I know I can find a good load. I am fairly new to rifle reloading so any help would be greatly appreciated. 
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