Reloading 7.62x39 - Regarding bore diameter

[E Flow]

I have a Hornady LNL AP.  I have had it for years and never set it up.   After years of trying I finally got my CZ527 in 7.62x39mm.  Hunting ammo is extremely hard to find.I found this forum online trying to find out how to load my own.  Then I found out about. 311 diameter.   I found a great deal on .310 SPRN. CZ said they legally couldn't give me any insite.  Hornady said they wouldn't work.  I read on the forums from years ago guys were loading all the way down to .308 and having success.    Hornady dies come with .308 and .310 neck dies.   I am open to any and all info you can throw my way.   Powders, bullets, weights, best dies.   I deer hunt in WV.  99% of my shots are well within 100 yds.

[Wobbly]

Welcome Aboard !

I also reload 7.62x39, but for a slightly different gun. But I can throw some ideas at you...

• Brass is you first big hurdle. The cases you might have saved from foreign ammo has 2 things going against its reuse: material and primers. Most of the import stuff is steel cased. Test it with a magnet, they have gotten really good at disguising this small fact. You cannot reload anything but pure brass.

Secondly, even the European stuff that IS brass, is typically primed with Berdan primers. If you look into the case and see 2 small primer holes (the "snake bite") then it can't be reloaded. You'll need Boxer primed brass with the single, larger, central primer hole.

I avoided all the hassle and went online and bought 200 pieces of new brass (a life-time supply for me) from Star Line. This was 3 years ago when people had a choice, I really don't know what's available right now.

• You'll be loading 0.310" dia bullets. Yes these bores are bigger, typically at 0.311 or 0.312" but it works. The guns IMHO are nothing more than magnum pistols with a longer barrel. You won't be making any 200 yd shots with 7.62x39 !! I'm using Hornady #3140 Spire Point for my purposes.

• Forget about OAL. You'll trim your brass to length, then load to the cannelure and stop.

• I'm using IMR3031 (a single-base powder) with good results. It's very clean shooting and other than a little soot , there's no evidence the gun has been fired. Accuracy is good enough for my uses at 50 yds.

• Sizing the case is proabably the most important aspect. The height of the Sizing Die is set in the press by where it places the shoulder of the cartridge. What you want to achieve is a shoulder placed so that the cartridge slides easily into the chamber, the bolt will slide forward, but the bolt handle experiences resistance on the last ~30° of the bolt handle locking. This insures the shoulder of the case is making a gas-tight seal at the front of the chamber which in turn insures the shooter's safety.

• Lastly, this all goes so slowly that a LNL AP is proabably not the best choice for rifle reloading. (If you were entirely accustomed to the idiosyncrasies of the AP, and doing thousands of your pistol ammo, then OK.) But so much of the rifle loading process is done OUTSIDE of the press, that a single stage would be far better and possibly just as fast.

Hope this helps.

[E Flow]

Thanks for the info.  I wonder why Hornady told told me the .310 wouldn't work.   I read one guy on this forum shooting .308 in his .311 gun and said it worked fine.   If I shoot my gun at 200 yds it will probably be a gong.  Most of my shots on deer are 75yds.   I had been buying ammo with reloadable brass for a while.  And i found some Lapua.  I hopefully will get good for a while.

[skin]

 I load Speer 123 gr gold dot and hornady 123 gr sst. Both are. 310 Dia. Both shoot really well out of my 527. Sierra 125 gr (.311)shoots well also.

[Wobbly]

I wonder why Hornady told told me the .310 wouldn't work.

Because it won't work in every gun, and their PRIMARY concern is giving safe information.

I read one guy on this forum shooting .308 in his .311 gun and said it worked fine.

He might. And it might work OK. But you need to fall back to the No.1 Rule.... we don't get safety information from strangers on the internet. And that also includes me.

So the first thing YOU need to do is slug your bore. Los of vids on YouTube to tell you how.

[armoredman]

I loaded 7.672x39 for a CZ 527M for years. I used the Hornaday .3105 diameter spire point as my go to jacketed bullet, and the 129gr  NOE cast at .314, powdercoated and sized down to .311. Both worked perfectly. had a few molds, gave one away, hanging on to the 129gr NOE mold as it also works in .308. My go to powder for 7.62x39mm was always Accurate Arms 1680, always had great results.

[E Flow]

I believe it was your posts I read from way back like 2013 or 2015.   I just got a 6.5 Grendel in the fold now as well.      I got some .311 123 grain hollow points for my 7.62.  I got some brand new Lapua brass.  They are necked for .310.    Do I need to get a .311 piece to fit in my die to expand these cases?

[Wobbly]

You typically want the Outside Dia of the bullet to be 0.002" larger than the Inside Dia of the case neck. That creates "neck tension" (or what some might call "a press fit") between the larger part in the smaller hole. Neck Tension is what holds the bullet in place until the cartridge is fired.

[Some military cartridges (because the ammo containers are dropped out of airplanes and other such ROUGH handling) may also have a crimp into the bullet's cannelure to make "double darn" sure the bullet stays where it's supposed to stay. However, on civilian rounds this is NOT necessary, and in fact can ruin, degrade, and otherwise be detrimental to your finely crafted Neck Tension.  ]

It doesn't really matter what or how the die maker labels their Dies and Expanders.... YOU need to measure the results with your own caliper and make sure you are generating those type sizes... on more than one example. You can easily do this with an accurate pair of hand held calipers using the Inside and Outside measuring tines. Use the same set of calipers on BOTH parts. In this way if the instrument isn't "zeroed" properly it won't matter. What you are actually seeking is the differential measurement.

If you are using a "digital caliper" there is a trick to make your job easy. When you measure the bullet OD, simply push the ZERO button while you measure the bullet. Then when you measure the case mouth ID, the number on the screen will be the exact difference between the 2 features. That will save you from having to do the 1st Grade math, which at times even befuddles me !!

Hope this helps.