Accubond 200gr

[dzechm1]

Is anybody getting 3000+ FPS with 200gr accubonds in .300 win mag? I'm shooting a 111 LRH. 24in barrel 1/10 twist.

[darkker]

Not without going well over pressure

[dzechm1]

I was afraid of that.

[darkker]

Here is a little info for you, do what you would like with it.

From testing over the winter with a Pressure Trace, from a few powders in the Creedmoor, and limited testing in the 308, it would appear that under the normal load range, that each 75-100fps will come at the cost of an additional 10-15,000 psi.

All book data is pressure tested, and usually will be faster than production firearms. They use SAAMI minimum spec equipment.
So book data has you about 200 fps short of that mark. that will give you a vague idea of the additional pressure required to reach it.

[LongRange]

just curios...was your pressure testing done with a short throat barrel or factory barrel where you were compressing loads at or before book maxes?

[darkker]

Pressure testing was done on factory rifles, one of which has a SAAMI standard throat, the 308 has a VERY long throat.
None of the loads were ever compressed. Some powders were over book max, some were under.
For anyone who doesn't yet realize this, I will point it out for safety sakes.
NO manual I'm aware of, since the very old A-Squared manual, actually posts lot numbers of components tested. The very limited resellers who DO post nominal lot variances, will show you that there is a VERY good reason why all powder gives the "Drop 10%" warning. Assuming that you have the same burning rate on your powder as was tested is not smart.

Based on some conversations I've had with folks, I assumed that the powders listed in the Creedmoor had a book operating range of around 40-60,000psi. Testing with it showed that assumption to be rather close. While not a perfect fit, and limited testing, it fit the 308 as well.
In the Creedmoor, the lot of 760/414 we tested was close to book, but a bit faster. The Superformance lot was MUCH slower than book data. Interestingly enough, the progressive burning curve of Superformance tends to peak-out, more like a traditional powder; when pushed against max pressure.
Now does this hold true for all cases? Likely not, but did for all powders and bullets tested in the two cartridges.