Pressure Trace Jan. 24, 2011
Jan 24, 2011 20:51:37 GMT -5
Post by Richard on Jan 24, 2011 20:51:37 GMT -5
DISCUSSION THREAD CAN BE FOUND BY FOLLOWING THIS LINK
OK, today’s weather was excellent for shooting. Outside was 32 to 40* with no wind and mostly cloudy. Of course, always toasty inside!
I had a theory that the recessed breech plug might be causing some of the lower pressure readings so to debunk it, I installed a brand new Savage plug with their vent liner. My first two loads were shot so they could be compared with last weeks…………“recessed vs. Non recessed”
The first thing I noted was a duplication of what happened last week on my first two groups with straight 50 gr. of N-110. The first two shots went three inches left and maybe 6” low?
?? This phenomenon has never happened to me before last week………..But then again, I never shot straight N-110 (maybe being a cold barrel?). Note: as I was having problems getting the Trace to talk to the computer, when I finally got it going, I forgot to turn on the chronograph for the first two shots. That being said, the velocity was almost identical to last weeks test……..2842 this week and 2832 last week. Pressure last week 32,626.……..this week 34,978. So, was this the recessed plug vs. the non???
To get another comparison, I shot the same load of 13/55 and got an average velocity of 2871 vs. 2793 last week. Pressure this week of 28,710 ….last week mid to high 27,000. Fairly low ES’s both times!
Next, I shot a powder I hardly ever shoot…………Yes, SR4759. I forgot to load this powder up for last weeks side by side tests with N-110 and 5744 so today I shot 50 gr. of it and got a good surprise……..It shoots darn good as a single in the PN.
On target #4 I tried another variation of 13/55 using Re-7 for the main charge. Man, this one moves the velocity right on up.
Now here is the kicker with 5744.…………I shot four groups with the same 13/55 combination only substituting 5744 for N-110 and all four targets reflect higher velocities along with higher pressures.
Please note that on target #5 with the Barnes 195’s? After I got done with the traces I did something stupid and clicked on something wrong and lost all the information………..Just like that the screen lost all those little blips L. Fortunately, I had physically written down all the velocities but not the pressures. They were running in the 28,000’s. Dadgum computersL
Since I was numbering the traces, I just skipped that one. The target is there and it is labeled “No Trace Group”
The remaining targets are self explanatory.
After this session, I really do not see any big difference in recessed vs. non-recessed breech plugs. I do believe that cold weather ignition would probably benefit from it and I like the fact it concentrates the starter powder in a duplex load??
I will have a few more comments on other aspects of the days shooting but will save them for discussion.
Richard
OK, today’s weather was excellent for shooting. Outside was 32 to 40* with no wind and mostly cloudy. Of course, always toasty inside!
I had a theory that the recessed breech plug might be causing some of the lower pressure readings so to debunk it, I installed a brand new Savage plug with their vent liner. My first two loads were shot so they could be compared with last weeks…………“recessed vs. Non recessed”
The first thing I noted was a duplication of what happened last week on my first two groups with straight 50 gr. of N-110. The first two shots went three inches left and maybe 6” low?
?? This phenomenon has never happened to me before last week………..But then again, I never shot straight N-110 (maybe being a cold barrel?). Note: as I was having problems getting the Trace to talk to the computer, when I finally got it going, I forgot to turn on the chronograph for the first two shots. That being said, the velocity was almost identical to last weeks test……..2842 this week and 2832 last week. Pressure last week 32,626.……..this week 34,978. So, was this the recessed plug vs. the non???To get another comparison, I shot the same load of 13/55 and got an average velocity of 2871 vs. 2793 last week. Pressure this week of 28,710 ….last week mid to high 27,000. Fairly low ES’s both times!
Next, I shot a powder I hardly ever shoot…………Yes, SR4759. I forgot to load this powder up for last weeks side by side tests with N-110 and 5744 so today I shot 50 gr. of it and got a good surprise……..It shoots darn good as a single in the PN.
On target #4 I tried another variation of 13/55 using Re-7 for the main charge. Man, this one moves the velocity right on up.
Now here is the kicker with 5744.…………I shot four groups with the same 13/55 combination only substituting 5744 for N-110 and all four targets reflect higher velocities along with higher pressures.
Please note that on target #5 with the Barnes 195’s? After I got done with the traces I did something stupid and clicked on something wrong and lost all the information………..Just like that the screen lost all those little blips L. Fortunately, I had physically written down all the velocities but not the pressures. They were running in the 28,000’s. Dadgum computersL
Since I was numbering the traces, I just skipped that one. The target is there and it is labeled “No Trace Group”
The remaining targets are self explanatory.
After this session, I really do not see any big difference in recessed vs. non-recessed breech plugs. I do believe that cold weather ignition would probably benefit from it and I like the fact it concentrates the starter powder in a duplex load?
?I will have a few more comments on other aspects of the days shooting but will save them for discussion.
Richard
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