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fillers in 30-06

Posted: Sun Feb 17, 2008 5:54 pm
by mtngun
from the old forum, table function not working yet:

I had tried everything else, so it was time to try a filler in my high velocity 30-06 loads. I've ordered some shotgun buffer to try as a filler, but today I tried powdered mica. The hope was that it would improve the gas seal and/or scour the fouling out of the barrel. A 0.5cc Lee dipper of mica filled the case to partway up the neck.

Also, pressure had been too high, so I dropped the powder charge.

My jug of WW760 was almost empty, so only 10 rounds were loaded for each experiment.
[mrow] load [col] PSI [col] FPS [col] FPS std. dev. [col] 5-shot MOA 100 yards
[row]53.2 WW760, 180 loverin [col] 61,653 [col] 2678 [col] 0.45% [col]4.98"
[row]53.2 WW760, 180 loverin, mica filler [col] 67,762 [col] 2687 [col] 1.00% [col]6.60"
[row]53.6 WW760, 180 loverin [col] 65,379 [col] 2701 [col] 0.44% [col]4.15"
The mica filler was a failure. Pressure increased 7000 psi but velocity only increased 19 fps. The standard deviation doubled, and groups were wild. The only good thing is that it totally eliminated the secondary pressure spike. The trace dropped like a rock as the bullet exited the barrel. In theory, that's a good thing.


I am not excited about buying more WW760. This new jug has not given the velocity and accuracy that I got from the old can of WW760. It looks like velocity will only be 2650 - 2670 fps when loaded to sane pressures, and the accuracy is not there. What we need is a low-spike powder with a burning rate better suited to the 30-06.

Even though the bullets were nose-sized in a tapered nose die that is supposed to create a perfect fit in the tapered freebore, I continue to have problems with inconsistent chambering. Some cartridges chambered easily, some encountered slight resistance, and some were extremely difficult to chamber. I have decided to abandon the tapered nose. If you are familiar with the tapers used to hold machine tools, you know that the fit is either very tight or very loose, with nothing in between. Cast bullets need need a consistent "in between" fit, and it's very hard to do with a taper-inside-a-taper. I think it would be better to have a 1-diameter nose inside a 1-diameter freebore, and someday, after I win the lottery, I'm going to get a custom barrel chambered to fit a 1-diameter 0.309" cast bullet.

I'm not sure what to do in the meantime. My shooting season is nearly over, as the moose season begins next week.

Re: fillers in 30-06

Posted: Sun Feb 17, 2008 6:09 pm
by mtngun
30-06: buffer, crimp, diameter, 2005 conclusions

Some of these experiments may seem like I'm going over old ground, but bear with me, I do have a plan, believe it or not. :wink:

Powder I ran out of WW760 but had a jug of Ramshot Big Game taking up space on the reloading bench. Big Game has a burning rate and load density practically identical to WW760, except Big Game produces the dreaded secondary spikes. It would be a good test to see if shotgun buffer eliminates the spikes.

309/314 loverin I sized the nose of the usual 180 gr. loverin in a 309" die. Actual nose diameters were 0.3085 - 0.3090". The bottom half of the bullet was sized 0.314". The reduced diameter nose is necessary to fit in the tight freebore section, while the 0.314" bottom helps to fill up the sloppy chamber neck. Even with the nose sized to 0.309", the bullet would run aground in the forcing cone before reaching the rifling. Apparently the forcing cone is 0.3085" or thereabouts.

0.3085" lovernin The same 180 gr. loverin was sized in yet another 0.309" die. The actual diameters were 0.3080" - 0.3085", though, and this bullet could be seated out far enough to engrave the rifling. This is the third time that I have tested skinny bullets. An 8mm throating reamer has been ordered, so this was the final chance to shoot skinny bullets in the skinny throat.

roll crimp Some of the 0.3085" bullets were roll crimped into one of the lube grooves, just as hard as I dared. This experiment was motivated by an intelligent caster who wondered if my oversize bullets shot better because the extra engraving force improved ignition. If the extra initial force is the key, then the roll crimp on these skinny bullets should provide a similar "extra force" and should shoot as well as the fat bullets.

buffer 0.3cc of Graf's generic shotgun buffer filled the case up to the bottom of the neck.

All loads used:
54.4 gr. Big Game
CCI #250
heat treated mystery metal HVR lube
COL = 2.940" fat bullets, 2.980" on skinny bullets

Here's the 0.3085" trace, without buffer.

Here's the 309/314/buffer trace.

Here's the 309/314 trace, without buffer. During this string, the strain gage adhesive began to fail, but the "good" traces average about 62,000 psi on the primary peak.

Here's the 0.3085/crimp trace, without buffer. The gage is definitely out of whack now.

Here's the jacketed validation load shot at the end of the session. Normally it would be around 54,000 psi. Yup, the gage is dead.

Let's summarize the results. 10 shots for each load.
[mrow] load[col]avg. FPS[col]std. dev. FPS[col]avg PSI[col]5-shot MOA
[row] 0.3085" [col] 2672[col]0.55%[col]60,000[col]8.75"
[row] 0.3085" / crimp [col] 2702[col]0.57%[col] ??? [col]8.90"
[row] 309/314 [col] 2701[col]0.52%[col]62,000[col]3.15"
[row] 309/314/buffer [col] 2731[col]0.53%[col]67,000[col]2.95"

What I've learned this year

Crimp Did not improve accuracy or standard deviation one iota ...... leading me to believe that my fat bullets shoot better because they fit better, not because they ignite better.

Skinny 0.3085" bullets sprayed all over the target just like they did in previous tests. The standard deviation suggests that ignition is not a problem.

buffer appears to increase pressures about 5000 psi, though I can't be certain due to the adhesive failing in the middle of this session. The shotgun buffer did not reduce the secondary spike. So far buffers are not looking good, but I want to do more buffer experiments before drawing a conclusion.

0.314" bullets grouped from 2 to 4 inches with a variety of loads, all summer long. Not great, but at least they were groups. Definitely, positively, absolutely better than the skinny throat-diameter bullets. Why 0.314"? Because 0.316" bullets are sometimes difficult to chamber unless the neck wall thickness is carefully controlled. For everyday use with unturned cases, I think you need to allow 0.0025" clearance in the chamber neck, which is about how much there is with a 0.314" bullet.

tapered bullet in a taper throat is supposed to be the holy grail of cast bullet fit, but I was never able to achieve a consistent fit with a tapered nose, even after carefully sizing the noses in a tapered die. A taper-inside-a-taper produces a fit that is either extremely tight or quite loose, with very little in between. I think it is better (and easier) to have a one-diameter nose inside a one-diameter freebore, lightly engraving a tapered leade. Today\'s two-diameter 309/314 bullets and one-diameter 3085" bullets chambered with consistent light resistance. That's the way it should be.

Bullet fit Conventional wisdom says "size the bullet to fit the throat", but that's turned out to be yet another old wives tale. The 0.006" oversize bullets shot better today, and previous tests showed slightly better results at 0.009" oversize -- despite the fact that the oversize bullets must surely be shaving lead and deforming as they pass the sharp-edged shoulder at the entrance to the throat. The 309/314 bullet is just a bandaid -- the real solution is a chamber that's an ideal fit for a 0.309" - 0.310" one-diameter bullet. The SAAMI 3006 chamber has a neck that is too sloppy and a throat that is too tight, IMHO.

Strain gage this gage was glued on with Loctite 4211. As discussed on another thread, Loctite 4211 is not recommended by RSI, and I have learned the hard way that 4211 does not stick reliably to the strain gage. The gage worked well all summer, until today. In general, the RSI Pressure Trace works great if the gage sticks, but I have been plagued with adhesive failures.

Pressure signs this gun does not show so-called "pressure signs" until primers fall out and cases seperate, which happens around 75,000 psi. Loads that I used to think were safe, actually produce 60,000 - 70,000 psi, and sometimes more. This gun cannot exceed book velocities at normal pressures, even though sometimes it can digest a couple grains more powder.

Secondary Spikes we are still missing many pieces of the puzzle, but it's starting to look like the spike is happening after the bullet exits the barrel. I say that for two reasons 1) the barrel shortening test where the spike kept moving backwards as the barrel was shortened and 2) the mica filler test that graphically indicated that the bullet was exiting at 1.0 - 1.1 millisecond. That contradicts theoretical estimates of the exit time which generally put the 30-06 exit point at 1.2 - 1.3 millisecond, but remember that there may be some error in the way the PT triggers. If the trigger has a 0.1 - 0.2 millisecond delay, that would explain the discrepancy.

Now, if the spike is outside the barrel, are we off the hook? No, because the spike still puts stress on the barrel -- maybe not as much because then there would be some pressure on the outside of the barrel, too -- but still worrisome. High pressure at the exit may still affect the flight of the bullet. One way or the other, the secondary spike is not a good thing.

Lubes The loverin design is not as sensitive to bullet lube as some other designs, but nothing that I have tested to date has outperformed Rooster HVR in full throttle loads.

What's next?

1) An 8mm Manson throating reamer has been ordered, because if I am going to shoot oversize bullets, why not shoot them in an overize throat? The 8mm Manson is supposed to create a .3125" - 0.3130" freebore. I don't know if that's optimal, but let's just see if it moves things in the right direction, and go from there. I'll have to regrind the reamer pilot to fit a 30 caliber bore, but I think I can do that.

2) A custom chamber & barrel with the neck and freebore cut for a 0.309" bullet, and a 1-12" twist instead of the usual 1-10". It may take a few years to save up for the custom barrel & reamer.

Re: fillers in 30-06

Posted: Tue Feb 19, 2008 1:59 pm
by mtngun
more filler experiments: baking soda, mica, and shotgun', 'Another experiment to see if fillers can make the secondary spike go away.

I used H4895 in the 30-06 because I knew it would create a spike and it would leave plenty of space for a filler. The powder charge was reduced one grain for loads with a filler to compensate for the higher pressure that the filler usually creates.

I was interested in pressure, not accuracy, so only 3 shots were fired for each test.

Here's the control load with no filler.

Here it is with a baking soda filler. The secondary spikes are almost gone.

Here's a mica filler.

Here's Graf's shotgun buffer.

It takes more than 3 shots to prove anything, so I'll try to repeat the test with baking soda.

I don't recomend using baking soda as a filler because it may clump together and form an obstruction. This was just a test to prove a point about secondary spikes.

Baking soda is used to extinguish fires, among other things.

Re: fillers in 30-06

Posted: Tue Feb 19, 2008 2:41 pm
by mtngun
More experiments with baking soda.

Today's filler experiments all used:
45 gr. H4895
0.313" HTWW 180 gr. loverin, Rooster HVR, seated to nudge leade
Fed 210 primer
5 shots each test

Here's the control load with no filler. Trace #1 looks OK but then the gage started to fail after that. Ignore the erroneous primary pressures -- the point is that the control load had significant secondary spikes. 4.5 MOA.

Here's a 0.7cc baking soda filler. Again, ignore the erroneous primary pressures, and focus on how the secondary spikes have been greatly reduced. 5.5 MOA.

Here's 0.7cc baking soda mixed with the powder charge. Not good. It really screwed up the powder burn. 6.7 MOA.

Here's a filler consisting of 0.3cc baking soda mixed with 0.5cc shotgun buffer. 4.5 MOA. This seems to be the best filler to date -- greatly reduced spikes, consistent velocities and pressures, and accuracy no worse than anything else.

Conclusions so far A baking soda filler does reduce the secondary spike (we still aren't sure what the secondary spike is or if we should care). As little as 0.3cc of soda is required. Mixing the soda with shotgun buffer seems beneficial. The only catch is that you gotta have space for the filler.

Next time try reducing the amount of soda. Will 0.1 cc work?

Re: fillers in 30-06

Posted: Tue Feb 19, 2008 5:09 pm
by mtngun
Today's experiments were aimed at testing the effect of more lube and testing the effect of dilluting baking soda filler with shotgun buffer.

A new bullet was created with double the lube capacity.

The reason for diluting the baking soda filler with shotgun filler is that baking soda is not free flowing. It tends to clump together. After shooting baking soda filler I have found big clumps of soda in the case and in the barrel. This causes erratic velocities and pressures and could even be dangerous. Mixing soda with shotgun buffer seems to eliminate the clumping. The "2:1" filler refers to 2 parts shotgun buffer and 1 part soda, and so forth.

All of today's cast loads were heat treated mystery metal lubed with Rooster HVR. The bottom 2 bands were sized 0.3135" and the rest of the bullet was sized 0.309". It was seated to nudge the leade. Only 5 shots for each load.
[mrow]powder[col]filler[col]GtoB[col]primary ksi[col]2nd ksi[col]fps[col]MOA
[row] 45 H4895[col]none[col]0.7[col]48[col]47[col]2509[col]2.5
[row] 45 H4895[col]1 cc 2:1[col]0.7[col]64[col]33[col]2595[col]5.7
[row] 45 H4895[col]1 cc 4:1[col]1.5[col]64[col]35[col]2625[col]2.5
[row] 61 RL 19[col]none[col]0.7[col]52[col]108+[col]2716[col]6.8
[row] 61 RL 19[col]0.3 cc 2:1[col]0.7[col]54[col]108+[col]2746[col]10
[row] 61 RL 19[col]0.3 cc 4:1[col]1.5[col]54[col]108+[col]2743[col]2.15
[row] 61 RL 19[col]none[col]1.5[col]53[col]108+[col]2736[col]7
[row] 54.5 Big Game[col]none[col]0.7[col]53[col]108+[col]2673[col]5.7
[row] 54.5 Big Game[col]none[col2]1.5[col]56[col]77[col]2726[col]3.4
[row] 54.5 Big Game[col]0.7 cc 2:1[col]0.7[col]53[col]73[col]2651[col]7.1
[row] 54.5 Big Game[col]0.7 cc 4:1[col]0.7[col]53[col]72[col]2657[col]7.3
[row] all 0.7 GtoB combined[col] [col]0.7[col] [col] [col] [col]6.44
[row] all 1.5 GtoB combined[col] [col]1.5[col] [col] [col] [col]3.76

Also I tried a 150 gr. Hornady jacketed bullet with and without filler. In this case, the filler served only to increase the primary pressure.
Here are the rest of the pressure traces.

The big GtoB almost cut groups in half.

Diluting soda with buffer doesn't seem to be very effective.

What's next? A new barrel with a custom chamber. I'm giving up on the spikey powders and going back to WW760. More lube groove experiments.