Necking down brass for wildcat

[mechengr]

I'm starting down the path of my first wildcat and need some help figuring out what's going wrong. I've decided to build a 22x6.8 in an AR for use as a coyote thumper. I made my first orders and started out by getting stuff to mock up dummy rounds for me to oogle at while I gather up the rest of the rifle parts over the next few months. Starline 6.8 SPC brass, a 6.8 SPC Redding Type-S bushing die and a bunch of bushings to progressively neck it down to 22 cal. I've got bushings in size .288, .280, .269, .260 and .250, I read somewhere that recommended a .010 step down in bushing size and those are the closest I could get for what was in stock at the time I ordered. The problem I'm having is that after two steps down, the case mouth flares out causing it to not be able to enter the next smaller bushing. All the coaxing I can give and it just crushes the shoulder instead of reducing the neck.

Here's the full progression of how it's going down:
1. I chamfered and deburred the case mouths prior to any work. Checked diameter along the full length of the neck and they're straight (no flare) when they come out of the bag. Also, case length is about .002 below book trim length
2. Setup the die to just touch the shoulder with ram at full extension. For this wildcat the shoulder doesn't have to move, only the neck gets reduced. Bushings are floated using the "rotate 1/16 off" trick the Redding instructions call for.
3. Lubricated the neck OD thoroughly with Hornady Unique and run the case through. The factory brass measures .299 outside neck diameter, so the first step down to .288 is 11 thou. Brass runs through smooth and easy. Case length grows by .001 and no measurable flare at this point.
4. Next up is a .280 bushing. This is the one that's giving me the issues. Lube case neck again and run it through, feels no different than the .288 bushing did but comes out having the case mouth flared. Case length grows by .003-.004 this time. Measured with calipers the mouth is flaring out about .003 from the rest of the neck
5. The .269 bushing does have a radius lead-in, but I have yet to get these flared case mouths to enter the bushing without completely crushing the case. Already ruined three cases trying to finagle it and don't want to ruin any more until I can get some advice on how to move forward

Any idea what causes this? I'm considering buying a .275 bushing to try and go a smaller step thinking maybe the flare will correct itself... Not sure if it make a difference, but all the bushings are LE Wilson except the .280 that's causing the issues is a Redding bushing. Could it be a bad bushing? Do I need to do any other brass prep between bushings? Everything I read about this cartridge said brass prep was easy as a few passes through a bushing die, no trimming necessary. Hope I can figure out a way to make that true!

 

[tim_w]

So after running the necks thru the .280 bushing your necks at the mouth are .003/4 larger than the rest of the case neck? Leaving you with a belled case mouth?

Did you make sure to remove the die's neck expander ball?

 

[tim_w]

You also might want to turn those necks before that final reduction or one before. Set the final neck turn to give 0.004 clearance with loaded bullet from your chamber spec.

Also look into a annealing system if you want those cases to last unless you plan to max pressure them for only a couple reloads.

Do you already have the barrel chambered?

 

[Dmagna]

You are probably going to need to anneal

 

[L.Sherm]

If you anneal first you will crush even more cases, anneal after all your necking down cases is done. I've made about 500 cases for my 17 badger from straight wall 30 carbine.
Get some double ended forming dies from Bullberry they work better necking down that far. Just going down 1 step with a bushing works fine I do it with 270wsm to 6.5 and 223 to 20 but use my forming dies going from 6mm to 20 and if I make anymore 17 badger brass.

 

[mechengr]

So after running the necks thru the .280 bushing your necks at the mouth are .003/4 larger than the rest of the case neck? Leaving you with a belled case mouth?

Did you make sure to remove the die's neck expander ball?

Yes, as weird as it sounds that's exactly it. Last night I was just zeroing the calipers on the neck to measure the delta. I double checked this morning and the main part of the next measures .2770-.2775 and the case mouths measures .2805, so that seems even stranger to me. The mouth of the bushing. Measures right on .2800

Recapping rod is totally removed, just have the bushing retainer in the top of the Type-S die.

Do you already have the barrel chambered?

No chamber yet, just the brass and dies. Barrels are available through Ritch's Precision Guns or Black Hole Weaponry, my plan was to place an order next month

 

[J E Custom]

Some good suggestions. First off. the Starline brass is tough but hard and is not good for making wildcats.
With the multiple sizing you are work hardening the brass even more.

I would suggest finding some Remington brass, (New or once fired) then remove the expander on the .224 die.
Then lube the case (and inside of the neck) And size the case. Normally good annealed brass will take some neck sizing without problems. If it doesn't want to size down that much you may have to step size it in 1/2 size steps (.025 the first step and then the final sizing) remember every time you size the case it gets harder and resist sizing more.

If you look at a bushing die the bushing is not designed to size very much sizing, so I would look for a conventional die for neck sizing instead of the bushing dies. The bushings don't have enough starting taper to do it in one or two steps. so you have to use many bushings and that could be your problem with the Starline brass.

I have/do many wildcats and find that the brass quality and hardness is very important in order to form different cartridges from parent cases. Starline brass seems fine and works well if you do minimum sizing because of it's toughness, but it doesn't re form well to other shapes, A good friend even tried to anneal some new Starline before fire forming it to a different chamber design (The caliber was the same) and it split at the neck shoulder junction. He then tried a different brand of brass and his troubles went away. You can also buy a die blank and build your own sizing die for the wild cats using your regular chamber reamer to bring the case close to the final size and switch to the bushing die for final sizing.

I use quite a bit of Starline brass on pistols and factory chambers where minimum sizing is needed and have good luck with it but have learned that the alloy they use just doesn't lend it.s self to re forming in any manor.

Hope this helps

J E CUSTOM

 

[mechengr]

I guess that makes sense if Starline brass is really that tough, I'll try to pick up some Remington brass and see if that works better. Most of the forums I've seen discussing this caliber make reference to either Rem or SSA brass. I see Hornady makes 6.8 SPC brass too, might give that a try as well. Thanks for the recommendation!

 

[sedancowboy]

Am I missing something? I have read every post. Isn't the .224 Valkyrie a necked down 6.8 SPC? If so why would you be going to all this trouble to neck down to a known cartridge with brass available. Part of the reason you are crushing the shoulders is because as you neck down the neck the shoulder gets longer. I would think after each step down you would have to back the sizing die up a bit.

 

[mechengr]

I'm going through all this trouble for probably the same reason as anyone else who decides to build a wildcat. I am a tinkerer by nature and this sounded like a fun project that more or less maximizes performance of a 50-60gr bullet in a small frame AR. The 224 Valkyrie is indeed based on the 6.8 but has a shorter case optimized for really long sleek bullets. It's not as ideal for fast light varmint bullets that I want to use this rifle for. The closest SAAMI equivalent to the 22x6.8 would be the 22 Nosler but in all the research I did there were several aspects of that case design that I felt the 22x6.8 does better, minus brass availability obviously.

 

[MNbogboy]

One thing comes to mind that LE Wilson dies have a slight taper, while Redding dies do not. Redding instructions if I remember right say "lettering down" while Wilson say "letters" up. If the Wilson is turned over it sizes a slightly tighter neck but because of "spring back" may leave a slight bell mouth.
Not saying that is the case but may be worth looking at.

Another thing in a "severe" brass sizing of wildcats I found that automotive "STP" makes a super lube. Better than imperial sizing wax.

Hope you get it figured out.
Randy

 

[nvschütze]

You are probably going to need to anneal.

How I anneal. I do it in a semi-darkened room. As soon as I see even the tiniest bit of orange glow in the neck, I flip it into a sink of cold water. I direct the long pencil of bright blue flame (in the center of the flame) right at the ripples in the conical portion-- that is what has been work-hardened. The heat goes up toward the neck and it gets flipped as soon as I am dam-ned sure I see some orange. Takes maybe fifteen to twenty seconds to do each one; you'll generate a technique once you've done a few and get the hang of it.

The image shows a 14mm socket for use with cases of .532" head diameter. Cases of .473" or .378" head diameters would use a smaller socket. You have to have the socket directly on-axis with the spindle or the oscillation will allow the case to walk up and out of the socket. I solved that problem by truing the spindle to the outside of the socket on a lathe. I think a .473" case uses a 12mm socket, but I'm not signing any contracts on that.

The spindle is a 3/8" bolt, welded into and axially-trued to a 14mm deepwall socket. The bolt is turned-down to fit both 3/8" and 1/4" drill motors. This is the prototype and working model, so it ain't all that good-looking. It fun-king works, so that's all that matters to me. The cases fit tightly enough to stay in while being turned in a drill, and they flip right out with a quick bit o' wrist action.

 

[tim_w]

Yes, as weird as it sounds that's exactly it. Last night I was just zeroing the calipers on the neck to measure the delta. I double checked this morning and the main part of the next measures .2770-.2775 and the case mouths measures .2805, so that seems even stranger to me. The mouth of the bushing. Measures right on .2800

Recapping rod is totally removed, just have the bushing retainer in the top of the Type-S die.


No chamber yet, just the brass and dies. Barrels are available through Ritch's Precision Guns or Black Hole Weaponry, my plan was to place an order next month

Ok I just wanted to confirm it was nothing basic.

I would also recommend paying attention to JE Custom. While I have done wildcatts and know more about the 6.8 AR15s than most he has likely done 10x case forming for every one I have done. i.e. he knows his stuff from everything I have seen him post on the forums over the yrs.

Honestly the issue you are having is minor. As he stated its likely hard brass at the case neck. You could switch brass going forward. As you already have what you have why not try a few seconds spinning the neck under a propane torch flame to fix it. You do not need to anneal it to ideal loading level just stress relieve the crystal slip joints in the brass structure of the necks. Its called the recovery phase of annealing. (IMO it likley what the low temp molten slat pot annealing kits are actually doing give temp and time vs typically foubd using torch or induction) Start out with a few seconds (3-4) in the flame spinning on a drill and go up or down in time till you find what allows you to finish the sizing.

Another suggestion for good brass is S&B its tough and might be hard but IMO to do this right no matter what annealing is in your future. In general its the closest I have found to my old early runs of SSA brass when Art Cox was still the owner. He was a great guy and super supportive and helping with testing etc donating ammo components piezo pressure test our barrels etc. Glad I had a large supply.

Another thing is if you turn the brass prior, then as you neck down, some of that neck becomes shoulder of the same thickness as the neck. That will reduce the likelihood of doughnuts forming as you have multiple loadings on it. You also will have less to finish turn and should make sixing down the necks easier with less snap back after coming out of the neck bushing.

The reason I asked if you had a barrel already chambered is you can do more to improve the case if you want.

But first what is your plan for this cartridge? What barrel length? What bullets are you planning? Paper punching varmint hunting what?

As your platform is ar-15 you are limited in COAL to 2.30 maybe another.01 but that's it with the roomiest mags unless you notch them. So the bullets you plan can play into what ideally you may want to change. Not to mention how much freebore you have cut.

The AR feeding angle has no issues with sharp 40° shoulders etc. Heck, it can feed short super fat sharp shouldered WSSM cases no issue which most bolt actions have a seriously hard time with. So lots you can do here if you are game and it fits your goals.

 

[nvschütze]

Another thing: in a "severe" brass sizing of wildcats I found that automotive "STP" makes a super lube. Better than imperial sizing wax.

The Hornady One-Shot case-sizing wax is really good stuff. A tiny bit of it goes a long way, like lubing four of five cases with just a small dab on the index and middle finger. Doesn't spill and run, either. Washes or wipes off quite easily. About $10 per tin, and it will last you for years an' years...