Fire Forming- Turn Into Shoulder?

[Gergg]

Planning on prepping some .220 Russian for 6ppc fire-forming and wondering if while I'm turning the neck I should cut into the shoulder a bit before the first firing, after, or both?

Thanks,
Greg

 

[BoydAllen]

The reason that I turn into or onto the shoulder, is that if I do not, cases that have had their necks expanded and which have been turned, with no material removed on the shoulder, chamber very hard, well beyond having some feel, to the point that one should be concerned with frequent lug greasing. There is not virtue to this, and it fact at the moment that the bolt is forced closed, a doughnut if formed inside of the case at the neck shoulder junction. Given the short bullets and their typical neck engagement, this is of no functional consequence, but I thought that it was worth passing along. When I turn, I cut a on the shoulder such that as soon as I see the full width of the angled part of the cutter, I quit, leaving an edge of cut that can hardly be caught with a fingernail. Properly done, this leaves me with some light feel of the case as the bolt is closed prior to fire forming. An extension of this situation has come about because no matter how carefully I try, expanding up from .220 to 6mm makes the necks crooked enough so that when I turn, the cut on the shoulder is uneven, because the necks are cocked in relation to the case body. For this reason, given that I have a dedicated fire forming barrel, I try to use a different method most of the time.

I expand to .22 cal and turn to .010 thickness (for a .262 chamber neck) and then prime put in powder (NOT PISTOL BUT ONE SUITABLE FOR A 6PPC) up to where the back of the bullet will be, and seat a cheap 55gr. BT bullet carefully using my 6PPC Wilson seater. The seating depth is not important. I usually seat them so that there is about a caliber of shank in the neck, or a little less. The BT helps them seat straight in the oversized seater. The next step is to fire them in my 6PPC fire forming barrel, standing close enough to a safe backstop s that the inaccuracy will not put a bullet over it. Do not shoot at some low distant backstop when doing this. The result is a very straight case that is close enough to the neck diameter that I will turn at so that the slight expanding to 6mm leaves the cases very straight. I do not try to remove all of the powder fouling from the forming shot before lubing the inside of the necks, expanding and turning. I just run a bronze bore brush that has been retired to case neck duty, in and out 3-4 times. After I have turned them, I trim to 1.490 lightly chamfer and deburr. The cases that I make this way are very straight. Because these cases are fired at .22 cal, and there is none of the neck in the shoulder from expanding to 6mm I don't have to turn onto the necks except to finish the neck cut, to get them to chamber. This should be tested on your rifle.

 

[ShootDots]

When necking UP, you always have a little "fold" or "gathering" of brass at the neck shoulder junction. So when you use your mandrel to open the case to whatever caliber you are necking up for, THAT is the best time for neck turning. 1.) your necks have really been "ironed out" so to speak (imperfections pushed to the outside of the neck) and 2.) that little bit of brass has gathered at the neck shoulder junction. So turn it AFTER you have necked up and cut just a smidgen (a relative term for "small amount") into the shoulder to rid yourself of that potential doughnut!

 

[BoydAllen]

In the case where you are necking up, part of the thicker shoulder becomes the base of the new larger diameter neck.

 

[Gergg]

So I was messing with a case today.....necked up with a K&M expanding mandrel, then with K&M neck turner, started turning to get down to .0086(.262 neck), dang, cut the neck clean off at the shoulder....makes me wonder if I got the correct blade/angle on my cutter? Or did I just go too far onto the shoulder? I'm sure the blade is oriented in the cutter properly, the angle is positioned to meet the shoulder angle, I was watching for the shoulder cut but it never seemed to get there, then off she came....Hmmm....Well, if nothing else, the neck wall thickness was right on the money all the way around, the K&M is accurate.

 

[Webster]

Tony Boyer's book p. 146. Since the case is already head spaced and the shoulder is pushed back there is no reason to cut into the shoulder. Just touch the shoulder or you may weaken it. I don't know what a head spaced case is???

 

[Gergg]

Tony Boyer's book p. 146. Since the case is already head spaced and the shoulder is pushed back there is no reason to cut into the shoulder. Just touch the shoulder or you may weaken it. I don't know what a head spaced case is???

Interesting as it seems everyone else says you should cut into the shoulder a bit. My understanding of head space is from the rear/bolt face end of case to the center of the shoulder, though I have seen it expressed differently as well.

 

[BoydAllen]

When fire forming a .220 Russian case that has had its neck expanded to 6mm and turned, the shoulder angle of the case before forming is less than that of the chamber. This is similar to fire forming an Ackley Improved case. The only point of contact with the chamber is at the neck shoulder junction. Because the case if being necked up, part of the thicker brass in the .220 Russian case's shoulder becomes the base of the 6mm neck and there is some distortion of the top of the shoulder such that the fit in a properly headspaced 6ppc chamber would be excessively tight. That is the reason for turning the neck so that the leading bevel of the cutter cuts very slightly on the cases shoulder. The problem that the OP had is likely because the K&M cutters bevel is very narrow, making it harder to judge the cut than if it was wider. I have two other tools that have wider bevels and use one of them to make my first cut, and the make my finish cut with the K&M because it has a carbide mandrel, and the one that I use for the rough cut is set up with a looser mandrel fit because it has a steel mandrel, and I want to avoid brass transfer to it during turning. The fit does not matter because it is the finish cut that controls the precision of the final neck dimension. With the wider cut on the shoulder of the rough cut, it is easier to see what I am doing as far as that part of the finish cut.

 

[Gergg]

The problem that the OP had is likely because the K&M cutters bevel is very narrow

Thanks for your help Boyd, if you happen to have a close-up pic of your K&M Cutter blade orientation that would be really helpful as I would like to verify that mine is proper....though I can't see any other way for the cutter to be positioned and still have the bevel meeting the shoulder.

 

[Gergg]

The problem that the OP had is likely because the K&M cutters bevel is very narrow, making it harder to judge the cut than if it was wider.

Boyd....this is exactly what was happening, thanks for the hint. I think I have it figured out now, turned a bunch of cases today and they are darn near perfect.

 

[BoydAllen]

Ba da boom! ;D Good for you.

 

[artbosco]

Last week I asked Roger Miller, owner of K&M, to make me a 30 degree angle cutter for my K&M turner, vice the standard 50 degree. Roger threw in a 35 degree cutter with the hunch that it would turn into the shoulder better. The 30 degree matches up with the 30 degree angle of the 220 Russian and the 6mm BR the parents of the 6PPC and 30BR respectively.

Bottom Line: the 30 degree cutter blends in perfectly. I ordered 3 more. Not a part of his lineup yet, but maybe in the near future. I attempted to over-cut into the junction but all I got was a nice smooth blend. Might help folks from cutting too deeply. I turn for about a 1/64" cut into the junction. Try one.

 

[Gergg]

I turn for about a 1/64" cut into the junction.

Yeah, I was reading that people went 1/16" into the shoulder, your 1/64th sounds more doable with the cutter I have.

Try one.

Would love to, I know the cutter angle I have is not perfect.

 

[BoydAllen]

What you are looking for is the full width of the angled part of the cutter on the shoulder. Once you have that, you are there. The step at the end of the cut should be so shallow that it is hard to catch a fingernail on. BTW the .220 Russian has a 21 degree shoulder, but the 30 degree cutter works fine. The PPC has 30 after being fire formed.
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[artbosco]

What you are looking for is the full width of the angled part of the cutter on the shoulder. Once you have that, you are there. The step at the end of the cut should be so shallow that it is hard to catch a fingernail on. BTW the .220 Russian has a 21 degree shoulder, but the 30 degree cutter works fine. The PPC has 30 after being fire formed.
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I stand corrected. You're right. A 21 degree cutter would be the appropriate angle for the 220 Russian. I'll have to ask Roger to make me a couple of those.

I used the 30 degree on previously fired older 6PPC cases I had on hand.

I'm currently turning expanded up 6mmBR cases for the 30BR and they work perfectly. I run a finger nail over the neck/shoulder cut and barely feel a thing. It's very very smooth.

 

[BoydAllen]

Actually, I wasn't saying that the angle has to match, as long as you keep an eye on the cut. If you section a case that you have turned you will see that there is plenty of brass thickness in the shoulder. A larger angle will only thin the part of the shoulder next to the neck a little, but not enough to hurt. One thing that I do is look at the transition between the angled part and the part that is parallel to the mandrel. If it is too "pointy" I work it over with a diamond lap and stone so that it has more of a radius. I have turned all of my brass with cutters that have more angle than the .220 Russian. One of my tools is a Stiller, that has a 30 degree cutter with the angled part wide enough to cover the entire shoulder of a fire formed case. I discovered this when returning some fire formed cases to thin the necks. The whole shoulder was cut!

 

[Gergg]

I got ya Boyd......I cut up onto the shoulder approx. .015-.020, I think this is conservative but after cutting off 2 necks I figured this was a better way to go.

 

[BoydAllen]

I stop advancing the cutter the instant that I see the full width of the bevel on the shoulder.

 

[Gergg]

I stop advancing the cutter the instant that I see the full width of the bevel on the shoulder

.
Right, the bevel on my K&M is really small, so I was just blowing right through the shoulder not thinking I was even onto it yet. When you mentioned that I was most likely doing this I looked a little closer with reading glasses and sure enough that fixed it.

 

[ALBULLET]

If your wondering if your necks are turned correctly try this:
Take a fired piece of brass and seat a bullet into the neck with your fingers.
If it seats without force you have a good turned neck. Your Bullet should be getting a free release at firing.
If the bullet you are seating with your fingers is stoping at the neck shoulder junction. You have a thick spot, a doughnut or brass build up. Mostly referred to as a doughnut.
I have great luck using my very hard to adjust NT300 neck turning tool made by Sinclair.
It has a 30 degree cutter which works great on the 21 degree shoulder of the 220 Russian brass.
I turn the neck about .070 up the shoulder more than into the shoulder with this cutter.
Please understand that the angle and width of your cutter makes all the difference on the appearance of everyone's brass after turning. I expand my neck to 6 mm then turn.
1) lube and expand my 220 case by leaving it on the expander a few minutes. (Not a push on pull off)
This move will really help. Your new brass has great spring back. Especially at the neck shoulder junction.
2)chuck brass into my .5 inch cordless drill. Chuck brass into drill with just enough pressure to turn it over the turn mandrel. Lube the mandrel and inside of neck. Brass will run very smooth. Cutter in my left hand ,drill in my right. Neither one is stationary. While I'm turning this piece of brass I have the next piece on the expander( not a push on pull off) waiting to be turned.
Most the turn mandrels have a stop or step up on them to be adjusted to prevent turning too deep into neck.
I set the turn mandrel to stop cutting about .070 up the neck. You know all the 220 brass is not the same length nor is it same head space. This will cause some difference. While I have the piece of brass in the drill I go ahead and spin the neck in some steel wool. This just smoothes it up a little.
Sometimes after turning a 220Rus it will not chamber in ur PPC chamber. It needs the head space set back a little. It's much easer for me to seat the bullet hard into the lands rather than create a crush fit with head space. Holding the case head against the bolt face is important for good fire forming. Nothing like going to fire form some brass and find out half of it want chamber. Don't say it has never happened to you. Many new bolt lugs have been scared while fire forming because the crush fit was tooooo tight.
Now we have turned our necks too the correct numbers. You should have your PPC die in a press somewhere. Take this expanded and turned piece of brass with some lube and size it in your PPC die which you have set up for proper head space for the PPC chamber which you are making this brass for.
This will head space it for good fit and also size the neck for tight bullet seating. Prime and Full with your powder of choice . Seat a bullet LONG into the lands for a good bolt face to brass head fit.
Go out and fire form your brass. It will take two or three firing to get ur brass competition ready.
Hope this helps someone. If anyone can add to this and help me do something better, please do so.

Scotty G