Request for computer modeled pressure data

[Marlin Junky]

Could someone please provide pressure data for 24 and 25 grains of both the 4198's using RCBS-30-180-FN at 196 grains (ready to fly weight) in the 30-30 with a COL of 2.57" (just touches the rifling). I don't have a boolit handy to measure its length but the diameter is .3105-.3110" running through grooves that go from almost .310" at the chamber to .309" at the muzzle. I think this boolit measures about 1.06" long with the check installed. That length should be close enough because of all the air space in the case but I'll provide an exact length if necessary. The BHN would be 15. If it could possibly make a significant difference, the primers are Fed 210's and WLR.

Thank you,
MJ

[Bass Ackward]

Both powders are in the 40k /41k range. @1950 fps from 20" tube.

[Marlin Junky]

Thanks Bass, I knew you would come through for me :-D

A couple questions though. Are those numbers in terms of PSI or CUP and is that 40K for the 24 grain charge and 41K for the 25 grain charge?

Thanks again,
MJ

[Bass Ackward]

No powder or charge was under 40k and neither powder with the 25 was over 41K. And those are PSI figures. 25.5 went red line with either charge. There wasn't 50 fps difference betweeen any combo.

Bear in mind that is ballpark without making all the adjustments for case capacity, etc. What this tells me is that you are still a little fast for your powder selection. What I normally look for is an even velocity spread right up to the max charge. This way I don't subject the bullet to more pressure without a velocity payoff.

[Marlin Junky]

What I'm actually trying to do is make DP68 work for me in the 30-30 with the heavy RCBS boolit. I've tried 22 and 23 grains and both charges (the former more than the latter) have produced wide velocity spreads so I have concluded this powder needs more pressure to burn properly. I'm going to go ahead and try 24 and 25 grains 'cause it'll probably be safe in my early 336 but it looks like heat treated boolits are in order. I think DP68 is nothing but WC-680 or AA1680 (the AK-47 powder).

Accurate has published the following on their website about DP68: "The grain loads will be the same as for Accurate 2015. Although 2015 is an extruded powder DP68 is very close to it in relative burn rate." I have actually found DP68 (at least my lot) to be 3% faster than XMR2015 and the both produce pretty large ES's at 23 grains (right around 100 fps for a 15 round string)

Here's another thought: could my lube be too slick/oily! I might try another lube at 23 grains to see if the ES will tighten up.

MJ