Quick question on this process. It's the first time I have tried it with my 338-06AI, and I am not getting very good results. Here is what I'm doing:
- start with once fired Federal 30-06 brass
- neck up in 35 Whelen die
- neck back down in 338-06AI sizer to establish a slight crush fit in the chamber
- load with small charges of bullseye and the rest of the case filled with COW to the top of the neck
- push the neck into a bar of soap to seal and pack it
- chamber and fire

I'm having trouble getting the shoulders filled out nice and sharply. The case holds 44.5 gr of bullseye to the brim, so I started with 10% of this value and topped off with COW - made just a barely noticable rounding of the shoulder area. I have worked up to 25 gr bullseye (which is over half a case full) and this is now giving me pretty good shoulder definition, but still a bit lacking compared to what it looks like when fireforming using bullets. How much bullseye can a guy use in this process? 25 gr seems like a lot to me. Would another fast powder be better suited?

Is it because the shoulder size is small (as compared to the neck area)? There is not a lot of shoulder to push on in this case - compared to necking something down and blowing the shoulder out, anyway. Should I not fill the case to the top of the neck with COW, leaving more room for the soap plug? Since I'm new to the process, any tips would be great. thanks, maxman

The COW process often fails to provide full form to cases. Your 10% charge is what is often used, but I'd say your 50% level a bit ambitious. The procedure recommended by most involves the use of virgin brass for fire forming. That you are using once fired is probably not a big deal, but by the time you shoot it once, then expand it substantially and then size it back down, well, the necks are going to be harder, no way around it. In your shoes I'd skip the COW and use a mild load with a cheap .338 bullet after you've set up your crush fit. The cartridge is not a high volume shooter, you don't need a huge amount of formed brass.

The trouble you are having is the same problem I had many years ago when I tried to fireform cases with inert filler and Bullseye powder. I changed to Unique and large pistol primers and solved my problem.

The first thing I discovered was that large rifle primers did not produce consistant results. Switching to large pistol primers solved that.

Just a few of the cartridges I fireform and the charge of Unique is as follows

219 Donaldson Wasp 7gr
7x57 Ack Imp. 10gr
30-40 Krag Imp. 15gr
I fill the case with COW and cap with bee's wax. I have heard of using a 1/4 sheet of toilet tissue between the powder and COW. I have never found this necessary.

I agree with the way you are preforming your cases by going to 35 and then back to 338 to set the headspace. I would then use a large pistol primer and start at 15gr Unique, fill the case with COW and cap with wax.

The case capacity of a 30-40 Krag is 59gr and the 338-06 is about 73gr. You may have to go to 18-20gr of Unique before you get full shoulders. Do this one gr at a time and do about three of each load so you get a little better sample to compare.

Believe it or not but it is possible to get a high pressure overload with only COW and fast pistol powder so pay attention to what you are doing. This is one of the reason I did not like Bullseye for this because I believe the pressure peak is way to fast.

So what you have here is the way I do it and have been doing it for 40 years. I am sure that by explaining this I will bring out a whole bunch of people that know this is no good and they have a better way. For them I really don't care. It works for me and has for a long time.

I hope this helps fix your trouble. Good Luck Jerry

Interesting. By default I have always used large pistol primers for forming because I have so many more of them, and also by default, Unique, which I don't like in handguns because it's so dirty. I too have been using this system for many, many years with complete success.

If you'll look at most rifle cases fired in standard chambers with a full load, you'll see that even after just one shot they truly aren't completely formed with sharp corners. It takes a couple of loads to completly sharpen up the case. That doesn't mean there is much change in the internal capacity. If after you form with COW, or cornmeal, you fire with a regular load and bullet, the case will sharpen up pretty well but you still may need another full load for it to complete the forming with sharp shoulders.

Bob338

Right on. I can see that you have also done this a couple of times before. Jerry

maxman.....a question? You aren't using nickel-plated brass are you?

The suggestions about changing primers are fine and you seem to understand the process but let me give you a suggestion that will take a little more effort but will yield what you want the first time.

1. Expand the case necks in two steps...first to .338 and then to .358

2. Run them thru your 338/06 Imp Dies as you have been doing

3. Anneal the necks

4. Fire-form

nope, no nickel-plated brass. Never use it. I have wondered about the use of that stuff though. Does it fireform well using any technique? Is it possible to anneal nickel-plated brass so it will fireform better? I've never worked with it at all, but it looks interesting.

I haven't tried large pistol primers. I can give it a shot. I don't have any Unique, but do have Blue Dot and Lilgun on hand. I don't have any other use for Unique at all, and I'd hate to buy a special powder just for fireforming. Both of these are slower burning than Bullseye (slower than Unique too, for that matter), so they may work ok.

I get good results from my normal fireforming load of 55 gr Varget under a Hornady 200 gr SP, but I'd like to not use bullets and full powder charges for forming. 50 rnds of this load is a lot of heat and wear on the bbl to produce cases, where 50 rnds of some COW load would be much easier and cheaper. I may have to resort to annealing the cases before forming. I'd hoped to avoid that process, but it shouldn't be too bad, considering that the brass was free.

I think I've got a pretty good grip on the process, but ran into a couple small speed bumps while trying to apply it. I knew there were more little tricks to it than meets the eye. I am worried about pressure excursions with Bullseye, even with no bullet involved. That's why I posted initially. The need to use 25 gr of this fast powder just seemed too much to me. Thanks for the info so far. It gives me plenty to try. maxman

Max, I firfoemd some .375URM cases for my .404jeffery just to see how they would work. I sized them 1st & then used some old 4227, 27gr, filled w/ COW to the middle of that long neck & capped w/ a candle wax plug. It makes a pretty good .404 case. Bulseye would scare me so I think the one of the slower pistol powders.
I just got my .260AI & plan on using bullets to form cases. I need to sight in & bbl. breakin anyway. After that I may try COW to fireform my .260/.243 cases.

Grits are good to eat,cream of wheat isn't.Why waste something that is good to eat?

WC

I cant belive you'd lie to all these good folks here! grits good to eat?! You've been brainwashed since birth to belive that, but I did my basics and jump school at Ft Benning, I know better. I joined the rangers and was shipped to Ft Lewis just so I wouldnt have to eat grits anymore.

Heresy, Heresy! Off with their Heads!

Grits, Redeye gravy, and Cream O Wheat! Breakfast of Champions!

Get a Rope!

Personally I favor Heuvos Rancheros but they are too messy for fire forming. Our local "gun hacker" tried his hand at fire forming with some left over pistol powder ("I dunno, I just grabbed whatever I had laying on the bench... I think") and toilet paper - 3 sheets of two ply. We now have a perfect 1" 3 shot group in the wall where his TP left the barrel and pierced the corrugate steel siding. BTW, the holes are perfectly circular, too. He managed to leave the cartridge name etched into the bolt face of the gun .... he don't work here no more ...