Fire Forming

[Danth]

Maybe a stupid question, but I see there are numerous suggestions as to how to blow out a case to fire form, like forming a 218 Bee case into a Mashburn Bee. Why not just load to 218 Bee load specs and fire form? I have a bunch of cases that are partially formed that someone was attempting to fire form, but didn't quite get there. I would think that firing a 218 Bee loaded case would get the job done. Am I missing something? Thanks, Dan

[smithnframe]

That's how I make my 257 Ackley Improved with 257 Roberts ammo. Also 22 K Hornet from standard 22 Hornet ammo.

[garandsrus]

Forming to a bigger neck size might work but could cause problems also. For example, going from .223 to 7 TCU or 30-30 to 375 Win. Going to a smaller neck, like 30-30 to 7-30 Waters, requires a different procedure also.

[fguffey]

I would think that firing a 218 Bee loaded case would get the job done. Am I missing something?

I am the fan of forming first and then firing. And then there is the load them up and fire; I want to know what is going to happen to the case when fired. Most reloaders never mention the make and model of the rifle when fire forming.

F. Giffeu

[fguffey]

Am I missing something?

I do not know. I built a rifle, formed the cases and loaded the cases with a load that seemd to be wild; a very kind smith in Arizona accused me of getting off into something what was on the scary side.

After forming the cases I called Hodgdon with all of the details. They said I was correct in deciding the forming load was safe. And then they said the case forming load would be the maximum load (or above maximum) for the chamber after the cases were formed.

The case forming load was the maximum amout of H4895 for a 150 grain bullet when loaded for the 30/06.. Instead of using a 150 Grain bullet I used a 200 grain bullet.

I used 4 receivers, 1 bolt and 1 barrel; I purchased 4 rifles that were advertised as suspect so I had to test all of them, they all survived.


Why not just load to 218 Bee load specs and fire form?

I have no clue how reloaders form cases; I determnie what is going to happen to the case before firing. I can only suspect other reloaders do not know how to check the chamber and bolt arrangment. Others are convinsed the firing pin strikes the primer and then the firing pin drives the case, powder and bullet forward until the shoulder of the case hits the shoulder of the chamber. Anyhow, when reloaders start making this stuff up it gets impossible to explain.

F. Guffey

[Rigsby]

There is not much voodoo over forming, at least not in my house.

I expand the case to seat the correct caliber bullet and load the case with a few grains above the minimum load for the specific bullet weight, off to the range and get some shooting done.

Cases come out of the rifle perfectly shaped to the chamber.

just my humble experience.

[ipopum]

I use cornmeal . mine is the leftover from making alcohol from ground corn. They sell it for livestock feed.

You could also try rice. I think that the wad between the powder and the cow is important.

[Bad Ass Wallace]

I form 218 Mashburn fron 32/20, first reduce the case neck to 25 cal, then anneal and form down to 218 Mashburn, then fireform with a near max. (not over load). Yesterday I fireformed 50 cases and did not lose one to neck splitting. The formed case is then given a new load accounting for the increased capacity.

https://i.imgur.com/6AFUHJMm.jpg

[flounderman]

A rimmed case should be load it and shoot it, because it headspaces on the rim. An improved chamber, you can shoot the standard load. I think Ackley designed his chambers so you can use factory, standard loads in a pinch. I might drop a grain or two off the load for the standard case, when fireforming, and I test to examine for pressure by firing a test load. If the case isn't formed out, I add a grain or two

[fguffey]

The formed case is then given a new load accounting for the increased capacity.

I was going over some material by Easton-Ackley from the 1960s, they said the same thing; that was before the Internet. They mentioned the difference in capacity between minimum length/full length sized cases and fired formed cases.

F. Guffey

[shaggy357]

A rimmed case should be load it and shoot it, because it headspaces on the rim.

The gun is headspaced on the rim when the chamber is cut. Reloaded ammunition is not measured on location of the rim. The only case that that should headspace on the rim after a chamber is cut, are rimmed straight wall cases...oh, and straight rimfire like 22lr and 22 mag. A rimmed case can help minimize headspace issues as it can only be pushed so far into the chamber.

Headspace issues arise when the distance between the bolt face (or action face) and the chamber restriction is greater than the length of brass from it’s base to where it restricts in the chamber. Perfect headspace is base of brass against bolt or action face, and shape of brass restricting perfectly with contour of the chamber. Some folks size brass a to allow .002” growth upon firing. Makes for easier loading in chamber and easy closing of the action. My brass for fire forming is sized about .001-002” long for bolt action so action takes some effort to close. This eliminates brass growth in length and allows brass to form to chamber contour.

Excess headspace is when a loaded round will chamber in a gun but is shorter than the distance between the bolt face and the chamber restriction. The round is too short to fill the space. The brass has no restrictions as to exactly where it will grow in length upon firing. Several firings on a case that is as little as .004” too short can cause a crack to form in the brass. This crack forms where the brass has the least resistance in the chamber. In most bottleneck cases, this crack forms very near the depth the case fills the sizing die. That portion of the case in the shell holder generally fits the chamber and the peak pressures push the shoulder forward. The shoulder can be pushed back on sizing, but the sizing die is forming at the shoulder, not the full length of the case. The weak spot is where that case stretches several times, but does not get restored, near the case head. A total failure aka case head separation, can leave you with the upper 2/3rds of your brass stuck in the chamber. What can be worse? Not realizing the case separated and you chamber another round that stops well short of closing the action. The big bull runs away and you head for camp hoping your buddy has the tools to clear your chamber

[EDG]

I fire form .303 Brit brass to 6.5X53R Dutch Mannlicher.
I use the same loads that I use for normal shooting with fired cases.