Captivated from Learning

[ET]

I decided to make any relative commentaries about testing powders and some resulting response to the Back Porch for any who are really interested. Most shooters are only interested in results such as peak pressure, particular load components and resulting velocity, not the behind the scenes activity.

For some reason in my later years I’ve taken a renewed interest in SML, more specifically the 50Cal. I feel that there is still a lot to learn in this area. TG, bless his heart, gave the 45 community a lot of insight with the traces he generated. Now I don’t plan to compete with TG’s work but focus on the potential of the 50. Very little tracing was done with 50 so there are many unknowns yet to be seen.

The 2-main key elements are powder and strength of the ignition to get the proper response IMO. Once the ignition starts then there is the load resistance factor that that helps develop pressure before the bullet moves. That level of pressure developed dictates the following burn acceleration. Okay that’s straight forward.

Now with having PT trace capabilities I can observe the actual pressure cycle and what influence it has on a particular bullet. For now, I have divided the trace into 3-parts.
Part 1 - deals with the ignition and rate of pressure acceleration that is referred to as Rise Time. The faster the Rise Time the stronger the ignition. Also, the faster the Rise Time the stronger the thrusting pressure behind the bullet.
Part 2 – this is basically understood as we want Peak Pressure to remain in what we set as a safe zone. The safe zone will differ with different shooters. Another thing to keep in mind is that a slower Rise Time indicates pressure occurring further down the bore. Whether this is detrimental or not I don’t know but prefer my Peak Pressure occurring deeper in the bore where there is more barrel material.
Part 3 – observing the rate pressure drops off from Peak Pressure to muzzle. The higher remaining pressure contributes to higher velocity. The rate of acceleration is dependent on the pressure behind the bullet. Of course, with higher pressures retained at the muzzle there’s a louder bang.

Now to add a little intrigue to this testing 4227 is going to get another kick at the can. With a Standard Sav. BP and 250 gr bullet that was a real flop. But yet with a recessed BP it fired like gang busters. Okay let’s team a 225gr bullet with a recessed BP and 4227 to see what happens.
Care to guess, chuckle?

[jims]

No guesses but always interested in the results. thanks for your efforts.

[ET]

Jims

Appreciate the kind thought for my efforts.

The concept of how a recessed BP promotes a stronger ignition is not hard to understand. What it does is open doors to powder usage that are hard to get the desired ignition response. I’ve paid my dues for modifying my equipment and now to reap the rewards that will be revealed from trial testing. Here I can compile the info for best response. The days of anticipating how my load will perform under given conditions are numbered once I compile the data I need.
Not to get into a long-winded explanation of what’s happening at each phase I will just provide the particulars for loads I try. If anyone has any questions, I will try to answer them.
For now, it’s a waiting game for the next outing.