Home Forums Hunting & Shooting Custom Rifles & Wildcats COW fire forming question.

I just completed my 257 AI and this is my first experience with fire forming brass. What powders are acceptable for the COW method? I don't load for pistols and the fastest burning powder I have is IMR 4227. Will this work or do I need to pick up some Unique or similar burn rate? Thanks in advance for any advice.

I can't answer your question but I will say after doing that one time, I doubt that I will go that route again. I would just load some ammo to 257, near max loads, and fire form that way. miles

Don't screw with COW. A waste of time and components. Just load with bullets and go shoot. Choose a powder and bullet. Start at the top of std. 257 loads and go from there til you find best accuracy, that'll be your fireform load. It'll be as accurate as formed brass and very nearly the same velocity. My fireform load used W760 and an 85/87gr bullet doing high 3700's with 28" barrel.

I used Bullseye. PM Mule Deer and ask him. He seems to have some experience with it.

+ 1!!!

BULLETS!

I have used Bullseye and a wax plug for fireforming. Do whatever you want.

I used Bullseye when I formed my first 400 Whelen cases. It was about the only way I had to make cases at the time as I didn't have reloading dies or an expander dies set for it. I used about 16 grains of Bullseye and topped it off with COW and jammed a crayon in the case mouth. It worked well.

However, for the 257 AI I wouldn't bother. Just load up your standard cases and fire away. Unless you just don't want to burn up that many bullets. In that case I think the 4227 would work. I'd start around 12 grains and go up till you come out with well formed cases.

I'm with these guys, COW will form out about right, but the shoulder will still not be as sharp as it will be with a good stiff load! I got a box of plus P rounds and they still weren't hot enough to get it done completely!

Work up an accurate load with bullets, it will probably be an over max load for the regular cartridge, hunt while fire forming. Accuracy and speed will be spectacular. I am assuming that you are not shooting over 300+ yards.

I don't think that Bullseye can be purchased anymore, they may have closed the plant down in Va. that made Unique, Red Dot, Green Dot, American Select, and Power Pistol.

I too have used Bullseye and wax plug..works well...

I've used Unique and Bullseye in my 6.5-06 AI, but I gave up on it and just load cheap bullets and a max load of fast powder for the parent cartridge and shoot. My chamber is properly head spaced for the crush fit (I watched the gunsmith gauge it) but for some reason I got a few case separations with COW, go figure.

"Hunt while you're fireforming" would work with something like PDs, and would be a lot of fun. My FF loads were very accurate.

Not very glamorous, but you could just load up some according to a 257 Roberts recipe out of a manual and just go kill something.
Fireformed brass would then be a bonus.LOL

Best,

GWB

Sounds like the general concensus is to load and shoot. I dont really feel that "crush fit" and I dont have a gauge to check head space. However, it was done by a competent smith and a new barrel...I tend to over-think these things. Thanks for the advice, guys.

Can't feel the "crush" fit? I'd be inclined to load the first batch of bullets into the lands.

Now you have me thinking again, Mathman. What type of charge do you recommend with the long seated bullet? Moderate or Max charge?

You'd be OK with the upper end charge for the parent cartridge, but there's nothing wrong with backing off a grain or two. If you have a choice, use a heavy bullet and a powder toward the fast end for the cartridge.

257 Roberts max charges are pretty tame in the overall scheme of things. This is similar to the 250 Savage.

I recently formed some 22-250 brass for my 250 Savage, regular, not AI. I seated some 90 grain Sierras so they'd be firm into the lands, and loaded them with a full load. The cases fireformed quite nicely. Bolt lift and extraction were smooth and easy, and primer signs indicated a load that was still quite mild.

You're blowing out the brass to a larger chamber, which would lower pressures even more.

If you want to be prudent, you could make up a series of one each at increasing charges to get a feel for it.

Not a waste of time when opening necks up to larger diameter!

Probably a waste of time if only AI'ing the brass!

Mike

Its probably a toss up. A one lb. can of shotgun powder, vs. some cheap bullets. C of W can get pretty violent, but I use a 5 gal. bucket with a lid, lined with carpet scraps, in my garage.

Hornady's new hydraulic case forming die doesn't completely fill out the shoulders either. Dupont 700X is what I use. Start out at about 10 grains, and work up until its close enough to filling the shoulders out. Powder plus a primer, vs. Powder, primers, and bullets. Neil Jones specified that I should fire three full power loads, to get my cases formed out, completely.

The brass stabilizes after three firings. The C of W makes for decent first shot fire forming duties.

When I've done it, I've used Bullseye.

Use Bullseye. You want the fastest powder available. Charge is 20% of what max charge weight is for your formed cartridge. Adjust until you get a formed case. Don't over do it. The case will not look as crisp as one fired with a full working load. Use PISTOL primers for forming step. Put those pistol primers away after forming!