False shoulder questions

[bigedp51]

First off I'm not dealing with scoped bench rest rifle here, I'm just fire forming .303 British Enfield cases and I have a few questions.

I have a new Sinclair Expander Die and two mandrels, a 8mm and a .338, my problem is I'm worried about split necks. Will going from .312 to .338 over stress the brass and cause split neck problems down the road.

The 8mm mandrel is too small and the chamber neck is too large for the 8mm mandrel to create a false shoulder. The .338 works in most of my Enfields but in some of the chambers the neck would accept a Mack Truck. So how big is too big when creating a false shoulder in relation to case neck life and reloading.

Also will the stronger firing pin strike of a milsurp drive the false shoulder forward and defeat the purpose of the false shoulder.

Up until now I have been fire forming the .303 rimmed cases by slipping a small diameter rubber o-ring around the base of the case and this forced the rear of the case against the bolt face when the cartridge was chambered.

I would like to use less force closing the bolt and eliminate the chances of damaging the locking lug recesses. On the plus side when the o-ring is compressed it centers the rear of the case in the chamber and promotes better case alignment.

Comments please on false shoulders and if hard bolt closing is detrimental to the locking lugs and lug recesses in the receiver. (for either the rubber o-ring or false shoulder method)

O-ring around the rim and no false shoulder???

The Enfield "problem" short case life if not fire formed properly.

 

[jonbearman]

I would buy brand new brass and anneal it and then fireform. If you are fireforming and have a head space problem ,you can get different bolt heads for the enfield to tighten up the headspace properly.They normally shoot pretty good with out doing all the fireforming or making the neck bigger? Why would you use a 338 expander for a .311/.312 bullet?

 

[RonAKA]

Doesn't the 303 headspace on the rim, and not the shoulder? Also another way to firm up the cartridge is to seat the bullet long so it has a solid jam in the lands.

 

[bigedp51]

OK a little more info, I'm 60 years old and I have reloading for over 40 years, and I have never had the need to create a false shoulder before now and I'm looking for advice.

The Enfield rifle shot hot cordite powder which caused throat erosion, plus they were made long throated. You can't seat the bullets long enough to touch the rifling unless you shoot a heavy flat base bullet backwards.

You also can't find Lake City match grade military cases for a British Enfield rifle so your stuck with a long fat military chamber. To add insult to injury American SAAMI .303 British cases are on the "small side". Small base diameter, thin rims and if they are not fire formed correctly they will stretch and thin in the base web area.

Below is a factory loaded Winchester case, minimum head space on the Enfield is .064 and the Enfield rifle that fired the case below has the head space set at .067. I have .009 head gap clearance and the case stretched .009 in the web area.

I'm unable to seat my bullets long, and longer replacement bolt heads are very hard to find and expensive$$$

I'm looking for answers on creating false shoulders and the effects on case necks if you take the neck from .312 to .338 or even to .35. Because the chamber neck area is so large a .338 and at times a .35 diameter expander mandrel is needed to create a workable false shoulder.

Using the rubber o-ring method of fire forming I have gotten over 30 reloadings from my cases "BUT" the initial chambering and bolt closing is a little stiff with this method.

I want to eliminate the o-ring and have the bolt easier to close using the false shoulder method.

Below is a Wilsons case gauge with a unfired .303 British in the gauge, it is sitting as it should be just .002 below the lip of the gauge

Below is the same fired case resting in the case gauge, the amount the case is sticking above the gauge is how much "longer" the British military chamber is than the American SAAMI commercial chamber.

The American .303 cases have thin rims, and the case shoulder is way short of the mark, I need to make false shoulders to fire form my new cases and prevent stretching in the web area.

Below is an exaggerated false shoulder BUT very close to actual size I will need to make the .303 British case necks to contact the chamber shoulder.

How much abuse can the average case neck take?

 

[jo191145]

Lynns advice is spot on.

Assuming new brass in good condition it'll take quite a bit of punishment. ONCE. ;D

Conventional wisdom would suggest annealing before fireforming.
Personally I would try annealing after fireforming. You want that false shoulder hard to take the force of the firing pin strike. Protect the web first, you can soften the necks, shoulders after it fits your chamber for longer life. Just the way I would go about it.

After its formed you'll then be headspacing off the shoulders.
For my own enlightenment. Would'nt those case guages be put into a drawer and forgotten?
Unless they were specifically made for a particular rifle they're just a generality.
I don't know, never used one. Just asking.

This thread reminds me of when I started loading for my 30-40 Krag.
Found out I needed to turn the necks as the chamber was too tight on modern brass.
Only had .002" clearance on loaded brass. Last thing I wanted to do was put any extra pressure on that action.
Turning necks for an old milsurp. Now thats funny!