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View Full Version : Blowing out 30BR , COW method ???



Larry M
01-12-2008, 07:22 PM
When I made my first set of 30BR cases I used a K&M expandiron with the one pass 6-30 mandral and lots of Imperial wax on the mandral and in the necks. Well the cases came out pretty bent, so bad that some wouldn't chamber and had to be run through a FL die and had .015 runout. When I fire formed them I jammed the bullets and lubed the case walls. A lot of them never did straighten all the way out even with a 12 firings. So I have decided to make some new ones. I want to try blowing them out before I turn them this time using the COW method. I have done a bit of research here and from what I have read I need 13-15 grains of reddot/bullseye/unique (would any one of these powders be suitable?) fill to the neck with cow and top it off with wax,plumbers putty or toilet paper to hold it all in. I cant do this at home and at the range and there I the rules stat that i have to be at the firing line which ic covered so I have to do it on a rest rather than pointing in the air. The problem is the new cases head space measures .004 less than my fired cases. The only thing I can think to do is make sure I push them all the way home tight with my finger before I close the bolt. I there a better way? The next thing is that my chamber is 1.528 and the cases are 1.550. Will they shrink when i blow em out or should I trim them first?
Thanks in advance.
Larry

pbike
01-12-2008, 07:31 PM
How do you know they aren't straight? You are measuring them. Are you measuring after you size them, or when they come out of the chamber? How do you know your chamber is straight? Years ago we were talking about squaring bases of brass. Stan Buchtel mentioned that after the PPC puts 75,000 PSI on the case, the base will be only as square as the bolt. I believe he is right, and furthermore I believe that after just one firing that case should come out of the chamber, as straight as the chamber. If it's not... Is your chamber straight? If you're measuring after sizing, then how straight are your dies? Also I think in order to use the measurements to your advantage you should measure every step of the process so you know where the brass is getting "bent". Does this help?

Paul

Larry M
01-12-2008, 07:49 PM
My main questions still are what is the best way to headspace them for blowing out and do I need to trim them? I measured them with a concentricity gauge from Hollands on the case neck after I expanded them and after firing them sevral times I checked loaded rounds on the ogive. Then I started checking them after firing them guess what... still bent. I thought the chamber at first too . But after much thought considerable advise and discussion I don't think that's it and those cases were BENT BAD. I am going to make new cases I have them already. Now back to the original question. Any ideas?

pbike
01-12-2008, 07:54 PM
I'd still look at the chamber, those cases get slammed in there pretty hard to the point where they should be as straight as the chamber when they come out. If they come out bent, it may very well be crooked.

Paul

ReedG
01-12-2008, 08:27 PM
Larry:

I did my cases from 6mm to .30 in one pass with the tapered expander in my Hornady .308 die. I did not turn my necks until after I had expanded them. I use Lee case lube paste and it is excellent. Then I annealed and full-length sized before firing loading and firing. Everything is very straight.

I am puzzled by the problem you have, but as to your question, I'm sorry that I have no experience doing anything with CoW but eating it!!! I believe some posters on the forum have told of resizing 220 Russian to 6 PPC by firing them in a 6 PPC chamber with a .22 bullet. It may be that you could do something similar with some inexpensive bullets. Don't know if going from 6mm to .30 would work, but seems if it will do it with CoW it should do it with a loaded round.

You seem to have your mind made up, but I don't understand how a case, no matter how out of concentric it is, can be fired in a straight chamber with a full power load and still be crooked. Some of mine were off .008 to .010 after expanding; resizing took some of it out and firing took all of it out. I can easily bend a case neck with just the strength in my arthritic old hands; surely 65,000 psi and several hundred degrees F. during firing should make the brass conform to chamber dimensions.

Anyway, I hope you find your answer.

Larry M
01-12-2008, 09:26 PM
The fallowing is a quote from another poster on this board.

I have always used the expanding mandrel to size up brass but the necks are always crooked. When they are fireformed the neck goes forward crooked. The neck in response to 50,000 psi does not wait until the "short" side comes even with the long side and then they proceed forward. The neck goes forward crooked.

All I can attribute it to is brass spring back. I started a topic when I first thought it was the chamber. Here is what some other folks thought.

http://benchrest.com/forums/showthread.php?t=46099

crb
01-12-2008, 09:34 PM
I used dental wax instead of COW. After firing the case mouths were not full diameter so I still had to run them over a mandrel. I then did the rest of my cases using 3 mandrels, 6.5mm, 270 and then 30 if I remember correctly [ ScottD loaned me the mandrels ]. I lost 3 cases to split necks.

Honestly, next time I think I will call Ron Hoehn and get some of his necked up, turned and weight sorted brass.

jackie schmidt
01-12-2008, 09:46 PM
If you want perfect 30BR cases, try firing a full charge of 4198 in the 6mm case with a 6mm bullet in a 30BR barrel. The cases will come out darned near perfect, ready for turning.
But, be warned. They will be longer than if you expand the cases with an expander. The reason is, with an expander, you are constantly moving metal back. When you blow it out using the method I described, all of the metal is moved forward.
The Robinette Reamer, which many shooters use, was designed for cases that have been expanded with a mandrel, hence the short overall length. That is how they come out. Our reamer is a zero throat Robinette, so we have to trim quite a bit. If I had it to do again, I would have the overall length of the reamer increased so it would make a full 1.560 length chamber........jackie

Larry M
01-12-2008, 10:05 PM
Jackie I have read your posts on that method, but I only have 1 30BR barrel. If you tell me it won't damage the barrel that would be great. Should I not worry about the .004 headspace difference?

henrya
01-12-2008, 11:28 PM
The .004 won't matter - it'll go bang!

Holding the rifle vertical won't make a bit of difference unless you don't have something to plug the end of the case to keep the powder and filler from falling out.

I'd try the basic method you mention in your first post but maybe a different combination of powder and filler. One old time standard was kapok and a grease wad. I've used fast powder with cream of wheat, corn meal and just lots of powder with a square of toilet paper to hold it in. Also wax plugs, paper wadded and rolled into a bullet, felt cleaning pellets to plug the end.

Be careful as some of those things might make a projectile that can hurt someone. They all worked for me more or less. Using powder only (no filler) you kinda have to sneak up on what kind and how much it takes to move the brass enough.

Maybe my first guess would be the case full of 4198 and a wax plug. The powder charge is pure speculation on my part. Maybe start with half a case full and work up. I'd also think about something faster but not too much.

Melt a candle onto a flat surface that will let you puddle it up about 3/16 inch think. Press that sheet of wax over the case mouth after you drop the powder. You'll fill the mouth with wax from the sheet like a cookie cutter. This will hold what's inside inside.

Look down the bore after each shot to check for obstructions.

Go slow and be careful. If it seems wrong don't do it.

And nothing I wrote had anything to do with real bullets!

Tony C
01-13-2008, 07:00 AM
I've tried a COW method and did not have good results. Sometimes the stuff caked inside cases.

Tony

Stubb
01-13-2008, 09:04 AM
Larry,
I started shooting the 30br last summer. After reading posts about expanding necks I too got the K&M expandiron and I had the same results you have had. Runout was .025 or more. I then loaded up some cases with 15gr of unique with a cotton ball stuffed in. Most of these expanded fine but a few required a second attempt. They do grow in length but that is easy to trim. I only have one barrel so I only did 20 or 30. I then ordered the expander die, a .277 and .308 mandrels from Sinclair. I used plenty of case wax and started the case over the mandrel then pulled the case back and turned it a quarter turn and did some more. I changed the mandrel to .308 and repeated the process. Finally I ran the K&M mandrel in, trimmed the cases and turned. I did 150 this way. I split 2 or 3. I shot these 4 or 5 times and I got a Sinclair concentricity gauge for Christmas. These cases run .001 or less now. I recently took the 25 cases that originally would not chamber and necked them back down to 6mm and expanded again. These are now running .005 to .010 out. I have them loaded up now to fire. I use the crooked ones for foulers.

ShelleyDavidson
01-13-2008, 09:09 AM
I've never tried fire forming 30BR cases using 6mm bullets. But...... how accurate will the bullet be. At Denton, the closest berm on the main rifle range is at 200 yards. Is a 6mm bullet shot from a 30 caliber barrel going to be accurate enough to reliably hit the berm at 200 yards or might it fly over the berm and get into unknown mischief a mile or so down range? This is the kind of thing that gets ranges shut down. I have nothing against this method but I'd feel better if that kind of fire forming was done within 20 or so yards of a berm.

Also, I do a lot of fireforming on cases that the shoulder of the brass is up to .125" from the shoulder in the chamber. I use the wax sheet / no bullet method. To do this with one of my Stiller drop port rifles, I place the rifle upside down in the rest. Then, with the bolt open I place the round onto the face of the bolt so the rim is between the Remington style extractor and the bolt face. Being upside down keeps the round from falling off of the bolt face when I close the bolt. Then I pull the trigger. The gun goes off 100% of the time. And, everyone at the range thinks I'm de-ranged for having my gun upside down.

I don't know if other extractors will work with this method. (Almost all of my rifles are drop ports.) They might so long as the bolt face is the correct size. I'm pretty sure you'd not be able to do this for a ppc if you had a universal bolt face that'll fit both a ppc and a br case. I'd think that any rifle other than a drop port would need to be on it's side to keep the round from falling off of the bolt face. It'd be easy to try. Just try it with a primed case with no powder in it. If the primer will fire, then you can do this. And it'll also work when using bullets when you have too much headspace on a fireforming round so long as the bolt face will trap the round well enough. If you want to, it's cool to turn the gun back right side up before pulling the trigger. This'll be real important if you're using a bullet and need to aim the rifle.

Shelley

eww1350
01-13-2008, 10:15 AM
Larry, I use the same method as Jackie S.
I used my new match grade Kreiger barrel...I clean the barrel with wet/dry patches every 3 shots...The brass will come out longer than your chamber...I use a Lee 7.62x39 case trimmer stud to cut my cases back to 1.510"...I have made brass for several other 30BRs using this method and all shoot very well..
One last thing..VERY IMPORTANT...have your gunsmith use your 30BR chamber reamer to cut a tight neck seater (one that matches your rifle chamber) to eliminate any chance of a crooked round...the standard Wilson seater has a .343 neck dimension..plenty of space for a miss-alligned bullet..

Bob Kingsbury
01-13-2008, 10:31 AM
My method for making 30 BRs is not for everyone, but works well. It is
not simple. First I expand case necks in two steps. 270 then 308.
then case necks are annealed in a rotary unit that is not unlike a
record player. It has a pan of water and each case is done one at a time.
Then Remington 125 grain .308's are turned down in dia. from the
cannalure back to the base to a dia which allows the bullet to be
installed by hand.Forward is full dia. and allows jam. Enough 4198 H
is used so bullets are well tensioned against lands. Cases are great
and have no shoulder /neck junction line. there also very straight.
In hindsight, a cast bullet would be very simple- 284 cal.
Necks are turned after firing

Larry M
01-13-2008, 04:34 PM
Thanks everyone for all your input. The method with the bullet seems the most simple but I'm worried about the bullet skipping down the bore and damaging the lands and besides I'd have to borrow a 6BR seater. So I think I'm going to going to start out trying the COW and wax. If it totally does not work out I might try getting a few smaller mandrels and going up in steps and checking the runout. I will be glad when I get another barrel I'd like to try Jackies method with 100 cases and then check it with a scope.
Larry

eww1350
01-13-2008, 04:54 PM
Would you think a 6mm copper jacketed bullet skipping down a 30 caliber barrel would cause damage:confused:
The biggest issue I think should concern anyone fireforming would be to minimize the HEAT in the throat area and immmediately down the barrel while fireforming a large number of cases...
try to keep the temperature at the chamber area of the barrel to less than warm to the touch...clean the powder residue frequently with cool wet patches...chose a cold day (available this time of year) and go to your local gun range and take your time...It may take several trips to the range, but preparing wildcat brass has never been a quick easy job..;)

David Halblom
01-13-2008, 04:55 PM
Thanks everyone for all your input. The method with the bullet seems the most simple but I'm worried about the bullet skipping down the bore and damaging the lands and besides I'd have to borrow a 6BR seater. So I think I'm going to going to start out trying the COW and wax. If it totally does not work out I might try getting a few smaller mandrels and going up in steps and checking the runout. I will be glad when I get another barrel I'd like to try Jackies method with 100 cases and then check it with a scope.
Larry

is putting a "false" shoulder on your brass before you fireform it. When I make my 30x44 brass from Lapua .308 brass, after I get it down to the ready to fireform state, turned, trimmed, etc., I run a .338 expander into the neck and then run the case back into my F/L size die. This creates a small "shoulder" that I set for a .002-.003 crush fit. I have used as much as a .008 crush. There is no question with this method that the case is TIGHT in the chamber and it is going to expand out to the chamber shape and dimension the first firing. No web stretch, no headspace issues.

If your cases come out crooked using this method on the first firing, I would bet even money you have a crooked chamber. Does not matter if you do it w/ a bullet after expanders or w/ C.O.W..

Pete Wass
01-13-2008, 05:40 PM
I've never tried fire forming 30BR cases using 6mm bullets. But...... how accurate will the bullet be. At Denton, the closest berm on the main rifle range is at 200 yards. Is a 6mm bullet shot from a 30 caliber barrel going to be accurate enough to reliably hit the berm at 200 yards or might it fly over the berm and get into unknown mischief a mile or so down range? This is the kind of thing that gets ranges shut down. I have nothing against this method but I'd feel better if that kind of fire forming was done within 20 or so yards of a berm.

Also, I do a lot of fireforming on cases that the shoulder of the brass is up to .125" from the shoulder in the chamber. I use the wax sheet / no bullet method. To do this with one of my Stiller drop port rifles, I place the rifle upside down in the rest. Then, with the bolt open I place the round onto the face of the bolt so the rim is between the Remington style extractor and the bolt face. Being upside down keeps the round from falling off of the bolt face when I close the bolt. Then I pull the trigger. The gun goes off 100% of the time. And, everyone at the range thinks I'm de-ranged for having my gun upside down.

I don't know if other extractors will work with this method. (Almost all of my rifles are drop ports.) They might so long as the bolt face is the correct size. I'm pretty sure you'd not be able to do this for a ppc if you had a universal bolt face that'll fit both a ppc and a br case. I'd think that any rifle other than a drop port would need to be on it's side to keep the round from falling off of the bolt face. It'd be easy to try. Just try it with a primed case with no powder in it. If the primer will fire, then you can do this. And it'll also work when using bullets when you have too much headspace on a fireforming round so long as the bolt face will trap the round well enough. If you want to, it's cool to turn the gun back right side up before pulling the trigger. This'll be real important if you're using a bullet and need to aim the rifle.

Shelley

Is to take 10 at a time to work with me and on the way to work I have a place where I shoot into the ground close to where I am shooting from; of course I live in Maine and Maine is 97 % forrested but it is pretty easy to find a place where one can just shoot from the hip into a bank of dirt, then there are no worries about erant bullets.

Plugger
01-13-2008, 07:20 PM
The way I do it and seems to work is;load the 6br case with enough of fast pistol powder to well form the 30br case, top with cream of wheat then a piece of paper pushed hard on top. Fire, then the case is ready to neck turn. After turning I load with a light 30br load with the bullet jammed in the lands and use this load for practice. If something is wrong with way people ,then I would really like to know for my own information.