Two No 4s. One is in .303 British; the other is in .223 Remington.

Following the repeal of the Australian Rifle Club (A.R.C.) Regulations, which had been a part of the Defense Act since 1907, all legal ways of owning and using a self-loading rifle have disappeared. Like many active target shooters in Australia, I was stuck with a large quantity of .223 Remington ammunition, but with nothing to use it in, after having to hand-in my self-loading rifle. Many of us were digging up a Lee-Enfield, Mauser, Springfield, Enfield, etc in order to continue competing. We were very lucky with a large quantity of 1989 production HXP .303" ammunition being available but I'm cursing that I only bought one case. Reasonable quality .303" ammunition is usually scarce, and quite expensive, if available at all. Costs have spiraled up to the point that good quality factory ammunition can cost more than a dollar per cartridge and hand loading is not much cheaper. This has left service rifle shooters two options:

1) to find a service rifle in a more readily available caliber,
2) or, convert an existing service rifle to such a caliber.

I decided to follow the latter course, converting a No 4 Lee-Enfield to 223 Remington. The conversion took almost a year from the decision to go ahead to having the finished product in my hands. I'm glad I didn't rush the project, and the rifle I now have was worth the wait.

The 200 metre line at Malabar. We stand at 100 metres, sit/kneel/or squat at 200 metres, only at 300 metres and beyond do we go prone. In the large version, four-foot targets are visible (just!) below the target numbers.

 

The story began in late 1996 when we heard some stories about the Canadian Army converting No 4 Lee-Enfields to .223 Remington for use by their cadets. The story was never proved, but a number of gunsmiths were intrigued by the notion, and started to work on making it possible. Obviously the design has evolved from the early "trial" efforts.

Why a No 4 action? The No 4's Mk 1 Singer type 1 MOA per click sight is easier to adjust than the sliding ramp of the No 1 (SMLE). Just count the clicks for the various distances, and note them down. If your No 4 has the sliding ladder (Mk 3 or Mk 4), adjusted in 100 yard increments, or the 300/600 yard 'flip-over' (Mk 2), swap it for the Singer sight immediately, regardless of what calibre your rifle is. The No 5 (Jungle Carbine) sight is in 2/3 MOA increments. This offers more precise adjustment than the No 4 Singer sight. A useful hint if you can find one. The .223 Remington cartridge generates about two-thirds the back thrust on the bolt compared to the .303 British, so it is hardly going to put undue stress on the bolt lugs and receiver recesses. The No 4's trigger, while not match grade quality, is still better than many current out-of-the-box sporting rifles. The No 5 action is not recommended for conversions because of the 'lightening' cuts made to reduce the weight of the action. Many No 5 .223 conversions have been built from No 4 actions. A historical note is that the late production No5 carbines reverted to the unaltered No4 type receiver.

There was concern from some quarters about the difference in chamber pressure between the .303 MkVII and the .223 Remington. The figures are 45,000 psi and 49,000 psi respectively, but most fears were allayed when the deciding issue was the back-thrust on the bolt. Quoted figures from Bill Davis (one of the foremost ballisticians in the US) are that the .223 had a chamber pressure of 55,000 psi and a back-thrust of 4,620 pounds. The figures for the .303 MkVII are 49,000 psi and 6,076 pounds of back-thrust. Please note that the figures given for chamber pressure are above that produced by standard Australian loads.

Keith Hills, a full-time professional gunsmith raised three important issues. The first was that any conversion needed to be carried out by a recognized professional gunsmith. The reasoning behind this is simple. While the theory of converting a Lee-Enfield to .223 is fine, there are a number of practical operations that must be carried out by a knowledgeable gunsmith, if safe operation of the rifle is to be guaranteed.

The second issue was that the rifle in question must be suitable for conversion. Worn out pieces of junk that have already fired tens of thousands of rounds should not even be considered. Any rifle should be carefully inspected and certain critical measurements checked before a conversion is attempted. While on this point, Keith Hills has the opinion that the No 1 MkIII SMLE action is as just as suitable for conversion to .223 as the stronger No 4 action. There is no question that the No 4 action is stronger than the No 1 action, but there is ample safety margin in the No 1 action to function reliably and safely with .223 ammunition. The preference for the No 4 is primarily for the sights and the rifles, in general, are younger in age. Knowing that brave, or foolish, shooters have used .303 MkVIIIz Machine Gun ammunition in No 1 rifles without injury is a case in point.

.303 MkVIIIz ammunition uses a nitro-cellulose-based propellant instead of cordite and develops much more rearward thrust on the bolt. The Australian Army considered the use of MkVIIIz in No 1 rifles a dangerous practice.

The third, and most contentious, issue concerns modifying the bolt head. There is a need for a supporting collar to be attached to the standard .303 bolt face, because the cartridge base of the .223 is much smaller than the .303 cartridge, and is rimless as well. The purpose of this collar is to support the standard rimless round and hold it in a consistent position so that extraction and ejection of the spent cartridge case can be made as reliable as a factory product. The contention arises in regard to the method of attaching the collar.

Keith Hills advocates the use of silver solder for attaching the collar to the bolt face. He says that the melting point of the silver solder filler rod is below the tempering point of the metal used in the bolt head and that attaching the collar in this way cannot have any affect on the hardness of the bolt head. Apparently, some conversions have been attempted where the collar has been brazed on. As the melting point of brass filler rod is above the tempering point of the metal in the bolt head, this practice should be avoided. As a result, it is recommended that recognized professional gunsmiths perform the conversion work.

The Conversion Procedure

The conversion procedure in simple terms, involves mating a new barrel, a modified magazine, and modified bolt head (on the original bolt) to a standard No 4 action. At first glance, the rifle resembles a standard No 4 with a replacement barrel (i.e.: no bayonet lugs). Only a closer look highlights the changes.
 

The magazine is converted by adding an insert to the existing hull. Use a bad magazine for this. Keep the good magazines for your original No 4. In the insert is a new spring and follower for the .223 Remington cartridge. The original front feed lips are retained. From the picture, the rear feed lips for the magazine insert can be seen. The length of the insert can be seen in the large version of the picture on the right. From this, the size of the insert can be estimated. The new spring and follower are the length of a standard .223 Remington cartridge.

 

A Ruger Mini-14 20-round magazine was tried and gave excellent results but it is necessary to attach it to the back section of a No 4 Lee-Enfield magazine. This is so the Mini-14 magazine will lock into No 4 magazine well and use the original magazine catch. The disadvantage of the Mini-14 magazine the overall length of the cartridges you can use. Some gunsmiths have made their own modifications to the receiver to take unaltered Ruger Mini-14 magazines.

The reamer used, which gave the best accuracy, was a JGS223 Remington. And the tooling shown in the picture was home made. The picture shows barrel bushing rings (left) to suit a Brownell's barrel vice, and on the right is the receiver wrench.

Obviously, the hole at the muzzle is a lot smaller than the original (5.56mm versus 7.7mm); the screws in the magazine hull to hold the magazine insert; and the new bolt-face, resembling a smaller version of the 7.62 conversion bolt face. The barrel is cut to standard No 4 Lee-Enfield profile with a .224 diameter hole. Barrels intended for No 4s use a 1 turn in 9" rifling pitch, while barrels intended for No 5 conversions use a 1-in-8 rifling pitch.

Experience has shown that the 1-in-9 pitch is the best regardless of barrel length, standard or carbine length. 1-in-7, 8, or 10 pitch barrels probably will not shoot as accurately as the 1-in-9 pitch. Other rifles can use these barrel pitches and shoot well because of the different barrel-receiver harmonics.
 

Note in the accompanying pictures that the back of the barrel has been chamfered around the back of the chamber, down as far as the feed ramp. This aids in reliable feeding of cartridges from the magazine. Care must be taken not to extend the chamfer too far into the chamber. It is suggested that the chamfer is not taken past the reinforced section of the case ahead of the rim. Rifles where only the bottom edge of the chamber was chamfered will not feed reliably because the case wall can catch on the sharp edge on the top of the chamber. The purpose of this article was NOT to present a step-by-step conversion process, but an overview with enough detail for a competent gunsmith to recreate what was done here. By telling you what problems have been encountered and how they were corrected, you can avoid the mistakes that have been made.
 

Design Evolution

The design has undergone a series of improvements since the original version. The original version used a blade type extractor similar to a Mauser. When the bolt was at its rearmost travel, the blade fitted into a slot in the bolt head. The current design uses a spring plunger to eject the empty cartridge case. See the image below for the current design of the bolt head.

The original magazine insert was held in place by a single screw, but the insert kept moving in the magazine hull. The current version uses two screws to hold the magazine insert in place.

 

The original magazine uses a flat spring. The problem is that the springs were often not heat-treated properly and lost their temper after about a year of use, causing failures to feed. The current version uses a coil spring, not dissimilar to a Colt AR-15 or Ruger Mini-14 magazine. The picture on the right has the insert, spring, follower, and the wooden spacer to be inserted in the No 4 magazine body.
 

A local gunsmith has an improved design magazine that is more robust and feeds more reliably than the original design. Instead of using the original feed ramp, the new design magazine has a curved front piece that bumps the shoulder and provides the necessary angle for reliable feeding. The new magazine design also has another advantage. It takes twelve rounds, which is useful in some of our matches. As can be seen by the picture, there is plenty of space to use cartridges that have an over-all-length much greater than the SAAMI specification.

 

However, it is necessary to relieve (about 0.060") the underside of the receiver to raise the magazine high enough so the bolt can pick up the cartridges. (Note the area indicated by the arrow in the above image, and do both sides of the receiver!)

The modifications are often retrofitted to the older rifles. At the time of writing (1998), my rifle was still in its original configuration. It was assembled with the later bolt head and magazine insert, but it still had the old type magazine spring. In the two years since then, the magazine is now the new (more robust) type (see above) and a half-minute Central target sight has replaced original rear sight.

In September 2001 the original MAB barrel was retired after firing more than 4,700 rounds. The accuracy was somewhat diminished compared to when it was new, but it was still producing groups of about a minute to a minute-and-a-half, depending on ammunition. It has now been replaced by a Walther barrel, and this one shoots like a laser! And the Walther barrel was less than three-quarters the cost of a new MAB barrel.

It has been observed that no No 1s (SMLE) have been converted, at least not in the MRCA. All the work has been on No 4 and No 5 rifles. To date I have seen only one conversion based on a SMLE rifle. No1s tend to be converted to 7.62x39mm. There is a brief section at the end of this document for 7.62x39mm conversions.

 

Advantages and Disadvantages

The positives of a .223 conversion are many. The advantages I have found so far are:

The rifle is very pleasant and comfortable to use. When using the original No 4 (in .303"), I usually wore at least one, often two, jackets, and had a slip-on recoil pad fitted to the butt-plate. With the .223", just a T-shirt is fine, and more comfortable on hot and/or humid days.

The ammunition is readily available, and reasonable quality ammunition is available at decent prices. The main reason for the conversion was that I had almost 1000 rounds of .223 Remington ammunition, and nothing to use it in. It was just my luck to obtain the ammunition almost immediately before the A.R.C. regulations were repealed. The other advantages with regard to .223 Remington over .303 British, are that components (especially projectiles) are much easier to obtain and are cheaper as well. Also, .223 uses about half to two-thirds of propellant powder when compared to most .30 caliber cartridges.

The Lee-Enfield action is regarded as the slickest, smoothest, and the fastest of all bolt-actions, although some American writers consider the Krag-Jorgensen to be smoother. With the .223's almost complete lack of recoil, the recovery time between shots is minimal. An impressive rate of fire (for a bolt-action rifle) should be possible.

The performance is not to be discounted. A No 4 223 conversion was used in the 1997 Champion-of-Champions match, but the user found that the Norinco .223 Remington ammunition to be lacking at 400 meters, but no problem in the snap stage tying for 1st place.

Gary, who built my rifle, has won many major Australian Service Rifle competitions with a No 4 .223 conversion. The matches include the Military Rifle Club Association's Champion-of-Champions match (twice in 2 consecutive years - 1998 and 1999) and the Year 2000 Queen's Service Rifle Championship. In the 1999 Champion-of-Champions match, 10 of the 15 competitors were using rifles built by him.

The conversions respond very well to the usual accuracy tricks that can be performed on standard No4 Lee-Enfields. How accurate can they be? I know one person who routinely attaches a Leupold scope (6.5-20x40AO Vari-X III) and takes the rifle out varminting.

The disadvantages of the .223 conversions are listed below, along with their counter arguments and how we were able to work around them.

Reliability. There is always a cloud over conversions when it comes to reliability. This is often the bug bear of 7.62 conversions, which never seem to feed and (especially) extract quite right. Original .303's are usually all right, with the most common hang up being the last round in the magazine. Modifying the front feed lips will usually correct this. 5.56 conversions, according to the gunsmith who worked on my rifle, need to be worked as if in a rapid match at all times. In simple terms, close the bolt fast and hard. Extraction with my rifle so far has not been a problem. For a left-handed person, working the bolt in this manner could be awkward with the angle and position involved. Try before you buy.

Surplus ammunition typically have harder primers than commercial ammunition and primers used for reloading. Also, No 4 firing pins can be heat-treated to the point where the structure is like glass or crystal. The hard primers can rupture, causing a fragment from the primer to blow back into the firing pin channel. When the rifle is fired again, the firing pin will break. Swapping for a SMLE firing pin is one way to fix the problem. Remember to also purchase the SMLE cocking piece and other parts.

"Yellow Box" Norinco .223 Remington ammunition has already cost me one firing pin. I now keep spares in my rifle case. What was mentioned in the previous paragraph occurred. On one match (not the one that destroyed the firing pin), the primers of 1 in 4 cartridges ruptured. 7 blown primers in 28 rounds. Between each stage of the match, I was unscrewing the bolt head to remove the fragments of the primer. What do I do with the other 900 rounds of Yellow Box Norinco ammunition I have? Drop the powder charge from the original 24.5-25 grains of ball powder to 23.5 grains. Now there are no problems with blown primers.

Otherwise, machine the firing pin to a narrower diameter (one-sixteenth of an inch) and sleeve the firing pin recess for the smaller diameter firing pin. This procedure has been done to many rifles. This has had to be done, because primers give a flash in proportion to the size of the firing ping. A small firing pin gives a small flash. The standard firing pin in the Lee-Enfield, being one intended for large mil-spec primers, gives a very large flash like a magnum primer. This causes the powder to combust too quickly and causes the chamber pressure to build-up at an accelerated rate.

Good quality commercial and reloaded ammunition from commercial components performs very well. Federal "American Eagle" 50-grain flat-base hollow point performs very well. Despite the hollow points, the cartridges feed and extract without any problems. Winchester "Super-X" and "USA" 55-grain FMJ also performs well without any problems. Factory ADI-62 grain ammunition (SS109 specification) also shoots very well.

Hand-loads using 69-grain Sierra Match King projectiles, Winchester cases, and ADI BM2 powder (approximate equivalent powders are IMR3031, Reloader-12, Hogden H322) perform exceptionally. When hand loading, a velocity target of about 2850-2950 fps usually give excellent results (try confirmed half-minute groups at 300 yards, prone and no bipod or rest, only a sling). Surplus ADI 62-grain projectiles (SS109 specification) are a cheaper alternative for close range matches.

Despite having the range cleared for the use of soft-point ammunition, it is preferred that competitors use FMJ or hollow point projectiles. Soft-point projectiles splatter when they impact with the wooden target supports.

Weight. Since the .223 barrel is cut to standard No 4 profile, the extra metal in the barrel is going to make itself felt. The 5.56 conversion weighs 4.65 kg, compared to the standard .303's 4.45kg. Both rifles were weighed unloaded, complete with bolt, magazine, and sling. The extra weight is in the "front" of the rifle. This is a plus for rapid matches, but a minus for standing off-hand matches. That extra weight at the muzzle end makes itself felt after a while. The consensus of other users is that the No 4 5.56mm conversion is for 200 meter and 300 meter matches, and the No 5 5.56 conversion is better suited for standing and walk down matches. If only to have the resources.

Sights. I'm yet to see a No 4 5.56mm conversion that doesn't have the foresight blade offset an almost ridiculous distance to the left. Work around, adjust it to the left, and live with it. It looks unattractive, but it works. The story I've been told is that it has something to do with the barrel's harmonics. Apparently the original Lee-Metford had a similar problem with placing shots consistently off to the left. The solution was to place the foresight on a mounting block permanently offset to the left. Adjust the windage on the foresight. A rough guide, adjusting the foresight 1 millimeter will move the point of impact 10 to 15 centimeters (4 to 6 inches) in the same direction at 100 yards.

An A.J. Parker sight unit can be attached to the original Singer sight. Another modification is to bush the back sight to a diameter of 2 millimeters. This "poor man's target sight" enhances the performance of the rifle. It gives the enhanced alignment of a target aperture, but keeps the ruggedness and handiness of the original sight. It works well for standard No 4 rifles as well. Otherwise install a Central, Rawson, or any other similar type of diopter target sight place of the original back sight.

The conversion procedure is non-reversible. I would recommend that conversion procedure not be performed on a good shooting rifle. Good collecting and shooting No4 Lee-Enfields are getting scarce, with the associated rise in the price. The rifle I used for the conversion had a barrel that had been used and not properly cleaned. As a result there was a noticeable amount of rust in the bore. I asked the vendor for a rifle suitable for conversion. My recommendation would be to convert something that has already been altered or to build a conversion from a collection of parts.

Cost. For a good No 4 5.56mm conversion, it is going to cost more than a standard No 4 .303". A lot more.

Here is an itemized list of my costs, rounded to the nearest $50.

Note that the costs are in Australian dollars.

Rifle $200
Woodwork refinished $100
MAB Barrel $250
Bolt face and Magazine Hull conversion $100
Assembly $200
TOTAL $850


I will admit that rounding up the numbers added $50 to the price. Using an old 'clunker' No 4 I have, and not worrying about the rifle's appearance could have negated the rifle and woodwork costs. But I'm happy with it. For the money, I have a repeating rifle in .223 Remington, with a detachable 10-round magazine, good iron-sights, good trigger, and smooth bolt-action. This is not available over-the-counter by any manufacturer or retailer.

I have since bought another rifle already converted. This one has seen very little use and has been stored for the last few years. As such, it has missed a few upgrades. Notably the new design magazine.

My aim was to present a balanced view of the advantages and disadvantages of a No 4 5.56mm conversion. I know the argument was skewed by the fact that I already own one, but how else am I to perform the evaluation?

Tribute must also be paid to James Paris Lee (1831-1904) for creating such a versatile and adaptable design, and to the designers who refined the original design to the No 4. The detachable magazine makes is easy to fix magazine related problems, and to convert the magazine to hold a new caliber. The removable bolt head means that it is easy adjust headspace, and to modify it to hold a new cartridge. The Mark 1 sight does not require a new ramp to reflect the trajectory of the .223 Remington cartridge. Try doing a similar conversion to a Mauser.
 

7.62x39 Conversion

At the same time as the .223 Remington conversions, another caliber conversion also appeared. 7.62x39mm. I experimented with a 7.62x39mm conversion before I started on a .223 conversion, but later sold the rifle and ammunition.

The 7.62x39 conversion is a little cheaper, because the original .303 barrel is recycled. The bore diameter is perfect for surplus Com-Block ammo. There are two methods of chambering. The first is to cut off the original threads and then machine new threads onto the barrel. The headspacing is more than good enough. If you look at the shoulder/neck areas of a 7.62x39mm and a .303 British, they are almost identical. The second chambering method is to cut more than the threads, like 5mm (or about .2") more and then use the appropriate reamer to cut a new chamber from the metal. The collar on the bolt head is similar to the .223 Remington, but narrower because of the wider base. For magazines there are two possibilities. The first is to modify an AK-type magazine to fit the Lee-Enfield's magazine well. Some gunsmiths managed to alter the receiver to take an unaltered magazine. The magazines were typically shortened to a more convenient length (typically 10, 12, 15, or 20 rounds). The second is an insert, again similar to the new design .223 Remington conversion magazine, but altered to fit the dimensions of the 7.62x39mm.

The problem with 7.62x39mm conversions has very little to do with the rifles. It is the availability of the ammunition. The best ammunition, with regard to both accuracy and reliability, is the Norinco copperwash coated FMJ. However, this ammunition is almost all-but unavailable. The Australian Federal Government has banned the importation of this ammunition on the pretext that it is being used in prohibited SKS rifles.

Those who have conducted experiments report that not even handloads shoot as well as the Norinco ammunition. The brown-lacquered cases have been reported as being difficult to extract when the barrel heats up. If you have a good supply of Norinco copperwash ammunition then consider such a conversion. Otherwise, spend the extra and convert the rifle to .223 Remington.


Why not 7.62mm NATO?
There are several reasons for not converting to 7.62mm NATO (.308 Winchester). The most important one is that in Australia all No4 conversions have to be proofed tested by Lithgow Small Arms Factory, and have the appropriate proof stamp. That stamp is only valid for that particular barrel, bolt, receiver combination. If the rifle has a new barrel installed then it has to be re-proofed and stamped. Fine in theory. But, the facility at Lithgow was corporatized and then privatized prior to being sold-off. The costs of having rifles proofed quickly rose to the point of being prohibitive and the service was ended because of the lack of use. Needless to say I don't think very many rifles were re-proofed after being re-barreled.

The reason for the proof testing is because 7.62mm NATO exceeds the performance of the cartridge originally designed for the No4 receiver. A gunsmith has shown me several No4 receivers that have stretched, because of too many hot loads used in them. Locally, a "Technical Advisory" was issued recommending that Norinco steel-cased 7.62mm NATO ammunition should not be used in No 4 rifles.

.223 Remington and 7.62x39mm are well within the limits of the No4 receiver and don't have to be proof tested.
 

The Author

I have interests in Military History, and in the design and development of firearms, and other militaria. In particular, I have an interest in how designs and tactics influenced each other to create the progression that has occurred since the turn of the 20th century.

Note that while I am right handed, I'm following standard rifle range safety procedures by keeping the muzzle pointed down range. The stop-butt is to the left of the picture.

I have been target shooting for over ten years and have been a member of Royal Australian Naval Reserve Rifle Club (RANRRC) from 1992 to 2003 when I transferred to Royal Army Engineers CMF. The club is a part of the Military Rifle Clubs Association (MRCA). The MRCA is a part of the New South Wales Rifle Association (NSWRA) and we are based at the Malabar Rifle Range located in Sydney's eastern suburbs.

Our matches take place at various distances from 100 to 400 meters. We use standing positions at 100 meters, we sit or kneel at 200 meters, and only go prone at 300 meters and beyond. The rifles are used as they are intended to be used, with the exception of actual combat. Courses of fire involve the following practices:

Thanks to Gary for the rifle's conversion and for some of the technical details, to Marco for some of the photos, and to Vic for refurbishing the woodwork, and Edwin for the proof reading.