HXP 303 Now Available

[Edward Horton]

The people who complain the least about head space are shooting Greek HXP ammunition designed to British specifications. The problem is Greek HXP loaded ammunition is very hard to find.

The two type cases that give the least amount of problems when reloaded are Greek HXP cases and Serbian Prvi Partizan cases.

With the rubber o-ring the word head space becomes meaningless and even second and third rate commercially made cases will last longer.

Five years ago Beelzebub the New Zealander at Gunboards told me about Prvi cases and I didn't want to listen to him and shoot Commie Pinko ammunition when I could "buy American".

Four years ago a Canadian told us about the rubber o-ring method of fire forming cases in a different forum and it sounded too much like Bubba or a shade tree mechanics way of doing things, and I didn't try it.

I ordered 500 once fired Greek HXP cases from Brian Dick and I also let Brian know I was testing any cases I could find for wall thickness and rim thickness.

I measured all 500 HXP cases at three different points "inside" the case checking for stretching and thinning in the web area. This was very time consuming but I was very surprised at the answer.



Not one single Greek HXP case had any stretching or thinning in the base web area.

Brian also tossed some in some extra cases of different case manufactures as a freebie for me to look at and inspect (thank you Brian) and the Prvi Parizan cases jumped out at me immediately. The Prvi Partizan cases are .010 thicker in the base web area than ANY other brand of .303 British case on the market. These Prvi cases also have a larger base diameter than ANY case on the market.



I spent time and money providing all the manuals to give you all the best information possible.

Whether You Like It Or Not headspace is determined by the cases you shoot and not the rifle. The British military didn't design our American SAAMI cases or the European CIP designed cases, and that is a written fact.

[RobD]

Jeez, this is like deja vu all over again...

[Bindi2]

Jeez, this is like deja vu all over again...

But ED is so right. The truth only hurts those that are untruthfull or ignorant of the the truth.

[jmoore]

Now if we could just find a way of having it presented in an brief manner-such as a link to a sticky or something...

[Son]

Now if we could just find a way of having it presented in an brief manner-such as a link to a sticky or something...

Now there's a good idea! I don't think anyone can speak against the method demonstrated or the reason it came about...

Perhaps Mr Horton, you might submit a piece for Badger to consider for the "Technical Articles" part of the MKL!

[coppertales]

OK, I am going to bite. WHERE on the case do you put the Oring? chris3

[rondog]

OK, I am going to bite. WHERE on the case do you put the Oring? chris3

As I understand it, all the way to the head, or rim of the case. The idea is to use the o-ring to fill in any space between the case head and the breech, to force the case back tight against the bolt head.

The way I interpret it, when the cartridge fires, the sides of the case expand and grip the walls of the chamber and the case doesn't move. But if there's too much headspace between the bolt face and the case head, the case head can/will move backwards towards the bolt face, even though the sides of the case are gripping the chamber walls and don't move.

This can stretch the case wall in the web area just above the case head, causing thinness, cracks, and case head separation and an early death for the case, resulting in fewer reloads for the case. I understand the whole purpose of this is to "fire-form" the case to the rifle, so you can get more reloads out of your cases. For rifles with mis-matched bolts and excessive headspacing, or cases with rims that are thinner than mil-spec.

At least that's how I understood it. I could be way off. Wouldn't be a surprise.

[Edward Horton]

OK, I am going to bite. WHERE on the case do you put the Oring? chris3

The only place that will "push" the rear of the case against the bolt face and create a zero head space condition.





A new modern commercial rifle has 3 to 6 thousandths head gap clearance or "air space" between the rear of the case and the bolt face. A Enfield Rifle at the maximum head space setting of .074 and a cartridge with a rim thickness of .058 can have .017 "air gap" between the rear of the case and the bolt face.

This means the base web area of the case when fired can stretch as much as .017 (seventeen thousandths) this weakens the case and causes case head separations and short case life when reloaded.

Below is an example of case thinning and stretching in the base web area.



With the rubber o-ring around the rim of the case, the case is forced against the bolt face and the case does not stretched when fired.
The rubber o-ring also compresses and centers the rear of the case in the chamber helping increase accuracy when the case is reloaded.



The rubber o-ring doesn't care what the head space is set at or your Enfield or even if the head space is larger than the maximum setting of .074 within reason. After the case is fire formed you neck size only and the case will head space on the shoulder of the case and not the rim.



Your are "fooling" the case into thinking it was fired in a tightly head spaced Enfield or "fooling" the rifle into thinking the rim of the case is much thicker. The end result is no case stretching in the web area and cases you can reload many more times before case failure.

Below is a factory loaded Winchester case fired in an Enfield with the head space set at .067. The case stretched .009 thousandths when fired without an o-ring.



Even the European CIP who governs firearms and ammunition states that modern commercially made ammunition has a head space problem in the Enfield rifle.

Delta L problem

The delta L problem (ΔL problem) is a condition that occurs regarding certain firearms chambers and their practical incompatibility with ammunition made for the corresponding chambering. The ΔL refers to a Commission Internationale Permanente (C.I.P.) geometric dimensioning and tolerancing definition for firearms cartridge cases which are longer than the chamber they have to fit in.

If the chamber in a C.I.P. conform firearm (a firearm with chamber dimensions specified by the Commission Internationale Permanente) is shorter than a non-C.I.P. conform maximum sized cartridge (a cartridge with external dimensions larger than specified by the Commission Internationale Permanente), use of that ammunition in the firearm may lead to chambering and/or feeding problems in the shoulder area or other headspace issues.


Firearm cartridges with otherwise problematic headspace

There are also some firearm calibers with problematic headspace listed by C.I.P.[2]
The headspace defined by:
Depth of rim recess

* .303 British
* .38 Sp AMU
* 6.35 Browning
* 7.65 Browning
* 9 mm Browning long

Delta L problem - Wikipedia, the free encyclopedia

The basic problem is modern commercial ammunition is not made to British military specifications and does not like the longer head space settings of the military Enfield rifle which it was NOT designed for.

[Son]

Yes, the oring holds the case in the centre of the chamber and back against the bolthead. On firing the case will expand out to the chamber walls equally all around, evening out the stresses around the case head. Without the oring, the case will sit in the bottom of the chamber and expansion will only be into the vacant space above the case (however small)- all the stretching is on one side.
Once the case has been fired in the centred position, it will be centred every time it's chambered after that untill you have to full length resize.

[Bindi2]

Have to agree with Son about the centering of the case in the chamber has more to do with case life than zero headspace with the first fireing. Excellent post ED. Can some thing like this be put up as a sticky as it is always on the go.