military brass vs commercial brass

[Edward Horton]

The number of angels which can dance on the head of a pin is determined by WHO made the pin.

Below, .303 British once fired Prvi Partizan case on the left and Greek HXP case on the right, after checking and measuring 100 Prvi Partizan and over 500 Greek HXP once fired cases I was very surprised. The Prvi Partizan and Greek HXP once fired cases had NO stretching or thinning in the base web area after firing. This means NOT all types of cartridge brass are created equal and American commercial cases stretch more than some other brands.

Bottom line, military cases are generally made thicker in the base web area BUT the quality or brass mixture also plays a big part in case life.



Please notice above that the Prvi Partizan brass is larger in diameter and also thicker than the Greek HXP cases, and the HXP case expanded more in diameter. The point here is though neither type cases stretched or thinned in the web area when fired.

A once fire American made Winchester case fired in the same Enfield with the same headspace setting (.067) the Winchester case stretched .009 in the web area.







Military designed and manufactured cases are made to shoot in long fat chambers, commercial cases are designed and made to shoot in smaller shorter chambers and can cause problems in military chambers.

Below a case in point, the 7.62 NATO case did not separate in the 30-06 M1 chamber.





Headspace is governed by the cases you shoot and NOT the rifle.

[Parashooter]

. . . Enfield with the same headspace setting (.067) . . . Headspace is governed by the cases you shoot and NOT the rifle.

Please explain how that Enfield with .067" headspace no longer has .067" headspace if you use different cases.

[Skip]

Here is a 5.56 fired in an AK. On the right is the standard fired 7.62X39.

[smellie]

Parashooter, it's not hard at all.

When you check a Lee-Enfield rifle and the 'headspace' measures out at .067", it means that there should be .067" between the rear butting-point on the chamber, where the FRONT of the rim butts solid, and the forward resting-point of the bolt-face. Absolute minimum measurement here is .064". So, IF you are shooting proper maximum military brass, which has a rim thickness of .063", you then will have .001" (from the brass) plus .003" (from the rifle) for .004" total headspace. And that is just FINE.

BUT........ some DWEEB turns out a batch of ammo with rims only .037" thick (I have actually seen a specimen) and you now have .003" from the rifle plus (.064-.037=) .027" from the ammunition and this adds up to .030" practical headspace, which is THREE TIMES absolute MAX, nearly EIGHT times what you should have, even though the rifle gauges perfect.

Milspec ammo for the .303 was controlled rigidly, with minimum rim thicknesses of .058" and maximums of .063". But this is peacetime and the Army isn't gauging the stuff any longer, so the civilian companies will attempt to sell anything they can cram into a box and put a label onto. Fortunately, most of them are pretty careful about what they make but one maker in particular got REALLY sloppy a few years back and some of that junk is still around.

In the case of the 7.62 NATO in the .30-'06 chamber, you have a theoretical EXTRA quarter-inch of headspace. It is the relatively straighter case of the 7.62 preventing it from zooming all the way forward which prevents more separations and blow-backs than actually occur.

Some rifles are more forgiving than others, also. I would never attempt some of the things I do with Mausers and Lees and Rosses, were I restricted to something with push-feed and a snap-in extractor; I would have blown my head off long ago. As one example, I needed some .308 cases blown out straight.... I just loaded them up fairly mild and shot them out of a .30-06 Mauser. That long-claw extractor held the cases firmly against the bolt-face and the lack of taper helped to wedge them in place in the chamber. Pressures were low and the primers back out about .010" but otherwise no troubles at all. I had my dozen cases in a couple of minutes and could proceed on to what I wanted them for.

But it IS possible to have a perfect rifle and still have excess headspace. And that is with a rimmed cartridge.

With a RIMLESS cartridge, it is even easier. All you have to do is shave a shellholder a few thou and then proceed as to the instructions in the loading manual. When you screw your FL die down against the shaved shellholder, you will be SHORTENING the distance between the case-head and that all-important point on the shoulder from which the headspace is taken. Your ammo still will measure proper OAL of the completed rounds, it still will measure proper case length. This is something which often is done if a rifle has a particularly tight chamber. But use that ammo in a rifle with a slightly over-length chamber and you have a potential for trouble.

As the man said, headspace is governed by the ammo you shoot.

Good point to remember, I would think.

[Edward Horton]

smellie

My Enfield Rifle headspace of .067 didn't change BUT the head gap clearance can change depending on rim thickness. Head gap clearance is the air space between the rear of the case and the bolt face. On the Enfield rifle this can be as much as .020 (twenty thousandths)

American SAAMI commercial .303 British cartridge cases are NOT made to British military standards and this is why short case life is a problem if the cases are not fire formed properly.

The head gap clearance with my Winchester cases was .009 and this is how far these cases stretched and thinned in the web area when fired.

The main point I was making was the Prvi Partizan and Greek HXP cases did NOT thin or stretch in the web area when fired in the same Enfield rifle.

My statement "Headspace is governed by the cases you shoot and not the rifle" simply means not all cartridge cases are made or constructed the same.

From my testing and taking case measurements I would put the .303 Prvi Partizan cases in the same category as American military Lake City brass and much thicker in the base web area.






I use a rubber o-ring to fire form my cases.





When the o-ring fire forming method is used the rubber o-ring centers the case in the chamber and holds the case against the bolt face and the cases will not stretch and thin in the web area.

In another forum one member did a destruction test after using the o-ring fire forming method and got over 30 reloadings from his .303 cases before the first neck crack happened. (NO case head separations)

I do understand what the thickness numbers on my headspace gauges mean and where the front and back of the gauge rim touches when used.

[smellie]

That rubber "O" ring is a really good idea for forming brass. What size do you use when running .303?

As to the difference between 'headspace; and 'casehead clearance', I guess I've been spoiled by a lifetime supply of really good brass: Dominion, early Imperial, Defence Industries. It was ALL manufactured absolutely as close as possible to the MAX rim thickness of .063".

You're not SUPPOSED to have anything like .020" clearance on a Lee-Enfield anywhere. If the rifle is at max headspace, this is .074". With decent ammo this means (.074-.063=) just .011" casehead clearance. This can grow another .005" for really rough wartime ammo which never would be accepted normally, but you still have just .016". If you have .020" you either have really bad ammo or a rifle needing the Armourer... or both.

There WAS a manufacturer about 35 years ago that was turning out the most awful crap you ever saw, putting it into boxes and selling it to people. Hard brass, splitting case-necks on first firing, primers in backwards, hard primers that pierced when shot no matter what rifle, rabidly erratic charges, splitting cases, separating cases, case rims so far out of spec that it was scary (I have actually seen .037"!), things like that. The whole tale is long and tedious but in the end they didn't sue the newspaper writer who pointed out the dangers (me) and they did spend one awful whack of money telling people what a fool I am. They tightened things up a LOT after that newspaper article had people in 2 provinces taking their ammo back and demanding their money back for the stuff... but I still haven't bought any and still won't fire their product if I cannot determine its age. There were just too many wrecked rifles from the stuff.... and none of mine are 'disposable'.

One thing I have found is that if you fire-form the .303 case as you are doing and then treat it as if it were a rimless case and neck-size only, they last about 5/8 of forever.

Keep shootin'!

[res45]

May or may not be relevant to this discussion but I take LC 7.62 x 51 brass and convert it to 300 Sav. for use in my cast bullet loads in my Sav. 99 Why you may ask well the brass is dirt cheap and I like trying something new on occasion. I use a load of 16 grs. of Allaint 2400 with a 150 grs. RNFP GC bullet. I haven't gotten around to working up any J bullet loads as of yet.

Running an identical load over the chrono with only the difference being the LC converted brass vs. Win factory 300 Sav. brass I get close to 100 fps. more MV using the LC brass,so it does affect MV and pressure to a degree.

[Elliott]

"That rubber "O" ring is a really good idea for forming brass. What size do you use when running .303?", to quote smellie.

Inquiring minds would like to know?

[Edward Horton]

The size will depend on your Enfields headspace setting and how thick the rims of your cases are and the base diameter of the case. I bought a package of o-rings at Home Depot but can't remember what sizes were written on the box. Winchester cases will require the largest o-ring and Prvi Partizan cases the smallest.

Below are the three sizes I use at the range and the smallest is the one I use most of the time. Size does matter, as the o-ring is compressed and flattened it will center the case in the chamber and help promote equal case expansion.






The o-ring method works much better than trying to seat your bullets long or creating a false shoulder on your case neck to push your case against the bolt face.

The best of the currently made cases you can buy today are Prvi Partizan cases, the case walls are .010 thicker, the base diameter is larger and the rims are thicker than any cases made.



A once fired Prvi case showing no ring around the base due to its much thicker base diameter and wall thickness.

[JBS]

In complete agreement with Ed. The Prvi Partizan brass is currently the best and most available brass for .303. The Oring method eliminates all headspace problems. Make sure the case web support is with in a safe range if your correcting a long gap. If you have more than one LE then purchase a set of colored Sharpie markers and color code your fire formed reloads for each rifle by ringing the primer pocket with the marker. Once I Oring fire form a case for an LE I neck size the case only from that point forward. The 303 case in the EL have the luxury of being double secure. If you reload you can use the rim to set your head space, the case shoulder, or both. Leave it to the British to wear both a belt and suspenders.