reloading 303.

[RobD]

Ireload,
The point about stretching and subsequent separation is that it always takes place about 8 mm in from the case head. That shoulder is not weher teh case splits, strangely, and this is why: As the case expands during firing, it adheres to the chamber where it is thin (at the neck, then shoulder) and the thick part is pushed back. This thins out the case. The little O ring serves to press the case head snug against the bolt face before firing, so that it is already as far back as it can be when the expansion-adherence-stretching takes place.

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[Baal]

The little O ring serves to press the case head snug against the bolt face before firing, so that it is already as far back as it can be when the expansion-adherence-stretching takes place.

I tried the O ring method a few weeks ago for the first time. Five shots, 5 O rings split in two down the middle leaving me with 10 thinner O rings. The brass looked only slightly better than without the O ring.

[Edward Horton]

I tried the O ring method a few weeks ago for the first time. Five shots, 5 O rings split in two down the middle leaving me with 10 thinner O rings. The brass looked only slightly better than without the O ring.

Baal

The last 100 cases I fire formed were with the same o-ring without any damage to the o-ring, your o-ring size will depend on your headspace setting, rim thickness and the diameter of your cases. I also remove the extractor when fire forming, the problem with American made cases is they tend to run to the smallish side on base diameter. When the o-ring is compressed and squeezed by the bolt it centers the cartridge in the chamber, and helps promote equal case expansion.

You can also try and use Sierra 180 grain bullets and see if when seated long the bullets touch the rifling and push the cartridge case against the bolt face for fire forming.

The idea of using the rubber o-ring is not mine, I first read about the o-ring method in the old Jouster forum, and I believe it was posted by "Terry in Victoria". I thought the idea was a little too Bubba for me, then one day while fixing the kitchen sink I held an o-ring in my hand and decided to give it a try.

The main problem you will run into if your use American made cases is the fact that you have a large British military chamber and smaller American made cases not designed for the rated pressure of the military Mk.7 round.

The bottom line is if your cases are not fire formed correctly they will become warped or banana shaped and your reloaded bullets will be out of alignment with the bore and accuracy will suffer.

Baal, the o-ring below fire formed over 100 cases and is still in good shape.



For fire forming my cases I use 100 grain .312 pistol bullets and a reduced load of SR 4759, it saves $$$MONEY$$$ and your shoulder when firing 100 to 200 rounds at the range.

[Edward Horton]

For those of you that missed my other 17,286 postings on this subject, the photo below shows that American manufactures can't even make a .303 British case to American SAAMI standards. The shoulder of the American made case should be in the same location as the shoulder on the "foreign" made military surplus case.



If you actually measured the difference in shoulder location you would "SEE" that it is over a 1/4 of an inch short of the correct position.



Our American made .303 cases have thinner rims than "foreign" made military cases.



Our American made .303 cases have smaller base diameters than "foreign" made .303 cases.



Our American made .303 cases are thinner than "foreign" made military cases.

[Rick]

The last 100 cases I fire formed were with the same o-ring without any damage to the o-ring, your o-ring size will depend on your headspace setting, rim thickness and the diameter of your cases. I also remove the extractor when fire forming, the problem with American made cases is they tend to run to the smallish side on base diameter. When the o-ring is compressed and squeezed by the bolt it centers the cartridge in the chamber, and helps promote equal case expansion.

While this is getting well beyond the original question, there are different routes to the same destination.

I've never heard of "the o-ring method" before.

On the other hand, what I have always done with new .303 brass is use M-dies to set up a false shoulder on the brass before loading that results in just being able to get a crush fit when closing the bolt. With this method, there is not much question that the brass is firmly supported between the shoulder of the chamber and the face of the bolt, and any movement of brass is going to be outward only.

I am also anal enough that I wrap thin strips of masking tape around the base of the brass (having determined how many wraps are required) which allow it to just be chambered before first firing. This generally takes place during commercials while watching the military channel or whatever on TV. The idea of this is to ensure that if the false shoulder doesn't center the case within the chamber, the tape certainly makes sure it does.

I keep a good thing going by using Lee's collet dies for resizing so the brass gets worked no more than necessary.

I don't know about others, but this certainly works for me.

For better or for worse, using this to set up brass for all future loading, results in brass that has long life and accuracy out of my two LE's that I certainly can't snivel about. I buy all my brass in lots of 500, so it is a relatively infrequent chore which I consider to be acceptable in exchange for what I think it delivers in ease of reloading and case life.

With all of that in mind, the o-ring idea is now busily racing around in my mind. It seems to me that this would replace the irritant of wrapping tape ahead of the rim quite nicely while ensuring the base of the case was centered in the chamber at the back.

This bears investigation. What size o-rings do I head out and search for?

[Edward Horton]

Rick

I waited over five years after reading about the o-ring method of fire forming the .303 British and I wish I had started as soon as I had read about it. I have been reloading for over 40 years and the o-ring method just seemed a little too far out in left field until I tried it.

Optimist over at Gunboards did a destruction test with new Remington cases after I posted the o-ring method of fire forming there. Optimist reached 32 case reloading number before the first case failure and had NO case head separations.










Your o-ring size for fire forming will depend on the case base diameter and your headspace setting, I use three different sizes depending on the Enfield used.

I even lapped a zero bolt head to give me a headspace setting of over .084 and used the o-ring method with no ill affects. I like having tight headspace but the o-ring method makes the word "headspace" meaningless (within reason) on the Enfield Rifle.

[Rick]

Optimist over at Gunboards did a destruction test with new Remington cases after I posted the o-ring method of fire forming there. Optimist reached 32 case reloading number before the first case failure and had NO case head separations.

Well, it sounds like we're taking somewhat similar paths to the same results. O-rings, obviously, are a lot faster way of centering the brass up in the chamber than wraps of masking tape. However, I'll continue putting a false shoulder on each new piece of brass prior to first firing, even though I see no mention of him doing that. The false shoulder ensures there is hard contact at both the shell base and shell shoulder - something the o-ring won't do. Whether hard contact versus o-ring will make any difference, I don't know and am too lazy to investigate. But putting the false shoulder there takes no time at all, so I'll continue with that. I do like the idea of no more tape wrapping, however, for centering the brass.

Your o-ring size for fire forming will depend on the case base diameter and your headspace setting, I use three different sizes depending on the Enfield used.

I even lapped a zero bolt head to give me a headspace setting of over .084 and used the o-ring method with no ill affects. I like having tight headspace but the o-ring method makes the word "headspace" meaningless (within reason) on the Enfield Rifle.

Hmmmm... well, there's no "headspace slop" (for lack of a better term) once you put a false shoulder on the case that just barely allows the bolt to close. I suppose when I try it I might want to start on the smaller sizes, because with a false shoulder the o-ring is more about centering the case than keeping the base back against the bolt head. And my LE's are nicely minty with "0" bolt heads, so there isn't a lot of extra room in there to begin with.

[chevy1981enfield1943]

damn, this thread was fun. can someone point me where to go to learn about the pupose and use of this o-ring procedure? please

[ireload2]

RobD,
So tell that to the guy claiming the location of the shoulder is the problem. You have missed several thousand posts about the same subject.