303 case forming

[blackthorn]

If you analyze the reasons for brass failure

You will find that the British ammo specs and the SAAMI specs are very different from .303 Brit rifle chambers.
Don't try to FL resize fired cases with USA -SAAMI standard loading dies.
The location of the shoulder is very different.
The SAAMI shoulder is about .04 shorter than the shoulder of a Lee-Enfield rifle chamber.

OK---now you have aroused my curiosity again! If one does not use USA-SAAMI FL spec loading dies, what dies should they use? Are there dies produced off shore i.e. Briton or perhaps Australia that address the shortcomings identified?? Or, do your comments simply indicate we need to partial-full-length size only?

[44magLeo]

For the first firing of a USA case, The rim of the case will control the head space The same as it will with a European case.
Once fired, then you adjust the size die for minimum sizing, just as you would any caliber.
I haven't checked SAMMI or CIP for the case and chamber specs for the 303 British so I can't say for sure what they are. I have read about the 303 chambers on some rifles being a bit loose. Not just in base to shoulder length but the diameter and taper of the shoulder. Some factory chambers can look like an improved version.
Most of these rifles were built for a battle field. The looser chambers let dirty are slightly damaged ammo to chamber without malfunctions cropping up the jam the rifle. The rim controlling head space lets ammo a bit short function well.
Most ammo used on a battle field is factory stuff and doesn't have to meet the reloaders specs for chamber fit.
On reloading dies I don't think they used worn battle rifles to determine the specs they build dies to. I think they would use the SAMMI or CIP specs. I think
They would make them to fit some where between the minimum and maximum case size specified.
On the topic of hydro forming cases. The process is very similar to fire forming. The case is held in a chamber and pressure is exerted inside the case to swell the case to fit the chamber.
As the pressure inside the case increases the weakest part of the case expands first. This is the neck and shoulder because these are the thinnest. As pressure increases the expansion moves down the case expanding it along the thickness of the case walls. The head of the case is the last to expand.
This will happen this way with hydralic pressure or pressure of burning powder. As the case expands at the neck and shoulder it expands out to match whatever the chamber is. If the shoulder ans body expand more it can't draw the brass it needs from the base of the case it comes from the neck. This shortens the case as much as it needs to so the case can form to the chamber.
The case shortens as the case expands radially. The two changes go hand in hand. One can't happen without the other.
Leo

[Mk42gunner]

On hydraulic forming of brass, whatever caliber. I have never done it, but I did see an article in either Nonte's book or one of the old Gun Digests' from the 1960's.

It doesn't look too terribly hard, and minimal special tools needed. A solid shell holder, a fired primer and a close fitting punch. The picture I saw in the article even used a claw hammer, which would not be my first choice.

I do think it would be a good idea to do this outside just in case water sprays everywhere.

Read through some of Grumpa's old posts about case forming, IIRC he did a lot of hydroforming on the brass he converted for sale.

Robert

[EDG]

For the cost of hydraulic forming you could pay half the cost of a new SAAMI chambered barrel that would avoid the need for case forming.

[samari46]

For regular shooting with my two Lee Enfields I'm trying something different to prolong case life. I've hear of this being done with other cases. Would neck up the factory 303 brass to 8mm and use a form and trim die to slowly neck it back to its original caliber leaving a secondary shoulder. And Ignoring the rim an it will headspace off the new secondary shoulder and hopefully eliminate the case head failures due to improper sizing die. All the local ranges are closaed due to the virus. So will have plenty of time to see how all this is going shake out. Frank

[Watergoat]

As a very long time 303 British shooter, I will tell you that the post above on big chambers on battle rifles is spot on. The Brits had long experience fighting in some of the worst places on earth, and had figured out what works to keep rifles firing. For those of us who are target shooters and reloaders, here are two things that do wonders for case life. First, get a neck sizing die, or a set that has neck and full length dies. Mine is Redding, and it is great. Next, get one of the Ruger #1 rifles in 303 that were made a few years back. These are cut with SAMMI spec reamers, and the fired cases come out looking normal, not like some improved wildcat. I suppose one could get a custom barrel made, but that would be kind of spendy for an old mil surp. Better to just neck size only, and keep the brass separate for each rifle.