I'm working on a 6mm arc AR15 build, can't find any ammo under $2 per round and no brass in sight. Noticed grendel basic brass and a few folks saying grendel could be sized down to 6mm arc. I'm not having much better luck with finding grendel brass aside from the basic (no neck) version. Anyone experienced forming cases like this from basic brass that could give me an idea of what I would need to pull this off and how good of an end result i could expect? My searches left me with more questions than answers, figured I should just ask.
6mm Arc brass
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troy fairweather
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It will be a pain making it from basic, many steps and probably need a few dies to form them. Get some 7.62x39 or even 220 Russian. Have you checked your lgs for ammo my buddy found 3 boxes set week for $21 each.
I think I've seen both of those available, would it be as simple as resizing?
My area has been a components and ammo wasteland for over a year now. I'm 2 miles away from a cabelas, they don't even have shelf space for more than a handful of rifle bullets lately. The other shops don't carry much because of the cabelas being here, aside from one. That shop gets picked clean by some regulars and all the folks that know about it.
My area has been a components and ammo wasteland for over a year now. I'm 2 miles away from a cabelas, they don't even have shelf space for more than a handful of rifle bullets lately. The other shops don't carry much because of the cabelas being here, aside from one. That shop gets picked clean by some regulars and all the folks that know about it.
FROGO207
Member
I find if you change sizes drastically when forming it works better to do it in stages and to anneal inbetween stages to avoid splitting/crushing and such. So look at a way to anneal as well.
That said, I am not familiar with this round so no help there.
ETA: after a bit of research they use a 6.5 grendel brass, neck it down, and set the sholder back. Then they trim it.
That said, I am not familiar with this round so no help there.
ETA: after a bit of research they use a 6.5 grendel brass, neck it down, and set the sholder back. Then they trim it.
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Ohen Cepel
Member
Starline won't even let you backorder the Grendel even and don't make ARC (bad sign). However, can get the Grendel basic and form it from there; Grendel Basic Brass - Small Rifle - Brass Cases (starlinebrass.com)
Likely best option aside from paying the $2/rd price when you can find it. Or, wait months or years for it to be readily available.
Likely best option aside from paying the $2/rd price when you can find it. Or, wait months or years for it to be readily available.
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Dane R. Marley
Member
Checkout this video:
If anyone is interested, I can confirm that you can resize 7.62x39 starline brass down to 6mm arc pretty easily. I have lee and hornady die sets. The hornady seems to be less likely to buckle the shoulder, but both require a single, full speed pull stroke to prevent most buckling. I used sizing wax first, but the homemade lanolin/ alcohol mix worked as well. The body of the brass is still tapered, I'm expecting fire forming to remove it. I'm going to leave them a little long when I trim them, just in case the expansion draws it back. I'm not sure if it's going to be helpful that they take large primers, but I guess having options is better than not. The grendel brass was much easier, but I was only able to get 50 pieces 1 time. I got 250 of the 7.62x39 for much less per piece.
It'll be a couple of weeks before I actually get to try them. I'm going to try salt bath annealing them before loading.
It'll be a couple of weeks before I actually get to try them. I'm going to try salt bath annealing them before loading.
USBP379
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Any updates?
horsemen61
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Ttrl
kmw1954
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Guess I'm fortunate in that the range were I am working there are a couple of guys shooting ARC's and they have been leaving me their brass. All new Hornady and I now have a few hundred pcs.
My hope is to build a bolt rifle for target shooting. Just don't see the need for a CREEDMORE sized powder charge to kill paper.
My hope is to build a bolt rifle for target shooting. Just don't see the need for a CREEDMORE sized powder charge to kill paper.
Haven't been able to get to the range yet, but I have found post's on other forums suggesting this works well for making grendel brass. Some even claim the large primer contributes to more consistent rounds. I doubt i will be able to verify that part.
They also noted that the tapered body, before fire forming, has significantly less case capacity. They suggest reduced loads for the first firing.
If anyone else intends to try this, I suggest trimming before attempting to resize. It seems the mouth of the case is reaching a few thou beyond the resizing surface in my dies, forming a slightly rolled lip. This is removed entirely when trimming, but it required using a chamfer tool to get the trimmer pilot to fit.
They also noted that the tapered body, before fire forming, has significantly less case capacity. They suggest reduced loads for the first firing.
If anyone else intends to try this, I suggest trimming before attempting to resize. It seems the mouth of the case is reaching a few thou beyond the resizing surface in my dies, forming a slightly rolled lip. This is removed entirely when trimming, but it required using a chamfer tool to get the trimmer pilot to fit.
USBP379
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I'm assuming these won't stack/feed well in Grendel/ARC mags being that sizing and trimming won't do anything to remove the case taper. But I guess that isn't really a big deal since, hopefully, the cases will be the proper dimensions after initial firing.
All this makes me curious about hydro forming. Both Whidden and Hornady make 7.62x39 to Grendel form dies so it should be possible for either company to make an ARC die. Down side is price. These dies are about $200. Then again it probably wouldn't take long for a die to pay for itself based on current prices/availability of powder, bullets and primers.
All this makes me curious about hydro forming. Both Whidden and Hornady make 7.62x39 to Grendel form dies so it should be possible for either company to make an ARC die. Down side is price. These dies are about $200. Then again it probably wouldn't take long for a die to pay for itself based on current prices/availability of powder, bullets and primers.
USBP379
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Alright so here's a little update:
Sizing 7.62x39 directly to 6 ARC usually results in a crushed case. I think of the five or six I tried I got two usable cases. Much better results were had by sizing to 6.5 Grendel first and then sizing to 6 ARC afterwards. Even then I buckled a couple cases at the shoulder. R-P brass seem to survive better as do Winchester. Hornady brass doesn't seem too happy with the idea of changing especially with going directly from 7.62 to 6.
Case length is also going to be an issue. Overall length of the resized brass is all over the place. Some is about 1.49" and seems to load okay. Some is as long as 1.51" and those won't chamber once loaded. I guess I'll trim to 1.48 or .49 and hope the brass doesn't loose too much OAL upon firing.
So yes it appears quite do-able and will produce brass for those who need it. Is it worth the effort? Probably not given that 6 ARC ammo seems to be breaking loose.
On a related note, I asked Hornady about a hydro die. The tech says they are currently 5 to 6 months behind on custom products.
Sizing 7.62x39 directly to 6 ARC usually results in a crushed case. I think of the five or six I tried I got two usable cases. Much better results were had by sizing to 6.5 Grendel first and then sizing to 6 ARC afterwards. Even then I buckled a couple cases at the shoulder. R-P brass seem to survive better as do Winchester. Hornady brass doesn't seem too happy with the idea of changing especially with going directly from 7.62 to 6.
Case length is also going to be an issue. Overall length of the resized brass is all over the place. Some is about 1.49" and seems to load okay. Some is as long as 1.51" and those won't chamber once loaded. I guess I'll trim to 1.48 or .49 and hope the brass doesn't loose too much OAL upon firing.
So yes it appears quite do-able and will produce brass for those who need it. Is it worth the effort? Probably not given that 6 ARC ammo seems to be breaking loose.
On a related note, I asked Hornady about a hydro die. The tech says they are currently 5 to 6 months behind on custom products.
Wow, it seems I had much better luck. I think I may have buckled 6 out of 56 of the starline i was working with. All but 1 of them were from me trying to do it in stages or trying to use the lee sizing die.
Once I got the hang of it, I only had 1 buckle, and I don't know why. I didn't have any other brands of 7.62x39 to try, so it may be that starline is better suited for this.
What brand/ Type of 6mm arc die were you using?
Once I got the hang of it, I only had 1 buckle, and I don't know why. I didn't have any other brands of 7.62x39 to try, so it may be that starline is better suited for this.
What brand/ Type of 6mm arc die were you using?
USBP379
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Something else of note.
Most cases sized fine but a couple of them sort of folded in on themselves when sizing the necks. I'm curious to see if the crease will form itself out or if cases will split when firing.
Annealing might help with all this. The struggle is real....
Most cases sized fine but a couple of them sort of folded in on themselves when sizing the necks. I'm curious to see if the crease will form itself out or if cases will split when firing.
Annealing might help with all this. The struggle is real....
Do you mean something like these 2? These are 2 of the buckled failures from the lee die.For some reason the hornady die seems to be a little more forgiving with doing this. I didn't try trimming them first yet, but I'm thinking the lee die doesn't have room to accommodate the extra length of the neck. If you look close, the rim of the mouth almost has a crimped look to it. This isn't the same as the rolled edge i mentioned getting from the hornady die
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USBP379
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No although I did have some cases end up looking like that. The Hornady brass seem more likely to buckle where the shoulder ends and the tapered case body begins. The R-P brass seem to be the best at sizing down without much drama.
With that said, I have two or three cases that are Remington that have the creased case necks I'm talking about. The crease is vertical and runs basically from the bottom of the neck into the start of the shoulder. Almost looks like a case lube dent but I believe it is sort of a "crushed" area from squeezing the case neck.
USBP379
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Loaded them with a 100gr Sierra soft point and a starting load of Ramshot TAC. The Hornady manual showed 2.18" loaded length IIRC but I went with 2.25" OAL.
The cases did shrink a bit during forming but most are still 1.485ish and trim fine to 1.475. A couple did end up being 1.470 or so for whatever reason.
Also had three split at the junction of body and shoulder.
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FROGO207
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Well only three split when fireformed is a good ratio. So did you anneal them? That would help prevent split necks. Or ateast I have found out it helps me when reforming brass.
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