Originally Posted by burnsoft
My First Batch that i'm going to test out saturday is using the hornady 123G Z-Max with Winchester Large Rifle Primers
Winchester Cases, and two set of powder loads
H322 @ 26.2g
H322 @ 27.6g
Using a 1-10 twist in the barrel
All the other powders for that load sheet i posted i don't have, which will need to do some research and testing to see if
IMR3031, IMR4064 and VihtN140 will work and what to start out with.
Any recommendations for a good 100 yd. 7.62x39mm?
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I haven't used H322 in 7.62x39 but some people claim it works really well. I have used it in other calibers and I think it might might be a bit slow for 7.62x39 but it shouldn't be bad. Hopefully you got a good batch of Winchester primers. Their quality has seemed to have dropped off recently.
The load guides require a lot of study and some experience with this caliber. First the old pressure limit using the copper crusher CUP method was 45,000 CUP in Europe and Ruger is the company that submitted the cartridge to SAAMI but Ruger bumped up the pressure limit to 50,000 CUP because this was about what they got firing a .311" diameter in a .308" barrel bore, with a "standard" chamber. Ruger also modified the chamber to reduce the pressure increase effects of firing a larger bullet in a smaller bore.
Ruger determined that both their rifles and Colt's could handle the pressure. Then SAAMI switched to transducer PSI method of pressure measurement. This resulted in some high number that was considered too much, so SAAMI knocked the specs all the way down to 45,000 PSI transducer, not CUP copper crusher.
This low pressure limit set by SAAMI caused a lot of the load guides to go very mild with their load data. More recently the powder companies have updated their load data to be more practical and closer to the standard European pressure limit.
Some manuals have some very hot load data, like the Speer manual does with some powders. The Sierra load guide has load data for both .308" bullets and .311" bullets. The load data is not very different for the two sizes and it isn't too hot and it's not bad with some powders.
Of the best powders I've found are, H4198, A1680 and RL-7. A note about the current IMR-4198. It is not the same powder that most of the load data used. It used to made in Canada and was less dense than H4198. It filled the case full. It had a larger diameter and longer kernel size than H4198 and it was black due to graphite. Now IMR-4198 is made in Australia. It is the same powder as H4198 but is cut longer and is dyed black to "look" like old IMR-4198 It does now have the smaller diameter of H4198. The older load data is usually based on how much could fit inside the case as the burning rate wasn't much different from H4198. Using either H4198 or IMR-4198, I recommend using H4198 load data. The shorter cut H4198 is easier to measure, so there isn't much point in buying IMR-4198 anymore.
Hornady used to make super accurate .311" FMJ bullets that weighed 123 grains. They have replaced them with 123 grain .310" FMJ bullets that aren't as accurate, in European firearms anyway. I think the AR15 might have a .308" diameter bore. The Hornady SST which I think is the same or similar to the Z0max bullet should be very accurate. The Speer 123 grain bullet is accurate. Sierra makes some bullets but they may be more for 303 British velocities.
From the powder companies the load data that is good is,
123 grain bullet
26.5 grains H4198
27.0 grains A1680
27.0 grains RL-7
There is at least one load guide that shows 22.5 grains of IMR-4227. This isn't a bad load but it may not provide enough gas for some rifles. I have bumped this load up a bit but pressure increases quickly.
Speer shows 28.0 grain of A1680. This may be too hot for some rifles.
One load guide had 30.0+ (30 plus) grains of RL-7. It is in the slower range of powders but seems like too much to me. Norma had a slightly lower max load of N-200.
The Lyman load data is mostly useable but I think the load data from powder companies seems best and the most up to date.
Winchester cases often do not last for many, if any reloads in this caliber. The Lapua cases are more expensive but should last for a few reloads. In an AR15 the Winchester cases may last better than in some other rifles though.
Most die sets come with two neck expanders. One is meant for .308" bullets and one is meant for .311" bullets. Often the .311" expander is a loose fit, even on .311" bullets, maybe due to the 7.62x39 case neck. The .308" expander often works well with .310" and .311" bullets, especially if they are boat tail bullets and the case life may be longer. It depends on the brand of dies which expander will work best but I like to use the tightest one that will allow seating the bullets.