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Post by TGinPA on Mar 28, 2011 13:27:54 GMT -5
Pressure Trace: PN45 N120 60gr 200xtp Because others have noted good accuracy with N120 as a single at powder weights close to this, I tested this load today. Gage and Module Manufacturer = RSI USB model Trigger Sensitivity = 2, Strain Gage Voltage =4.9 Gage Factor =2.1 PSI Correction Factor: 0 Barrel Temp = 60-66 degrees F. measured at the sensor (IR). Rifle Stand: Caldwell Lead Sled Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (8 fps added to all recorded velocities to correct for distance of chrony from muzzle.) Barrel Type: PacNor .45 Cal Muzzleloader Barrel OD = 1.06 in Barrel ID = .452 Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=1.1 in. Bullet Diam.= .458 in. Bullet Type = Hornady 10mm xtp Bullet weight = 200gr. ,unknurled. Sabot: Harvester Smooth Blue. Wads: .060 x .462in. fiber (Cabelas) under lubed wool wad Powder: All Traces: N120 60gr. Primer :Fed 209 Shot fm dirty barrel. This load seemed safe in my barrel under the test conditions but may not be so in other conditions.  Of interest are peak pressures in the low 30k psi range with relatively gentle upslope of the pressure curve and with peak pressures occurring at least .38 milliseconds after initiation of the upslope of the curve. As I collect more data (IMO) all three of those factors seem to favor sabot stability. Also of interest is the low 3 shot extreme spread of velocities for this load even in the presence of prominent secondary pressure peaks. Comparing this trace with a trace I made on 3/1/2011 in which N120 65gr was used behind the same bullet but without wads, average velocities were about 150 fps slower but velocity ES was lower (by 18fps). IMO, pressure testing suggests accuracy potential for this single powder load. TG |
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Post by Savage Shooter on Mar 28, 2011 13:55:57 GMT -5
The 2nd spike with this load at both 60 and 65gr loads has me scratching my head. I expected there to be much less spike looking at the level of accuracy I am seeing with it. I too have noticed how much lower ES it gives, it shows on target.
P.S. You are right on about the time extending out in milliseconds to peak pressure, this is where speed is being made without additional pressure.
Also spot on about the slow rise (flat dip) on the upside of the curve and what it does for the sabot, IMO this is crucial for sabot integrity.
Good work.
Mark
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Post by Richard on Mar 28, 2011 14:03:17 GMT -5
TGinPA..........I looked back thru my notes and could not find any traces I ran with 60 gr. of N-120 with a saboted 200 gr. bullet. I did find that I shot 55 gr. N-120 with a 200 XTP and blue Harvester and recorded 2552 fps, ES=48 and Av. Pressure = 21,967. I also recorded 55 gr. of N-110 with the 200 XTP and recorded 2934 fps, ES=40 and average pressure at 36,101. So, my question is...........would it be possible for you to run traces on both these loads (when you get a chance) for a comparison. This is the first trace you have run that is in the same neighborhood as mine. Maybe some correlation could be made? Savage shooter had asked me whether I had shot 5744 as a single? On 1/12/11 (see traces for that day) the 200 XTP, blue Harvester and got 2744 fps average for four shots, ES was 17 fps and pressure was 34,128 psi. Mark then sends me a second PM and says "never mind"......I'm blowing sabots at 45 gr.  ? I was able to put 3 shots in 1" with the fourth making it 2.2" but no blown sabots? Maybe a trace could be run here? Thanks Richard |
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Post by Savage Shooter on Mar 28, 2011 14:12:20 GMT -5
TGinPA..........I looked back thru my notes and could not find any traces I ran with 60 gr. of N-120 with a saboted 200 gr. bullet. I did find that I shot 55 gr. N-120 with a 200 XTP and blue Harvester and recorded 2552 fps, ES=48 and Av. Pressure = 21,967. I also recorded 55 gr. of N-110 with the 200 XTP and recorded 2934 fps, ES=40 and average pressure at 36,101. So, my question is...........would it be possible for you to run traces on both these loads (when you get a chance) for a comparison. This is the first trace you have run that is in the same neighborhood as mine. Maybe some correlation could be made? Savage shooter had asked me whether I had shot 5744 as a single? On 1/12/11 (see traces for that day) the 200 XTP, blue Harvester and got 2744 fps average for four shots, ES was 17 fps and pressure was 34,128 psi. Mark then sends me a second PM and says "never mind"......I'm blowing sabots at 45 gr. ? I was able to put 3 shots in 1" with the fourth making it 2.2" but no blown sabots? Maybe a trace could be run here? Thanks Richard Thanks Richard My bad I should have stated that it appeared in the traces TG performed today that he thought 5744 due to the big fall off in speeds he had it appeared to blow sabot at 45gr. I have not shot any loads with 5744 as a single. But it appeared to me from TG's info that sabots were letting go, at first glance. Sorry did not mean to confuse, but see where it would. Also had asked Edge for QL info, but that was before TG sent me PT data on the load. I am sure TG will be posting results of the 5744 PT's later. |
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Post by TGinPA on Mar 28, 2011 14:56:30 GMT -5
Richard: The difference between your 1/12 numbers and mine doesn't make sense. The only explanation I can think of is an error in my velocity readings. I had decided not to redo the pressure readings because the velocity readings are usually the most reliable. Something is wrong here and think it is most likely in my numbers. So, I will repeat the test tomorrow, weather permitting. QL numbers may be helpful as well.
TG
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Post by jims on Mar 28, 2011 15:42:18 GMT -5
I am awaiting the new testing. That load looks like it has some real possibilities.
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Post by TGinPA on Mar 28, 2011 16:38:45 GMT -5
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Post by Savage Shooter on Mar 28, 2011 17:59:13 GMT -5
You know the N110/H322 at 15/55 has produced a good reproducible trace several times but pressures are about at peak for what sabots can stand in anything but super cold barrel.
Have you given any thought to using N120 under the H322 at the same rate or a touch more H322 to see how it reacts.
I keep coming back to the "soft start" we keep seeing on the upside of all the N120 based curves.
If we have enough barrel to burn 72-73 grs this might get our speed up without putting quite so much on the sabot.
The N120/H4198 type loads were still building just a touch too much pressure with higher ES. They were extending the time under the curve and getting the speeds and pretty accurate, just a bit too much pressure to stay dependable year round.
Might be worth looking at.
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Post by Richard on Mar 28, 2011 18:33:04 GMT -5
TG.........I see what you mean! You are showing about 10K more pressure with only about 25 fps more velocity  And I was not cleaning my barrel during that test either?  So, the quandary is............Which PT is right? I would think your velocity should be up around 3000+ fps rather than 2860. Hmmmmmmmm? Richard |
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Post by ET on Mar 28, 2011 22:08:19 GMT -5
TGinPA
Just playing with my Point Blank program I find that the distance from the muzzle to your chronograph you are losing slightly over 100fps. So if you added at least 100fps this would closer represent your actual muzzle velocity.
I agree that rate of pressure rise is a key element to keep an eye on and that should include the secondary spike. From what I read a secondary spike occurring before the bullet exits the bore can help aid velocity to a given load. But how much of a secondary spike is one comfortable with?
On this last trace I also noted that as the primary pressure increased the secondary pressure indication decreased. The first shot I assume from a cold barrel had the least primary pressure of the 3-shots. In order for the next 2-shots to have increased primary pressure with the same load the barrel had to of warmed up some.
Makes me wonder if this info might be somehow used to determine how responsive a powder load is to temp change?
Ed
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Post by Savage Shooter on Mar 29, 2011 6:57:20 GMT -5
TGinPA Just playing with my Point Blank program I find that the distance from the muzzle to your chronograph you are losing slightly over 100fps. So if you added at least 100fps this would closer represent your actual muzzle velocity. Ed I must be missing something, I too use 1fps per foot of distance to chronograph. I see that TG is setting chrono at 8ft from muzzle so he should add 8fps to chrono reading and that is what he has done. Am I missing something? I have noticed that TG's barrel is a bit faster than I can reproduce with any load across the board, but barrel difference can easily cause this. The load traced above I am getting 2760 at about 10ft from the muzzle so I think the fps is right on. Mark |
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Post by edge on Mar 29, 2011 7:48:56 GMT -5
I estimate about 15 fps at 9 feet (3 yards) from the muzzle if starting at 3000 fps.
edge.
EDITED.
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Post by Savage Shooter on Mar 29, 2011 8:24:50 GMT -5
When I plug in all the parameters of this load using BC of .19 into JBM using 2750 chrono reading at 8 ft (TG's distance) i get a MV correction of 2763.
13fps change at 8 feet. I am doing something wrong?
If I use all equal parameters and just change the BC to .4 then the MV correction goes to 2756 or a 6fps change at 8ft.
I have found that BC under .3 will average velocity correction of about 1 to 1.5 fps per foot and BC over .3 will average 0.5 to 1.0 fps per foot so I have always just used 1fps per foot on average.
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Post by edge on Mar 29, 2011 13:04:34 GMT -5
I edited mine to about 15 fps from 3000fps @ 9feet. I misread my notes and used energy by mistake  edge. |
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Post by ET on Mar 29, 2011 16:13:56 GMT -5
Sorry my mistake in reading the numbers off my point blank calculator.
It is 15fps as Edge pointed out.
Ed
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? I was able to put 3 shots in 1" with the fourth making it 2.2" but no blown sabots? Maybe a trace could be run here?
And I was not cleaning my barrel during that test either? 
So, the quandary is............Which PT is right? I would think your velocity should be up around 3000+ fps rather than 2860. Hmmmmmmmm?
