misc experiments in 30-06

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misc experiments in 30-06

Postby mtngun » Sun Feb 17, 2008 5:10 pm

from the old forum:

Another attempt to combine lube testing and ongoing load development in the 30-06 ........

Last time pressures were 67 ksi :( so the powder charge was dropped a full grain down to 54.2 gr. WW760.

Last time several rounds refused to chamber. Close inspection of the uncooperative cartridges revealed that the second band from top was binding whenever this band was 0.3102" or more. The nose die was barely touching this band. The nose die was honed and the sizing depth adjusted so that the problem band was sized more, down to 0.3095" - 0.3100" (sized bullets still have tolerances).

Last time an M-die was used that left the neck ID about 0.304" - 0.305". Some of the pulled bullets had been squeezed down to 0.001" in diameter by the tight neck, so a larger M-die spud was used that left the neck ID about 0.307".

Last time Felix lube created huge clouds of smoke so Felix got the boot and Speed Green was tried instead. Speed Green is a soft lube that performed nearly as well as HVR in some previous tests. It is available from http://www.bullshop.gunloads.com

All powder charges were weighed. The barrel was cleaned at the end of each 15 shot string, before switching to a different lube. Other load details are 54.2 gr. WW760, CCI #250, 2.930" COL, and 0.314", heat treated mystery metal, 180 gr. loverin.

The paper patch loads were the same loverin bullet sized to 0.3015", then heat treated, patched up to 0.310", lubed with Rooster Jacket, then dusted with mica. The patch covered about 3/4 of the bullet, and the top of the patch snuggled into a lube groove. They were seated out to 3.010", making light contact with the throat.

Here's the gory details:
[mrow] [col] paper [col] speed green [col] HVR [col] zambini
[row]avg. fps [col] 2610 [col] 2720 [col] 2727 [col] 2728
[row]fps std. dev. [col] 2.52% [col] 0.97% [col] 0.55% [col] 0.40%
[row]avg. 5-shot @ 100 yards [col] 3.98" [col] 4.07" [col] 3.40"[col] 6.70"
[row]avg. KSI [col] 53.8 [col] 64.2 [col] 65.0 [col] 64.6
[row]KSI std. dev. [col] 9.67% [col] 4.88% [col] 2.07% [col] 2.57%

Here's the trace for the paper patch bullets. Obviously, something was wrong, because the velocities and pressures were erratic and generally lower than expected. It's fair to say that the patch is not making a good gas seal. It may be getting torn in the throat.

Here's the Speed Green traces. Darn it :evil: , despite dropping the powder charge by one grain, pressures are still way too high.

Here's the traces for the reigning lube champion, HVR. HVR scored well in every category, and even though the differences are too small to be statistically significant, it keeps scoring well in test after test after test.

Here's the trace for Zambini. Its last group was pretty wild, perhaps due to fouling. Image

Lube-wise, HVR is still the champ. Sometimes it isn't best in every category, but it's always near the top and best overall.

Load-wise, I don't know what else to do with this load. Obviously the pressure is still too high -- and this jug of powder is almost empty. :x Other than fixing the pressure, its hard to think of anything that I haven't already tried. It hasn't shot well since spring when it was shooting 2 MOA. Maybe the lubes work better when the weather is cool ????????

Did you notice how today's secondary spikes were higher than last weeks secondary spikes? For example, today Zambini's spikes averaged about 40 ksi vs. 28 ksi last week.

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