303 Brit & o ring size?

[Willyp]

I would like to try this o ring thing on my 303! What size o rings are used on the cases,which are new?
What happens if you use the o ring thing on once fired cases?[ of which were fired with out o rings] Are they removed,after shooting them once or reused again after reloading the cases?
After firing them,you only neck size cases,correct?

[curator]

Willyp:

You only need to use the "o" ring trick on the first firing on new brass. This prevents the case from stretching just forward of the case head. Once fired brass (without the O ring) are doomed, having probably already stretched this region. Use these for light loads and be aware of possible head separation. Once properly fireformed with the "O" ring in place neck sized brass will last a whole lot longer. Just be sure to not set back the shoulder when resizing.

[walltube]

Hello Willyp,
I have four rifles in .303 Brit caliber. Three are SMLE and one a P14. This is my proceedure when fire-forming new, unfired brass. In my experience, this applies to all brass regardless of make or manufacturer.

Segregate a particular batch of brass to be fire-formed to fit a particular rifle. This is important. No two rifle's chamber and head space are the same. Carry with you a sample of brass to your favorite hardware store or plumbing supply house. Or even an automoblie parts house. Any place with unpackaged stock where you may try fitting the 'o' ring is most convenient. Merely slide the 'o' ring down to the rim (flange) for a slightly snug fit. Choose an assortment of rings of different thicknesses. This will allow you to "adjust" the case to the closed bolt.

All is needed is a gentle amount of resistance when closing the bolt on the case. If there is difficulty closing the bolt, choose a 'thinner' o ring. Should there yet be too much effort, the o ring may not be needed. "Effort" is a subjective term here. If you are a Lou Feringo....well..you get my point I'm sure

All my fire-formed brass is neck sized only. When, and only when, there is some undue resistance to closing the bolt on an empty, much fired case, will I bump the shoulder. Redding bushing neck dies are my hands down favorite.

One thing more: I do not re-size the neck completely down to the shoulder. I stop just short, leaving an un-sized, narrow ring. This ring is the fire formed portion of the chamber's neck. This ring (or doughnut?) guides and helps to aligne the boolit and cartridge to the rifle's bore. Not every shooter agrees with this..however it works for me.

This is my story and I'm sticking with it..

Good luck and hope to have been of some help,
Wt.

[Willyp]

Walltube,
i neck size my other rifle brass as you do. Not the whole way to the shoulder.

[walltube]

At present I am firing only bolt action rifles. Neck sizing only works well with this type firearm. Certainly saves brass and $$$$..

One other rimmed cartridge rifle I have is a M. N. M44, 7.62x54r. This one's brass were all new, loaded Privi. Sooner or later this muzzle blast beast will need new, unfired brass to test the 'o' ring trick. I can hardly wait..

[303Guy]

I haven't used it much, being a new one to me but I've found that an oversize o-ring will crush and burst and be counter productive. A size that did work for but was still a bit large, was this one.



It's about the same thickness as the rim. It's for centering the case as much as setting the head-space on the shoulder.

I do get bolt closing resistance from not setting the shoulder back but usually this is self limiting. On occasion I get the wrong case in a gun. This requires stiff closing force but they loosen up on firing. It's not a good idea to force tight cases in. I've still got one to remove. The head is off, the barrel is off and now there is a lead boolit stuck in front of the chamber. (It just slipped in and stopped but locked up on attempting to tap out - unrelated to the stuck case body).

It's a good idea to partially neck size leaving that 'dough nut'. That 'dough nut' isn't actually a dough nut but if there is one then that saves the day. You would probably not be seating that deep anyway.

[Multigunner]

All my fire-formed brass is neck sized only. When, and only when, there is some undue resistance to closing the bolt on an empty, much fired case, will I bump the shoulder. Redding bushing neck dies are my hands down favorite.

One thing more: I do not re-size the neck completely down to the shoulder. I stop just short, leaving an un-sized, narrow ring. This ring is the fire formed portion of the chamber's neck. This ring (or doughnut?) guides and helps to aligne the boolit and cartridge to the rifle's bore. Not every shooter agrees with this..however it works for me.

This is my story and I'm sticking with it..

Good luck and hope to have been of some help,
Wt.

Great minds move in the same channels I see.

I've long recomended only sizing 2/3 the length of the neck. This I got from tricks old time benchrest shooters once used. Along with presenting the bullet to origin of rifling with out cant, the less pull strength at the neck means the lesser the effect of variations in pull strength, another reason its best not to crimp if you don't absolutely have to.

Marking case rims, then making sure you rotate the once fired reloaded case 180 degrees from the orientation of its first firing will insure equal cencentric expansion so the case will be formed prefectly to the chamber. Firing pin strike is then as near dead center as you'll ever get. Also no room for canting of the projectile.

PS
Using each fired case with expended primer still in place as a snapper for dry firing practice loosens the case up just enough for reliable feeding without need for extra effort in closing the bolt.

[Jack Stanley]

Multigunner , If one marks the case say on a factory round . Would the second round that is rotated and fired need to be loaded to a similar pressure level ?

Thanks , Jack

[Multigunner]

Multigunner , If one marks the case say on a factory round . Would the second round that is rotated and fired need to be loaded to a similar pressure level ?

Thanks , Jack

I've always handloaded mine to above aprox 46K CUP with J-word bullets, any lower pressure with the powders I've tried doesn't give me the bump up necessary for the bullet to fill out the oversized bore.
I don't use factory rounds anymore, prefering to start fresh with bulk unfired Remington cases, but theres really no difference so long as whatever load you use is stout enough to expand the cases properly.

I figure anything 40K or over should have basically the same effect on the brass.

I doubt you'd want to exceed 40K unless absolutely necessary. I reserve my 46+K loads for my No.4 with replacement bolt and #3 bolthead, which gives pretty tight headspace. That rifle requires no O-rings or other tricks to produce fired brass with very long reloadable life.

[303Guy]

The O-ring is not really needed on a properly head-spaced rifle no. It's probably a good idea with unknown or loose head-space and is not difficult to do. A pack of ten plus some spares is all that's needed for convenience. It does no harm anyway. I've only used it a few times to centralise a case. I would full length size the offending case then use the O-ring. Normally I use another trick. That involves lower pressure loading and lightly lubricating the loaded rounds. Not saying anyone else should do it.

Something about a bolt that closes with some resistance is that it is pre-loading the bolt which reduces shock loading on the lugs which is a good thing.

[af2fb751]

Is it necessary to remove the extractor when using the o-ring?

[Multigunner]

The O-ring is not really needed on a properly head-spaced rifle no. It's probably a good idea with unknown or loose head-space and is not difficult to do. A pack of ten plus some spares is all that's needed for convenience. It does no harm anyway. I've only used it a few times to centralise a case. I would full length size the offending case then use the O-ring. Normally I use another trick. That involves lower pressure loading and lightly lubricating the loaded rounds. Not saying anyone else should do it.

Something about a bolt that closes with some resistance is that it is pre-loading the bolt which reduces shock loading on the lugs which is a good thing.

Since in normal operation with a dry chamber the stretching of the cartridge case absorbs some of the energy before the case head comes into contact with the breechface.
An unstaked standard commercial primer cup also slows the rearward movement of the casehead, acting as a hollow piston filled with the high pressure gases of primer discharge and backwash of propellent gases through the hole.
The quality of the impact seems to be more of a factor than the total energy level of impact of casehead to bolt face.
Hatcher wrote of one of the brittle low number Springfield breaking like a dropped jelly jar when a low pressure gallery load was fired. That rifle had withstood a 70,000 CUP proof test load and thousands of rounds of full power milspec Ball.
His theory was that the light charge of the Gallery Practice load did not momentarily expand the case sufficiently to allow the case wall to grip the chamber wall.
Total energy was low, but delivered as a sharp rap rather than as a smooth application of pressure.

The SMLE had a rep for action body cracking if wet ammunition was fired or the chamber was wet or oily. I figure the same sort of sharp rap as opposed to smooth application of force was responsible.
Apparently cracking would appear near the rivet holes of the charger guide bridge. Never heard of this being a problem with the older LE and Lee Metford action bodies without charger guide bridge, or of the No.4 with integral guide bridge.

With zero headgap there would be no hammer like blow to the boltface, or at least very little chance of one unless striker and primer pressures forced the case deeper into the chamber before ignition.
The difference would be like that of pushing a coffee cup across the table or driving it the same distance by whacking it with a mallet.

Whats easier on the rifle may be destructive to the cartridge case, while whats easiest on the brass may be detrimental to the rifle over the long haul. Its a trade off.

Early testing of the .30-40 Krag indicated that accuracy was best with a .004 Headgap. At .002 Head Gap group sizes increased. At .006 groups sizes also increased compared to the test firing at .004.
Could be the brass of the case neck was cold flowing momentarily. With next to no slack the neck would then bind on the bullet giving variations in pull strength affecting bullet release.
With tougher cartridge brass alloys than those used at the time, extremely tight headspace might not cause the same result.

[Jack Stanley]

I bought a few O-rings today and tried the thinnest one with an unfired HXP ball round . It took a whole lot of muscle to close up the action , without gauges I'm lost whether the headspace is long or not . Experience with my rifles doesn't show case problems but I do try to keep cases separate .

Jack

[303Guy]

The O-ring gets squeezed between the case head and the chamber. They should be lubricated for this (the O-rings, that is).

[Multigunner]

Excessive force in closing the action can cause undue wear of the locking lug surfaces and seats.

There are a great many sizes of O-rings out there, some not much thicker than a needle.
They can be stretched to some extent but if way too small in diameter they will break.

If theres very little slack in headgap to begin with you can try the original method that the O-ring method is based on.
Take a length of monfilament fishing line, stretch it by pulling over a hard edge to get the line to form tight curls, then cut of whats needed to fit around the case head above the rim. It should hang tight to the case, but a spot of glue may help keep it in place.

Extra thin pinstriping tape might do as well, and has its own soft glue backing.

[walltube]

This 'O' ring thread is another good one for .303 SMLE shooters. Good pics and text. Multigunner's contributions make for fine, in depth reading beyond the OP's question. Kept yours truly at the keyboard and monitor this rainy day.

As 303Guy says, there should be no need of an O ring in a properly head-spaced SMLE to fire-form brass. In my experience, I say 303Guy is correct. This of course implies that one's rifle is known to be so head spaced.

There are a many members here from the UK and Commonwealth Nations as well as we Americans having more than cursory experience with James Paris Lee's brainchild. Quite a brain trust if I may say so. I drink from this well.

Now, that said, if I am overstating the following, so be it. There is a responsibility that compels me to do so.

Newbies! take heed and read:
Buyers of any newly aquired mil-surp rifle of unknown and dubious history are cautioned to have its headspace measured by a competant gunsmith. In particular those SMLE with removable bolt heads.

What prompts my above off-topic are the shooters that approach my bench with tales about their having less than happy times, and then chuck an SMLE because of case-head separation, etc, etc. Really scary naratives! The folks here at CB can, and do, nip in the bud most SMLE wive's tales before they take root.

All my congratulatory hugs are exchanged, exclusivley, with the chicks...

Ya'll, thanks for listening; hoped to not have been too much of a bore..
Wt.
I have an SA '03 in need of a cleaning..

[Multigunner]

As 303Guy says, there should be no need of an O ring in a properly head-spaced SMLE to fire-form brass. In my experience, I say 303Guy is correct. This of course implies that one's rifle is known to be so head spaced.

In the normal course of events a SMLE or No.4 would not have left the factory if headspace measured over .067 after proof testing, with minimum headspace of .064.
After years of use headspace might increase significantly after many thousands of rounds were fired, or if used in an environment where the lug surfaces and seats were ground away by cycling the action while contaminated with accumulated wind borne sand and other grit.
Even residue of the atomized glass used in earlier Mercuric primer mixtures mixed with oil or the vasoline used as a lube could act like a lapping compound.
Then theres the possibility of a soldier in the field having a broken extractor spring and taking the easy way by switching the bolt head for one taken from a battlefield pick up.
Many of these rifles never saw the inside of an armorers workshop, and were put back into firing condition after decades of neglect using salvaged parts.

Some would have any rifle judged by the condition of a few safe queens or rifles properly refurbed. One can't make blanket assumptions.

Headspace of .067 is plenty tight enough for reloading, but few used Enfields will come near that unless refurbed or properly serviced before having been sold off.
Max headspace of .074 is still safe to shoot, but cases aren't likely to be reloadable, unless fireformed using the O-ring or similar methods.

When rifles were brought in for repair the armorer was more concerned with how well the bolthead clocked in than with achieving the factory new headspace. Used boltheads were always tried first, and so long as the headspace was below the maximum allowable limit the rifle was considered good to go.

Some milspec cases show no stretch marks even if headspace is at maximum, but all these I've tried were berdan primed and not easily reloadable.
Boxer primed ammo with cases that sturdy would be ideal for reloadable .303 ammo.

[walltube]

"In the normal course of events a SMLE or No.4 would not have left the factory if headspace measured over .067 after proof testing, with minimum headspace of .064."

As a matter of fact, thank for your post in its entirety. I try to steer some folks here to CB that they read articles such as yours and other members in this thread.

The thrill and anxiety of a public range when some total stranger asks of me, "... how do I adjust the head space on an English rifle?". "It must be adjustable! The damn thing has threads on it.", or, "..well, you got one, I see ya here all the time with yers." I don't dare mention "O" ring.

....then my head begins to hurt, spots dance before my eyes, I want to go home. Open a fave brew and visit CastBoolits.

Tomorrow will be a better day....

Hoard Yer Lead,
Wt.

[303Guy]

Multigunner is a great asset to us. He has amazing learning and experience!
What he doesn't know off-hand he goes and finds out! Yup - a great asset!

I've seen a Lee Enfield (SMLE) with excessive head space. This thing was separating the heads. I lubed two cases for the guy which he fired. One of those remained forward leaving the primer protruding. The other reseated the primer without the incipient head separation. This guy continued shooting this thing until it began to jamb. The bolt lugs were peening the locking recesses until they burred enough to lock the bolt. And that is the problem with excess head-space. It increases the shock loading to a destructive level. For me it was interesting because it supported my theory on shock loading and also my theory that a lubed case actually lowers bolt face thrust. My theory is that it does this by allowing the case head to progressively creep back with the shoulder locked in place by the case body expansion. Being lubed, this rearward creep takes place at lower pressure levels so that the load is applied onto the bolt face at a slower rate, thereby reducing the actual load 'felt' by the locking lugs.

I also theorise that it should improve accuracy by reducing that vibration inducing shock load and also by making the bolt load more consistent.

The only evidence I can provide to support my theory is that I do not have head separation nor do I have case elongation. The fact that I've never blown up a gun or even damaged one could be attributed to luck so that's not proof. Luck and the fact that I don't load to book max. (Well, I exceed book max in the hornet but even there I get indefinite case life. Besides, book max is a SAAMI thing related to the original gun designs).

[Typecaster]

OK, so if I have a bunch of (maybe?) once-fired .303 brass, am I wasting my time using the O-ring trick? Is this techniques just for virgin brass? I can easily section a case of each headstamp batch to see if there's a stretch problem (assuming all the cases with the same headstamp were fired in the same rifle) I can't feel with a hooked wire. I'm loading for a Jungle Carbine only.

Thanks,

Richard