stabilizing cast boolits

[looseprojectile]

I am begining to see a pattern here.
I figure I am near the same place in time as chargar, in that I have shot mostly cast in pistols for the last fifty years.
I only have one .30 cal. mold, a Lyman 311 41 which produces a hair over .311 boolits. I have shot some very good groups out of the 94 Win. carbine, sized to .309 .
I am now going to try the same boolit, unsized in a 1909 Arg. cavalry carbine that shoots as well as a target rifle with .312 dia. J word projectiles.
Now comes a question. How does boolit weight, velocity and twist relate to stability of boolits? I suspect that if fired at very slow speeds most CBs might not stabilize.
I am interested in loads that will be accurate,[ can be low velocity], and some higher power loads for hunting deer and pigs.
I understand that the powder charge weight relates to velocity and mostly we start light and add a little until a good group appears. Are we, at this point seeing the boolit starting to stabilize?
I know there are lots of other variables such as barrel harmonics that influence accuracy . Am I just being too nit picky?
Happy shooting

[buck1]

Bass could answer this much better than I. Watch for his reply ....Buck

[44man]

The same thing should hold true for cast as it does with jacketed. Rifling twist, boolit bearing surface and velocity to stabilize. In other words, if you want to shoot a cast boolit out of a certain twist at a certain velocity, you must match the bearing surface (length of boolit) to get stability.
If you are shooting a jacketed bullet at 3000 fps, do not expect the same weight and length cast boolit to shoot good at 1200 fps.
If you want light plinking loads and heavy hunting loads, you need two different boolits.

[looseprojectile]

The real reason for my post is ------
I had good groups, [1.5"@ 50 yds.] with 19.5 grains of XMR 5744 behind the straight lino. 176 grain 311 41 GC in the Win. 94 carbine.
Same boolit same powder and weight in 7.5X55 swiss with a perfect bore gives 4" groups and flyers at 50 yards. I'll work up to to 22 grains of same powder same boolit for the K 31. Also will be on the lookout for some additional 30 cal. molds.
Thanks for your input.
Happy shooting

[sundog]

Loosey, first, welcome aboard. Y'all sure y'all wanna be here? Yer name fits in good, because this here is a loose bunch. They play'em loose, too. As a matter of fact, they's a few of them what's got screw loose. Don't think we got any loose women runnin' about though. And better not be any loose boolits....

Twist is velocity times 720 divided by twist. In a rifle keep'em below 130K as a general rule, unless your make'm hard somehow. The twist has everything to do with how long a boolit you shoot, faster the twist, longer the boolit, slower the twist, shorter the boolit. For example, a 311299 might be good in a 10 twist 30 bbl, and a 308-165-SIL might be good in a 12 twist bbl. Doesn't make any difference whether it's a 30-06, .308, or any other 30 bore. That said, bigger boolits generally do better in bigger cases and vice versa. However, with cast boolits, you generally wind up with empty powder space in the case, so a smaller sized cartridge would be nice, but it doesn't always work out that way. Try shooting cast in, say, a 7 mag. You can, but it's a challenge. Same with an issue Swede because of it's 7.5 twist barrel, or a 3589 in a 16 twist. It's kinda like Harry Calahan (Clint Eastwood in 'Dirty Harry') said, "Ya gotta know yer limitations."

Slug your bore and try to get a thou or two over. Find a boolit length (relates somewhat to what) to fit you twist. Also need to find a diameter which will fill the throat. In the old milsurps, this can be a challenge.

And then, y'all gotta find a powder what will handle it.

Welcome to the world of cast boolits. It never fails to thrill me when folks at the range look at my targets, and say something like, "you were shooting cast bullets?" sundog


oh, a little add on here. Sometimes I look at my targets wonder why I bother....

[Bass Ackward]

I am begining to see a pattern here.

I know there are lots of other variables such as barrel harmonics that influence accuracy . Am I just being too nit picky?
Happy shooting


Loosy,

Stability is achieved in nice round holes. Once you have round holes, look for some other solution to accuracy than stability. Corky and 44 gave you solid guidance on basics. But this Cast Boolits board demonstrates that patterns are not always easily found.

Some accuracy levels are more than the mechanicals of your rifle. Bullet hardness is an example. There is a theory that top accuracy occurs just before the hardness / lube combination leads. This means you have achieved balance in your bore condition. (blackbore) So if you want to shoot slow, try to go soft.

Bullet design can play a big part also. If the entire length of your bullet pulls it's own weight, you will have a higher velocity potential than one that doesn't. Or you can use softer bullets at the same velocity level than one that doesn't. Many ways to say the same thing.

Solid fillers can help even when you don't have enough rifling if circumstances can allow it's use. But you will need to learn all this by caliber.

How well the mechanicals turn out in your rifle and the strength of your chosen bullet design will be the big factors in your quest since you mention hunting. But difference in guns is why one guy can shoot exactly the same thing dead soft that some else might need lino to achieve.

Beyond this simple reply, accuracy is what and where it is. Dwell on it if you like, just don't take it so seriously that you forget to have fun with the journey.

[Wayne Smith]

Loosy,


Solid fillers can help even when you don't have enough rifling if circumstances can allow it's use. But you will need to learn all this by caliber.



Huh?? You lost me on that one. I was following along fine until then. Not enough rifling depth?, length?, and how do fillers compensate?

[sundog]

There's also something that I call 'accuracy gates' that you pass through many of which occur at some interval to be determined by your combination of variables. Felix says intervals of roughly 300 fps, e.g., 1500, 1800, 2100, and so on. I have several rifle and load combinations with which I cannot dispute this. And, of course, the transition from sonic to subsonic has a very determined affect on accuracy. I'm no ballistician, and don't play one on TV, but some of this stuff can be witnessed in everyday trials called load development. On some other boards I've seen discussions of 'laddering', and it appears to me to be a highly organized method of determining a sweet spot, which is not much more than consistently launching boolits which are very stabilized. Our own Sailman espouse 20 rounds groups to establish norms. Either way, there is more than one method to determine if a boolit is stable, which to me equates to accuracy. I guess you could have stable boolits that are not accurate, but what worth would they have?

Now, if you want to talk about slow, check with the single shot fellers. MVs in the 1000-1200 range and 200 yard groups in the stick your finger in the hole range - well, maybe not quite that small, but certainly many groups way under MOA. And that's with plain base boolits, too. Of course, just about all those rigs are multi thousand dolla setups with top notch sighting devices and excellent bbls and triggers.

Lots of variable to play with. Just letting my mind meander while having my morning java.... sundog

[Bass Ackward]

Huh?? You lost me on that one. I was following along fine until then. Not enough rifling depth?, length?, and how do fillers compensate?


Wayne,

Yea. Jack, 30wcf, reported about solid filler like poly shot buffer working in a bore that had rifling height so worn that portions of were gone and it enabled him to group fairly well. Search for "Fillers? In Pistol Cases"

[David R]

Sundog's accuracy gates.

I did some load testing. I have a 22-250 that shot 18 grains of SR4759 really well at 2684 av. 1" 10 shot groups at 100 yards. I bought some surplus 4895 to try. I ran out of 4759, so I tried the 4895. I loaded 10 rounds of 20, 22, 24..... I crony'ed those loads. When I got to 26, the ES and SD were way down. After a bunch of shooting groups, I ended up using 26 grains as it shot the most accurate and had an av of almost 2600. This is what Sundog is talking about laddering, I think. I also had another low SD and ES at 3200, but never explored that one. I did another test to see if I could lead the barel of my 32-20 with pure tin boolits. The test showed tin doesn't lead any more than pure wheel weights or #2 alloy. I did see a sweet spot where the ES and SD went way down using WC820. I bet that that will be the accuracy load. I have not tested it YET, but will.

David

[Larry Gibson]

looseprojectile

"I had good groups, [1.5"@ 50 yds.] with 19.5 grains of XMR 5744 behind the straight lino. 176 grain 311 41 GC in the Win. 94 carbine. Same boolit same powder and weight in 7.5X55 swiss with a perfect bore gives 4" groups and flyers at 50 yards."

I've found 5744 to be a good powder with cast bullets in certain bottle necked cartridges. However it is usually with heavier than normal cast bullets. The 30-30 load was about right but with that light of a bullet in the 7.5 (almost '06 capacity) the 5744 powder was not burning efficiently. I'd say that was your accuracy problem, not the stability of the bullet. With 5744 and the 176 gr bullet by the time you get the powder to burn efficiently you will probably be driving it to fast for very good accuracy. The lightest .30 bullet I have got to shoot well in the '06 with 5744 is the Lee 312-185 and that is with 26 gr of 5744. It runs 1876 out of 24" barrels. Any less powder and accuracy goes, any more and it goes to. A firend of mine likewise found in his K31 that with 5744 it too a heavy bullet like 311299 to make the 5744 burn efficiently at 1800 fps or so.

As to stability and accuracy I agree with the max RPM concept. Take a cast bullet much over 130-140,000 rpm and accuracy will fall off. Whether to go over that depends on ones concept of good or ok accuracy. My concept of good cast bullet accuracy is 1-2" 5 shot groups at least at 100 yards. Ok accuracy is 3-4" at 100 yards. Anything over that is a no go.

At the other end there is considerable information on what is referred to as "cats sneeze" loads. I think Paco Kelly also has an article on really light loads with soft heavy cast bullets for pesky varmint removal with long barreled milsurp rifles. I have developed such loads myself. For instance I shoot 200+ gr cast bullets (really soft almost pure lead) in .30 cal and 8mm milsurp rifles at about 550 fps. The bullets stabilize without problems in the 1-9.5/1-10" twist barrels out to 50 yards. I haven't shot them any farther because the military sights are pretty max'd out at that range. I have shot them down around 300 fps (any slower and the bullet doesn't get out the barrel sometimes) with good stabilization and accuracy at 50 yards but the sights don't adjust enough to hit point of aim at said 50 yards. BTW; by "good accuracy" I'm refering to 1-1 1/2" 5 shot groups at 50 yards in this case.

Larry Gibson

[crazy mark]

looseprojectile,
Where abouts in SW WA are you. I personally like BLc-2 and 3031 in my 30/30 loads. Be as picky as you want. We seem to all want different things from our cast loads but accuracy is the one thing that is pretty much agreed on. To waht degree that accuracy is depends if we is shooting paper or animals. Just don't get c-man going on cats. Welcome aboard. Mark