7.62x39 Question

[chrisf8657]

Hi guys,

Just started on reloading 7.62x39, and chrono'd my first loads today.

Factory Brown Bear: 1350 fps avg
My Loads: 1280 fps avg

I'm loading 25.7g of 1680. Speer manual goes up 28.0g for 2544 their figure.

How much more of a charge do you guys think will match the Factory load?

(No signs of pressure BTW on the load I shot)


Thanks

 

[bullseye308]

I would not guess, I would load up a few going up in 1/2 gr increments and see what you come up with. Are you after a certain velocity for a reason, or just trying to duplicate the factory load? How was the accuracy so far for the factory and your handload?

 

[ants]

Chris

1. You gotta update your signature line. If you're loading 7.62x39 I don't think you're shooting it in the handguns you list.

2. Did you type correctly? You should not be getting velocity as low as 1280. Maybe 2280? Confirm your velocity for us and we can help you get to your target.

 

[joneb]

AK pistol ? What grain bullet ? AA1680 may not give the highest velocities but it can give very good accuracy.

 

[Remo-99]

Did you type correctly?

Ants asks the same question I would, those velocities are way low for 7.62x39mm, even in a pistol barrel.

 

[Marlin 45 carbine]

yeah those fps's are about 1K to slow from a rifle barrel.
1680 is about the best for the X39 IMO.

 

[steve4102]

Yup, your velocities are way out of whack.

What rifle are you shooting? What bullet and bullet weight (I assume 125gr).

Note the 7.62x39 data in the Speer manual is pretty hot. As you stated Speer lists 28gr Max for the 125gr bullet, but Sierra lists 24.7 and Hornady 23.9/123gr bullet.

Proceed with caution!!

 

[chrisf8657]

Yes that was a typo.
2280 was the velocity (2350 for factory) and I'm just looking to duplicate the factory load.
It is a 123g Hornady or Speer SP being shot from a standard AK.

 

[jmar254]

26.4 grains should give you 2350. According to formula I found online. Number of grains/current FPS * FPS wanted -10%
25.7/2289 = .0112719 * 2350 = 26.488965 - 10% = 26.3890. I know the 10% part looks weird, but that's how it works out in MS Excel. I seriously suggest starting at the low end, it is much easier to recover from an under charge than an OVER CHARGE. I am looking for the web addy that I found this on, it's been a while. If I find it I'll post it later.

http://www.handloads.com/calc/reduced.asp and now that I found it, that formula is for reducing a powder charge so use at your own risk, as you should with anything you read online.

 

[chrisf8657]

Do you have a link to that formula, or additional formulas?