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Post by TGinPA on Jul 2, 2011 16:22:14 GMT -5
Pressure Trace: PN45 Reverse Duplex Sabottless Because the heat at this time of year makes it hard to get reliable numbers with sabotted loads, I traced a duplex with an unsabotted bullet and then reversed and traced it for comparison. Between standard and reversed duplex, peak pressures overlapped. Velocities spreads were narrow for both standard and reversed duplexes with smaller differences noted for the reversed duplex. As might be expected, the rate of pressure rise after powder ignition was faster for the standard duplex. Somewhat unexpectedly, velocities for the reversed duplex were slightly higher. Under the conditions present today, because of such limited data, it would be hard to say for sure that there is any difference between standard and reversed duplex loads. But, the slower rise to peak pressure and the slightly higher velocities obtained with the reversed duplex are tantalizing and make me wonder if a reversed duplex might offer some advantages in sabotted loads. TG Gage and Module Manufacturer = RSI USB model Trigger Sensitivity = 0, Strain Gage Voltage =4.9 Gage Factor =2.1 PSI Correction Factor: 0 Barrel Temp = 73 degrees F. measured at the sensor (IR). Rifle Stand: Caldwell Lead Sled Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (13 fps. added to all recorded velocities to correct for distance of chrony from muzzle.) Barrel Type: PacNor .45 Cal Muzzleloader Barrel OD = 1.06in. Barrel ID = .452in. Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=1.2in. Bullet Diam.= .448in. Type = Hornady .452in. 250xtp resized to .448in Bullet weight = 250gr. ,unknurled. Sabot:None Wads .462x.06in lubed fiber under lubed wool. Primer: Fed 209A Powder: Trace 1-2 = H322/N110 55/14gr Trace 3-4 = N110/H322 14/55gr Shot fm. dirty barrel. These load seemed safe in my barrel under the test conditions but may not be so in other conditions.  |
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Post by Richard on Jul 2, 2011 16:34:32 GMT -5
TG...........I know you have some situation where you cannot shoot targets? It is too bad since this information would be so much more meaningful if the results could be related to groups  Richard |
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Post by Jon on Jul 2, 2011 18:18:46 GMT -5
TG Interesting trace especially the lack of much secondary spike. Keep up the good work
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Post by Deleted on Jul 2, 2011 19:43:25 GMT -5
Richard,
Now you know what the trace looks like would you please go show us some reverse duplex groups.Have you ever tried any before ? The slower developing pressure might be more of a sabot friendly load. Iirc, that was one the loads you and Herman were playing with. Try it out and see what groups it produces,
who knows.....
Greenhorn
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Post by deadeye on Jul 2, 2011 20:32:06 GMT -5
tg-this is very interesting & thx again for your contribution. there was some discussion prior about reverse-duplexing. i would think for the people that are "plinking" for possible new loads to test. the "groundwork"(pressure wise ) has been done! greatly appreciated!  |
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Post by Dave W on Jul 2, 2011 20:40:22 GMT -5
TG, in the trace it says 200 XTP but in the data above the trace it says 250 XTP??
Good looking trace, thanks!
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Post by ET on Jul 2, 2011 22:24:52 GMT -5
TG
As always you do a great presentation and hope to match your organization skills one day.
Anyway there was a short planetary alignment this weekend and will be posting some newbie PT results tomorrow. ;D
Ed
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Post by TGinPA on Jul 3, 2011 6:53:54 GMT -5
Dave W: The trace above is with 250xtp. You wouldn't believe the number of steps needed to make the presentation above. Anyone doing this stuff needs a proofreader. Thanks for picking up the error. The trace has been corrected.
TG
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Post by ET on Jul 3, 2011 8:02:39 GMT -5
Dave W: The trace above is with 250xrtp. You wouldn't believe the number of steps needed to make the presentation above. Anyone doing this stuff needs a proofreader. Thanks for picking up the error. The trace has been corrected. TG I believe. Ed |
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Post by 153 on Jul 3, 2011 8:33:30 GMT -5
TG I like the out of the box thinking. I will try this when I shot again. May be a while as I have been working 70-80 hours a week lately. Also 1-shot has my second Savage ML installing a PacNor barrel that should be ready within two months. I do like the trace, it looks on paper lets hope it shots as well. Thanks for the trace.
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Post by Dave W on Jul 3, 2011 8:50:28 GMT -5
Dave W: The trace above is with 250xrtp. You wouldn't believe the number of steps needed to make the presentation above. Anyone doing this stuff needs a proofreader. Thanks for picking up the error. The trace has been corrected. TG Kind of figured it was the 250 based on velocity since that was what we talked about but I thought I would mention it for clarification. Thanks again for your time and effort! Found this to be interesting. When you traced this load: i32.photobucket.com/albums/d17/4321rtg/pn45n110-h322115-585gr250ftxvegolddirtyfed2094-11-2011.jpgThe velocity was higher with less booster at cooler temps. Not apples to apples since the loads are slightly different and a different bullet also. Do you recall if you were using the same powder lots for both sets of traces? I did use a new booster lot# for the numbers I gave you the other day so that may play into the loss of velocity over the original trace you ran for me. |
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Post by dave d. on Jul 3, 2011 9:09:08 GMT -5
 nice job tg. I commend you guys for all the hard work you do.
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Post by TGinPA on Jul 3, 2011 9:44:50 GMT -5
Dave W: The lots for both traces were the same. I should have added this to the original post. It was your your question to me regarding reversed duplex loads was the reason I ran this trace. Hope this one adds something useful to our data base. Richard: Indeed this is a load taken from your "Load Info" data base (9/1/2009), though with a different bullet. You have posted accuracy data for this duplex. dougsmessageboards.proboards.com/index.cgi?board=smokeless&action=display&thread=2397TG |
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Post by Richard on Jul 3, 2011 17:16:01 GMT -5
TG........Dang! I shoot so many different loads I can't keep track of them ;D
Greenhorn..........I have shot reverse duplex, mixed duplex, mixed triplex.........lets see........what else? I mainly did it to show that no matter how you load them you can't screw up to cause a dangerous situation. In fact everyway I messed with them, the velocity/pressure became lower.
Richard
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Post by ET on Jul 3, 2011 21:01:51 GMT -5
TG That trace of the reverse duplex clearly shows that peak time pressure can be altered or adjusted. This could be very useful to possibly reduce sabot disruption found with a faster burning duplex. Also by increasing the time it takes to reach peak pressure the resulting pressure decline is extended further out resulting in slightly higher velocity. Another observation is how well the trace repeats itself almost on top of each other and the bullet exit points are almost identical. IMO this information is very useful. Ed |
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Post by Dave W on Jul 3, 2011 23:31:30 GMT -5
It is cool how you can manipulate the curve by switching the loading order of the powders. Raises some additional questions for me.- Would 4759 reduce the drop off even more if it was the reversed booster and do away with the secondary spike altogether, which was the primary reason for requesting the trace in the first place?
Another question, since saboted loads probably produce a quicker seal and sharper pressure rise, how will the secondary spikes be affected by the reversed loading order?
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Post by ET on Jul 5, 2011 19:38:03 GMT -5
It is cool how you can manipulate the curve by switching the loading order of the powders. Raises some additional questions for me.- Would 4759 reduce the drop off even more if it was the reversed booster and do away with the secondary spike altogether, which was the primary reason for requesting the trace in the first place? Another question, since saboted loads probably produce a quicker seal and sharper pressure rise, how will the secondary spikes be affected by the reversed loading order? DW Some interesting thoughts there to follow. Theoretically the same reaction with saboted loads should occur of reducing any secondary spike affect. As for extending the pressure decline you would have to go a slower powder such as 4198 that would still burn faster than H322. Would even a small a secondary spike reappear? That I don’t know and only trace testing could confirm that. The big question for me in using such a reverse duplex is how temp sensitive H332 would be in colder temperatures? Ed |
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Post by ET on Jul 17, 2011 14:39:23 GMT -5
Okay I just had a, Wow I could have had a V8 moment with a rap to the head.
I have been reviewing this trace numerous times because I felt I was missing something. I was because I was focusing on the possible temp sensitivity of H332 in colder weather when used in a reverse duplex. But that is not an issue when used in the duplex format of having the booster of a faster powder ignited first.
So an additional observation now would suggest that this duplex load could easily cover a wide range of temperature and maintain a given velocity.
Use the duplex as originally intended for colder weather and reverse the powder load sequence in warmer weather. Of course discovering at what point the changeover should be is another chapter in itself.
Even though I’m still a single powder fan at the moment I still want to expand my knowledge of powder burns and will eventually try some duplex testing to see what results can be achieved and also what can be learned from them.
What can I say but another addiction to learn is taking hold. ;D
Ed
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Post by TGinPA on Jul 21, 2011 11:40:18 GMT -5
After several difficult weeks dealing with gage malfunction, my PT setup again seems to be stable, but with a new strain gage. The new gage is measurably (about 2kpsi) less sensitive against my calibration load. The PT program allows me to add a graphical pressure correction factor which I have elected to do to at least keep new and old traces at comparable pressure levels with traces prior to 7/4. With the new gage, 2kpsi has been added to all readings and this will be noted in the setup description I append to most of the posted traces. With the new gage, the pressure point at which the gage initiates a pressure recording has also changed, so that time to peak pressures may be slightly different from that seen with the previous gage. It remains to be seen how long the setup will maintain stability. Reverse Duplex: Just to be sure, I repeated the previous trace of the 7/2 load. The result was almost identical. I am now certain that under conditions of the test, the differences are real and may be useful. Gage and Module Manufacturer = RSI USB model Trigger Sensitivity = 0, Strain Gage Voltage =5.0 Gage Factor =2.11 PSI Correction Factor: 2kpsi.Barrel Temp = 75-78 degrees F. measured at the sensor (IR). Rifle Stand: Caldwell Lead Sled. Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (13 fps. added to all recorded velocities to correct for distance of chrony from muzzle.) Barrel Type: PacNor .45 Cal Muzzleloader Barrel OD = 1.06in. Barrel ID = .452in. Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=1.07in. Bullet Diam.= .448in. Type = Hornady .452in. 250xtp resized to .448in Bullet weight = 250gr. ,unknurled. Sabot:None Wads .462x.06in lubed fiber under lubed wool. Primer: Fed 209A Powder: Trace 1-2 = H322/N110 55/14gr Trace 3-4 = N110/H322 14/55gr Shot fm. dirty barrel. These loads seemed safe in my barrel under the test conditions but may not be so in other conditions.  |
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Post by edge on Jul 21, 2011 12:15:02 GMT -5
I would love to see the Mixed duplex again if you don't mind I just can't see the higher velocity at lower pressure AND less under the curve! Thanks for all of your time and effort. edge. PS if you do do the mixed again and you it duplicates the last trip could you lower the overall charge to see if the sabots are having trouble with the load |
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Post by TGinPA on Jul 21, 2011 15:30:55 GMT -5
Edge: I agree, as you point out that sabot disruption may well have made that test meaningless. This is not the best time of year (it hit 100 degrees here today) to get good data on sabotted loads (unless I take a trip to Richard's shooting palace or move to Montana). Maybe an acceptable alternative would be to use an unsabotted load to remove that variable from the equation? How about using the 110/322 14/55gr 250xtp load instead?
TG
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Post by edge on Jul 21, 2011 17:19:34 GMT -5
Your the boss, and the one putting in the time, I'll defer to your decisions.
edge.
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Post by Dave W on Jul 21, 2011 18:57:03 GMT -5
Thanks TG and glad to see you got the equipment back up and running, hope it did not set you back too much.
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Post by ET on Jul 21, 2011 19:11:45 GMT -5
Oh I know I’m going to get feedback on this. ;D
The way I am observing a trace is in 3-stages.
The 1st stage is the building of pressure that in turn supports the acceleration of the bullet.
The second stage is when the peak pressure occurs is where the bullet has accelerated to max bore velocity.
The third stage is when pressure begins to drop it no longer supports the bullet accelerated velocity in the bore and the bore resistance begins to decelerate the bullet. Now depending on the amount of remaining pressure behind the bullet (rate of pressure decline) this should work against the rate of bullet velocity decreasing from bore resistance.
Now what should also be factored in is where the pressure decline occurs in relation to the bullet’s position in the bore. If the pressure decline is shifted closer to the exit point of the bore this in turn should reduce the bore resistance time affect on deceleration resulting in slightly higher velocity.
Anyway this is how I currently view traces from results seen.
Ed
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Post by ET on Jul 23, 2011 20:25:37 GMT -5
I have to post a correction to my previous post concerning bullet travel in a bore.
It has been brought to my attention that my reasoning on what is occurring in the bore is incorrect.
A graph from Quickload shows constant load acceleration in the bore to the muzzle. The rate of acceleration starts to decrease about ½ way of bore time as bore pressure has already started decreasing.
Here I can only apologize if my previous shared reasoning has caused any confusion.
Well it’s back to the think tank to try and determine exactly why a slower extended pressure decline gives additional velocity.
Ed
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Post by Deleted on Jul 24, 2011 8:12:04 GMT -5
Could it be just that the bullet is being accelerated for a longer period thus the higher velocity ?
Just a comparison take it or leave it, in gasoline engines using 87octane compared to 92 octane. The 87 burns FASTER than 92
but does not give the power of the 92.
So in the 87 the pressure curve would be a faster spike than the 92.
If i'm way off lets debate.
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Post by ET on Jul 24, 2011 13:41:26 GMT -5
Greenhorn I always enjoy a good discussion that in turn often leaves me with a better insight when viewed from another’s perspective. In this case a common ground is needed so I’m including the graph I mentioned.  Your analogy may prove correct but at the moment my focus is on the affect of a pressure decline that extends to the muzzle. This is what I’m now seeing from the above graph. The bullet is on a constant rate of acceleration but that rate begins to decrease after reaching a specific point associated to bore pressure. As pressure in the bore continues to drop so does the rate of acceleration. This is about as far as I’m willing to comment until I have further studied the graph from Quickload. Now if the current PT unit could be made to calculate/show the acceleration of the bullet on the graph that would be the ultimate PT unit. If it can calculate the exit point from resulting velocity then there should be a way to show the acceleration as well to reach that exit point. Ed |
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Post by Deleted on Jul 25, 2011 22:45:48 GMT -5
Et
If the acceleration were constant would not the velocity curve be a straight line, I believe the slope = acceleration in this velocity curve, right ? I believe the pressure drop is due to the volume is increasing as the bullet goes further down the barrel.
You superimposing both graphs on each other really gives me a better understanding of whats going on here,thanks for all of your efforts and more to follow.
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Post by ET on Jul 26, 2011 4:47:10 GMT -5
Greenhorn The graph originally came that way with both pressure and velocity shown. The graph now included has some reference points I have added to see if some of the readings can be correlated into more useful information. I have found that there is a state of constant rate of acceleration occurring just before to just after peak pressure. But that’s as far as I have gotten so far. I agree that volume is causing the pressure drop but that the burn characteristic of the powder for resulting pressure also plays a role here. 1-graph may not sufficiently show enough information for a correlation.  Ed |
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Post by Deleted on Jul 26, 2011 9:36:35 GMT -5
I see the straight line now,HMMM. After reading your first idea about the stages of pressure vs. velocity I totally agree that bore resistance is a negative on velocity and if the pressure curve is a slower one the higher velocity is obtained because BF=barrel friction, has been reduced. I've been questioning the head pressure being on the front of the bullet being a factor in stability.
But, on the velocity side a sst compared to a xtp has the same
muzzle velocity . So, they both have same velocity and spin when they exit the barrel and fly the same path for at the minimum 50 yds. After that or even further the xtp's Bc can't keep up with the sst's bc.
So, I guess the head pressure idea is going nowwhere,lol.
Thanks for reading my ramblin.
I love physics and at one time was the top in my class, you all here inspire me to at least TRY to grasp what is going on,excuse me if I'm being a greenhorn here,lol.
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nice job tg. I commend you guys for all the hard work you do. 
