Home Forums Hunting & Shooting Ask The Gunwriters Fireforming 7x57mm in a 8x57mm?

I have a new-to-me Yugo 24/47 in 8mm mauser. The rifle is in excellent condition with matching numbers. I also have a couple hundred rounds of 7mm mauser standard pressure factory loads. A few questions...

Is is safe to shoot the 7mm mauser rounds in the 8mm mauser rifle to obtain 8mm mauser reloadable brass? If it is safe, is it likely to cause a lot of copper fouling in the rifle?

If it is not safe, can I pull the 7mm bullet and leave the factory charge and use some type of plug in the neck case to create enough back pressure to fireform the case? What should I use for the plug?

Many thanks.

<>< Brian

Headspace! Don't do it. Got any 06 brass?
If not, head to your local sighting in area and pick up some from the guys who hunt but don't reload. Size in 8x57 die and trim. If you are new to 8mm...good cartridge. 4895 to 4350 works great.
If you want to use the 7mm, pull the bullets and resize in at least 2 steps. Notice the 7mm shoulder is shorter than the 8mm. You will have to create another shoulder for the final case.
Bill

Thanks Wahoo.

Didn't think of the 30-06 brass. That sounds like the way to go for me.

<>< Brian

Run the 7 X 57 brass over expanders up to .338, then pass it through the 8 X 57 die before fireforming. On the other hand, 8 X 57 brass isn't expensive. Just call Midway and be done with it.

I already have a small batch of brass in the mail.

I just wanted to see if there's a good use for the 7x57 ammo and brass I have laying around.

Thanks for the specifics on expanding the brass.

8x57 brass is the way to go.

I would suggest you buy a rifle to fire that 7x57 ammo in next hunting season.

JW

Aussie,

That's how all of this came about. I am a Ruger #1 fan that had a 1A in 7x57mm that I couldn't get to shoot well.

Through a series of trades and buys I now have a 300 H&H and a 375 H&H. I'm quite happy with this pair.

The 8mm mauser belongs to my son. He's really into classic military rifles.

I tried selling my 7x57 ammo locally. Just not much demand for it.

<>< Brian

You can seat the bullets out to touch the lands and fireform 7x57s to 8x57s. I have fireformed a lot to them this way...I also know a bunch of Africans that just shoot up tons of free 7x57s in there 8x57s to get the brass and they are all still alive, I know folks that have been shooting .270s in the 06 or 30-06's in their 338-06s and 35 Whelans. I never much like the idea of a 30 caliber bullet rattling down my bore but it doesn't seem to hurt anything and a great smith once told me copper and lead is softer than steel so why would it hurt......folks have been doing all of these things for ions against sage advise..???????? I always wondered where that advise came from and what it was based on? is it some gunscribes gem of wisdom or does it really have substance and is it based on proven fact. I know of nobody that has ever been injured by this practice..'

I don't know the answer but it would not bother me to fireform in the above calibers. However I don't mess with fireforming anymore, too many good calibers out there and brass ain't that expensive unless you shoot a lot more than I do...

Does a .284 bullet touch .315 lands? Is there a typo here?
Remember 7mm and 8mm don't headspace the same.
Do you mean expand and seat 8mm bullets seated to touch the lands?
Bill

Could you use a 7.62 expander ball in the 8 mm die, then go with an 8mm expander ball? I've never gone this much before on expansion, but seems if you anneal the necks of the 7mm and go up in steps, it might work?

Huh?

Ray,

Will you please elaborate on your post? Are you saying that the 7mm bullet in the 7x57 case must be touching the lands in order to keep the case from stretching too much when the its fired? I think that the diameter of the 7mm bullet would prevent this from being possible.

I value your opinion on this. I just don't want to do something unsafe because others have gotten away with it.

<>< Brian

I've got a good use for it if you were going to throw it away

Perhaps someone will respond to help me further my education on this subject...

My understanding is that when a beltless and rimless case with a shoulder that is too short for the chamber is fired, the case drives forward from the blow of the firing pin, ignition occurs, the case expands to the chamber walls while temporarily sticking to the them and the case then begins to elongate backwards toward the bolt face. This can be a primary cause of case head separation when the tolerances are too great.

If this is true then what would happen in the following scenario with a 7x57 in a 8x57 chamber? You are using a CRF bolt that captures the case with very little slop. You fire a case that has practically the same dimensions except the shoulder is about 0.01" short. Wouldn't the case flow forward primarily in the shoulder and neck area because the rim is captured by the CRF bolt?

This may explain Ray's experiences with this particular setup.

Thanks for your time in dicussing this.

<>< Brian

(edited for spelling)

I've never tried firing 7mm in an 8mm chamber. I suspect it would be a good test of gas handling properties.
Everything I think I know about guns says this would lead to a good story, hopefully w/o injury.
When buying military rifles for $15 at K-Mart was a big deal, we would test them, after cleaning out the bore, by tying them in a fixture with the butt against a tree and a string on the trigger. If you didn't have trouble, we proceeded to cut them down into sporters!
Bill

Mtngoat,
My bad, I ment if you expand the 7x57 neck to accept a 8mm bullet it is recommended that the bullet should make contact with the lands or be very close when fireforming to get a full fireform or so is the accepted therory.....sorry, and thanks for the heads up. However I have fireformed many 30-06 with cormeal, Unique pistol powder, and a wax gob or stuffed a Kleenex piece over the powder charge to fireform a case.

As to the other, I have shot a few 30-06s in a 35 Whelan to fireform the case, and never had a problem. This was a very common practice back in the early days and I never heard of an accident in doing so.. Like I said in my previous post, I have watched some African sit and shoot many 7x57s in there 8x57 Mausers with no harm at all. I think perhaps "like cartridge cases" may be the antedote in that your not moving the shoulder, your just expanding the neck in both instances..

I have seen folks shoot .270s in their 30-06s..I was with a guy that shot up 3 boxes of 270s in his 30-06 at Antelope and never hit one, I finally gave him my gun and he killed the next one he saw, then I looked at his rifle and while unloading it I noticed the cartridges were .270s, bingo! problem solved, he had grabbed the wrong ammo. He had sold his .270 some months prior. Again your just expanding the neck, and not moving the shoulder.

There are instances where you can get into trouble for sure, such as shooting a 243 in a 257 or someting like that..I had a ranch hand that fired a 250 Sav. in my .243 Savage 99F that he borrowed..It locked up the gun and took a piece of pipe and hammer to open it. He said it really kicked the snot out of him, but no harm..It sprung the lever, but I did repair it..That was a close one I suspect, as it had to swedge a 257 caliber bullet to .243, no damn wonder it kicked...:)

Keep in mind that when you fire a 30-06 in a 35 Whelan chamber you have less pressure than you will have firing a 35 caliber down the barrel, and the cases are the same, all your doing is expanding the neck, same with the 7x57. You are not moving the shoulder forward and this is the key as I said above.!!!..

I never particularly liked the idea of a the smaller diameter bullet rattling down the barrel even if copper/lead is softer than steel, but it has never harmed any bores that I know of...

I am not talking about therory, I am talking about what has been done pretty regular over the years and has been accepted in some circles I suppose, at least as long as I can remember.. Many of you are talking about what you think could happen, and that may or may not be correct.

I don't reccommend anything, it's all I can do to take care of myself, so I am just passing on some things I have seen, done, or know have taken place for for a long time for what ever its worth one way or another..

Thanks for clearing that up for me. I much prefer experience to theory!

The 270 and 35 Whelen have the same headspace dimension as the 06.
The 7mm is shorter (shoulder) than the 8mm.
Bill

Wahoo,

I realize that the 7x57 shoulder is about 0.01" of an inch shorter than the 8x57. I stated that in a prior post.

I am not advocating doing what I mentioned in the title of this thread. I am just trying to learn something here. I guess the real question is how far can a case shoulder safely move forward by fireforming? I know there are a lot of variables involved.

Perhaps I shouldn't have even asked the question.

Thank you for all of your input.

<>< Brian

(edited for spelling)