Discussion on Dec. 28 Pressure Traces

I see you threw the 3 shot and 5 shot group average in at the bottom, ;D

Richard

I’m no expert on reading these graphs but two things stand out for me are:

In graph 3a with the 250gr bullet sabotless has the least amount of graph shifting.
Now in 4a you mention a delay in shooting causing the graph shift from the first shot as compared to the next 4 consecutive shots.
In graph 6a the last 3-shots showed a consecutive shift increasing in shot order. Any additional thoughts why this might have occurred?
Here I also wonder if increasing the sensitivity level to trigger the unit might reduce the shift seen in the graphs?

In graph 2a the first shot appears to have a strong secondary spike that matches peak pressure level. But because the 1st spike is so low it appears the powder started to ignite, hesitated and then completed its burn. So I can’t really consider it a secondary spike but a delayed primary spike.

Am enjoying following your work on this project.
Thanks for taking the time to compile the graphs.


Ed

Well , here's what I see in the graphs---Richard is figuring out his instrument and pressures are lower than what I would have expected based on the velocities he is getting out of some of these loads.


Here's what I think I see in the graphs---some traces show a slower time to peak pressure(shift from left to right) which I believe could be a result of different loading pressure when the bullet is rammed home---kind of similar to what different neck tensions might do on a center fire cartridge?

Steve

You're not the first one to mention this. Given this latest round, the way I am personally interpreting these is that anything over 30K psi is a suspect load in my book. You don't get something for free; physics don't lie; if the pressures seem unusually low the most reasonable explanation is that the system is not correctly calibrated. This most recent round with loads I'm more familiar with has increased my thoughts on this. Yes, another explanation is that assumptions about what pressure we should see are wrong, but without a calibration load I take a conservative angle on what I put down my barrel. Personal choice!

Kudos to Richard (and Jon) for bringing all of this together. Breaking new ground increases the difficulty level -- like the lack of some validated reference load to calibrate the system and verify that the overall accuracy of the readings. Even without that, the ability to see how all of these loads compare to each other, in the same gun, allows very informative and valuable conclusions to be made. I already feel better about what I shoot in mine.

I ran a load close to one of the loads Richard posted from 12-28 using the following setup:

Computer: Dell Inspiron Mini Notebook Gage and Module Manufacturer = RSI USB model
Trigger Sensitivity = 5 Strain Gage Voltage = 4.9
Gage Factor =2.1 PSI Correction Factor: None
Barrel Temp = 68 IR Temp. measured at pressure transducer. Rifle Stand: Caldwell Lead Sled
Chronograph Chrony Alpha Model
Barrel Type: PacNor .45 Cal Stainless Muzzleloader
Breech Plug: Pa Machine Recessed (screw-in ventliner)
Barrel OD = 1.052 in Barrel ID = .452
Bullet Diam.= .448 resized Bullet Type = Hornady XTP #45230 Bullet weight = 300gr
Powder: N120 55gr Primer: Fed 209A Sabot: None
5 shots from barrel cleaned after each shot, 1 patch Bore Shine, 1 dry patch.

If you look at the stats, my pressure readings are somewhat higher that those seen in Richard’s data with average PSI close to 7kPSI higher than his average. If anything, I would have expected to see lower pressures given that his bullet was heavier with the same powder load. Pressure of one shot (#3) was significantly lower than the others, though the velocity of that shot was not. To me that suggests a problem with the sensor on that shot. For this run, I did not knurl or use a wad over the powder. In a second run, using the same load with an over-powder wad, both velocities and pressures were noticeably different and I will try to present those findings at a later date. There is quite a bit of dispersion in the pressure data. I believe some of this may be due to differences in bullet seating pressures and some due to the fact that I am new to this and still learning. These bullets were hard to seat! I had to use my entire body weight to get them seated and I am a little guy. On some it was not easy for me to tell when they were firmly seated. I hope I am not confusing the issue by posting this. If it seems to be, I will stop.

My readings were even higher!

dougsmessageboards.proboards.com/index.cgi?board=smokeless&action=display&thread=1751



I could send both of you a few of the bullets that I shot.
Will they fit, I don't know, but they are knurled for a short starter fit, NOT a slide fit. If interested let me know.

The only problem I have is I only have less than 10 bullets from that run and to ensure continuity the sized and knurled bullets should come from the same batch.

edge.

Well, I just got thru with about an hours worth of typing on this thread when my computer came up with some C_ _P! about MALWARE!!! In dealing with that, what I had typed got wiped out! and I just threw a "Hairy!" so this will be brief.
Tar....1 thru 4 sabot less and 5 &6 saboted.
I just sent Jim Ristow an e-mail with a number of questions and all the Tuesday's traces.
While the pressure level of the traces I am getting might be suspect, one this is certain in my mind. The triplex loads I have been shooting show lower trace pressures than some single and duplex loads. This is comparing oranges to oranges.
Bullet fit is another issue. Last week I hammered down a 250 gr. XTP and got 34,000 psi. This week the same bullet after resizing fit "hang on the rod" tight but did not need a hammer. 27,000 psi. This load also gave three of five shot at the same exact velocity with a low ES for all five.
In the end, for me? I believe I can develop good accurate loads with just my chronograph. I am convinced that my rifle can handle duplex loads pushing 3100+ fps safely and I am content staying well below that.
Man I was mad!!!
Richard

Richard,
I feel your pain! Computers are the Devil's Spawn!! My experience with those pop up notices that you got, is they just try to fool you into doing their scan, and sell you anti-virus/malware service. They are scams that can be a bear to delete.
You smart guys are leaving me in the dust with the scientific theorizing, but it seems to me the catch in all this, is having an accurate, and consistent, baseline starting point. I'm not sure how that can be accomplished using several different rifles and several different testing rigs, but I have every confidence that all you guys, working on this, will get it all figured out, and that the end results will be an important addition to the smokeless muzzleloading book of knowledge.
Boarhog

OK, so here is my letter to Jim Ristow and his responses:

On Dec 29, 2010, at 5:43 PM, Richard DeSimone wrote:


Jim: Several weeks ago I e-mailed you after the first time out with the PT II. I have included 6 traces from my third trip to the range. I am starting to get a little more familiar with the workings of the instrument and the program. As I had indicated, this is a .45 cal. SMOKE LESS muzzleloader. Due to the fact that I play with various powder charges of many different types including using two and three powders together (stacked) (fastest to slowest). I could not get an exact position to mount the strain gage. Plus the fact that I use a modified breech plug which has been recessed to fit 11 gr. of powder. Normally the powder would stack right from the front of the plug but in my case, part of the charge is in the plug. So, with say a 50 gr. charge of V V N-110 the strain gage is 1" from the end of the breech plug and .250" from the top of the charge...........so, not really centered. When I shoot a 65 to 70 gr. charge, it is more centered. Does this make a big difference in the pressure reading?
On PT #2a, the very first shot showed a really low trace line but the printed reading was up with the rest of the succeeding traces?
On the batteries.............How low can the voltage go before the unit fails to function? I have been checking the batteries with my digital volt meter each week. When I started shooting this past Tuesday, the voltage was at around 1.490 v or thereabouts.........When I finished they were around 1.414 v. I noticed the aux. power jack indicates 6 - 9 volt................So, if my batteries were down to 1 v. each, that would be 6 volts.........Is that the point where the unit would fail to function? Also, do you sell an external power supply? I see Radio Shack has them in various milliamp ratings. From you manual I see 100 mili amps are required.
One problem I seem to have is if I close out the (this is hard to explain) the program while shooting and then start it back up, OR when initially starting it, I have a problem getting the PT to talk to the computer? I usually have to go into the blue tooth part of my computer and check com ports and play games finding the one it wants to talk to?? It seems that port 4 is the one. How come it wants to loose this? Like I told you originally, I am no computer geek so this gets a bit frustrating. Any help? I hope I'm not being a PIA! Do the traces look OK? Mark Edgerton seems to feel the pressures might be a bit on the low side? Could anything I am doing cause this?
Thanks in advance
Rich DeSimone

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Richard;

Any firearm is a sealed but dynamic system until the bullet exits. Pressures in the system are
the same anywhere behind the bullet. The instructions indicate the ideal place for the gage is
over the main body of a necked cartridge because the chamber metal is thinner in that location
which serves to increase the system resolution (more movement) and smooth out traces.


The traces are nice and smooth and about what they should be. The ignition delays are typical
of ML's and might be helped by changing nipples, more consistent tamping, etc.


I believe PT #2 may have had a bad connection. Notice the odd squiggles mid point on that string.
Are you using the "Pause" menu when reloading? That will drop the system out of capture mode so
you can disconnect it and reload. When you continue it will also recalibrate the system.


The battery compartment holds 6 to ensure more then 5 volts is available for the system. It can
only detect low voltage when it is "not" in shot capture mode.


Unfortunately not all batteries are the same. Duracel brand seems to drop voltage quickly under
a load when the system enters capture mode (the highest consumption) while EverReady brand seem
to just slowly, and predictably loose power. Any 9 volt power supply "should" work if decent quality
and 200 milliamps or higher. If you have one from an old external hard drive, etc. it will be
better quality then something for a radio or kitchen appliance. A 100 milliamp may work but that's
getting minimal and some might drop voltage under a load if only 100. I would use one from an old
computer peripheral before buying something from Radio S**t.


If you are using an internal laptop's bluetooth it may use third party drivers. Check for an update
on the computer manufacturer's web site. When the laptop fully boots, if preferences in the BT
settings allow devices to auto discover/connect to the laptop, turning on the module should then
initiate the connection automatically and turn on the sync light so when you launch the program
all is ready. I would anticipate the drivers need updating or your preferences are not set
correctly. Check your BT control panel for items that might need to be changed.


The typical internal BT has only a 30 ft range (weak transmission) and you should notice the radio
does not broadcast well in all directions due to internal shielding. If this is the problem simply
locating the PT module on a different side of the computer may help.


Is the barrel Chrom Moly steel? Some ML's are mild steel which will affect readings. There is
an undocumented feature to change/over ride the default Chrom Moly values if you can learn the
Modulous and Poissons Ratio for the barrel steel. If you know what kind of steel it is there
are references on line that provide these numbers. Email if you need to change these numbers and
I can send the instructions. Or, Mark has been doing allot of this, you can simply try one of his
loads and add a correction.


Hope I answered all the questions.


Jim Ristow
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I am not sure I necessarily understand everything........
I did not change or alter the connection for T-2 so that one does not make sense?
I am using the Pause mode inbetween shots.
He talks about needing 200 mili amp but the instruction manual I downloaded from his web site indicates 100 mili amp? I don't happen to have a 9v. from some unused equipment?
I have not hooked up this lap top to my internet yet. I would assume everything should have been up to snuff since it was a"refurbished" Dell computer?
He keeps talking about barrel steel and chrome moly? Edge.......does stainless barrel steel have a different rating than CM? Do I need to do something here?
The PT II is kept only a foot or two away from the lap top as can be seen in the pictures from three weeks ago.

This computer stuff for a non-computer type person is not my cup of tea
Jon.........maybe you want to try your hand at this thing? ;D
Richard

So therefore, the stainless should be giving a higher reading than CM?
Richard

It would depend on the exact heat treatment of the steel to ascertain the modulus of elasticity.

In general both a 4130 CM or a 416r stainless barrel would be very close and probably around 29,000 ksi or 200 gigapascals.

I think that Jim may have been questioning the use of a non alloy steel as was used only for BP rifles and not standard rifle barrels.

edge.

In attempts to make pressure trace comparisons between different barrels, it goes without saying that testing conditions should be as close to the same for all as possible. That is often harder than it sounds. For instance, the trace I posted on 12-29 was shot using a load Edge first posted with a pressure trace in 6-09. As Edge stated, the peak pressure he posted was higher that either Richard or I recorded. When I asked Edge why my recorded peak pressures with the same load he asked whether I had used a wad over the powder and my answer was “no”. Yesterday, I had the chance to shoot and record peak pressures and velocities with everything being the same but with the addition of a fiber wad over the powder charge. This was my second run of the day and performed about 30 minutes after completion of the first run which I posted yesterday in this pressure trace discussion. The wad made from fiber gasket material (unlubricated, thickness=.030 in, diameter=.462 in.) was sold by Cabelas. The data and pressure graph are shown below under the same conditions I used in my post on 12-29 in this pressure trace discussion. Though nine shots do not present enough data to make a definitive statement about anything, there are some things which the data suggests:
1. Use of this wad under the conditions present at the time this study was performed increased average peak pressure by about 9k psi over average peak pressure measured when not using the wad.
2. Under conditions present at the time of this study, use of an over powder wad seems to decrease variance in both peak pressures and velocity and increase velocity a small amount.
3. Using a wad brings my peak pressure readings very close to those seen by Edge in June 09 shooting the same load. Of interest is whether Richard and/or Edge were using over powder wads when they tested this load?

OK.........First off, I only use Harvester smooth Easy Load sabots with my .40 cal. bullets. I use .060" veggie wads .462" diameter under every sabot less bullet.
Here is a second set of questions and the answers from Jim Ristow:

On Dec 30, 2010, at 11:27 AM, Richard DeSimone wrote:


Just a couple points..............First of all, this is an "inline" muzzle loader. There are no nipples. A shotgun 209 primer is forced by the bolt into a recess in the end of the breech plug. The opposite end of the plug is threaded 10/32 and a flat head screw with an .031" hole is screwed in. The flame from the primer is channeled thru the hole in the "vent liner/screw" to ignite the charge of smokeless powder. The small .031 hole is there to prevent a lot of pressure coming back to the bolt. In my case, I have modified the plug so the powder end is recessed, then re-drilled and taped for the vent liner. This puts the flame closer to the powder. This recess contains about 11 gr. of powder.
You have mentioned Chrome Moly steel.............These barrels are stainless from a custom barrel manufacturer called Pac-Nor www.pac-nor.com/ Would there be an appreciable difference in the expansion of the two and if so, would that be a factor?
Also, if you are advocating 200 milli amp on the auxiliary supply, your manual needs to be changed as it specifies 100.
Yes, I have been using the pause feature. Also, I never disconnect the rifle. It goes from the Lead Sled ( the rifle weights 13 lbs) to upright along side the bench for loading and then carefully put in place. I use the short pig-tail supplied and have it taped to the barrel. The main wire is secured with your velcro strap so it never moves. Actually the gun and sled only recoil about 3/4" each shot so there is not a lot of gun movement.
Again, thanks for being patient with me
Richard
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Richard:


The property of stainless will vary depending on the annealing step. Without testing it in a lab
there is no real way of knowing the numbers. Generally stainless barrels can read a little low, but
only a couple thousand PSI.


If an inline, I would try some different brand primers. There is allot of junk on the market right
now by normally good manufacturers.


A good 100 Milliamp power supply will work. Unfortunately some cheap supplies will drop voltage under
a load close to their max rating. That's why I suggested finding one from old computer equipment you have
laying around rated higher to 200 Milliamps.


Jim Ristow

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I have always and still do use Winchester 209 primers. My present batch was purchased about two years ago. Herman and I split 5,000.
I might try some CCI 209M primers I have but seriously doubt this will change anything as far as pressure goes. With pretty low Extreme Spreads, primers do not sound like an issue.
I suspect possibly............my firing pin might be causing some problem? Several weeks ago when I posted about problems with gas cutting on the firing pin support and the tip of my firing pin being eaten away? Well, I re-shaped it and extended it out further to compensate for the shortening. Anyway, I had another misfire last Tuesday and examination of the pin showed it was again cratered on the very tip. This could be causing irregular ignition. I have been generally shooting lighter loads and did not think this situation would return? Maybe cutting it back left metal that was less hardened? I would think something as thin as the firing pin would harden all the way thru? So maybe that is why its deteriorating? Anyway, I pulled it again and put a nice rounded, polished tip back on it and again extended it out further. I may just order a new one from Savage if it continues to wear.
Richard