Headspace...

[Badger]

Member "Parashooter" published a good article in the Technical Articles for Milsurp Collectors and Re-loaders(click here)

Headspace 101 for .303's (click here)

Also, you might want to try our Google CSE custom search engine located in the top right corner of the web site titled Search Milsurps.Com. It only searches our site using Google techniques and can be quite fast and more efficient then what other gun sites on the Internet utilize. For example, in your case, type in the words enfield headspace and see what happens. There are over 10 pages with dozens of old threads with many with pictures that you might enjoy, covering various aspects of this topic.

Hope that helps ..

Regards,
Doug

[Brian Dick]

It does get aggravating. Beware the coin gauges too. I've had several rifles sent here for "correction" after being checked with Okie gauges and found that they were perfectly fine using real MoD specification gauges. I'm not sure if it's the way folks install them or what but either way, I don't trust them and don't own them. No offense to American shooters but for some reason many seem to think that over headspacing the rimmed and very forgiving .303 British round will increase accuracy. This may well be the case when shooting rimless, higher pressure calibers like .30-06 or 7.62 Nato but it simply isn't true with the Lee Enfield. The chambers were designed with reliable function under all combat conditions in mind, not target shooters and reloaders. That little ring just up from the base of your fired brass is probably from a chamber that's slightly oversize but not out of HS specification. The reason the supply of long bolt heads has virtually run dry, is because so many have upgraded headspace in rifles that were perfectly fine to start with making it hard for guys like me to repair the rifles that really need them.

[englishman_ca]

Just as Enfield had to put a stick in the sand and develop their own inch standard, there was an information void in that north american ammunition manufacturers were at a loss as to the standard 303 British chamber. The dimensions were all over the place.
But north american ammunition manufacturers had to be able to make ammo that would fit north american rifle makers' product.

So the Sporting Arms & Ammunition Manufacturers Institute (SAAMI) stuck thier stick in the sand and settled on their own set of standard chamber dimensions. Along with this came their SAAMI spec headspace guages.
Not a problem if one keeps everything as intended. Modern sporting rifles made to SAAMI specs take SAAMI spec ammunition and they are snug in the chamber helping reloaders. Chamber reamers are available to chamber or rechamber barrels.

Now everything is real cool and groovey shooting SAAMI ammo in a SAAMI chambered gun. Check the nice tight head space with SAAMI gauges and you are good to go.
But when a north american gun owner buys a set of headspace gauges from the local gun store shelf to check his ex military Lee Enfield in all probability, they will be SAAMI. Stores here tend to stock products for current mechandise, and not for obscolete Brit rifles that are no longer made. One has to really hunt around to find mil spec gauges. I had mine made for me.

Big problem, or what appears to be one when a mil spec rifle is checked with SAAMI head space gauges. It is possible for a mil spec rifle to pass the mil spec field guage, yet fail on the SAAMI field guage.

Vici verci, you shouldn't use mil spec head space gauges on a modern commercial sporting rifle made in north america that is chambered in 303 Brit. (eg. Ruger).

Confusion happens with the two standards.

So if your mil spec rifle fails the SAAMI field guage, no panic, check it with a milspec field guage, it might be just fine and pass.

[Bruce_in_Oz]

"Vici verci"? On this topic, as they say, (in a Marlene Dietrich accent), in show-biz, "I'll show you where the "Vice is Versa"".

Headspace is important for assessing the potential "state of play" regarding striker "reach" and the possibility of primers backing out.

BUT, the latter is not a big problem when the "approved" ammo has its primers firmly held in via a heavy annular crimp.

As long as the striker has enough "reach" and power behind it, things will work. How many folk obsessively gauge their striker protrusion AND striker spring pressure?

As for "case life": in the "real world" of "authorized" ammo supplied, via tax-payer Dollars, Lira, Roubles, etc., the stuff is generally on a one-way trip after issue to the GI, Digger, Ivan, etc.

All through its production and even in storage, ammo itself is subject to its own rigorous regime of testing and gauging.

On the "two-way" rifle range, NOBODY is likely to be ferreting around trying to recover their brass during a "hot" contact or "fire and movement" operation.

For the rest of us, a "sloppy" chamber will radically shorten case life, as the brass is blown outwards to fit said "dubious" dimensions, and squeezed back via reloading dies. Millions of Arisakas operated just fine with "out-of-spec" chambers. They were "in-spec" just where they needed to be for reliable ignition and extraction, ONCE per cartridge.

As for actual specs; a quick comparison of "SAAMI" and "original" .303 chamber drawings reveals remarkable similarities. What happened in the "real world" was another thing altogether, ESPECIALLY after the rifles left the tender care of PROPER Armourers and Ordnance techs.

[ricohman]

What a great thread. And I totally agree with the head space obsession.
The first thing I was told when I bought an Enfield was "better check the headspace!".
I was also told that I wouldn't have to dedicate brass to each rifle if the headspace was correct.

[Maxwell Smart]

I was also told that I wouldn't have to dedicate brass to each rifle if the headspace was correct.

Sounds like you have found out that such is not the case!

[ricohman]

Sounds like you have found out that such is not the case!

No kidding!
Each of my rifles has its own bag of brass.

[Maxwell Smart]

No kidding!
Each of my rifles has its own bag of brass.

Pretty much the same for me too. I've got a couple that will use each other's brass quite happily, but no way for the rest.

They might headspace the same on the rim, but at the other end of the chamber they often are all different shapes

[CINDERS]

I had a fitter & turner machine me up 3 gauges I gave him a Mk VII round so he could mimic the unfired body taper they are within 1/2 - 1/1000th of an inch .064.5, .067.5 & .073.5 dont ask why I had the .067 made just read it somewhere I never use it anyway. I made him give me the round back all done for the universal Australian payment of a slab of beer.......

[Peter Laidler]

I only ever take issue with Englishman CA (thread 13) with my tongue gripped cautiously between my teeth....... But...... I dispute that the spec for .303" ammo chamber spec/dimensions are all over the place. The actual chambers might vary due to wartime needs etc etc or just plain fair wear and tear but the spec is well recorded in fact. And additionally, in reality, what goes on inside the chamber is almost academic in this respect BECAUSE THE CHS IS MEASURED OUTSIDE - FROM THE REAR OF THE BARREL TO THE FACE OF THE LOCKED BOLT. Nothing else matters.

As for different cases for different weapons, sorry, but it's just mind boggling!