Question on 25-06 fire forming

[lowmileage]

I have a 25-06 that has a long chamber. It was made when the cartridge was still a wildcat. It will take a no-go and a field gauge. Without going into details, I was going to fire form .270 brass. I've created a false shoulder on the .270 cartridge so that I need some resistance to close the bolt on it. I plan to now trim the brass being the .270 length is much longer than the .25-06 but I will do that after I measure the chamber as I plan to leave it longer than a standard 25-06 chamber. I'm aware of the cream of wheat method using fast burning pistol power to fire form. My question is after trimming as mentioned above, am I good to go without fire forming? In other words, can I just start out with a 25-06 starting load and have that blow out (bad choice of words) the cartridge to fit my expanded chamber with the firing of a regular bullet? Thanks,

 

[joelkdouglas]

I have no problem fire forming 7 Mashburn cases with just a starting load of powder.

Can you reach the lands with a bullet? Or otherwise make the round chamber with any kind of tight fit?

 

[Dwh7271]

The false shoulder method with a starting load works fine from my experience.

 

[ShadeTree]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

 

[SJB358]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

Same here! On any cartridge that doesn't fit snug I will neck up and create the false shoulder so I am not stretching brass for no reason on the first firing.

 

[ShadeTree]

Not pertinent to Lowmileage's original post since he's starting out with 270 brass and simply necking down, but to anybody perhaps reading this topic that hasn't attempted this yet there's some things that makes life a lot easier.

Hornady expander buttons are almost a carbon copy of a spitzer bullet shape. So small at the starting end and tapering out until reaching full caliber size. Unlike the short, fat, and blunt design of an RCBS expander ball. The Hornady buttons can be purchased separately and will thread right onto your existing die stem. Makes expanding up way easier with way less stress on the neck and shoulder area of the case since you're not forcing an oversized blunt expander ball into the neck. If necking up 2 caliber sizes (25 to 27) it seems easier on everything to go in steps....25 to 26, then 26 to 27.

 

[lowmileage]

I have no problem fire forming 7 Mashburn cases with just a starting load of powder.

Can you reach the lands with a bullet? Or otherwise make the round chamber with any kind of tight fit?

The 7 MB, a classic. I've not wanted to push the bullet into the lands. I know the reason why people do it but I'm afraid of too much pressure. Thoughts unfounded? Thanks Joel.

 

[lowmileage]

The false shoulder method with a starting load works fine from my experience.

Many thanks for the reply.

 

[lowmileage]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

Thanks, the stripped bolt is a good idea. I didn't think of that.

 

[lowmileage]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

Same here! On any cartridge that doesn't fit snug I will neck up and create the false shoulder so I am not stretching brass for no reason on the first firing.

Good news, thanks for the reply.

 

[SJB358]

I have no problem fire forming 7 Mashburn cases with just a starting load of powder.

Can you reach the lands with a bullet? Or otherwise make the round chamber with any kind of tight fit?

The 7 MB, a classic. I've not wanted to push the bullet into the lands. I know the reason why people do it but I'm afraid of too much pressure. Thoughts unfounded? Thanks Joel.

No issues if you aren't starting with a max charge LM. Joel and I use 4350 and 139/140's and I can't detect a problem giving them just a touch.

 

[joelkdouglas]

I have no problem fire forming 7 Mashburn cases with just a starting load of powder.

Can you reach the lands with a bullet? Or otherwise make the round chamber with any kind of tight fit?

The 7 MB, a classic. I've not wanted to push the bullet into the lands. I know the reason why people do it but I'm afraid of too much pressure. Thoughts unfounded? Thanks Joel.

As you are just fire forming the brass all you need to do is find a safe load with high enough pressure (I’ve read over 40K PSI) to make the brass expand sufficiently but low enough to not damage the brass. I think even if you are jamming the bullet into the lands you’d be fine at a starting load. Jamming the bullets raises pressure but only 8-10K PSI.

The benefit of jamming the bullet or creating the false shoulder is to give the brass a ‘hard starting point’ from which to expand. Either way (or even if you could form the brass for a tight fit on the headspace datum) would work fine.

And probably it would work fine if you just fire formed spec 25-06 brass. Certainly let us know what happens, I’m always interested to hear others experience with fire forming because of the Mashburn!




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[ShadeTree]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

Thanks, the stripped bolt is a good idea. I didn't think of that.

Keep in mind if you're working with an action with a fixed blade ejector, you only need to thread out the shroud and firing pin assembly to have the bolt completely free falling so to speak, on closing. But if you have a bolt with a plunger ejector that would need to be removed also or else it would give a false reading of resistance when closing on a case.

 

[lowmileage]

Not 25-06 but done the same as what you're asking about with a 250 Savage. Necked up to 270 caliber then back down until I had a slight crush fit on the false shoulder right at final bolt closing. Fire formed with a starting load with no problems.

Not sure if it's necessary but I stripped the bolt so it fell shut freely. That way when I was setting my die up I had a positive feel for when it was a slight crush fit on final closing.

Thanks, the stripped bolt is a good idea. I didn't think of that.

Keep in mind if you're working with an action with a fixed blade ejector, you only need to thread out the shroud and firing pin assembly to have the bolt completely free falling so to speak, on closing. But if you have a bolt with a plunger ejector that would need to be removed also or else it would give a false reading of resistance when closing on a case.

Thanks ST, it's on an M98 action. It's real simple to strip the bolt so I'll proceed along those lines.

 

[lowmileage]

I have no problem fire forming 7 Mashburn cases with just a starting load of powder.

Can you reach the lands with a bullet? Or otherwise make the round chamber with any kind of tight fit?

The 7 MB, a classic. I've not wanted to push the bullet into the lands. I know the reason why people do it but I'm afraid of too much pressure. Thoughts unfounded? Thanks Joel.

As you are just fire forming the brass all you need to do is find a safe load with high enough pressure (I’ve read over 40K PSI) to make the brass expand sufficiently but low enough to not damage the brass. I think even if you are jamming the bullet into the lands you’d be fine at a starting load. Jamming the bullets raises pressure but only 8-10K PSI.

The benefit of jamming the bullet or creating the false shoulder is to give the brass a ‘hard starting point’ from which to expand. Either way (or even if you could form the brass for a tight fit on the headspace datum) would work fine.

And probably it would work fine if you just fire formed spec 25-06 brass. Certainly let us know what happens, I’m always interested to hear others experience with fire forming because of the Mashburn!

Sent from my iPhone using Tapatalk

Definately will do. I'm planning on hitting the range the week after next. I'm also doing alot of 7mm WSM test load firing so it will be a long day. Thanks for the reply.