Home Forums Hunting & Shooting AR and Tactical Rifles Converted 7.62 to 6mm arc brass

Found a guy selling converted 7.62x39 large primer brass to 6mm arc, using a water forming system.
Any issues on using large primers instead of small primers in this cartridge ?
1 reason I'm looking at it is, I have lots of large rifle primers, and only a few thousand small.

Tag

I can't speak to LRP's,but that certainly wouldn't turn me off. Have been slicking up Lapooey 7.62x39 to form into 224,243 and 264 Grendel/ARC/LBC/Predator/PPC AFI's...as I never don't not want a positive headspaced false shoulder,whether in Turnbolt or Krunchenticker. Hint............

Man, I feel dumb now. Never thought of doing that myself. Nice think is Lapua x39 brass is about the least expensive stuff they sell and I’d happily use LR primers myself. Just cause I have the most of them.

Do you have a link?

Link to this brass ?
Look on Gunbroker.
I bought 150 pieces directly from the guy on ARFCOM.

As long as you keep pressures in the AR reasonable range Id expect little or no issues. For the higher pressure bolt action reloader I may anticipate issues blowing out primer pockets at lower charges than the same load with small rifle primers. Why you ask? less material to support the pressure in the primer pocket with the reduced wall thickness.

Look forward to feedback from those who have given this a try.

That’s not how pressure works, especially in 6ARC pressure range.

Else, every magnum rifle cartridge would be blowing primers.

Brass is showing, being here tomorrow.

Would you detail your preferred method, or otherwise recommend steps to achieve 6mm ARC cases from the 7.62x39?

I was just thinking of trying it with my FL bushing die. Maybe go mid 6.5 first then again as 6mm. Load to solid headspace and fireform.

Haven’t done it yet but I can’t see it being that hard. Seems like FF’ing may take care of the length of the x39 as well.

I got the brass in just a bit ago.
Oal is running from 1.476 to 1.483 so far what I've measured.
Tried 5 pieces in my AR. All 5 drop all the way in, and bolt closes completely.
Ejection is positive when pulling the carrier group back.
Seated 10 primers all tight.
Loaded 1 round with a 105gr bthp over 748, and measures out just fine.
After my doc appointment tomorrow, I'll be test firing.
Pic of factory brass beside this formed brass in a bit. At doc office right now.
Here's a pic of factory, and resized.

Looks good SM. I think it’s a good idea for a shooter that has a lot more LR than SR primers as well.

So I loaded up 5 rounds with 105 grain bthp's over 748, and 5 rounds over Varget., set at 0.020 off.
748 barely cycled the action, and had some black powder over the neck and 1 round, down the body some. Accuracy was not good. (Pic later)
Varget would not lock back the action but did throw brass at 4/5 o'clock very close. Accuracy was about 1 1/4".
At doc appointment, be back later.
Not impressed. Seems pressure needed to fireform.

Wonder what sorta speed difference there was from your standard loads. I figured there might be a little experimentation with it. Thanks for the work.

Had to get to the doc appointment. But wanted to shoot before the wind got up.
I'll report back in awhile.

Lube Lapooey Russian 30 Virgins with OneShot Aerosol,run in FL ARC sizer about halfa' turn shy of shellholder. Headspace will obviously be too much and that is a good thing. Run sizer in towards shellholder,until you are happy with Relative Positivity. Once aligned,it's a one-pass operation. Simply mass produce and rejoice. Hint.

While I have bushels of Bushing Dies,I never could like same for said process and do not. Hint...............

Any trimming the x39 after the pass?

I stay the course and simply do no more and no less,which a given chamber dictates. Few things are more forgiving,than "established" trim lengths. Hint.

I positive headspace size,form and resize(this is where bushings come in and I shoot .003" constriction in everything)...then weigh trim determinations,via concentric fully formed brass. Hint...........

Stick,
I fl resized the 9 I shot.
3, I have to use a rubber mallet to tap out of my AR.
All 9 have a ring near the base that almost looks like the are belted magnums. I'm sure that's what's sticking.
Is it possible to turn the fl die up, to just size the upper part of the casing, neck sizing sorta, and turn the expander down to punch the primer out before the whole casing goes in.
Have never done this, but sounds possible to avoid that ring.