Pressure Trace:PN45 N120 65gr 200XTP

Thanks TG. Zen was experiencing sabot disruption in temps as low as 30 degrees with 65 grn plus loads with out a barrel cooler.Based on this I am going to work up to 64 grns and see how this plays out. I do not know if I will improve upon the accuracy or not as it is very accurate at 60 grns.

QL would estimate that load at 2830 fps @ 36.3 kpsi and 97% burnt.

Pressure is pretty much in line.

QL would estimate that the bullet left the bore in 1.06 ms and PT estimated the bullet exit pretty close to that on the first shot.

Shot #2 may have partial sabot disruption but that is just a guess.

It would be interesting to see this load 200 grain sabotless to compare velocity and trace shape.

I would probably drop the load before I went up just to see what happened to that second spike.

edge.

TGinPA

As always I enjoy following the traces you generate and seeing the results revealed.

Here again I’m scratching my head because of lack of understanding what is occurring.

A secondary spike larger than the primary spike is always seen on the 2nd shot and not on the first shot?
The primary spikes for the two shots almost follow the same path of rise and fall never reaching the base line. Then the secondary spike of the second shot dramatically climbs to a higher level than the primary spike. So the obvious question is “What the heck is going on here?”

At this point in time there are 2-things I can see causing this.
1) A false reading?
2) Load has moved far enough ahead from its initial acceleration to expose a larger volume of powder surface to the flame?

Observing the tracking of the of the primary pressure spikes almost on top of each other and pressure curve not reaching zero after the primary spike would suggest correct response from the unit.
So if I were to focus on the second reason as a possible answer then the big question is, “What is affecting the bore resistance to allow load movement to increase ahead of the burn on the second shot?”

Here I sort of come to the end of the road for what is occurring.


Ed

The 2nd spike is present on almost every load that is being traced in the .45.

Even here in linked trace where I am almost positive that powder is not too slow for bullet application.

I have no idea what but think something else is happening.

Look at link to this trace with 325gr bullet and 4198 @ 53gr......I would think this combo would have NO to very small 2nd spike.

It is looking more and more to me like the .45 with 200gr bullet is not making pressure any better or maybe even less than the .50 with 250gr bullets. Looks like burn advantages gained with bore size of the .45 are being more than offset by the lighter bullets.

Then look at the trace RB did (scroll down page 2nd link) with N110 with 300gr bullet and again tho not a large spike but it is still there and it for sure is not to light a bullet for the powder. I wish I knew what RB did back when he did this but he told me once he could make about any combo show this symptom with his settings.

TGs trace with 4198 @ 53gr and 325ftx in .45
dougsmessageboards.proboards.com/index.cgi?board=smokeless&action=display&thread=7715

Quote from RB "Secondary pressures often occur with the items you mention but I'd add there might be other factors in a muzzleloader such as very low bullet inertial resistance with light weight bullets".

RBs trace with N110 @ 44gr and 300gr bullet in .50.
dougva.proboards.com/index.cgi?action=display&board=Savage&thread=2981&page=1