7.62x39 supersonic but super-light loads?

Brobee

Brobee

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Hi there folks!

So while my 10 year old daughter is currently my shotgun-squirrel-hunting buddy extraordinaire, she has her sights set on deer hunting in a couple years when she hits the legal threshold of 12 years old.

She's 70lbs soaking wet and stands just under 4 feet tall - I've set her up with her first centerfire hunting rifle and it's a CZ 527 youth carbine in 7.62x39 that, while still just a bit big for her, she can position quite well and we've started practicing. The rifle is excellent for her vis-a-vis fit, however it is super-light and I'm hesitant to have her practice with full-power 7.62x39 loads as I want her to concentrate more on trigger control and sight picture rather than recoil management (as she does with her shotgun).

Hand loading with the intent to minimize recoil and get her clanking 8 inch steel plates at 100 yards or less, I started out with a load of 9.3 grains of Hodgdon Trailboss under a 123 grain hornady SST. She shoots it like a champ, however last week I hit the range by myself for one last safety test as the load seemed super-super-super light and my spidey senses were tingling.

Good thing I did, 'cause on the 98th round out of 100 that I fired to put my mind at ease, the bullet hung up 5mm from the crown, tip sticking out just a bit. While it only took just a small tap from a cleaning rod to pop it out, there is no way I am turning my daughter loose to practice with loads that have a chance of hanging up like that so.....back to the drawing board.

I've got lots of IMR 4198 on hand, and the lightest published load I can find is ~22grains @ ~2000fps. I have not tried it yet to see how powder-puffy it is in the recoil department; was kinda hoping for something in the 1500 to 1600fps range and wondering about reducing the charge weight further to 18 grains (75% of the max published load of ~24 grains). I'm wondering if there is anyone out there with either experience in light 7.62x39 (but not subsonic) loads or a copy of QuickLoad that might be willing to suggest some loads?

Many thanks,

Brobee
 
Innercity said:
Why not just bump the Trail boss load up a little? Say like 9.5-9.7Gr.
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Thought about this but Hodgdon says it is unsafe to create compressed loads with Trailboss.

9.3 grains is as much as I can get into the case before I would be compressing it....10 grains fills the case right up to the mouth.
 
I'd let her try a few regular loads. Odds are that with high quality hearing protection, and maybe just a touch of padding in a jacket, she will be able tohandle it just great. If, after a few, she flinches, move to a different load. Have you thought of a brake??
 
Well maybe Chrono some 17-18Gr loads with the 4198 and your shoulder behind it.

Best I'm coming up with online is 180Gr subsonic loads, yet I'm interested in this project for plinking loads.
 
You need to be using loads for cast bullets, which rarely exceed 2000 fps and make use of a vast range of powders. I think since you have IMR4198 you should use it as you've already suggested. I have found IMR4198 to be a great powder for reduced loads - no filler needed and no hangfires.

18.0 grs of IMR4198 with the common 123 gr jacketed bullet will give you between 1700-1800 fps.
 
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I have 93 gn .310 diameter cast bullets I was going to do some loading with for plinking. Haven't had time to get to them yet. These don't have gas checks so I guess would have to be loaded under 1500 fps to reduce chances of leading. Haven't worked with cast bullets before so it will be a new experience.
Scott...
 
Archer Sam said:
I have 93 gn .310 diameter cast bullets I was going to do some loading with for plinking. Haven't had time to get to them yet. These don't have gas checks so I guess would have to be loaded under 1500 fps to reduce chances of leading. Haven't worked with cast bullets before so it will be a new experience.
Scott...
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.310 is likely too small. My 527 had a .311" groove diameter and needed .313" to not lead. I just used .314" because Lee makes .311 and .314 nothing in between. Worked well. Have you thought about some of the pistol bullets made for I believe 7.62 Tokarev? Hornady makes a .312" XTP that's under 100 grains...90 or something. I've known people to use those over some Blue Dot with good success for reduced loads.
 
I'm working up a load for my CZ527M. So far this is what I have:

Berry 123 Gr .310 SP bullet
18.5 Gr of IMR 4198
Gecko Brass trimmed to 1.518"
Dominion Large Rifle Primer
C.O.L = 2.180" ~ 2.190"

Did not chrono it. Recoil was light from my cz527. Accuracy is good when they group, but I have a lot of flyers now and then that obviously do not belong to the group. I don't know if it's me or the load.

I tried anything from 16 Gr to 23 Gr in 0.5 Gr increment.
- Below 18 Gt I see lots of black soot on the brass after firing.
- Between 18~19 Gr gave me the best accuracy at 25 yard (have not take it out to 100 yet).
- At above 20 gr the accuracy degrade to be very poor (which I still don't understand, but at the moment I'm blaming it on the plated bullet I'm using. I will try out some Hornady jacketed bullet down the road).

Also went through about 10 round of 18.5 Gr in my Russian SKS, cycled no problem. Accuracy seems to be ok at 15 yard.

(Disclaimer: Use my info at your own risk, you may blow up your gun and hurt your etc. etc.)
 
The issue with the hung up bullet is more related to the rifle than the ammo. Very light ammo can stick in the bore if the barrel is very dirty. Clean the bbl regularly and you will never stick a bullet. If you are really worried about sticking a bullet, used lubed (either grease or moly) bullets.

I did a ton or work developing subsonic ammo and eventually stuck a couple. Somewhere I have a pic of a bullet just peaking out the tip of the barrel.

The upside is that with such light loads it is highly unlikely the barrel would rupture or even be damaged due to firing a second round. However pulling several bullets jammed into a bore may be a big problem.
 
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