7.62x39 – LeveRevolution Powder
In conjunction with a recent test of Junior1942s favoriteloads for his SKS using the RCBS 30-180-FN (197 gr cast of COWWs) I also tested the 7.62x39 cartridge with theGB C314-041 bullet with LeveRevolution powder.If you read the thread on Junior’s loas you saw that LeveRevolutionpowder under the heavier 197 gr RCBS bullet worked quite well in the 7.62x39cartridge.The RPM Threshold with COWWcast bullets was pushed up 150 + fps while maintaining quite less psi than withthe more popular medium burning powders such as 4895 and Varget.
Referring back to the 30-30 test I conducted withLeveRevolution powder it was found there a bullet of 170 + gr was really neededto get the LeveRevolution powder to burn efficiently.My testing of this powder with cast bulletsso far has consistently shown that LeveRevolution powder requires 26 – 28,000psi to begin burning efficiently.Withthe 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 gavevery 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 OALwas 2.206” the load density of LeveRevolution powder at 100% was 29.5 gr in theFL sized Winchester cases.I ran an initialpressure/velocity work up from 26.5 gr to 29.5 gr.That showed the 29.5 gr load might be 25,000psi at around 1900+ fps.I loaded 10shot test strings of 27.5, 28.5 and 29.5 gr to test.
Results;
Testrifle; Interarms Mini Mk X
Caliber;7.63x39
Bore;.301
Groove;.311
Barrellength/twist; 20”/1-9.5”
Sights;Bushnell 4X scope
Testequipment; Oehler M43 PBL
Range;Sara Park, Lake Havasu City, AZ
Testrange; 100 yards, solid cement benches
[FONT="Times New Roman"][SIZE=3][COLOR=#000000][FONT=Calibri]Rest;Hoppe’s front and leather sand bag (rabbit ear) rear
Attachment 150923
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 caseneck with light crimp under driving band.
The 27.5 gr load; we see this load did not burnefficiently at all. The cases were sooty clear back the case head and aroundthe rims.The large ES of velocity andgroup size of 5.5’ says it all.I tracethrough the target bullet holes onto the data sheet for a record of the group.
Velocity; 1781 fps
Psi(M43); 22,000
Accuracy; 5.5”
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Attachment 150927
28.5 gr; Accuracy got better and the ES was about half ofthe previous load.This indicates thepowder is starting to burn more efficiently except there still was soot abouthalf way back along the cases indicating the pressure curve was not sufficientfor the case to obdurate and seal the chamber.
Velocity;1884 fps
Psi(M43);23,900
Accuracy;3.6”
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Attachment 150928
29.5 gr; things are beginning to come together.The psi is still a bit low as we see a coupleof the shots fell out the bottom psi wise.The velocity ES is very good and the accuracy given the velocity is alsoquite good.Still some sooting of thenecks and shoulder area on the cases indicating obturation of the case is stilla problem.The average psi is stillbelow where LeveRevolution really burns efficiently.
Velocity;1944 fps
Psi(M43);24,800
Accuracy;2.5”
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Attachment 150929
Perhaps in the test rifle which is a bolt action necksized fire formed cases will allow 30 gr or maybe 30.5 gr of LeveRevolutionpowder with this 175 gr bullet in the small 7.62x39 case.If so then the psi may get high enough forefficient powder burning.However, forthose who might want to use this powder in the SKS or AK I suggest a heavierbullet of 180 at least and perhaps 185 gr or use the RCBS 30-180-FN which seemsto cast on the heavier side.
Larry Gibson