let's break this down.

[fiver]

it depends on what you want and the case size.
going 2 steps slower than the slowest jacketed powder usually works well for cast and for having a good case fill.

what happens is the slower powders provide more speed at the same velocity as the faster ones.
but as you go to slower and slower powders you still have the fill percentage but the pressure starts going the other direction as does the velocity.
on the other side of the coin just looking at the fastest powders available for the round gives the same max pressure but less gas volume.
these are generally good powders to reduce to get lower velocity's and pressure.
you can dial the faster powders back by 30% without any issues, this generally means a drop from say 2700 fps down to 2000 fps.
going to that area or even a little lower can show some velocity variations which would need a filler of sorts to trick the powder into thinking it is in another case size.
for example the filler makes the 308 think it is a 30-30.
now your using a 30-30 load to begin with.
if you read the earlier posts you'll see why the variations pop up from ignition inconsistency's.

one way around the problem is how it's generally dealt with.
you go to a lower amount of an even faster powder so that it is burning as the boolit starts moving, this makes the pressure rise kinda fluent with the primer popping off.
this works pretty well with a boolit seated out into the rifling giving some initial resistance, allowing the powder to burn completely within a very short distance of the boolits movement.
I'd describe it as a fairly sharp pressure rise, the boolit moves forward, it's pushed on briefly then the pressure drops off rapidly.

 

[freebullet]

I often make 3-4 batches of test loads. Each batch with different powders from fast to slow for the velocity range I've targeted.

In general I like to use the fastest burning powder that gives good performance for a given application. The reason- it uses less powder & gives the cleanest bore.

When targeting higher velocity slower powders have worked better for me. There is a point of diminishing returns where a case full won't give top velocity or clean burn. Sometimes slow for caliber powders won't give consistent performance when they are outside of their particular optimum burn pressure zone.

I love varget for example. It likes certain pressure zones though. Sometimes there is a middle ground where it just won't work well. When working above or even below a certain point it will work dandy. In that middle ground it won't work well, akin to using surplus in the wrong applications.

By making more test loads you get to shoot & learn more.

 

[KHornet]

Agree with Freebullet. However, for all practical purposes, when I am looking at HV in my loads to be about 2400-2450 max, and if I achieve that I am satisfied. When I make up test loads, I usually load 50 rounds with 10 each of the charges I am testing, and start at the low end and go up half a grain at a time. I shoot them in groups of 5, so I have for example 2 loads/groups of 5 each. This then gives me a start at least for comparison of accuracy potential, and probably the vols I am looking for. Then. if in that range I find what I am looking for accuracy/vol wise, I may do the old 5 ea 5 shot groups, and average.

For HV loads with slower burning powder, in med cap brass (7x57/308/06 etc) you can burn up a pretty fair amount of powder in the quest for accuracy. Also if I am looking for HV, I am probably looking for hunting vols in Med size cases, or for varmint loads in 22/6mm hases. With med brass, when I have accurate load, and I am going to load for deer for example, will probably go for a flat nose like 31141, with a Bruce B's nose. For the 22/6mm, will be looking for hard (22 Bh minimum), and hp'd . If I were smart, once I found that load, I would be happy and stop there. That said, am usually not that smart, and will try with a different powder to see if I can find an even better mouse trap. Regardless, as Freebullet says, "By making more test loads, you get to shoot and learn more". Shooting more is good, learning more is a bonus.

 

[Ian]

HV with cast is where the tricks come in. You're in a "tweener" zone, where full jacketed starting loads MAY be too hot (or not, depends), and the published cast data is way too slow and the powders way too fast. Like Fiver said you might have to use a bulky, slow powder and trick it into burning efficiently, sorta depends on how big the case is, how heavy the bullet, the expansion ratio, and how fast you're trying to get the bullet going.

One example is how I generally load for paper-jacketed bullets. Rule #1 is 100%+ density. Rule +2 is minimize jump by seating the bullet so there's as much pressure on the lands as possible without sticking the bullet in the throat when extracting a live round. Reason for this is the engraving force is pretty mild even compared to plain cast bullets, so the powder is difficult to light. Also, to fill the case as much as possible, I choose just about the slowest powder listed for a cartridge, sometimes a tick or two slower (helps with gentle launch and ultimate velocity), and that exacerbates problems with ignition consistency. I almost always end up topping off the powder charge with some sort of granular filler to make things nice and tight.

 

[KHornet]

Words of wisdom Ian. Have never used a filler with the slower burning powders, but will accept your experience. By granular filler, are you talking COW, or similar? And what about dac? For what I consider med cap brass, and per your recommendations, what would you think of AA4350. Have used Varget and H414 before when I wanted above the 1800 fps mark and have had good results up to an estimated 2200 fps range. On med cap cases would be using upper range of bullet weight for the cal. For small cap cases, would be using lower range of bullet weight (KHornet, 222, 223 etc). Thank you!

 

[Ian]

I'm talking about running Retumbo, H1000, WC872, and WW780 Supreme in things like the 6.5x55 and .270 Winchester behind heavy patched cast or plain cast bullets. Way slow powder for the cartridge. Gotta use HD filler for that such as COW, Puff-lon, and other cereal fillers (all caveats apply, I don't like it), BPI spherical shotshell buffer or preferably, the BPI granulated spherical polyethylene shotshell buffer.

Dacron is more indicated for "listed" slow powders for a cartridge when you want to go lighter with the charge weights and still get reliable, safe ignition, like running 38 grains of H-4350 in a .30-'06 behind medium-weight cast bullets (180 ish). Minimum load is around 39-40 grains for jacketed, but 38 gives about 1875 fps and stellar accuracy....IF you can just get it to ignite uniformly and consistently shot-to-shot and at different temperatures. 3/4 grain of Dacron lofted up in the case to keep the powder against the fire will make up the difference. I don't consider it safe to use granular fillers much below the shoulder/body junction of a bottleneck rifle case due to the obstruction it creates, which is more or less depending on expansion ratio and neck angle and which filler is used. Below the shoulder/body junction, Dacron is a better choice.

The .30-30 is an interesting bird because you can safely use several different powders in the 4350-4831 burn range at 100% density and no filler, you just won't get very high FPS.

 

[KHornet]

Thanks Ian, I wondered about reference to using gran fillers in bottle neck ctgs. I tried it way back in an O6, and (if I remember right 4831) got high pressure primers. Only loaded 5 of them, but was enough to show me that I didn't want to do any more. Then went to no fill, and dac fills, and got good accuracy with both, and 311284 and as far as I could at the time remember, little if any noticeable primer pressure. And yes, I agree that primers are an indication of pressure, but only that. Most definatellyi the powders you list are way slow for the ctgs you list. Have never loaded any of them, so will have to maybe consider trying one of them. Will try the 38 gr of H or AA4350 behind some 180-190 gr. Again thanks for the info.

 

[JWFilips]

The .30-30 is an interesting bird because you can safely use several different powders in the 4350-4831 burn range at 100% density and no filler, you just won't get very high FPS.

Ian,
I would like you to elaborate more on this is you will but do not want to muddy up this thread ( since what I'm asking is so specific) If you feel the same please PM me ( or what ever it is called here) if you wouldn't mind. If you feel it is noteworthy here that would be fine too....Just didn't want to drift this informative thread
Jim

 

[fiver]

34grs of 4831 under the 311041 [no filler] will push the boolit out at 1800+- fps [from a 20" carbine] and will burn clean, you can go up from there. [i'm usually in the 35gr range depending on where the dump stops]
it's an odd off the shelf load that actually works very well, I burn up that 'yard sale' and mil-surp 4831 this way.
it actually burns clean and shoots quiet [quiet enough to shoot indoors without going shell-shocked]
and it's accurate.

i'll make up a big batch of these this summer [4-500] to get rid of the old 4831 kicking around the place.
some of them will most likely go deer hunting this fall.

 

[Ian]

Jim, right here is the place, sorry I've been off but been very busy at work and home.

Fiver gave you a good load to start with, that's pretty much how I got rid of an old can of IMR 4831 that I wasn't going to use in anything else. Also, some of the WC powders (852 maybe?? I forget, but it's one of the 7.62 NATO powders, the sniper load one I think) are great for this. No kicker and no buffer required. The .30-30 case is very small for the caliber and bullet weights that it can accommodate and slow powders burn a little quicker in it than say a .308 Winchester, even with its taper and gentle shoulder. Study some of Lyman's loading data for .30-30 (both cast and jacketed) and you'll see a trend between velocity and pressure between starting jacketed loads and max cast loads listed with fastest jacketed powder and slowest cast powder. The info almost overlaps. You can jump right in with jacketed data for cast and go from there, and even extrapolate for powders more slow burning than listed. Make sure the case is at least 80% full of powder and that your load makes sense (cross-checked with other data like .303 British and .300 Savage) and you can just jump in with a load and chronograph and sorta work out data on your own.

 

[Barn]

I have tried some 7383 in my .30/30's. Loading data says to use same volume of 4831 or reduce 4831 weight by 15%. I played around with it until I got some good results. I came to two conclusions. First 190 grain cast worked better than 165 grain cast. Second best accuracy was where I had just a slight compression of the powder. Even with compressed loads and Winchester LR primers it did not burn very clean. You could look down the barrel and see a trail of powder bunnies.

I was approaching 1" at 100 yards with three different rifles. Best load was 29 grains of 7383 with a 190 grain cast bullet. 85% of fiver's 34 grains is 29 - how about that!

 

[Ian]

Yet another example of an improvement to burn efficiency yielding better accuracy. And right at 100% volume, or a touch more.

Seems pretty much universal that the slow powders light better when the kernels are forced to stay put and take the primer fire rather than blow around inside.

 

[freebullet]

I played with imr7383 in 3030 also. I did 3 batch tests from 80% fill to 105% with 160 gr bullets up to 30.7 gr. The velocity never exceeded 1850fps. I don't think you could go much higher with that powder. Accuracy for me fell off around 1700fps. In the 336 the incomplete burned powder would fall out when you rack the lever.
I haven't gotten around to doing same w/mag primers yet. My tests used win lrp.

 

[JWFilips]

fiver & Ian,
I'm sorry too ...been pre-occupied ( actually have been at work all week! So that is good news... not visiting here often enough ...well that is bad news)
Understand what both of you are telling me thank you... Another learning experience
I'm hanging in here at this thread for the long run
Jim

 

[fiver]

i'll get back with it when I get home.
I started in Gillette Wyoming this hitch and ended up in Odessa Tx.
I have switched from Day's to nights twice now.
and will probably make the swap over again this weekend, so my awake and sleep times are all over the map right now.

 

[fiver]

tested exact loads 3 different times now with just a change in a primer in the .223 case.
Just the primer change made almost 100 fps difference.

The slower round had less velocity spread between rounds.
2766 fps.
2764 fps.
2763 fps.
2769 fps.

Different Primer
2867 fps.
2850 fps.
2856 fps.
2824 fps.
Still another primer.
2834 fps.
2814 fps.
2829 fps
2804 fps.
2800 fps.

the primers were
the cci 550, 400, 450

 

[yodogsandman]

That's quite a difference for just a primer change! I'd guess that it would be hard to predict which one would produce the best ballistics, unless you had a lot of experience with a certain case and powder, too. You'd just have to try them all at some point in your testing. I've only considered primer changes when a problem arises, like inconsistent ignition. Even then, just switching from standard to magnum primers, I've always just used Winchester primers.

Which brings up another question. Do you have a standard set of testing procedures when loading a new cartridge to get to the best accuracy with HV? Or do you just let the rifle tell you which way to test. When do you try different primers? I've been first trying different powders, through their safe burning range for the cartridge first. Finding a fairly accurate powder amount and then I work on the overall length. When that's found, I go back to the powders. With so many powders to try, this is where I get stuck. Is this where different primers should be tried?

 

[fiver]

I do the same as you with a couple of different powders and oal changes but then try different primers at the end.
it's amazing to watch group size shrink [hopefully] even more when you put a different primer in the hole.
sometimes a primer change and a small powder weight change will get you the velocity and the accuracy.

anyway that test above shows why primers matter.

 

[yodogsandman]

Sure does! Did you bother to shoot for accuracy with those? Curious how the different primers affect groups.

 

[fiver]

I didn't shoot for accuracy with them I was more interested in the results.
I wanted the raw data more than the on paper holes which I thought could have been mis-leading.