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    • #31759
      Larry Gibson
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      A couple years ago I completed a test of heavy duty cast bullet hunting loads for use in 7.62×39 bolt guns, and the SKS. These should also be useful in Mini 14 Ranch rifles and AR15 7.62x39s. As always start low and work up in your rifle.

      Larry Gibson

      Junior1942’s 7.62×39 loads

      During the latest thread on LeveRevolution Powder Junior1942 PM’d me asking about the 30-30 testing I had done with the RCBS 30-180-FN and that powder. He asked about the test and was trying to correlate the psi’s from that test to the 7.62×39 for possible use in his Yugo SKS. He primarily was interested to see if the LeveRevolution powder would give him a bit better performance under his COWW cast bullets which weight 197 gr. I suggested there was no sense trying to correlate when I could pressure test in the 7.62×39 also. I suggested he send some bullets and the data for his other powder loads and I would pressure test those also. Junior thought that was a great idea. He asked how many bullets? I told him a hundred minimum.

      Junior scrounged around and found about a hundred (104 to be exact) he had already cast and said he’d cast up some more and send ’em if need be. He said a few were wrinkled. Told him they’d be fine for the initial LeveRevolution work up as we were interested there was the psi. I got the bullets a couple days later. They were sized at .314, had Hornady GCs and were lubed with LLA. The BHN measured 11 – 12. I proceeded to check out the Mini Mk X Mauser I would use for the test. Unfortunately the strain gauge had partially cracked for some reason. It hadn’t been used in over 2 years and the change in location, temperatures and humidity are my guess why. Called the company to order some more gauges and they would take about 6 – 7 weeks. Told Junior and he was a bit down over that. However, in about 2 weeks a package showed up with the strain gauges.

      I PM’d Junior and told him I was ready to test and asked a couple clarification questions about his standard loads. I didn’t hear back from Junior and just assumed he was away or busy. I did not know he had gone to the big range. I proceeded with the test and will post the results here…..for Junior…..rest in peace, may the sun always be to your back, the wind in your face and all your shots go true.

      Test rifle; Interarms Mini Mk X
      Caliber; 7.63×39
      Bore; .301
      Groove; .311
      Barrel length/twist; 20″/1-9.5″
      Sights; Bushnell 4X scope

      Test equipment; Oehler M43 PBL

      Range; Sara Park, Lake Havasu City, AZ

      Test range; 100 yards, solid cement benches

      Rest; Hoppe’s front and leather sand bag (rabbit ear) rear

      Test shots; due to limited number of bullets not all test strings had 10 shots. Some had less but not less than 7 shots. The LeveRevolution psi workup had 2 shots per powder charge.

      The test was conducted on two separate days early in the mornings. This gave the least heat (this is the desert with day time temps running 105 – 115) at daybreak (85 – 90) and the least wind. Juniors standard loads and the LeveRevolution psi work up was conducted on the 1st day along with a LeveRevolution psi workup with a 175 gr C314041 cast bullet of my own. The second day was the test of 3 loads of the LeveRevoltuion under Juniors 30-180-FNs and 3 loads under my own C314041.

      The 1st day’s tests;

      Reference ammunition test; The CIP Pmap (Maximum Average Pressure) for the 7.62×39 cartridge is 51,500 psi (peizo-transducer or strain gauge. Three factory loads were tested to set a base line for the mini Mk X.

      Wolf Factory FMJ
      Velocity; 2498 fps
      Psi(M43); 46,400
      Accuracy; 5.4″

      The pressure trace for this load was also graphed out to calculate the approximate psi at the gas port of a SKS. The Gas port was measured at 13.4″ from the bolt. Gas port psi with this load was approximately 13,200 psi.

      Herter’s Factory FMJ

      Velocity; 2549

      Psi(M43); 46,100

      Accuracy; 3.3

      Wolf Factory HP

      Velocity; 2581 fps

      Psi(M43); 46,700

      Cases; IMI 7.62×39

      Primers; CCI 200

      Bullet; 30-180-FN (197 gr)

      Cartridge OAL; 2.24 (fit the test rifle magazine and my Russian SKS and fed fine from both) which put the top of the GC right at the case neck.

      Crimp; Roll under the 3rd drive band


      Junior used 3 different powders for his standard loads; Varget, H4198 and surplus 4895. He sent 3 loads for the Varget and 4895 to test and 2 for the H4198.

      Varget loads; Junior sent 3 test loads for Varget powder; 23.3 gr, 24.7 gr and 26 gr. Junior stated the 26 gr load was compressed and it was.

      23.3 gr;
      Velocity; 1608 fps
      Psi(M43); 27,200
      Accuracy; 2.1″ (7 shots)
      24.7 gr;
      Velocity; 1700 fps
      Psi(M43); 30,300
      Accuracy 1.78 (8 shots)

      26 gr;
      Velocity; 1778 fps
      Psi(M43); 35,100
      Accuracy; 4″ (8 Shots)

      We see here the RPM Threshold of these components is between 1700 fps and 1778 fps. Accuracy went from very good at 1700 fps and 128,800 RPM to poor at 1778 fps and 134,700 RPM.

      Junior specified two loads for H4198 powder; 21.3 gr and 22.7 gr.

      21.3 gr;
      Velocity; 1820 fps
      Psi(M43); 42,200
      Accuracy; 4.9″ (8 shots)

      22.7 gr;
      Velocity; 1925 fps
      Psi(M43); 50,700
      Accuracy; 7.5″ (8 shots)

      With these two loads of H4198 we see higher psi’s and velocities and poor accuracy. Both loads exceeded the RPM Threshold for these components. The RPM was 137,900 and 145,900. The 22.7 gr load also came very close to the CIP Pmap.

      Junior specified three loads of surplus 4895; 23.4 gr, 24.5 gr and 24.7 gr. Hard to say how close our different lots of 4895. I have two lots and used the one that is closest to IMR4895 in burning rate.

      23.4 gr;
      Velocity; 1706 fps
      Psi(M43); 32,300
      Accuracy; 3.3 (8 shots)
      Note; comparing the accuracy with the Varget 24.7 gr load we see the Varget load is more accurate ate very close to the same velocity. Note however, the Varget load has the lower psi meaning the time/pressure curve was slower. We see that in the pressure traces and in the “Rise” data. The 4895 load reached pressure in 129 microseconds while the Varget load took 144 microseconds. Seemingly not much of a difference but when pushing the RPM Threshold the devil is in the details. Top trace is the 4895.

      24.5 gr;
      Velocity; 1767 fps
      Psi(M43); 35,200
      Accuracy; 4.8″ (8 shots)

      24.7 gr;
      Velocity; 1778 fps
      Psi(M43); 35,800
      Accuracy; 4.5″ (8 shots)

      Junior’s chronographed velocities were about 80 fps less than the ones I recorded. The velocities I list are corrected to the muzzle and different rifles were used of different actions. Additionally the lot to lot variation of the powder used and I was testing in 85 – 90+ degree temps all combine for the differences. For what Junior was looking for (a “smack down” hog load for 100 yards or less) his Varget or 4895 loads would have been fine.

      LeveRevolution Powder with the 30-180-FN at 197 gr in the 7.62×39

      I did a “workup test” using LeveRevolution powder. What I do is usually load 2 cartridges (sometimes just one) of increments from a start to a projected “max” load. I used to call this “ladder testing for velocity and psi” but too many confused this with the “ladder test” commonly used for working up loads. What I do does not consider accuracy at all. My testing is concerned with velocity and psi.

      With LeveRevolution powder I worked up from 23.5 gr to 28.5 gr in 1 gr increments. 28.5 gr was at 105% load density with the RCBS bullet. Velocities ran from 1554 fps to 1924 fps with psi’s from 20,100 to 36,300. Knowing the RPM threshold was between 1700 fps and 1750 fps with the other powders I loaded 25, 26.5 and 27.5 gr looking for velocities from the mid 1600s to the mid 1800 fps. The idea was to see how far the much slower burning LeveRevolution with its radically different time/pressure curve would push up the RPM Threshold.

      25 gr;
      Velocity; 1668 fps
      Psi(M43); 22,400
      Accuracy; 6″ (7 shots) and very poor. There was soot blown back the expansion ring on the cases indicating poor breech sealing.

      26.5 gr;
      Velocity; 1771 fps
      Psi(M43); 26,500
      Accuracy; 2.4″ (9 shots) no sooting on cases. Accuracy definitely improved.

      27.5 gr;
      Velocity; 1843 fps
      Psi(M43); 28,700
      Accuracy; 2.65″ (9 shots) definitely pushed the RPM Threshold up as RPM is 139,700. 28.7 gr is worth a try but alas I am out of the RCBS 30-180-FN bullets………note on the target the 1st and 2nd shots were right at the bottom of the target I was using. To make sure I didn’t lose any shots off target I moved the scope elevation up 3 moa. Those 1st two shots would have been in the group.

    • #31760
      Larry Gibson
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      (Cont’d)

      This definitely should be the better “smack down” load in the SKS that Junior wanted. Graphing out the psi at the gas port shows a projected 8000 psi which is less than with the different Russian made factory 7.62×39 ammunition. I would have tested this load in my own SKS but again, I am out of the bullets! Perhaps Junior is hunting with this load already! I sure hope so……and I’m sure he wouldn’t mind me sharing with all of you. That’s the kind of guy Junior was. He loved to share here and on his own web site. I will miss Junior……….

      Larry Gibson

      Continued test with 311041 and LeveRevolution

      In conjunction with a recent test of Junior1942s favorite loads for his SKS using the RCBS 30-180-FN (197 gr cast of COWWs) I also tested the 7.62×39 cartridge with the GB C314-041 bullet with LeveRevolution powder. If you read the thread on Junior’s loas you saw that LeveRevolution powder under the heavier 197 gr RCBS bullet worked quite well in the 7.62×39 cartridge. The RPM Threshold with COWW cast bullets was pushed up 150 + fps while maintaining quite less psi than with the more popular medium burning powders such as 4895 and Varget.

      Referring back to the 30-30 test I conducted with LeveRevolution powder it was found there a bullet of 170 + gr was really needed to get the LeveRevolution powder to burn efficiently. My testing of this powder with cast bullets so far has consistently shown that LeveRevolution powder requires 26 – 28,000 psi to begin burning efficiently. With the 30-180-FN seated to max magazine length for the SKS 27.5 gr gave about 105% load density and produced 28,700 psi(M43) under the RCBS 197 gr bullet and gave very good accuracy at 1843 fps out of the test rifles 20″ barrel.

      The question was; would the 175 gr (COWWs + 2% tin at 13 – 15 BHN) GB C314-041 provide enough mass for LeveRevolution to burn efficiently? With the bullet seated so the cartridge OAL was 2.206″ the load density of LeveRevolution powder at 100% was 29.5 gr in the FL sized Winchester cases. I ran an initial pressure/velocity work up from 26.5 gr to 29.5 gr. That showed the 29.5 gr load might be 25,000 psi at around 1900+ fps. I loaded 10 shot test strings of 27.5, 28.5 and 29.5 gr to test.

      Results;

      Test rifle; Interarms Mini Mk X
      Caliber; 7.63×39
      Bore; .301
      Groove; .311
      Barrel length/twist; 20″/1-9.5″
      Sights; Bushnell 4X scope

      Test equipment; Oehler M43 PBL

      Range; Sara Park, Lake Havasu City, AZ

      Test range; 100 yards, solid cement benches

      Rest; Hoppe’s front and leather sand bag (rabbit ear) rear

      Bullet; Lee Group buy 6 cavity C314-041
      GCs; mine out of .014 brass shim stock
      Lube; NRA 50/50
      Sized to; .312
      Alloy; COWWs + 2% tin AC’d BHN 13 – 15

      Cases; Winchester, FL sized

      Primers; CCI 200

      Cartridge OAL ; 2.206″ with GCs at the bottom of the case neck with light crimp under driving band.

      The 27.5 gr load; we see this load did not burn efficiently at all. The cases were sooty clear back the case head and around the rims. The large ES of velocity and group size of 5.5′ says it all. I trace through the target bullet holes onto the data sheet for a record of the group.

      Velocity; 1781 fps
      Psi(M43); 22,000
      Accuracy; 5.5″

      28.5 gr; Accuracy got better and the ES was about half of the previous load. This indicates the powder is starting to burn more efficiently except there still was soot about half way back along the cases indicating the pressure curve was not sufficient for the case to obdurate and seal the chamber.

      Velocity; 1884 fps
      Psi(M43); 23,900
      Accuracy; 3.6″


      29.5 gr; things are beginning to come together. The psi is still a bit low as we see a couple of the shots fell out the bottom psi wise. The velocity ES is very good and the accuracy given the velocity is also quite good. Still some sooting of the necks and shoulder area on the cases indicating obturation of the case is still a problem. The average psi is still below where LeveRevolution really burns efficiently.

      Velocity; 1944 fps
      Psi(M43); 24,800
      Accuracy; 2.5″

      Perhaps in the test rifle which is a bolt action neck sized fire formed cases will allow 30 gr or maybe 30.5 gr of LeveRevolution powder with this 175 gr bullet in the small 7.62×39 case. If so then the psi may get high enough for efficient powder burning. However, for those who might want to use this powder in the SKS or AK I suggest a heavier bullet of 180 at least and perhaps 185 gr or use the RCBS 30-180-FN which seems to cast on the heavier side.

      Larry Gibson

    • #31775
      kens
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      Good info there, Thanks Larry.
      I put together a M98 mauser with a 7.62×39 barrel, it has a .308 bore. It is a tack driver with good factory ammo, a few cast loads did show promise, then I put it up for awhile.
      My guess that you could possibly shoot a 200gr cast with LeverR powder , and get your pressure for efficient burning, maintain your 1700fps / rpm threshold at the same time.
      That would be a real McCoy deer slayer with 200gr cast @ 1700fps.

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