Fireforming 7.62x39 brass

[lamrith]

Skimmed a bit and see reference to fireforming The AK brass for use in grendel, but not much specifics on how to do it or what charges people are using successfully.

I see one reference to "2grain under min charge" However many of the Vol2 loads do not list a minimum charge and none of the load books I have even list Grendel so for me it is a bit difficult to settle on a fireform charge. I would like to see if folks have fireform charges they recommend and maybe get a theory discussion that could be pinned for people to reference when they are in a similar situation.

• Am I right to think that fireform you do not want a full charge? You want it on the light side, enough to definitely fire the round but not any "real" velocity?
• Seem that often I hear that when no min charge is listed take 10% off the max and start there for load development. SO maybe max charge -10%, then -2grain? Or would max -10% be fine as well? EX: 31.8 max charge, -10%=28.62, -2grn=26.62. Now would 27 be fine, would 26 be better, any reason not to use 25, or even min charge of 28.5?

Lets here thoughts and theories from you experienced loaders and fireformers...

I know I have a huge pile of 8 of these brass I have sized down, trimmed as needed and want to fire form and probably use for my hunting rounds so I am less concerned about losing them when they eject off into the sagebrush..

[bja1981]

I fire formed a few the other day and I used 1gr under minimum and it was on the hot side so I think 2gr under would be safe. Unless you are in desperate need of brass I really wouldn't waste the components and time doing it. I used Winchester brass and the fire formed cases have a lot less case capacity than factory Grendel brass. You would have to use very mild loads in the formed brass and I don't think they would last very long due to the thicker necks.

[lamrith]

Great info BJA. This a learning experience I hope to share with others as I am new to fire-forming and figure others are as well... I can understand that given the reduced volume it is probably not a super secret source for all a persons grendel brass, but it comes in handy.

So it sounds like shying to the low side is recommended. I just checked my *39 brass and it has a volume of 33.4grain. My grendel is 35.1 so that is a loss of 1.7grains of volume...

I only have ten of the *39 brass, I plan to use this *39 brass as my hunting rounds so I am less worried about losing it given it is free and large primer so oddball versus all the rest of my grendel brass..

[Rust]

Consider the cost of going hunting vs the cost of brass. Assuming you don't pay for the hunt or a guide or any other extra's you're still dropping a pile of money on your tags etc.. Spend one more dollar on a piece of brass and make sure you're getting peak performance out of your rifle to ensure a clean kill. Heck even if you launch five of them off into the brush its still probably less money lost than you spent on gas to get out wherever you are.

As far as forming for plinking where I don't mind loosing a piece of brass I use 24g of ramshot tac and a 120g Nosler. Then I turn the neck to remove the doughnut of brass from the shoulder. This load is fairly inexpensive with nosler blems, shoots pretty well, will cycle, and feed in my 20" mid length.

[txgunner00]

I've fire formed a lot of brass with sub-sonic loads. I have a couple threads on the subject. In my case, the fire formed cases are a byproduct of another process so it tips the economics of it in my favor. I've pretty much used FF cases 100% for my hog blasting loads the last couple years. For deer and long range loads, I use proper Grendel brass.

I wouldn't seek out and pay for 7.62 brass specifically for fire forming, but if you get it very cheap or free it's fun to play with.

[LRRPF52]

You need to know your brass's volume in H2O, then make a calculation based on that.

Different brands and lots of 7.62x39 brass will be all over the map in terms of weight and volume.

Some that I have were very close to Grendel brass as-is. In your case, I would reduce by 2gr as mentioned.

If you're wondering about starting loads derived from max loads where you don't have the start load data, reduce by 10%. Example:

Max load listed at 28.5gr. 28.5 x .10 = 2.5gr.

28.5 - 2.5 = 26.0gr

That 26.0gr load would be for the Grendel brass, or what was listed in the load data for brass type. If you had 7.62x39 necked to 6.5mm that had 2 gr less of H2O capacity than Grendel brass, then 24.0gr would be a reasonable fire-forming load.

I just weighed some fire-formed Remington 7.62x39 to Grendel brass, and several samples were 128.8gr, whereas Lapua 6.5 Grendel samples were 111.2gr, so the likelihood of there being less volume in the Remington brass is very high, meaning reduced charge weights. I'd have to prime them to get H2O weights.

[oxn316]

Back when I built my grendel brass was almost nonexistent. I picked up about 200 winchester 7.62x39 on the ground at a range. I annealed them and ran through the sizer die. After Fire forming with 25 grains blc2 I was able to get 4-5 reloads on them. They make great brass for when you don't mind losing a piece or two.

[Von Gruff]

Grendel brass was very expensive to get here as well so I got Lapua 7.62x39 brass and fire formed it to my Grendel-Max with a cast bullet and 7gn red dot. Almost no cost to FF and have a ready source of cheap(ish) brass.
I did get a couple of boxes of Grendel ammo to get brass for my hunting loads though but it still had to be ff to my longer chamber and the cast bullet/red dot worked just as well with that.

[cosh]

I got most of my brass from used 7.62x39. I have also been using 2.0gr less than the book loads. No sticking brass or ejector marks/brass flow. 1st time around they look good and FF'd with a crisp shoulder. Next time around is with the FF'd brass. I will still run 2.0gr down from book loads. +1 LRRPF52...." In your case, I would reduce by 2gr as mentioned."

[rasp65]

Here is a tip for fire forming. Don't trim until they are fire formed because when the case walls blow out the cases get shorter. Then trim to uniform. I have found about 1 grain reduction in case capacity using FF'd cases, so adjust your loads accordingly.

[BIPMaster]

Good info. I picked up 1k brass 7.62X39 cases for cheap to give fire forming a try. End state is that I have a bunch of cheap 6.5G cases for plinking loads in my carbine. Worst case I sell them for a profit. I am using 100gr AMAX and starting with 26.0gr 8208. Book minimum is 28.0gr so I think this load should work.

[sniper20]

I am waiting on the rest of my parts to complete a build for my Grendel, but I have been in a quandry about the brass and ammo... Would it be a better option to buy 7.62 brass at .60/piece and fire form them, or pay the extra .15-.20/piece for the actual 6.5 Grendel brass? I was going to get Hornady brass and load them, but for the price of buying new brass, it will actually be a wash, if not cheaper to buy factory ammo and shoot that up for the brass... Or, if you fire form brand new brass, would it be a better bet?

The issues I see coming with this is obviously the large primer vs the small primer and the "wasted" bullet to do the forming. I have thought about the corn meal and pistol powder method, or going with a "middle of the road" charge and seeing how accuracy is on an unformed piece. I have read many mixed reviews about doing both. Some say the corn meal is the way to go, others complain about it plugging up the gas system (I would leave mine apart for this, just cycling each round myself on a bare barrel).

Do you guys think it would be more advantageous to get factory ammo and shoot it up for the brass? Or buy cheap brass and have it formed? Has anyone loaded up a "regular" load and shot for accuracy? If so, what were the results?

[VASCAR2]

For me I have found it cheaper to buy loaded Hornady 6.5 Grendel A-Max or SST online and save the brass. I can't beat the price enough even with blem bullets and components to load in store bought new brass. I had a friend give me some 7.62 X 39 brass which I have fire formed and shot a couple of times. I have had a couple pieces of 7.62 X 39 brass that won't hold primers after one or two loadings. I have not had this problem with Lapua or Hornady brass.

I bought a couple hundred pieces of Alexander Arms marked Lapua brass on sale a few years ago for about the price of Hornady brass. I wish I had bought more AA brass at that price. I buy my powder and primers locally because I haven't needed enough to off set the hazmat charges ordering online. I think you have to run the numbers your self and decide.

[lamrith]

I am waiting on the rest of my parts to complete a build for my Grendel, but I have been in a quandry about the brass and ammo... Would it be a better option to buy 7.62 brass at .60/piece and fire form them, or pay the extra .15-.20/piece for the actual 6.5 Grendel brass? I was going to get Hornady brass and load them, but for the price of buying new brass, it will actually be a wash, if not cheaper to buy factory ammo and shoot that up for the brass... Or, if you fire form brand new brass, would it be a better bet?

The issues I see coming with this is obviously the large primer vs the small primer and the "wasted" bullet to do the forming. I have thought about the corn meal and pistol powder method, or going with a "middle of the road" charge and seeing how accuracy is on an unformed piece. I have read many mixed reviews about doing both. Some say the corn meal is the way to go, others complain about it plugging up the gas system (I would leave mine apart for this, just cycling each round myself on a bare barrel).

Do you guys think it would be more advantageous to get factory ammo and shoot it up for the brass? Or buy cheap brass and have it formed? Has anyone loaded up a "regular" load and shot for accuracy? If so, what were the results?

Buy Hornady Amax factory ammo and shoot it. watch for sales and free shipping deals and buy 1-200 to get yourself rolling.

Based on my experience the last thing I would recommend is using fireformed *39 brass to reload and shoot in a new build. Way to many variables going on. You do not normally want to run reloads in a new gun unless they are a known good load you already have developed. Even then it is usually better to run factory loaded ammunition in your new gun to break it in and make sure it is functioning properly. The last thing you want is to have any question as to whether the ammo or the gun is an issue with a new build.

Plus you then have Hornady brass saved up and ready to reload for about the same price as buying brass and then reloading yourself that 1st time anyway. My bare cost for grendel 123g Amax reloads without brass is right around $.42-.45/rnd. Add .50 for bought brass and we are right at the price range of factory ammo.. Plus then you also get free boxes to keep loaded rounds in..

Myself I am dropping the fireforming completely for now. I ran the 10 thru my sizing die and the shoulders are WAY off. They are not even close to pushed back enough for the rounds to chamber at all, even after repeated passes. I am not sure if the center decapping/mouth expander is pulling them back out or what, but it is a big difference and the extra work is not worth the few cents savings imho..

[ironhorse18]

Hello Folks, I am new to the 6.5 Grendel, I am in the process of putting one together now. Reference converting 7.62 X 39 brass to 6.5 Grendel, what's best process to utilize: Hydro Forming or Re-size with FLR size die. I have never tried the Hydro method, but I'm willing to try. Also, looks like all methods require fire forming. I have a small pile of Lapua "S-K" brass I could use. I ordered 50 Hornady to begin with, that's about a $buck a piece. Maybe a brass catcher is in order...............

At this time: on AR Platforms, .223 Wylde, 300 AAC, 25 WSSM, & 6mm X 45.