Headspace Gauges

Excellent. So basically I need to sell my full length .303 sizing dies, get Lee Collet dies, resize the neck only and use the o-ring a couple times, and make sure I use the brass only in one specific enfield, if I have that right gents? How many times can you fire full house loads using this method before your cases are toast?
Also, I am not quite sure what is meant by "headspacing off the shoulder"... I thought headspace was the distance between the rear of the case and the bolt face/chamber entrance? Why would an O-ring not be needed after the second or so shooting? In this case where the round will "headspace off the shoulder" where does the brass flow? or is it so tight the brass does not actually stretch? Thank you for all the great information fellows!
 
Drachenblut

Below is our rimed .303 British case, forward movement of the case is stopped by the rim of the case touching the mouth of the chamber.

Head space is measured from the mouth of the chamber to the front of the bolt face.

Head gap clearance is measured from the rear of the case to the bolt face

headspacestretch_frame_000.jpg


When you fire form your .303 case you are making the case a perfect fit for “your” chamber, and after fire forming the rim of the case no longer touches the chamber mouth. After fire forming the case it will head space at the shoulder and the shoulder of the case pushes the rear of the cases against the bolt face (ZERO HEAD SPACE)

fireformed-zeroheadspace.jpg


If you full length resize after each firing the case will keep stretching and thinning and you end up with case head separations.

headspacestretch-1.gif


Using the rubber o-ring method the case does NOT stretch and thin on the first firing and there after the “shoulder” of the case holds the case against the bolt face preventing any case stretching.

When the cases get too tight to chamber you then use your full length resizing die to push the shoulder back for easy chambering. I have special head space shims that I place under my full length resizing dies to control how much the shoulder is pushed back during resizing.

IMGP4385.jpg


Below is a Wilson case gauge, it represents a “commercial non-military chamber” it is used for setting up your reloading dies for minimum resizing or just pushing the shoulder of the case back .001 or .002 thousandths.

In the top photo a loaded South African .303 case is resting just .002 below the lip of the gauge just as it should be. In the bottom photo a brand new unfired Remington case is too far down inside the gauge, the shoulder of this case is ¼ of an inch shorter than it should be. (Americans don’t know how to make British .303 cases)

twocases.jpg


Now to the mud of Flanders, the military .303 British chamber was reamed out and lengthened to insure the cartridge would chamber under adverse conditions. What you see below is how much longer a fired military .303 case is than a fired case would be in a commercial chamber.

under-2.jpg


Our commercial American SAAMI .303 British cartridge cases are thinner and on the small side in the base web area of the case. On top of this every time you full length resize your .303 cases you are “over resizing” them or making them far smaller than they need to be to fit in the chamber.

Below, the reason you fire form your cases using the rubber o-ring method only and why you neck size only.

shoulder-a.jpg
 
cantom said:
I have both Field gauges, SAAMI and military. A rifle that passes to SAAMI spec has tighter headspace...that's not a bad thing.

As long as you don't reject a rifle because it failed SAAMI...if it does, you just insert your .074" military Field gauge next and if it passes then it's fine. Both gauges have their use.
Click to expand...

it closed when it shouldnt have, but after hearing from enough people about sammi vs. military gauges, i decided to try it anyways.

i told everybody on the firing line ' i re-blued this gun myself, handloaded the ammo myself, and it failed on the headspace gauge'.

suddenly i was alone..
 
PigEdP51. Thank you for the information, where can I buy a Wilson case gauge, and how would I go about doing "neck only" resizing? What tools do I need? I have a lee C press single stage and full length 303 dies... and why would I need to resize at all if the case is fireformed to my chamber? I am rather new to that concept and you seem to have a great handle on it. P.S. Where can I find that magnificent stout?
 
Drachenblut said:
PigEdP51. Thank you for the information, where can I buy a Wilson case gauge, and how would I go about doing "neck only" resizing? What tools do I need? I have a lee C press single stage and full length 303 dies... and why would I need to resize at all if the case is fireformed to my chamber? I am rather new to that concept and you seem to have a great handle on it. P.S. Where can I find that magnificent stout?
Click to expand...

Where can I buy a Wilson case gauge?

Don’t bother buying the Wilson case gauge, it is made for a commercial .303 rifle, and the Enfield military rifle has a larger diameter and longer chamber.

How would I go about doing "neck only" resizing?

With a neck sizing die.

Why would I need to resize at all if the case is fire formed to my chamber?

Because the case gets a little longer each time it is fired and eventually it becomes very hard to close the bolt. Then its time to full length resizes and bump the shoulder back .001 or .002 thousandths.

Where can I find that magnificent stout?

Here

IMGP6284.jpg


Or in here.

IMGP6286.jpg


smilingpig.jpg
 
Wonderful. I never did understand what the whole "headspace" topic was about but this explains it beautifully.

I don't think I have to worry too much about it with my Mausers (perhaps my 71/84 which uses a rimmed cartridge ?).
 
BigEd, this is brilliant stuff and it explains quite a few of the 'knocks' against the .303 from an accuracy/consistency/brass life perspective - thanks for sharing this in this forum. What size (thickness) O-ring do you use?
Drachenblut, the Lee collet die set is part#90717 for less than $50.00 the die may be available seperately, but probably only direct from Lee (there are no issues with the border on reloading tools).
 
Unless you're rechambering firearms, all the hobbyist and shooter really needs is a Field Gauge.

If a sized round chambers, it's a "Go". If a Field Gauge chambers, you are outside headspace specs.
 
Thank you Andy for that info, and to BigEdP51 as well. It has really helped me understand alot about the headspacing and reloading issues. I would still like to pick up a no-go guage so that I can be just within a little tighter tolerances. Now here is a question, do the same rules and tricks apply to the rimmed 7.62X54R cartridge? Any tips/tools or secrets there?
 
Enefgee

You asked what size/thickness o-ring do I use and all I can say is there is no perfect one size fits all o-ring. Your o-ring size is governed by your head space, rim thickness and base diameter of your case, it is also governed by the “material” the o-ring is made of. (soft-hard)

I bought and used different size automotive o-rings, pluming o-rings and aircraft grade o-rings, what you need to know is the bolt WILL be hard to close and you want the o-ring to squeeze and flow inward forcing the case to center in the chamber.

One of the major problems is commercial American SAAMI cases have smaller base diameters than “some” foreign non-American brands. With a LARGE diameter military chamber and a SMALL diameter cartridge case these cases tend to “lay” in the bottom of the chamber and off center with the bore. When fired these small base cases become “warped” and when reloaded the bullet will be off center with the axis of the bore and your accuracy suffers.

Below, the Greek HXP case is smaller in diameter and is “recessed” around the rim, and the Prvi Partizan case is larger in diameter and you might need a different type/size o-ring.

privihxp.jpg


I have below 3 different sizes of o-rings and I use the smaller size most of the time, I also remove the extractor to keep it from cutting the o-ring and pushing the case off center in the chamber.

IMGP6287.jpg


IMGP6289.jpg


IMGP6290.jpg


On a normal commercial rifle it is common practice to seat your bullets “long” when fire forming cases with a reduced load, this causes the bullet to touch the rifling and as the bolt is closed it pushes the case against the bolt face.

IMGP6291.jpg


Problem, the Enfield rifle is “long throated” and none of the bullets made today will touch the rifling so a smart Canadian came up with the o-ring method of fire forming the rimed .303 case. ;)
(and he did it without duct tape hoser! ) :D

Bob_and_Doug.jpg
 
Andy said:
Unless you're rechambering firearms, all the hobbyist and shooter really needs is a Field Gauge.

If a sized round chambers, it's a "Go". If a Field Gauge chambers, you are outside headspace specs.
Click to expand...

Sorry but the following is from the 2002 Canadian No.4 series military manuals.

I read this as:
.064 GO
.070 NO-GO
.074 Field Max

2002Can-headspace.jpg


Head space is governed by the cases you shoot and not the size in the military manual.
Remchester doesn’t make “commercial” heavy duty military grade .303 cases.

This book tells you to set your head space .003 (three thousands) larger than your rim thickess.

accurizing.jpg


The book below was written in 1946.

1A-Cover.jpg


page91.jpg


Within reason the rubber o-ring fire forming trick makes head space settings a mute point for the the hobbyist and shooter. ;)
 
You must log in or register to reply here.
Back
Top Bottom