,393 British large chambers

[trooperdan]

I often shop for used brass for my reloading and just recently got an order of four different rifle calibers from a brass dealer. For some reason, he included a couple of .303's in the mix. They showed why I don't even bother looking for once-fired .303 brass, all had a very pronounced swelling just ahead of the web. Apparently a lot of these rifles have very large chambers for functioning in extreme conditions but brass fired in those chambers is forever stretched beyond usability.
I've yet to reload for the .303 but I've heard of a procedure for the first firing that should eliminate the excess stretch. Find a rubber "O" ring that fits snugly around the head of the case before you fire that first load. The rubber holds the case firmly back against the bolt face as it is fired so the shoulder fire-forms to the chamber, hence forth those cases so treated fit that chamber and can greatly extend their reloading life.
So, that is the theory, has anyone used this process? And if you have, where did you find the appropiate o ring to use?

[NoAngel]

You can get the same effect (easier imo) by long seating a cast bullet so that it engages the rifling.

[Outpost75]

The "O" ring also helps by centering the base of the case in the chamber to equalize the expansion of the case body all around. Long seating a cast bullet may or may not do so, depending upon bullet fit and throat wear. The "O" ring gives better results IMHO.

Yes, "O" corrected fumble fingering from phone, thx. Jack.

[Jack Stanley]

I've used "O" rings that I found at the hardware store . It does seem to work rather well .

Jack

[303Guy]

I also lube my loaded cases. My cases last forever or the neck splits ir they get lost, whichever comes first.

I also don't load to max pressure.

Actaully, I have some cases that have worn out rims from chambering ahead of the bolt.

[trooperdan]

.303Guy, would wax also work to lube the case, maybe Johnson's floor wax? Also, heard suggested to use monofilament fishing line or dental floss just ahead of the rim to take up the space.

[303Guy]

.303Guy, would wax also work to lube the case, maybe Johnson's floor wax? Also, heard suggested to use monofilament fishing line or dental floss just ahead of the rim to take up the space.

I would imagine wax would work. The idea is not to prevent case to chamber wall grip but to reduce it so that the case can creep, thereby spreading the elongation over the full length of the case. With reduced loads and new or FL sized cases I lube them well with case lube (which in my case is STP smoke stopper) but with my full power loads I use only a light lubing.

[curator]

Lube, "O" ring or bullet jammed into the rifling leade--all work. Some a bit better than others. I am a big fan of the "O" ring as it keeps the cartridge centered in the chamber. Modern .303 british cartridges have much smaller case heads then WWII military brass. (.454 vs .456-.457) The most important part is to fire-form with the FIRST firing, not shoot factory ammo to get brass. The Lee collet die is a big help in getting long brass life as it does not push shoulders back but just sises the neck. I have brass that has been reloaded 20+ times with no head separation issues as long as I keep it separated for the specific Lee Enfield rifle it was fired in the first time.

[john.k]

Actually,Remington cases are usually just at or under .450", so avoid that brand.....the best cases for base dia are Lapua,commonly .458"..........the spec size for a 303 chamber at the base ( not .2" in front) is .460"-.462",.....rim thickness is variable too.....when I sleeved my DP Ross,I made the chamber .454" ,and some cases wont fit without jamming,so I use Remington ,and there is no visible bulge.

[303Guy]

I can't say that I have any chambers that seriously bulge the cases. To me the important thing is to centre the case so that they remains concentric on each refiring.

Something that I have found, is that with loading new cases, they tend to seat skew. I have now taken to expanding the necks using a rotation between strokes then resizing, also using a rotation between strokes, to the desired size.

The cases I have available to me are PPU and they seem just fine.

[Texas by God]

This is what happened after being fired and reloaded 5 times and fired in 2 different rifles. I would neck size only for one rifle and don't mix brass.https://uploads.tapatalk-cdn.com/20171226/cd568485e26ec8a3bb3fd3c372d3825e.jpg

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[square butte]

What would the proper "O" ring size be?

[curator]

What would the proper "O" ring size be?

I have used Ace Hardware 7/16 X 3/32 "O" rings quite successfully. They do require a bit of effort to close the bolt. I remove the rings after the case is fire formed, segregating the brass so that it will only be used in that specific rifle. Used "O" rings can be reused a couple of times on new brass or factory ammo.

[ascast]

O rings are great if you can find the right size. Home depot carries a variety, tractor supply, Lowes, and harbor freight (in a kit). Ace hardware also. any good hardware store is worth a look. Tape also works. electrical will stretch, Teflon also. Clear cellophane is maybe best. I have used a few wraps of dental floss. Any of these will work, just requires some fussy time. O rings best if you can get them.

[303Guy]

If the chamber is tight to start with but there is a headspace issue (which is what causes head separation) then the O-ring is hard to use as it has nowhere to go. In that case one is only trying to set the shoulder to headspace on.

Something I have noticed with a lubed case is if the case chambers with resistance on the bolt handle, after firing it will fit fine.

[Streetwalker]

Once your cases are fire-formed to your chamber, segregate those cases to be used in that rifle only. I was able to locate a .303 British neck sizing die [Herter"s] and I use that die to neck size only. My brass of various makes will last a long, long time and many firings. I anneal the neck and shoulder after every fifth firing and I shoot only moderate loads.

[trooperdan]

For neck sizing, wouldn't the Lee collet die be perfect?

[SNDBGGR1484]

I have a question for the 303 crowd. Does anyone know what a Saeco mold 303 is? I can't find it on their mold chart. Maybe a discontinued mold. I know I could cast some and then measure and weigh but was interested what the mold was designed for. Thanks for any help.

[longbow]

My RCBS dies not only push the shoulder back about 1/16", they size the necks to optimistic factory specs for 0.311" bullets. Since my chambers are typical military oversize chambers and groove diameters (4 guns) all run about 0.314" I have taken to neck sizing only using a Lee Collet die and more importantly neck sizing to 0.313" ID to suit my 0.315" boolits.

Regular annealing also helps.

The bulge ahead of the web won't hurt if you neck size only. If you don't like the bulge you can use .30-40 Krag brass to form .303 British and I understand the case head is a little larger so does not form the same "bulge" in the milspec chambers.

This all results in far less working of the brass and no resizing of boolits during seating in too tight case necks. Brass life is so far unlimited and accuracy has improved dramatically. This using relatively light to moderate cast boolit loads (favourite load is about 18 to 22 grs. IMR4227 depending on boolit weight ~ usually 180 to 200 gr.).

The O-ring idea, tape or simply making sure the gun has good headspace should solve any case stretch issues if you neck size only after fire forming in that gun's chamber.

So far my most accurate boolit is a smooth sided 215 gr. boolit from a home made mould but the Mihec 316410 (130 gr. HP) and NOE 316299 (200 gr.) both shoot very well from my Lee Enfields.

Longbow

[samari46]

I've shot Remington, Federal and Winchester 303 ammo and all exhibited the dreaded case bulge. I have some old PPU 303 which does not show the bulge at all. Greek HXP and the South African also does not show the bulge. This was shot in a 1949 Fazakerly #4MKII. I seem to remember reading that after WWII the British tightened up their specs on these rifles but cannot quote a source. Frank.

[303Guy]

I have some South African PMP cases. They have a smaller capacity than all the others I have measured. So perhaps the web area is thicker and stronger. I used them in my short barrelled pig gun because of the smaller case capacity.

I made a few neck sizers and expanders for minimum sizing to get the ID I need. Ideally, there should be no expanding required but my sizer is for jacketed's and it works just fine for that purpose. For paper patching or cast I expand to the size required and it basically stays there.

[Texas by God]

At last they are all gone. They were Remingtons and Winchester. I've started it fresh with PPU factory loads.https://uploads.tapatalk-cdn.com/20180110/74eb982be9c98509d9687bb415a1b32a.jpg

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[Outpost75]

This is a WRA drawing which dates from the Lend-Lease period and was later revised postwar, its dimensions being similar to the SAAMI chamber:

211568

[screwcutter]

I have a MK II that went through FTR in the 50s that has a chamber like that, like new bore.
Here is a link to some of my 303 cases.

http://castboolits.gunloads.com/showthread.php?297736-No-4-Enfield-chambers
mr

[Idaho Mule]

When loading cast in my 303's I use an 8x57 size die, on the neck ONLY. All 4 of the chambers I load for will accept this, and I am using NOE 316299 bullets sized to .315. I am experimenting with reformed 30-40 brass (longer neck to utilize long chambers) but can not comment on results , yet. I am sure others have gone down this path before. JW

[303Guy]

I have one chamber with a shorter than usual neck. I know it's shorter because longer cases fired in it have this tapered mouth tell tale.

Good idea on the 8x57 die.

It's interesting that with a head separation there is no gas leak - or at least, not when I had them. My last head separation was in my early days with my first Lee Enfield back in the seventies. My uncle, a retired gunsmith, gave me that tip for leaving the case lube on the cases at that time. Never looked back.

[madsenshooter]

When loading cast in my 303's I use an 8x57 size die, on the neck ONLY. All 4 of the chambers I load for will accept this, and I am using NOE 316299 bullets sized to .315. I am experimenting with reformed 30-40 brass (longer neck to utilize long chambers) but can not comment on results , yet. I am sure others have gone down this path before. JW

You can make some longer cases from .303 blanks that are on the market now. Don't shoot them first, the crimp sometimes splits back too far, ruining the neck. I made 30-40 from them, during the recent shortage of 30-40.

[Idaho Mule]

You can make some longer cases from .303 blanks that are on the market now. Don't shoot them first, the crimp sometimes splits back too far, ruining the neck. I made 30-40 from them, during the recent shortage of 30-40.

Thanks madsenshooter, I will keep my eyes open and procure some if they should become available in my area. BTW I have only "ruined" 31 of the coveted 30-40 brass to date, so don't shoot me !!! JW

[Gunfreak25]

I neck size fired HXP brass in my only No.4 with my 7.65 Belgium RCBS FL die. Works great, I stop just short of the shoulder and leave a little donut for neck support. I use the 7.65 seater too. I expand with an NOE plug to .311. I don't like oiling cases as it does increase stress on the bolt lugs, I have a calculator for this somewhere. O ring is the best method but is cumbersome for me even. I deal with the bulge and neck size. :)

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