303 british resizing problem.

[OptimusPanda]

I finally kicked off my .303 brit reloading project...Needless to say its not going well. The rifle is a no1mk3* the barrel is in great shape and does not seem to have a headspace problem. The field gauge is close to closing but I wouldnt dare try and smack it shut. This rifle shoots very well and does not have a problem feeding, shooting, or extracting any factory ammo I've tried in it.

Ok, now the problem. I neck sized a brass case (previously fired in this rifle) and checked to see if it would still chamber. No dice, gets about as far as the field gauge trying to close the bolt. Curious, I took an unsized case out of my sort bucket (also fired in this rifle) to see if it would chamber. Nope, same thing. Did this with a few pieces of brass to make sure I didnt have bad luck and all results were the same.

So with a cut off wheel on a dremel I started shortening one of the cases to see if I could figure out where it was sticking (dont know why I chose this method but it made sense at the time). The shortest I got was about an inch from the case head and it was still not chambering. So in some sense of frustration I smacked the bolt shut on the tiny case that now resembled a .455 webley. Well it does indeed chamber, but extraction is sticky. The chamber does not look like it has a ring in it though. A set of calipers did show that about half inch forward from the case head the case is about .002" wider than the brass before and after it.

Guidance would be appreciated as Im out of ideas. Thanks in advance.

[bouncer50]

Welcome to reloading 303 your going to have to fully resize the case. 303 has a habit to expand grow long in the chamber. I have to fully resize mine

[mrrch]

I only have to neck size. Every rifle is different.

[leebuilder]

Plus 1 on both. Sounds liks you need full lenght size, is the brass shot from the rifle?
Wide chambers will ruin some brass.

[enfield]

I keep all my 303 brass separate ( only goes back in the gun it was fired in ) and I only neck size with the Lee collet die ( I never full length size unless its range brass ). maybe you have a wonky chamber ( ok, wonkier than normal Lee Enfield ) if you make an index mark and put the brass back in the way it came out after firing does it chamber o.k ?

[N4AUD]

I have to full resize mine. These rifles are a conundrum but a fun one.

[OptimusPanda]

All my 303 brass was factory ammo and shot through this rifle. I was kind of fearing a full length resize as I've heard that 303 likes to get head seperations. Any tips on lengthening the life of the cases or just pick up a broken shell extractor and see? Also, I have never had a punctured primer or separated case, what should one expect? It shouldnt being dangerous if youre wearing glasses right?

[Ed Barrett]

I have found a very big variance in chambers I have owned about 20 over the past 50 years. Still have 2, One I can get excellent results, the other is a brass eater. Have to resize to get it to chamber reliably, it shoots too damn good with cast so I put up with it. Wonky about sums it up.


I keep all my 303 brass separate ( only goes back in the gun it was fired in ) and I only neck size with the Lee collet die ( I never full length size unless its range brass ). maybe you have a wonky chamber ( ok, wonkier than normal Lee Enfield ) if you make an index mark and put the brass back in the way it came out after firing does it chamber o.k ?

[OptimusPanda]

Hmm, I never thought to index the cartridge and see if the empty brass goes back in indexed. I need to look into this.

[Von Gruff]

If you are going to use the FLS die it pays to put something on the neck of the case like a little bullet lube smear (or similar) so you can see where the sizing is coming down the neck and you can set the die to stop before you shift the shoulder back. Set the die so it is at last 20-30 thou above the shell holder to start and do a trial case and adjust as needed.

[303Guy]

If the fired case came out it should go back in. It sounds as if someone used a dusty pull through from the rear on a regular bases. Then again it could be a manufacturing flaw. If you blacken a fired case and randomly chamber it, it might show where a potential out of round is. Sizing the case body should not be too detrimental to case life but setting the shoulder back should be avoided. Von Gruff has covered that one.

[leebuilder]

All my 303 brass was factory ammo and shot through this rifle. I was kind of fearing a full length resize as I've heard that 303 likes to get head seperations. Any tips on lengthening the life of the cases or just pick up a broken shell extractor and see? Also, I have never had a punctured primer or separated case, what should one expect? It shouldnt being dangerous if youre wearing glasses right?

thats just 303. Get a ruptured case tool and keep it in your shooting bag. Had many seperations, not to worry did not notice till i pulled the bolt back.
I full lenght size all mine, except for my hunting rifle. Some brands of brass are bad S&B is the worst, surplace is the best.
be safe

[OptimusPanda]

Whats a dusty pull through 303guy? The chamber looks like it was cut kinda crude I can see symmetrical tooling marks that dont look like they were made by hand. Had always assumed it was always that way since its a 1917 and the trenches needed rifles.

[303Guy]

The cleaning cord which got oily and picked up dust. If used incorrectly it can wear a groove on the side of the chamber or wear the muzzle. Yours sounds different when you say symmetrical tooling marks. Are those axial or radial? Radial can only be from bad tooling. Axial could be from tooling chatter. If that's the case then it's understandable that a fired case won't rechamber.

If body only sizing is required it is likely that a standard resizing die would do the trick by doing just as Von Gruff explained.

[OptimusPanda]

Radial I think. It looks like the outside of a barrel thats been turned down on a lathe, although inside an chamber and barely visible. I think a full length sizing die may be in my future though.

[Frank46]

Just out of the blue but try rotating one of your fired cases in the chamber. If you find a spot where it chambers easily you just might have a chamber that isn't perfectly round. So if that is the case you will have to index your cases for the sweet spot. I may or may not be right on this but worth a shot as fired cases should easily rechamber in the rifle they were fired in. Frank

[MtGun44]

LOL! Since headspace is on the rim, the chamber shape seems to be entirely
an optional thing. AMAZING differences. Just fine for the soldier on the battlefield
but pure nastiness for us poor reloaders. I bag cases from each rifle and mark which
SMLE it came from, gives me LESS headaches, but still some are not happy.

Not sure what is happening with the OP's rifle, I wonder of the chamber could
be egg shaped in cross section, so the case has to be clocked correctly to
go back in. . . . . :shock:

Remember, as far as the military and the gun makers were concerned the condition
of the case after firing had TWO requirements: 1) be intact and 2) will extract.
After that they are entirely uninterested in an "expended" case.

[1johnlb]

OP,
No dice, gets about as far as the field gauge trying to close the bolt

After reading this statement you made, I have to ask, are you inserting the case in the cylinder or are you clipping it under the extractor? The extractor takes a might bit of force to jump the rim of the case and can be damaged if repeatedly forced over it. Try making a dummy round with just a boolit, insert it in the mag and see if it will chamber. If it does your just hitting the extractor against the back of the case, this is normal, at least in my experience.

[Multigunner]

A set of calipers did show that about half inch forward from the case head the case is about .002" wider than the brass before and after it.

The chamber may have at one time been plugged. A friend bought a Savage drill rifle otherwise unmodified other than having the firing pin broken off and a chamber plug hammered tightly into place and lightly tack welded.
He had bought the rifle soley to use its wood and fittings to restore a rifle with broken stock set.
When he dropped a cleaning rod down the bore the plug just popped out.
There was an irregular ring in the chamber just where yours is bulged. Hammering the chamber plug in left that ring.

To ensure that my reloads chamber easily I manually retract the cocking piece and dry fire using the fired case as a snapper. You could try that. Otherwise you may have to resort to full length resizing with the sizing die set to size as little as possible and still chamber.

One SMLE I had seemed to have very generous headspace till I noticed that its bolt handle was not properly fitted to the action strap (butt socket). The bolt was not turning all the way closed. When I trimmed a bit from the under side of the handle so it would close all the way the headspace was excellent. A few degrees difference in rotation had made about .005 difference in the headspace.

[fred2892]

OP,

After reading this statement you made, I have to ask, are you inserting the case in the cylinder or are you clipping it under the extractor? The extractor takes a might bit of force to jump the rim of the case and can be damaged if repeatedly forced over it. Try making a dummy round with just a boolit, insert it in the mag and see if it will chamber. If it does your just hitting the extractor against the back of the case, this is normal, at least in my experience.

The extractor will not be damaged by being forced over the rim every time. Dont forget, the Lee Enfield was designed for single round loading by dropping a cartridge onto the magazine cut off. Now if you were talking Mauser, you'd be correct.

[1johnlb]

The extractor will not be damaged by being forced over the rim every time. Dont forget, the Lee Enfield was designed for single round loading by dropping a cartridge onto the magazine cut off. Now if you were talking Mauser, you'd be correct.

Let me refrase my statement, it stresses the spring. Isn't this why they have repeated spring brakes? Dropping the round on the cut off and closing the bolt will still allow the rim to fit under the extractor, but closing the bolt on a round in the chamber takes considerably more force to get the extractor over the rim. This happened to me with my first LE, this is how I know.

Op states, he cut the case way back then he forced it and it went.

Op also states, the fired case extracts normally, so unless the chamber is egg shaped and the cartridge needs to be timed it should rechamber normally.

I've had LE chambers that the fire formed brass had a considerable crook in the case and never had any issues with them chambering, and as a matter of fact were extremely accurate. So the only two things that I know of that would cause his condition would be a case to long and we know he cut the case back or he's trying to close the bolt on a already chambered case because it won't feed without a boolit from the mag. When I did it ,my first though was somethings wrong and I didn't won't to break nothing so I didn't force it, to quickly learn that the extractor was the culprit hitting the rim.

[OptimusPanda]

I fed the brass from the magazine guiding the case mouth with my finger so the case would present itself to the bolt as if it were being fed. As for checking the headspace I did take the extractor and spring out of the bolt head first so as not to damage them snapping over the thick rim of the gauge.

[303carbine]

Another possiblity is that the bolt head is not screwed in all the way.

[SOFMatchstaff]

I use a 44mag size die to iron out the base bulge/ring that you seem to have described in the webley test... I use a Dillon die, no stem, and it made a big difference in the used brass chambering issues. Lewis Gun and a couple P14s have good tight chambers, but field brass didnt quite come back with a full length die. you can run loaded ammo thru with no issues too.
I neck size in the first station and the 44 base sizing is in the second(RL1000) just to make sure the odd round doesn't slip thru. If you dykem or black the base and hit it with the 44 die you will see where it is oversize.

[Multigunner]

The extractor will not be damaged by being forced over the rim every time. Dont forget, the Lee Enfield was designed for single round loading by dropping a cartridge onto the magazine cut off.
By 1915 the regulations for musketry forbade single loading from the top, when single loading they were instructed to not use the magazine cut off and only insert rounds into the magazine so as to feed from the bottom.
Those troops armed with rifles that still had the cut off were instructed to use it only as a back up safety device, to avoid accidentally chambering a round without noticing it.

The extractor and especially the extractor spring are the most commonly damaged parts of the various Lee Enfield designs, and snapping the extractor over the rim is the primary cause of damaged extractors and weakened or broken extractor springs.

While target shooters often single load directly into the chamber replacing a broken extractor spring is not as difficult at home after a day of shooting at the range as it would be in the back of beyond in Afghanistan or India while a thousand sword wielding fanatics are coming your way.

Quality of mass produced springs was a bit iffy at the turn of the 19th-20th century. The best springs might hold up to decades of abuse while the run of the mill might break after half a dozen tries at single loading.

I've replaced an extractor with pivot hole wallowed into an oblong. The spring would still hold the damaged extractor well enough to extract but the extractor couldn't hold the extracted case rim against the left receiver wall to eject in the proper manner. Ejected cases often fell right back into the bolt way. The only time I've seen a Lee Enfield jam.
I've run across quite a few SMLEs with limp extractors.

Any one who owns a Lee Enfield should obtain at least one spare extractor spring and keep it handy.

When loading with the mag cutt off closed I first hook the rim under the extractor then guide the bullet nose into the chamber by hand. That takes away most stress on the extractor.

[303Guy]

Some Lee Enfield's have sharper extractor claw angles than others. My MLE has a longer claw with a shallower angle. It's mated to a No4 barrel so it likely climbs up off the rim anyway. It slips over the rim with ease while others don't. Either way it 'should not' break the spring but what happens in the real world depends on material quality and heat treatment. The spring may also have rough machining marks which might promote breaking. I've been lucky but I'm thinking having a spare spring or two might be a good idea. I do have spare bolt heads though. One rifle has a damaged extractor - the sharp tip has broken off from a jammed case. It still works though. That said, it's simple enough to single feed by inserting into the mag and that's what I intend doing from now on.

[groovy mike]

If it came out, it WILL go in. Get a rat tail file in case of head separation. Meanwhile anneal your case necks and shoulders (NOT case bases) and you will gain brass life.

[1johnlb]

I've had 1 savage 10fp 308 with a ringed cylinder that had hard extraction with well fire formed brass that I was able to hone out ( smooth out ) the rings with a 08 cylindrical hone. But, then loading wasn't a problem Only extraction.

[PAT303]

All you have to do is click the rear of the case into the mag and it will slide up under the extractor like it's supposed to do,I don't understand why people find the easiest things so difficult. Pat

[OptimusPanda]

The empty cases will feed just fine from the magazine so long as the mouth doesnt get bent or otherwise mangled from the feed ramp.

[leebuilder]

Hi Guys.
the exractor and spring have to be free of dirt and crud, extractors may be burred and or have an oversize hole this will shorten the extractor spring life, check the extractor cut too it may be dirty or not perfect. Never had an issue dropping rounds in and ramming the bolt home once they are cleaned and tuned. I prefer to load singly at the range and dip the rim in the mag so the bolt picks the casing up properly and under the extractor, mainly so i need not use extra effort and get out of postion before sending the boolit down range. Takes practice.
Plus one on getting extra springs.
be well

[EDG]

The No1 Mk3s do not have much metal on the right receiver rail to support the bolt head right behind the receiver ring. The sharp edge of the bolt head can scrape this area away and the bolt head takes on a little tilt. The extractor force helps to push the sharp front edge of the bolt head into the right receiver rail when the bolt is closed. You can find this sometimes by standing a deprimed case on its base and rotating it. The case will lean like the Tower in Pizza. When the case head is that crooked you will need to index the case exactly as it was fired to get it back into the rifle.

You can also spot the crooked head, sloppy chamber combo by looking at the primer indent. If the indent is only 25% of the way from the edge of the primer pocket you will probably find the crooked bent head issue too. If so your case life is not going to be very good with anything approaching a factory load.

[Multigunner]

A loose fit of the bolt head shank threads to to bolt body female threads may not always cause over clocking but can still allow the extractor spring force to shift the bolthead to the right when in battery. If the bolt body threads are worn they may be looser at the front causing a cant as well as a misalignment.

[atr]

Another possiblity is that the bolt head is not screwed in all the way.
This is a good thought about the head !

also try this,,,,
take one of your fired cases and instead of FL sizing back the sizing die off a quarter turn then run the case through. See if it will chamber then. If not you are probably stuck with FL sizing
atr

[Motor]

Like "atr" suggested I would start with the full length sizing die high. Then adjust it down a little at a time until it chambers. You may want to go a little bit more after that just to give yourself a little fit tolerance.

Motor

[OptimusPanda]

Just an update for this to close out this thread (or atleast the problem that prompted it). I got my paws on a FL sizing die, and threaded it in just enough to eliminate the problem of tough chambering. The die is about 2.5 or maybe 3 full turns from contacting the shell holder and they feed and chamber just fine now. The shoulder doesn't look like it has been pushed back when placed next to a factory round. Here are the first 10, loaded with 13 grains of RedDot and a 150gr SP.
138965

[303Guy]

The shoulder doesn't look like it has been pushed back when placed next to a factory round.Many if not most chambers have a clearance between the shoulder and chamber but not all. Smoke them before sizing to see.

Those look like Hornady spire points. I have had good accuracy with those and have just bought 100 and found a few lying around. I load mine out further than yours. As long as the magazine can handle in fact. I'm talking ten shot MOA (or was it 1¼?)

[OptimusPanda]

Oh I think I worded that kinda funny. I meant that the shoulder on the finished reload looks much more like a freshly fired case (with it's blown forward shoulder) than it does an unfired factory round. Also, in the picture you can see where the case looks like it was binding and giving me trouble in the first place there's a thin ring where the brass contacted the resizing die about a quarter inch from the head.

[fred2892]

there's a thin ring where the brass contacted the resizing die about a quarter inch from the head.

That thin ring near the head could just indicate a sloppy chamber which is allowing the case to over expand at the point where the case web thickness ends. But the most common reason for that ring is that it is the first sign of impending case head separation due to case stretch.
Don't forget your ruptured case extractor next time you go shooting. I keep one in the rifles butt trap as its not exactly a rare occurrence when shooting 303.

[303Guy]

I meant that the shoulder on the finished reload looks much more like a freshly fired caseAh, right.


Don't forget your ruptured case extractor next time you go shooting. I keep one in the rifles butt trap as its not exactly a rare occurrence when shooting 303.I hear this from time to time. Hasn't happened to me for nearly forty years. I still have some functional cases from back then. My WWII armourer uncle told me of a trick. That and not setting the shoulder back.

[fred2892]

You must be very lucky then. I see it two or three times a year on average at my local range. Last time for me personally was last year with a piece of HXP brass. Mind you, .303 is the most common milsurp here and every range date will have anything up to a dozen 303s on the firing line each popping off at least 100 rounds per session, so the law of averages say its going to happen again soon.

Just dug these out of my range bag
139193

[1Shirt]

They are all different! Mine is a cobbled together rifle, akin to the moose who was made on the 8th day from left over parts. It is about as ugly as home made snot. I bought at a gun show about two years ago from a guy who was walking around with it, asking 150.00. I looked it over, offered him 100.00, and we settled on 115.00. It shoots .315's, of just about any weight, into 3-4" at 100. For an ugly old battle rifle, to me that is fully satisfactory. Once in awhile I get a luck group of about 2". I nearly full length size (1 turn back out of the sizing die) about every 6-7 loadings. The rest of the time I neck size with a Lee Collet sizer.

1Shirt!

[3006guns]

Nothing to do with the OP's original subject, but about those bolt heads.......

I had an aquaintence who made Hollywood movies and considered himself quite the director. He mentioned a rifle that got ruined after his last cinematic effort and I offered to look at it. He brought in a 1918 Enfield MkIII* with a bolt that wouldn't close, stated that the rifle was junk and offered it to me for fifty bucks. I bought it, went out to my car, removed the bolt, screwed the bolt head home, looked at a good bore and replaced the bolt. My son has that rifle now and it shoots lead just fine.

Sometimes the good lord smiles on us commoners.......:)

[milrifle]

I bought a No 1 Mk 3 and when comparing fired cases to my No 4 Mk 1, there was a significant difference in length from case head to shoulder and angle of shoulder. The guy I got it from said he had checked the head space and it was OK. I wondered if he had lied to me. I bought a field gauge and the rifle does indeed pass that test. I'm thinking the chamber is just long. At any rate, I bought some O-rings to put under the rim and fired a bunch of factory rounds in it and intend to neck size only and let them headspace off the shoulder. Just have to keep the brass separate between the two rifles.

[leebuilder]

In my observations more 303 rifles suffer from " elongated chambers " and not bad headspace. Many rifles rejected at the military armory i would visit had been rejected for elongated chambers. The worst headspace i have encountered was on P14s and lee enfield with mismatched bolts, thats on a military .076" reject gauge.
be safe, have a broken shell extractor in your range bag!!

[OptimusPanda]

Here's one last update. I was finally able to get those two loaded stripper clips to the range today. They shot great. Maybe and inch and a half at 25 yards, not long range I know but atleast I could actually shoot them all day. They did shoot 3" high though, which does make sense as they're probably going half the speed of normal 303 and my understanding was that slower bullets of the same weight in the same gun tended to shoot higher on paper.

[Multigunner]

Broken cases were more common during WW1 before they began manufacturing cases sturdy enough for use in automatic weapons.
Theres a list of manufacturers of suspect cases on one of the ammo collector sites. The list is of headstamps of dud ammunition that should be discarded rather than re primed and processed for use in training. They actually salvaged hundreds of thousands of rounds in this manner, but in the end it was just too much effort to save a few pounds sterling in components.
The suspect cases often broke up at the shoulder during the resizing process or when bullets were being reseated.

When MGs or rifles became worn occasionally a case would separate on first firing.

[PAT303]

Simply bumping the neck up with a .32 or .33 cal button and then sizing back in a normal .303 die until you get a light ''crush'' fit when closing the bolt and then fire form with a squib load,neck size only from then on will solve all these case seperations.If you have an oversize chamber,not head space,oversize chamber simply get a smith to set the barrel back one thread,all your problems fixed. Pat

[303Guy]

It is indeed that simple but is it cost effective? I mean some of us have really budget rifles (which is why they have headspace issues). Well, speaking for myself anyway.[smilie=1:

My trick is load lighter than normal as in medium cast loads and to lube the cases with case lube (about the same amount as used for case sizing) and shoot them. The lube allows the case head to move back and the shoulder forward without stretching the case at the web. Cases do not elongate this way or if they do the stretching is spread over the length of the case. And no, it will not overload the bolt face. That's why a medium cast load is used. It has to be be stiff enough to push out the shoulder though.

I had a rifle that needed this treatment as the bolt had set back in the lug recesses and it had a Martini Henry barrel that didn't clock right so it was about half a thread loose. It still shot accurately though. Go figure!

[PAT303]

Whats 100 303 cases worth?,a sizing button or Lee tapered expander stem which ever you need is worth a few dollars,setting the barrel back a turn is $100 if it's really bad,headspace is not the issue,people keep that old wives tale alive,oversize chambers are the reason for blown out,lop sided or split cases. Pat

[303Guy]

Thankfully none of mine have extreme oversize chambers. Some do have the shoulder clearance. I used to get three firing from a new case in my tightest chamber rifle, that being my first Lee Enfield fitted with a No4 barrel. That was with full sizing. Even with partial sizing, cases didn't last that many firings. The cases and chamber were too dry. I stopped cleaning off the sizing lube and the problem went away. Accuracy improved too.

[leebuilder]

Thankfully none of mine have extreme oversize chambers. Some do have the shoulder clearance. I used to get three firing from a new case in my tightest chamber rifle, that being my first Lee Enfield fitted with a No4 barrel. That was with full sizing. Even with partial sizing, cases didn't last that many firings. The cases and chamber were too dry. I stopped cleaning off the sizing lube and the problem went away. Accuracy improved too.
I have the same issues with some rifles with the original chambers. I too have left the case lubed for firing, i assume the lube is centering the case and boolit hydrolicily in the chamber aiding in accuracy. I only partial size for my No 4 hunting rifle and only use S&B cases in her, the rest of my ammo is full lenght sized, just for universallity and only vary COL for a paticular rifle. I find this easier for me. I allways cull streched casings before resizing. Reloading the 303 can be a sack of rusty door knobs, with out of spec chambers, and bores, varying rim thicknesses and generous headspace, but once you figure out all the foybbles and and sifft through all the info and find what works for it is very rewarding, addictive and fun!!!!

Be safe

[303Guy]

I don't think there is any hydraulic effect with just a residue of lube. It does disappear on firing though although that may be an illusion. Case wall grip still takes place but any case stretch gets spread over the body length so the elastic limit doesn't get exceeded. The neck itself doesn't move in the chamber.

In the chaos of the past two years of my life I have lost track of which case fits which rifle so I will be starting from scratch again. I do have some nny cases which I will dedicate to one rifle. I'm just going to see which cases fit then load them and mark them for the rifle. I have some PMP cases which are thicker walled which I have dedicated to my short barrelled pig gun because of their smaller capacity and the fact that the patched boolits seat real snug in them with no sizing. I should try getting another batch of them.

The fact that lightly lubed cases seem to come out dryer makes me speculate that oiled cases (as in dripping or just wet with oil) actually injects atomized oil into the combustion chamber causing dieselling with the oxygen present and raising the chamber pressure. I'm not sure there is enough oxygen to make a difference but it is believed that oiling cartridges raises chamber pressure so who knows.

[leebuilder]

Hi 303guy my thoughts are with you today.

I read here before about hydrolic centering, i dont for fact if that is what is happening, i can only assume thats what is happening. Dieseling could be it too, never ever would of thought of that, if the lube burns it is making gases, and they are expanding. Been keeping my loaded cases free from lube since they attract alot of dust and lint, when i shot lubed cases i was still learning, clean cases are a must hunting up here. PMP is very good brass, mine is all berdan primed. I have been saving my nny/ppu cases for a rainy day. S&B is of low quality so no big deal if i lose them in the bogs.
I posted this pic before, no1mk3 barrel with dummy, this came from a cousins rifle and would not shoot. You can see it is baked. And the chamber is quite tight in apperance but over strected the brass on every shot
139637
be well

[Mike H]

Some years ago,our rifle club shot a lot of Service Rifle matches,most were using .303 Lee Enfields with jacketed projectiles in their reloads,we didn't have the troubles that people here seem to have.Keeping the cases trimmed before they got too long and carefull use of the Full Length Sizer was all we did.Cases will stretch because of the back locking action,but they still last a long time
Mike.

[EDG]

Mike H
I suspect you are using heavier brass than the common Winchester and Remington brass produced in the US. The US brass is only about .450 to .452 in diameter at the head. The US brass is also thin so it swells easily at the junction of the solid head and case wall.

The same brass used in 6.5 Dutch Mannlicher chambers which are about .452 to .453 at the head works great.

[Multigunner]

In my observations more 303 rifles suffer from " elongated chambers " and not bad headspace. Many rifles rejected at the military armory i would visit had been rejected for elongated chambers.
According to Reynolds excessive torque used to clock in a barrel that had not been properly prefitted caused many No.4 chambers to elongate with formation of stress lines that often caused the shoulder area of the chamber to swell. They developed the breeching up washer system to avoid this while still allowing faster production.

[303Guy]

I suspect you are using heavier brass than the common Winchester and Remington brass produced in the US.I'd suggest that commercial brass is all thinner than military brass. I have a number of commercial PMP cases (boxer primed but otherwise the same as military) and they are strong. I do not know how they compare with regards head separation as I don't have that problem anyway but I can see how they would be better. The case wall doesn't seem to expand as much and grip the chamber walls as much as the thinner cases. They would also have higher pressures than the regular commercial stuff. They are great for cast boolit application because of their smaller capacity and the fact that the necks don't expand as much (no sizing needed). I don't suppose one could import them into the US (or could you?) Shipping would cost as much as the cases but it's good brass.

[PAT303]

The only good 303 brass is PPU head stamp from Serbia. Pat

[303Guy]

Generally that would seem to be true but PMP brass is pretty good too (as far as I can tell). I have one dud PPU case that I keep out of curiosity - the rim hasn't properly formed. It would still work just fine though.

[OptimusPanda]

Time to resurrect this thread. I have come to find that after the second firing a fired case will go back into the chamber without undue force. This is strange as previously stated, a fired case from a factory round will not (even when cut down progressively until it's maybe an inch long). Anyone else run into a gremlin like that before? Recently found a 40 grain charge of varget shoots pretty good in this old girl too. In either case over the past 5 months I've become a happy .303 reloader!

[Motor]

Good to see you got it working well. The .303 with factory US type brass thing comes up often on the milsurp rifle forums. From what I read, most guys have the best results using the "0" ring method previously mentioned in this thread. The "0" ring not only squares up and centers ths case but also forces it to form to the chamber by expanding the shoulder forward.

Motor

[Geezer in NH]

Use an O-ring around the base to keep the cartridge centered in the over sized chamber. Then reload using Lee collet die for sizing.

Sorry for bad typing the band aids on my fingers from cutting up 150ounds of squash is showing