303 Head Spacing Gauges

[HollowPoint]

A couple of years ago I had the unfortunate experience of blowing up the
bolt head on my Enfield.

The bolt itself did not appear to be harmed in any way, nor did any other part of the
receiver. Just the bolt head was blown to smithereans.

Unless you've personally experienced this type of "KaBoom" experience it's difficult to describe the milliseconds during and immediately after the incident.

To this day I haven't figured out what exactly caused this catastrophe. I just thank God that I or no one else was hurt. I drove home from the range that day and immediately disassembled all of my remaining rounds in an effort to figure out what had happened.

I suspect that it may have been a Head Spacing Issue but that is just an unconfirmed guess.

I've stated all of the above to lead into my question.

I purchased a replacement Bolt-Head for my MK 4. I Bought the same size that it originally came with when I bought it.

I'm wanting to know which set of Gauges are most accurate; or are they all basically the same?

Since I'll only be using them once or twice at most, is there any place where I could rent a set of these Head-Spacing Gauges or any safe alternatives other than buying a new set of these gauges?

I've called around to local gun smith shops. If they have these gauges they tell me it will take a week or two before they can get to me. Or they'll want to charge me the price of a new set of gauges just to look at it.

If I'm going to spend that kind of money I'd just assume buy the gauges for myself rather than buy them a set of gauges and then be charged for the time it took for them to check the Head Spacing.

I know that checking the Head Spacing with an appropriate set of gauges isn't rocket science; so, as you may have guessed, turning to gunsmiths for help has left me with a bad taste in my mouth. (so to speak)

HollowPoint

[fireball168]

I rented a NO GO the last time I checked one, from these fellows:

http://www.reamerrentals.com/SearchResults.asp?Cat=48

$5+shipping.

[Multigunner]

A couple of years ago I had the unfortunate experience of blowing up the
bolt head on my Enfield.

The bolt itself did not appear to be harmed in any way, nor did any other part of the
receiver. Just the bolt head was blown to smithereans.

Unless you've personally experienced this type of "KaBoom" experience it's difficult to describe the milliseconds during and immediately after the incident.

To this day I haven't figured out what exactly caused this catastrophe. I just thank God that I or no one else was hurt. I drove home from the range that day and immediately disassembled all of my remaining rounds in an effort to figure out what had happened.

I suspect that it may have been a Head Spacing Issue but that is just an unconfirmed guess.

I've stated all of the above to lead into my question.

I purchased a replacement Bolt-Head for my MK 4. I Bought the same size that it originally came with when I bought it.

I'm wanting to know which set of Gauges are most accurate; or are they all basically the same?

Since I'll only be using them once or twice at most, is there any place where I could rent a set of these Head-Spacing Gauges or any safe alternatives other than buying a new set of these gauges?

I've called around to local gun smith shops. If they have these gauges they tell me it will take a week or two before they can get to me. Or they'll want to charge me the price of a new set of gauges just to look at it.

If I'm going to spend that kind of money I'd just assume buy the gauges for myself rather than buy them a set of gauges and then be charged for the time it took for them to check the Head Spacing.

I know that checking the Head Spacing with an appropriate set of gauges isn't rocket science; so, as you may have guessed, turning to gunsmiths for help has left me with a bad taste in my mouth. (so to speak)

HollowPoint

I've been looking into this sort of bolt head failure for some time.

The major cause of bolt head failure in the Enfield design is a split or blown out cartridge case. This is not necessarily due to excess headspace, which normally causes the .303 case to stretch, crack, and sometimes separate about 1/3 the way up the case body. Cracks there seldom even result in gas escape, the remaining case body at the base of the case still acting as a seal.

The real problems come in when the chamber is "Cord Worn" out of the round, allowing several thousadths clearance on one side of the case. This can be very dangerous in case of a longitudinal split.

I had a few boxes of Winchester sporting ammo that gave longitudinal splits in the chambers of several very good condition SMLE and No.4 rifles which had much better than average headspace and tighter than average chambers. There were no gas escape incidents with those rifles.
In that case the cases appeared to be defective, unevenly drawn and tissue thin at the point where they split.

If theres too much clearance between case wall and chamber wall gas escaping a split or separated case can be directed towards the cut out in the bolt head where the extractor operates.
The extractor/guide lug on the bolthead is not meant to handle this sort of high temperature blast of propellent gases.
People have been killed by fragments of shattered bolt heads severing arteries, and one Canadian range officer ended up with a snapped off bolt head passing through his neck, he survived.

Cord wear of the chamber seems limited to the right hand side, where some troops carelessly dragged the cord and wire gauze againt the side of the chamber while pulling the cleaning cord from the muzzle.

Excessive headspace will exacerbate any problem of an out of round chamber. The case is tapered so the more slack the fit the greater the side clearance becomes.

A rifle that still handles milspec .303 without case failures may not handle some commercial sporting ammunition cases. The case walls of milspec ammo is usually, though not always, much thicker and less likely to split.
Cases with the thicker rims can take up some slack in headspace.

Commercial headspace specs for .303 rifles are Minimum .064 with a maximum of .068. Military headspace specs for the .303 allow for .074 headspace.
Few milsurp Enfields would pass the SAAMI and Canadian civilian headspace specs, while still well within military specs.

Due to the very wide range of tolerances of .303 cartridge cases actual headgap for a specific ammunition type is more important than a reading of headspace by gauges.
Some milsurp .303 has been noted with rims as thick as .068, with .062-.063 more common, while commercial cases usually have rims of .058-9. A rifle with headspace of .068 might not always close easily on some milspec rims but have .011 heagap with most commercial cases.
A rifle that just passed the milspec .074 headspace gauge would have as much as .016 headgap when using commercial brass.

When building up my No.4 I replaced its badly worn bolt body and obtained a #3 bolthead. This brought headspace to very near minimum. Case life is excellent and accuracy greatly improved.

[HollowPoint]

Multigunner:

Thanks for the input. It's almost enough information to make a guy not even want to mess around with these Lee Enfields.

Right now I have the barreled action in the storage closet. I'll have to take the time to check the chamber for "Out-Of-Roundness."

A while back I was considering just having it re-barreled but, now with finances the way they are, I thought I'd just check the HeadSpacing and eliminate that as a possible source of any potential problems.

As I stated above, when I got home that same day I stayed up late into the night disassembling all my remaining cartridges and weighing charges and such just to confirm that a reloading error hadn't caused the blow-up. Everything appeared to be in order.

It's been close to three years since that happened and I just wanted to try to get it back up and running.

HollowPoint

[Multigunner]

Multigunner:

Thanks for the input. It's almost enough information to make a guy not even want to mess around with these Lee Enfields.

Right now I have the barreled action in the storage closet. I'll have to take the time to check the chamber for "Out-Of-Roundness."

A while back I was considering just having it re-barreled but, now with finances the way they are, I thought I'd just check the HeadSpacing and eliminate that as a possible source of any potential problems.

As I stated above, when I got home that same day I stayed up late into the night disassembling all my remaining cartridges and weighing charges and such just to confirm that a reloading error hadn't caused the blow-up. Everything appeared to be in order.

It's been close to three years since that happened and I just wanted to try to get it back up and running.

HollowPoint

Theres no reason to give up on the Enfields just because almost all have very loose headspace and chambers, it just adds a bit of challenge which for me has made shooting and loading for them much more fun.

Only reason I started gathering information on Lee Enfield action failures was because some collectors had bought into myth and urban legend on these rifles rather than looking at the facts.

A had seen more than a few claiming there had never been a documented failure of a Lee Enfield that didn't involve handloads. That was bull and I knew it. Federal recalled all its .303 ammo at one fter a hunter was killed by a shattered bolt head.
The rifle was at fault, a Cordworn chamber being the most obvious defect. A Gentleman named E C Crosman was the expert witness in the case, and in his testimony he said that the chamber wall has thinned on the righthand side.

The Bore of that rifle was not in great shape but though erosion at the throat and leade coupled with corrosion further up had caused a bullet to seize up and the core blow through the jacket, the worn out of round chamber was what caused case failure and the blown bolt head.

I've seen a few of the Internet experts, and few others with some actual knowledge of rifles, spreading some very dangerous misinformation about these old rifles.
Some claimed that no amount of gas erosion can make a barrel unsafe to fire. Others claim that theres no such thing as a dangerous situation due to excessive headspace.
A few even believed that theres no danger in firing muddy ammunition, or with the barrel full of water. They saw Mel Gibson do it in the Movies so it must be perfectly safe.
You'll occasionally see claims of a supposed blow up test run in Canada with the muzzle plugged by a steel rod , or some un verifiable claim of an Indian soldier firing his rifle with ten inches of ice in the bore. The claim is almost always that the action stood up to 100,000 PSI without damage.
In both incidents the barrels broke off. Pre WW1 Tests on the Rod type Rifle Grenade proved that when theres a bore obstruction further than three inches ahead of the leade the barrel would either split or snap off releasing the pressure before the pressure wave traveled back to the chamber. When the obstruction is within 3 inches of the throat the case would blow out and shatter the bolthead.
A claim of the action holding up without damage to 100,000 PSI when fired with a service cartridge and a bore blocked by ice is bogus on its face since modern cartridge brass will cold flow at 85,000 PSI, only special proof testing cartridges can survive at pressures over 85,000 PSI.

I've seen it claimed that SMLE rifles were rebarreled by RSAF to 7.62X51 and fired thousands of rounds without damage. in fact two rifles were rebarreled and tested, the tests ended when each was found to have developed from .01 to .03 increases in headspace.

The British NRA has recently had to try to impress upon shooters there that the Lee Enfields are not indestructable.

I like my Enfields, but like every thing else they have their limitations.

PS
While a blown bolt head seldom injures the shooter , injuries to bystanders are not to be over looked.

I know of one incident when a fresh from the Mummy Wrap FTR'ed No.4 suffered a shattered bolt head on its first shot out of the box. Luckily this happened while being remote testfired by a gunsmith.
I suggest that any old milsurp rifle be remote testfired, I even remote fire recently manufactured centerfire rifles if I've never seen them fired before purchasing them, always better safe than sorry.

[Brithunter]

Ahh now the problem with the NRA in England at Bisley camp and the converted 7.63x51 Lee rifles is not the rifle nor the conversion but the moron target shooters who are overloading said rifles and cartidges to obtain supersonic velocites at 1200 yards.

So the NRA are now insisitign that any Lee Enfields converted to 7/62x51 that are to be on Bisley ranges to be re-proofed to 20 tons which is magnum pressures. The 270 Winchester is proofed to 19 tons or it's equal in bars now.

The Lee Enfield No4 has prooved itself safe and stable at normal 7.62x51 pressures. Howe many reports are there os L42's or L39's blowing up in service? However these morons are over loading and so straining the rifles and instead of laying the blame where it lies with said morons they blame the rifle. I'll lay odds that several target rifles are blown up on Bisley every year through this overloading and not all are based on the Lee Enfield action.

Whislt on the very first NRA RCO course we were told of one "competitior" who found his competition ammunition tight so instead of stoppign and thinking he preceeded to hammer the bolt close and open for every shot until he broke the bolt handle off his single shot commercially manufactured target rifle with a live round in the chamber and the bolt not quite closed. It was down to the armourers in Fultons to retrieve the rifle and get it safely back to the workshop and get the bolt open and remove the live round.

Morons like that should never be allowed near a firearm for others safety as they obviously do not care about others let alone them selves.

[John 242]

The Bore of that rifle was not in great shape but though erosion at the throat and leade coupled with corrosion further up had caused a bullet to seize up and the core blow through the jacket, the worn out of round chamber was what caused case failure and the blown bolt head.

Multigunner,
I'm not sure I understand.
The bullet lodged in the throat. Pressure caused the core to push through the jacket and down the barrel. The jacket remained in the throat, AND the bolt head shattered OR the next shot blew up the bolt head when the bullet hit the obstruction (jacket) in the bore?

Another question... what is cord worn? I know the British used a pull-through to clean their rifles. Would that cord rubbing the chamber wall be enough to wear a chamber out of round?
I wonder because pull-troughs are popular today with the Hoppes bore snake being what I use from time to time.

The British issued a steel mesh screen to remove rust from the bore. I could see where injudicious use of the steel screen causing some serious wear.

[Multigunner]

Multigunner,
I'm not sure I understand.
The bullet lodged in the throat. Pressure caused the core to push through the jacket and down the barrel. The jacket remained in the throat, AND the bolt head shattered OR the next shot blew up the bolt head when the bullet hit the obstruction (jacket) in the bore?

Another question... what is cord worn? I know the British used a pull-through to clean their rifles. Would that cord rubbing the chamber wall be enough to wear a chamber out of round?
I wonder because pull-troughs are popular today with the Hoppes bore snake being what I use from time to time.

The British issued a steel mesh screen to remove rust from the bore. I could see where injudicious use of the steel screen causing some serious wear.

The wire mesh was one source of wear but the cord itself picked up grit and acted like sandpaper on the steel after awhile.
The Primers used for almost all WW1 and most WW2 ammunition contained ground glass to give the composition a source of friction to ensure ingintion. The ground glass became impregnated into the fouling and the mixture of fouling, sealants, grease, etc, acted like a grinding compound.
Theres really no way to get the pull through cord clean in the field, so the grit just built up more and more with every cleaning.
When the soldier cleaning his rifle did not take care in getting the patches or mesh started into the chamber the cord would naturally rub against the right hand chamber wall as it was pulled from the muzzle.
When care wasn't taken to pull the cord evenly up the center then it would rub one side of the muzzle or the other causing an oval muzzle opening.

Hesketh Pritchard was adamant that all sniper rifles be cleaned using a cleaning rod rather than the pull through. A few cleaning rods were kept by the platoons for clearing obstructions. Guides for chamber and muzzle were used with the rods to prevent those from rubbing against the lands or crown.
Since the bolt was removed when inserting the rod from the breech there was no contact with the chamber walls.

Federal issued the first voluntary recall of .303 hunting ammunition after the incident I described. The ammunition was safe for a rifle built to close tolerances of sporting rifles , but not suitable for the loose tolerances and wear patterns of the Enfield rifles.
The Military standard headspace of the .303 Enfields is far outside the safety limits for sporting rifles. Very few met the maximum headspace allowance of .068 when new and rifles were kept in service till headspace increased to .074.

PS



Ahh now the problem with the NRA in England at Bisley camp and the converted 7.63x51 Lee rifles is not the rifle nor the conversion but the moron target shooters who are overloading said rifles and cartidges to obtain supersonic velocites at 1200 yards.


That was the begining of the situation. Since then the NRA UK contracted with a German company to supply a standardized long range matchgrade ammunition for use at Bisley. They found they could not deliver the expected performance at pressure levels suitable for converted No.4 rifles.
The pressure levels are within CIP and SAAMI safety limits for rifles proofed by civilian sporting rifle standards.

When the British Metropolitan Police first contracted with the MOD to provide L42 rifles for police marksmen they found that one third of the surplus L42 rifles sent were dangerously degraded and unsafe to fire with modern ammunition.
Those rifles had worked fine with the 144 gr Radway Green ammunition originally intended for these rifles, the pressure levels not exceeding 48,000 CUP which is the NATO standard for infantry ball.
Use of later ammunition types as supplies of the older type ammo dried up caused bolt binding, action body spreading or warpage, and other problems in service before the rifles were declared obsolete.

The use of conversion barrels with undersized bores was another factor. Bores as small as .306 (afew as small as .305) were being used to compensate for the often undersized bullets of available surplus 7.62 ammunition.
When ammo with full sized .3085 bullets were used in these rifles pressures rose beyond CIP safety limits.
Chamber necks were also often too tight.
Full test results are available. Testing was done by Radway Green and the Birmingham Proof Authority.

[3006guns]

With the exception of being "cord worn" (a new term to me) it seems that the incident described by the original poster may have been caused by a soft headed case. From all of the descriptions of "my rifle blew up!" it is usually traced to a defective cartridge case that allow breech pressure into the receiver where it has lots of surface area to push on.

The statement about commercial vs. military brass is accurate. Don't forget, the commercial outfit is out to make a safe product......but with a profit. Most of my brass is of Dominion origin and pretty stout stuff. An occasional anneal and periodic inspection keeps me shooting. I shudder to think how much I threw away (surplus) before it occured to me to look inside the case....it's reloadable!

I've used the Lee Enfield for years.....some beautiful specimens and some real dogs and never had a problem with service ammunition OR reloads as long as I used common sense. They are a damn fine rifle.

[HollowPoint]

It's been a while; and I had completely forgotten I ever posted this thread.

I came back on just to clarify that I in no way was trying to state anything derogatory about
the Lee Enfield rifle; in any of its forms. I rather liked this rifle myself.

It's just that having one blow up in my face has had the effect of making me kind of gun-shy
toward this particular rifle.

It's just taken me a while to dust myself off to get ready to get back on this Lee Enfield/horse again. (so to speak)

I still haven't gotten those headspace gauges. I'm not in any particular hurry. I have a couple of other rifles that I've been playing around with in addition to other gun related projects but. I have no doubt that I'll get it up and running in time.

HollowPoint

[Multigunner]

I came back on just to clarify that I in no way was trying to state anything derogatory about
the Lee Enfield rifle; in any of its forms. I rather liked this rifle myself.

HollowPoint

I'm glad you posted of this mishap, and more happy that you weren't seriously injured.

Some Enfield collectors are overly touchy about any perceived denigration of the rifle, some go way overboard.

The Lee Enfield rifles were ahead of their time, and as a result there was a very long teething process in bringing the rifle and .303 cartridge out of the BP era and into the Smokeless propellent era.

A factor that should be considered is that many of the milsurp SMLE and No.4 rifles on the market today were out of UK custody for several decades, and if serviced at all it was most likely by a third world armorer with out the proper tools and gauges, and the only source of spares being whatever could be salvaged from battlefield relics or demilled Drill rifles.

Many of the Enfields I've examined had flat tipped firing pins that were never properly fitted to the bolt. These stuck out from the bolt face much further than they should have.
I'm almost certain those rifles had been used as Drill Rifles, but not condemed as unsafe to fire or stamped with the DP markings (unless the DP was removed in refinishing).
Rifles like these probaly had a snapped off firing pin , and possibly a chamber plug. When the opportunity came to sell these off someone with no knowledge of fitting a new pin just had unissued spares put in and sold the rifles otherwise unserviced or inspected.
When an unscrupulous importer could buy fairly good looking drill rifles for scrap value of 30 cents a pound, add a new firing pin and sell them by the tens of thousands, profit margin would be immense.

A visitor at another board was a recent victim of a reactivated DP rifle that he had been assured was in fine shape because it had seldom been fired. He lost part of a thumb when the crudely blocked hole drilled through the chamber vented the full force of a cartridge.
Whoever put the new pin in that rifle had not noticed the hole in the chamber. They'd probably put new pins in other DP rifles that did not have this drilled chamber and assumed the DP rifles were all the same.

With 19,000 Enfield DP rifles being offered for sale by Springfield Sporters, and several other major dealers offering DP rifles at fairly low prices, we can expect to hear of more such incidents in the near future.

A great many variations of the demilling process were tried in those countries that once used the Enfield, some methods are obvious while others are not.

[John 242]

Multigunner, thanks for the info.
I had no idea that a pull trough could do so much dammage. Something to think about.

It's great to have so much knowledge available at our finger tips.
I never knew what a DP stamp was until I bought a Lithgow with a big DP on the receiver. When I asked what the letters meant on a surplus rifle forum, I was told that it meant Drill Purpose and essentially the rifle was a wall hanger. Nice to know that... after I fired about 60 rounds of Wolf Gold through it.

That's the pitfalls of collecting and shooting old rifles. You've got to take the time to research a little and do your homework, otherwise you can easily end with a unsafe rifle, ammo, or both.

[LEDSLINGER]

Hollowpoint, you stated you bought a replacement bolt head the same size the rifle originally came with. The common sizes range 0 thru 3 as stamped on them near the extractor. Here's the catch, within each size range the oal or thickness from face of the head to rear bearing surface can vary as much as .014, so simply getting a replacement bolthead which has the same number stamped on it as the one you want to replace is not altogether safe.

[leadman]

If you do not find or rent the headspace gauges you can do as many old time shooters did to get an idea of any excess headspace. Shims can be used between the cases you are using and the bolt head you have to determine the actual clearance or headspace for this situation.
Add the rim thickness and shim dimension that gives a snug fit and you should have your true headspace. You may have to move the shoulder back on the case you are using if it contacts the chamber walls.
If the clearance between the case and boltface is not excessive the brass can be fireformed to fit the chamber then neck sized after that.

As an example of a similar issue with headspace my T/C Encore in 7mm Rem Mag has .004" clearance between the end of the barrel and the breech block. Most belts on the brass are also up to .008" too thin so this creats an excessive headspace issue with very short case life.
Because of this I fireform the brass with Unique, cornmeal, and a wax plug to keep the mix in the case until fired. Brass life and accuracy has been much improved with this method.
Use at your own risk.

[HollowPoint]

Greetings gentlemen:

Having read all of your input I find that some of these comments and perspectives I'd already considered or found out through informal online research.

I don't want to come off sounding ungrateful because, although I may have discovered them through a little research, it's always better to hear it from those who have first hand experience.

I think now having read what I have I'll just wait for the Good Lord to drop enough spending money in my lap to have it re-barreled with tight chamber so I can start form scratch.

If any thing, I consider myself a Lee Enfield novice. I think it's therefore logical to start with a new barrel and an unworn chamber with exact head-spacing for the brand of shell I'll be firing.

In theory this will mitigate the chances of having to deal with the myriad of different measurement variables that seem to contribute to my ignorance.

Since I have your attention; what would you guys say is a fair price of a re-barrel job on a MK 4?


HollowPoint

[leadman]

You could probably find a really nice #4 MKII for the same or less than a rebarrel job. I have read that these are somewhat of a chore to rebarrel as the barrels are screwed in very tight. Don't know if it is fact or not.

[HollowPoint]

Greetings leadman:

I've read and heard similar descriptions of re-barreling one of these Enfields. I actually have two barreled actions.

I tried unscrewing one of them with absolutely no success. They are on pretty tight.

On the other hand, I've also heard and read from other sources that re-barreling an Enfield is pretty straight forward. You just need the right tools. Of course the guys stating that it's easy have vastly more experience with this kind of stuff than I do.

My Lee Enfield was a really nice rifle when I bought it as well. For reasons I can't explain, it blew up in my face. (literally) This is why I'm leaning heavily toward just getting it re-barreled.

I realize that even re-barreling holds no guarantee of a problem free rifle but, there would be a certain psychological reassurance for me. Besides that; when I finally get around to actually having the work done, I was thinking of having the smith use a .30 caliber barrel (308) so I could consolidate my bullet casting sizes to that particular caliber.

I own two other .30 caliber rifles so barreling this 303 down from 311-312 to 308 would just make things more convenient for me. And re-sizing the necks on my 303 brass would present very little problem for me.

HollowPoint