I was happily popping away with my nice new soupcan bullets over 13 grains of Red Dot in a .308 getting groups of about 1.25 at 50 yards with a pronounced vertical spread.

A thought dawned on me (always a dangerous thing), just orient the powder and see if that helps with the vertical spread. Often worked in the past. So I shot five, raising the muzzle to vertical and gently lowering to horizonal.

Group opened to over eight inches. Never seen that one before. What the hell is going on here?

Btw, after that group, I tried another shooting normally and it went back to about 1.5".

[ 11-29-2003, 21:37: Message edited by: Leftoverdj ]

LOJ, you popped that boolit too hard, too quickly. Not enough time for the boolit to line up. Try seating out even further, closing the bolt more slowly, and slow the powder speed down some. Try the same load with GreenDot, for example. ... felix

Same load, Felix. Only difference was powder orientation. Already figgered I needed to change the load, but that big a difference from that small a change stunned me.

First powder orientation (horizontal spread) got a gradual ignition from the primer sparks raining down on the spread-out powder. Powder never really stirred around all that much, mostly burned in place. Bullet moved forward gracefully and slowly at first, aligning itself in the throat before the pressure got up into the yield range of the lead.

Second orientation (powder packed over the primer vent hole) got a more violent ignition with flaming powder granules (some mass there) impacting the base of the bullet while it was possibly still crooked to the enlarged throat area.

Pressure rise was much more abrupt, possibly exceeding the yeild point of the lead with the bullet still in the unsupported throat area?? Bullet might have "bumped up" crooked, in other words?

The soup can is very short compared to most throats, right? It could get crooked (as it is so short itself) if it was given a real hard slap on the butt when in a place with enough room to get slaunch-wise.

Some thoughts, not necessarily the right ones ...

Oldfeller

Leftoverdj, According to C.E. Harris, and my considerably lesser experience, Alliant 2400 is not position sensitive. In fact, I have found that some loads with 2400 are more accurate when no attempt is made to orient the powder. Also, I hear tell that Accurate 5744 also doesn't mind rattling around in the case. Haven't tried that one yet, though I have some on hand. So many experiments, so little time, curmudgeon

2400 probably hits the "happy medium" place of being slow enough not to readily overpressure a shot due to positioning it near the flame hole vs just lying it randomly along the bottom of the case.

The faster flake powders are apparently not so considerate.

I too like 2400 for lighter loads. It works well with a variety of middle caliber rounds.

I am still trying to learn to like large loads of IMR 5010 to get the same speeds but I am still dealing with the ignition and fouling issues that are found using the big stick stuff.

Oldfeller

Hey Leftover, what happens if you orient it to the FRONT of the case, by pointing the muzzle down before you aim and fire?

Curmudgeon, I got both and 5744 is the next on my list.

Reason I posted that was not to find a load, although loads are appreciated, but because had the horizonal load been just a squooch better, I could easily have found myself wondering why I was missing all those squirrels.

I have used that same 13 grains of Red Dot in a mess of stuff since C.E. Harris published it as THE LOAD 15-20 years ago and have never seen a reaction like that. (Granted I have never used it with a cast bullet as light for caliber as that)

Question I am raising is just how big an effect does a simple position change have? I could go shoot it and see, but I am pretty sure that a half grain increase would not blow groups up like that.

Could some of those cases of ringed chambers from using fiber fillers be extreme examples of this?

Sure wish I had chonyed those loads, but I don't think I am curious enough to repeat the experiment. At least not in that rifle.

I've seen one instance of powder forward that greatly improved accuracy. To my best recollection it was an '06, 170ish gr cast boolit, and a light load of H108. Not exactly text book example of how to shoot cast.... btw, on another day it did not work so well. It was not me but a shooting buddy what did this. I think I'll stick with more conventional loadings and techniques. sundog

Gee - what about the special little tube going from the primer forward so's you get FRONT ignition? How does that affect accuracy in cast?

(Sorry, just had to bring up something off-the-wall.)

Ok trk, got one for you.

Proposed solution for trying your trick on some really hard to find (Beridan primed only) brass.

Take a piece of tool steel stock slightly shorter than the start of the case neck distance from the headstamp surface and put it in a CNC lathe (for repeating the all the steps a hundred times or so).

(shorten the tube a bit to leave a little extra room for protruding bullets of course)

Drill the length of the stock for a primer flash hole. Make up a shoulder and a threaded end on the far side of the tube with a recess in the end for a standard small rifle magnum primer. Narrow the tube up from the shoulder to keep only as much powder space as you would need. Note, by making the tube fatter you could reduce some of the excess case capacity that exists on some of our rounds.

Heat treat (fast flame harden & oil quench) the pocket and threads end of the flash tube for good resistance to primer pocket expansion on firing.

Drill out the beridan primer pocket on a fired case and tap it to match the threads on the tube.

Install the flash tube with some sort of installation tool from the case neck side so the shoulder stops firmly on the inside surface of the case head. Installation tool could index off the case neck to guarantee good alignment of the tube and use a simple internal taper to grip the flash tube OD lightly.

Use 2 part epoxy on the threads to seal it and make sure it never moves again (or leaks) after being installed.

Problem now becomes decapping, but you could beat that with a long needle-like decapping pin that gets supported by the flash tube itself. So add a lead in bevel to the mouth of the flash tube to guide a decapping pin into the mouth of the flash tube.

This would tend to keep your flash tube properly centered even after many uses as it would get straightened after every use.

I can see one accuracy rub that would happen with a flash tube system like this. With fine ball powders a variable amount of powder would trickle down the flash tube on loading - in essence becoming part of the primer ignition force. This would give you a variable ignition, similar to mixing standard and magnum primers, which could give you some vertical stringing.

Plus it would be a whale of a lot of work to even try this trick out. It would have to be some really really rare brass to be worth the trouble.

Oldfeller

[ 11-30-2003, 19:13: Message edited by: Oldfeller ]