Need help with 300 wsm please!

[ZSteinle]

I have had good results with H4350 64gr. pushing a 168 SMK at around 3030 FPS not really pushing it but the accuracy was incredible so i left it at that, best group was .136 inch

[Scout1]

Originally Posted by freelunch

volunteerbee,
This may be off the wall to you, but I calculated the OBT node loads for you. If you want to take a chance, load 3 of each and see what kind of group accuracy you get. This is for RL-17 with 150gr Nosler ballistic tip.

67.8gr node 3, expected 3319fps
66.1gr harmonic between nodes 3 and 4, expected 3241fps
64.3gr node 4, expected 3161fps

If you try it, let us know whether the OBT loads are good.

Freelunch, how are you calculating OBT when I didnt see where he told us the length of his barrel.

I'm running a 155 Scenar out of a 28" barrel using cci br2's and 67.6 grns of 4831. Very accurate

[freelunch]

Scout1 concerning OBT method,

For those who do not know, OBT is optimal barrel time and is a theory that the accuracy nodes for any caliber, bullet and powder is dependent on specific barrel time nodes (pressure waves). People use Quickload to determine the exact powder load to equal the pre-calculated OBT node times.

The tables for OBT Scout1, are in 1/2" barrel length increments, and the time adjustment for each increment merely adjusts it so all barrel lengths will give the same OBT node. So in this case I just chose a barrel length of 24". I could have used 26 or 20" and it would have resulted in the same OBT node results.

I had an ulterior motive in calculating the OBT nodes for volunteerbee. This was a double-blind statistical test of OBT where volunteerbee probably didn't know about OBT and I didn't know the accuracy nodes beforehand for 300WSM.

Yeah, I was "using" volunteerbee as a test subject for my own purposes in proving or disproving the OBT method. But, but, if the OBT method calculates good accuracy nodes then volunteerbee gets them for use rather than using the max load for RL-17 from the Alliant website as he did (69.3gr), which wasn't on an accuracy node.

[Scout1]

freelunch, I have used the OBT as well, http://www.the-long-family.com/OBT%20Table.pdf with Q.L. there are way too many variables needed to calculate a good OCW in the middle of a node. Thats the reason Q.L allows you to manipulate so many varibles such as H2O cap, burnrate, bullets weight, temperature to name a few. Q.L. must be callibrated to your specific lot of powder and your specific chamber and barrel since no two barrels will offer the same pressure caricturistics(spelling?), throwing out a generic charge weight might not be safe in someone elses rifle even if it is in yours.

Sorry for highjacking the thread,

Jon Hetzler

[freelunch]

Scout1,
When the loads I mentioned are under the max load, they are safe in any rifle. In this case, volunteerbee used 69.3 gr max load already and didn't see overpressure signs. The loads I calculated are lower than he already used--they are guaranteed safe. I agree that when you have the exact H2O capacity of the brass used and COAL used, then OBT gives a more precise calculation.