Head Space???

case head separation.
Click to expand...
Time for a really dumb observation:
The OP wants to stop/minimize case stretch.

At this point I don't care that the case is supposed to "headspace" on the rim.
We're going to make it "headspace" on the shoulder.

PolarFBear:
- Begin sizing a fired case... gradually
- Sooner or later the dies' going to squish the case in enough that it will actually grow in length even before the die sets the shoulder back
- Keep trying that case in the rifle as you gradually squish-it-in/grow-in-length to the point that the bolt won't close (shoulder too far forward).
- Keep gradually sizing until the shoulder sets back now just enough that the bolt will close again. THAT's where you quit sizing.
- The case now sets up sitting directly on the bolt face, and stopping on the shoulder -- and quits stretching back to the bolt face when fired.
 
Last edited:
See OP's problem:
case head separation.
Click to expand...
How do you minimize/stop case head separation in a rimmed bottleneck cartridge ?
Same way you do it in a belted 375 H&H or 300 WinMag.

Ignore the orginal "head"spacing on the rim/belt.
Size for the shoulder.
 
mehavey said:
See OP's problem:

How do you minimize/stop case head separation in a rimmed bottleneck cartridge ?
Same way you do it in a belted 375 H&H or 300 WinMag.

Ignore the orginal "head"spacing on the rim/belt.
Size for the shoulder.
Click to expand...
Good idea.

Done right, 15 to 20 maximum loads per case is possible.
 
Polarbear, I load for a few No4 MK1 enfields and its fairly easy to extend case life.
Both Bart and Mehavey have given good advice on how to do it.

I went a simpler route when loading for .303 brit, I neck size only with a redding Die. I get 15 plus reload per case.
 
If mike is getting 15 reloads with neck sizing that is enough to not have to resort to special methods to avoid case stretch on the first firing before you can start neck sizing.

Things like necking new brass up and back down to for a false shoulder on the first shot.
 
I haven't read all the posts here because some of them are just ramblings of people who don't know but are trying to help anyway.
In your case, the 303 British, the head space will be measured from the bolt face, to a datum point on the shoulder of the chamber.
Click to expand...
No. I understand what the poster is trying to explain, but 303 British headspaces on the rim. This ensures good ignition and proper functioning of the rifle. Most issues with case head separation in Lee-Enfield rifles has to do with excessive headspace due to the rear locking action and the very malleable steel used in making the actions. Used to be you could find different bolt heads the Brits made to correct this problem, but I haven't seen one for sale in quite a while.

First step is to correct the headspace. Either find a longer bolt head or have someone who knows what they are doing fabricate one for you. Replacement is simple: unscrew the existing bolt head and install a replacement.

If this is not possible, then either retire the rifle or learn to do as many have suggested, do not resize full-length, turn your resizing die out a turn or 2 to just partially resize and use the fire formed cases as they are and headspace off of the case shoulder. 303 British does not headspace well this way due to the shallow shoulder angle, but you can make it work.
 
I load my 303 brits on the mild side, so that helps. I do not anneal cases.

I pitch them anywhere in the reload count when I can feel a rough spot on the inside of the cases near the head with a paperclip.

I usually load a batch of 50 rounds per rifle, shoot, neck resize 5 reloads, FL ( barely touching the shoulder) once, then neck resize only for 5 more. Lather/ rinse/ repeat until I get around 15 firings per case.
I pitch them out regardless of the condition at 15 reloads.
 
Most issues with case head separation in Lee-Enfield rifles has to do with excessive headspace due to the rear locking action and the very malleable steel used in making the actions.
Click to expand...

This isn't entirely right. Primarily due to the application of terms, because what is headspace in the usual rimless bottleneck rifle chamber is NOT headspace in the .303 British.

In the .303 British, headspace is on the rim, NOT the datum point on the case shoulder. SO, in correct terminology a .303 can have entirely correct headspace and at the same time have a hugely oversize chamber, which creates a case head separation problem WHEN RELOADING cases in the usual manner.

First step is to correct the headspace.
Click to expand...
Not necessarily. The first step is to measure and determine if the headspace needs to be corrected, AND, even if it does, doing it the way the British did it (with a different length bolt head) does NOTHING about the case shoulder to chamber shoulder FIT, which is what is causing the short case life.

In any rimless case rifle, that distance would be the headspace but in the SMLE it is not the headspace. Nor is it the headspace in any other rimmed round or belted magnums. It is a long accepted "work around" to size fired brass so it contacts the chamber shoulder (just as the case rim/belt reaches its proper position or just before) and people then say they are headspacing on the shoulder, and in a sense they are, but the RIFLE is headspaced to use the rim or belt by the maker.
 
The end result desired is to control head clearance and reduce case stretch.

A once fired,unsized case will have theoretically zero head clearance. In real life,brass springs back some,other variables play.

But once fired brass ,fireformed to the chamber is a good starting place. You have that.
As has been mentioned,the SMLE was made to have the situation corrected with standard armorers replacement bolt heads. That would be a great solution if you could find them. I would not expect to find them hanging on a peg at Sportsman's Warehouse.Thats the "cure" to resolve headspace in the rifle.

The "remedy" can be found in handloading techniques. Its really quite common for belted magnum handloaders to ditch the belt and rely on the shoulder for minimizing head clearance to extend case life.

We have more than one way to get there. One way is backing your sizing die off "some" mostly "cut and try,till it works". I have done that. I even introduced horribly messy candle smoke to the shoulder...about 45 years ago.

It was a variable,time consuming method. A machinist career taught me how to use measuring tools to determine first what I have,then make a correction of a known amount. The Hornady caliper attachment supplemented with feeler gauges is one reasonable way to do that.

The method I use involves inspection tools I already have. A granite comparator stand,a dial indicator,and Wilson bushing "Cartridge headspace Gauges" Thats what the maker calls them. I don't suggest anyone needs all that. It can be used. It works good.

Neck sizing. Great idea. Neck sizing is not the same as partial sizing.To truly neck size,you need a neck sizing die.

Partial sizing with a standards sizing die loses the idea of the fireformed case.

Peel a banana. Take half of it. Close your hand and squeeze.Note the banana gets longer as it oozes out the ends of your fist.Partial sizing still squeezes he case body down in diameter, You just give up any control over the shoulder. The shoulder will be wherever it oozes

Partial sizing will increase the case head to shoulder dimension. No big deal,but you still have to set the "shoulder bump" by adjusting the die.

I just accept that up front,measure the fireformed case,and adjust the die to give me a known ,repeatable head clearance, A feeler gauge set used between the shell holder and the die can give me a known.repeatable increment of change. If I want .003 head clearance,I can get there.

A feeler gauge set is a common ,inexpensive,useful tool.

You do it your way. I'm just passing on 30+ years career as a machinist who knows multiple ways to get the job done.

Feel free to take it or leave it.
 
Last edited:
I do not suggest anyone NEEDS this setup. I had bought one to have on my bench as a machinist Its now on my reloading bench.

I use a Wilson bushing case guage with this. I can zero the indicator either on the bushing or on the case head. If I zero on the case head, then run the case through the sizing die,I can directly read the change on the indicator.Its been there more than 10 years.

https://www.travers.com/granite-gage-stand/p/110337/?lite=true&pricelistname=SITE

Apparently someone at Hornady had a similar thought.

https://www.hornady.com/reloading/precision-measuring/precision-tools-and-gauges/

Here is a far more minimalist way to do the job just fine

https://youtu.be/htvk1UYOXm8

For rimless bottleneck cases,I prefer a Wilson bushing gauge. I have never used a Wilson gauge for a rimmed case. I have no reason to believe Wilson would design the gauge to work for measuring the shoulder. I would not expect it to.
 
Last edited:
PolarFBear,

One other thing a number of 303 owners have reported doing is putting O-rings over their cartridges at the front of the rim for the first firing that establishes the longer shoulder for subsequent shoulder headspacing. The idea is a thin rubber O-ring slipped over the cartridge gets squeezed between the front of the rim and the chamber's rim seating surface that defines headspace. The O-ring is supposed to hold the head back against the bolt face during firing so that no lengthwise stretching occurs in the pressure ring area and all the stretching of the case is forward by the annealed shoulder.

If I owned a 303, I would probably try that out, but I need to make it clear I have no personal experience with it and am only repeating what I've read others are saying they do. A minimum 303 rim thickness of 0.054" in a maximum chamber headspace of 0.071" allows for 0.017" of head clearance. That's a lot of stretching to have to happen all at once. The maximum rim and minimum chamber headspace are both 0.064" and that would be ideal to have, but on other rimmed and belted cases, the tendency I see is for the rims to be closer to minimum thickness than to maximum, and the stretch to fill the resulting large head clearance is what is making the brass life short.

By way of comparison, 308 Win loads made to minimum head-to-shoulder dimension and fired in a minimum 308 Win chamber is only 0.003" of head clearance for the stretch to cover. It goes up to 0.005" in an average new chamber (average new being about 0.002" over minimum headspace). For the 303, the minimum case rim thickness in a minimum chamber has 0.010" of head clearance (over three times the 308 minimum case and chamber head clearance) and 0.012" for a typical new chamber (2.4 times the 308 average). So it is no wonder these rounds tend to have a short case life if you don't go to the extra trouble to get them headspacing on the shoulder.
 
Per Unclenicks rubber O-ring suggestion... I,too have zero experience with this,
But it occurs to me orthodontic rubber bands might be a cheap and easy way to go for an "O-ring"

I found some reason to use them fishing. They come in different sizes and strengths (thicknesses).
 
Last edited:
You must log in or register to reply here.
Back
Top