A question about the COW method and case size.

[WildBillG]

So here is what I did. 2 brass with 9.5grns of Tite Group. 2 brass with 10,5grns. 3 with 12grns 6 with 17grns after reading I should use more powder. 26 orso with 27grns. All fire formed and made a nice shoulde at the neck. The first 3 loads were not nice sharpshoulders on the case though a little rounded. The rest though I could not see any noticeable difference in them. I did find though that the fired cases had the neck junction at 2,580. I readjusted my neck die so that when the brass was sized up the false shoulder would be there. When I neck sized the formed brass at this setting the shoulder ended up at 2.560. I have 50 more cases to fire form I am using 24 grns of Tite Group even though I think 20 would be plenty. I will add all the brass came through fire forming feeling like new brass inside..
On a side note when making a false shoulder do you guys still just move up 1 caliber or do you do more with biigger cartrages.

 

[just_jon]

Just an alternate perspective to consider: For any cartridge that does not head space on the shoulder, so rimmed or belted cartridges, COW fire forming is a waste of powder, primers and Cream Of Wheat. In addition, AI cartridges were specifically designed so you can shoot regular loads in them and end up with fire formed AI brass so not a lot of benefit to COW forming those either.

If the cartridge you are working with do space off the shoulder and aren't an AI, just create a false shoulder on the neck. Fire forming loads will shoot almost as good as post formed so you might as well get the benefit of the extra shooting in if you are going to burn up valuable primers.

Good point on shooting parent cartridge ammo in AI. I shot five boxes of factory 250 Savage in my first AI. I keep another box in my range bag in case I forget my hand loads.

 

[WildBillG]

I thought I would be able to just neck up and shoot the new cases with this Edge. Unfortunately it did not work out that way. Mostly my fault for not looking at the dies close enough. On the bright side this may save the barrel 100 rounds going through it.
Happy Thanks Giving weekend to all the Canadians the forum.

 

[nksmfamjp]

Just an alternate perspective to consider: For any cartridge that does not head space on the shoulder, so rimmed or belted cartridges, COW fire forming is a waste of powder, primers and Cream Of Wheat. In addition, AI cartridges were specifically designed so you can shoot regular loads in them and end up with fire formed AI brass so not a lot of benefit to COW forming those either.

If the cartridge you are working with do space off the shoulder and aren't an AI, just create a false shoulder on the neck. Fire forming loads will shoot almost as good as post formed so you might as well get the benefit of the extra shooting in if you are going to burn up valuable primers.

Maybe you want to reconsider based on barrel life. You may be able to form by just shooting, but do you want to run an extra 300 bullets down your bore that you cannot load develop with?

 

[Dean2]

Maybe you want to reconsider based on barrel life. You may be able to form by just shooting, but do you want to run an extra 300 bullets down your bore that you cannot load develop with?

Well, for most any gun where I am much worried about total round count like those in the 7 RUM over bore range, 100 to 150 brass is about all you need to wear out a barrel. On top of that, I have successfully done load development at the same time that I was fire forming brass. That is how I know that many times the unformed loads are every bit as accurate as the fire formed loads. Even making 17 HH brass out of Privi 22 H and 338-378 out of 460 Bee brass, the first firings of the formed brass made excellent starting load tests. I typically load those first test sies of rounds starting halfway between min and max, using .005 off the lands and getting progressively shorter. That load series gives completely formed brass after the first firing, and gives me group data, COAL data etc to work with.

Not saying COW doesn't work, just trying to offer a different option that has worked very well for me over many years.

338-378 from 460 PRIOR to being fire formed. 460 to 378 seating (no stem) die ,to 378 FL, to 378 seating die (No stem), o 338-378 FL Die.

 

[WildBillG]

Dean2 that was my original plan for my brothers Edge. How ever as I said I never thought to look the Redding dies over close enough and missed that they had a tapered expander. In fact my Redding 338 RUM dies don't and they are the same series of dies.. I was kind of forced into the COW method.
How does your 338-378 shoot. I read about you biulding it.

 

[Dean2]

Dean2 that was my original plan for my brothers Edge. How ever as I said I never thought to look the Redding dies over close enough and missed that they had a tapered expander. In fact my Redding 338 RUM dies don't and they are the same series of dies.. I was kind of forced into the COW method.
How does your 338-378 shoot. I read about you building it.

Now I get it, one of the reasons I don't use the expanders when forming new cases, I use a mandrel on the last step for that purpose.

With respect to the 338-378, unfortunately I can't tell you yet. The smith will have it done shortly. Barrel was done quickly but could not do the high gloss blue on it till all the bits and pieces were here. Good old supply chain problems slowed down getting the specialised items like three leaf express sights, for the build. All that was in hand finally last month so they are putting the finishing touches on the gun right now. The is far and away the longest I have waited for a build to complete. K.S. Arms makes fantastic hand lapped, cut rifle barrels, and do great gun work. Karl is a true old time master and a genius with metal. I am very confident it is going to shoot fantastic, just like the others he built.

 

[WildBillG]

I have heard K&S do great work. I hope it gets done soon so you can play with it. Nothing quite like getting your new rifle home and heading to the range to try it out.

 

[newmexkid]

When my 243AI is finished I will be fireforming with Accurate #2 with TP as a filler. Probably go with 11grs-13grs. I have always fireformed with loaded rounds so this will be a first for me.

 

[WildBillG]

I am kind if new to fire forming brass as well. Newmexkid what powder are you thinking of using. It may make a difference on how much powder you should use. When you said you were going to use TP you meant to hold the COW in right. Filling the Case with TP might cause some problems but I am not sure.

 

[newmexkid]

I am kind if new to fire forming brass as well. Newmexkid what powder are you thinking of using. It may make a difference on how much powder you should use. When you said you were going to use TP you meant to hold the COW in right. Filling the Case with TP might cause some problems but I am not sure.

I will be using Accurate #2. I looked for months for WIN 231 and finally gave up. I will be using about 1/2 sheet of TP without any COW. Info supplied by a long-time Ackley shooter on another forum. I've fireformed a few other cartridges shooting bullets with no problems. However, this time I will be using the process I mentioned just because I've never done it before. A little antsy about it but, I'm going to do it. Just make sure the TP is pushed tightly against the powder.