Target Sports

HANDLOADING : THE .30 CARBINE

Created on 15th May 2009

LAURIE HOLLAND tests the .30 US M1 Carbine, a cartridge with a popularity that belies its performance

ARMALON LIMITED'S generous loan of a neat AL30C Enfield-based bolt-action carbine for review (Target Sports October 2007, p.53) allowed me to do some load development with this cartridge in agreement with company proprietor Peter Sarony. Its proper title is the .30 US M1 Carbine - confusingly similar to that of the weapon it was designed to be fired from. To keep things simple the cartridge is normally called .30 Carbine, which I'll abbreviate to .30C while calling the rifle the M1 carbine. Both are very popular in the USA and some European countries, but the former sees limited use here thanks to a shortage of firearms, while the latter has been classed as a prohibited weapon under Section Five of the 1968 Firearms Act since the post-Hungerford amending Act came into effect nearly 20 years ago. Apart from the Armalon, the only .30C guns I'm aware of are two models made by the Southern Gun Company in AR15 guise: a straight-pull Speedmaster and the LAC30 lever-action operated by swivelling the pistol grip forward. There will also be a handful of Taurus LBR revolvers and even the odd manual straight-pull example of the M1 carbine. So, this was a rare opportunity I couldn't pass up.

World War II

Let's look at the background to the cartridge. Winchester developed it in a remarkably short time just before America's entry into World War II in response to a US Army specification for a 300yd-effective cartridge to be chambered in a proposed light rifle. The intended recipients were engineers, artillerymen, machinegun crews, rear area wallahs and others who didn't need a full-size and power rifle and would otherwise have been given an M1911A1 pistol, or something similar. The company completed the work quickly by adapting its obsolete .32 WSL (Winchester Self Loading) cartridge. WCC had also recently developed a new manufacturing process in which small diameter spherical propellant kernels were precipitated out of a solution in a still, the resulting dense ball-powder ideally suited to the small case. A relatively fast-burning grade was produced to give a 110gn 0.308" diameter jacketed bullet a bit over 1,900fps from an 18" barrel.

Carbine

There are few modern cartridges as closely linked to a single firearm as this ‘30', the overwhelming majority consumed in the short 5½lb gas-operated semi-auto M1 carbine, coincidentally also a Winchester design. An important requirement was suitability for mass production, and 11 contractors produced over 6,000,000 between 1942 and 1945. With large numbers issued to combat troops despite the original brief, the M1 carbine played a significant frontline role in WWII and Korea. US troops also used it in Vietnam for a time until the 5.56mm cartridge and M16A1 assault rifle were adopted, but its major use there was by the USA's allies, South Vietnam and the Republic of Korea, with around a million carbines having been supplied to each.

The combination employed several innovations - the first military cartridge to employ a non-corrosive primer from day one (although Remington ‘Kleenbore' sporting cartridges had had them for years) and also loaded exclusively with a ball powder. The rifle saw the first application of the short-stroke gas-operating system designed by David Marshall (‘Carbine') Williams. A port just ahead of the chamber bleeds gas into a cylinder underneath the barrel which holds a captive piston or ‘tappet'. Gas pressure pushes the piston back about four-tenths of an inch, striking a heavy U-section forging that slides between the barrel and stock channel. Its tail exits the stock alongside the receiver and works the bolt as per the M1 Garand, M14 and Ruger Mini-14, a cam track on the operating rod engaging a peg on the bolt-body.

The rifle's mechanism is of more than purely technical interest as the combination of a light, skinny-barrel military weapon with a chunk of steel belted furiously backwards and forwards between barrel and stock does little for its accuracy. These problems are compounded by the bedding system. The barrelled action is located and secured in the furniture with its rear tang hooking under a plate screwed onto the stock and is forced down into the stock channel by the handguard, with everything held together and tensioned by the stock/front sling band. But despite its shortcomings, millions were snapped up by civilian shooters worldwide alongside vast quantities of ammunition when sold off by the US government as surplus.

Popular

A line of a song runs: ‘Why was he born so beautiful, why was he born at all?' and one might wonder if the latter question applies to the .30C on studying its pedigree and reading the notes in reloading manuals. The M1 carbine-cartridge combination seems to be a universally poor performer! We've already seen it was no great shakes in the accuracy department (good ones produce around 3-MOA groups at 100yd, poorer ones twice that) and has a severely limited effective range, so forget formal fullbore target shooting. Sporting use is similarly constrained, and all American reloading manuals and ‘hunting' authorities warn it is quite inadequate for deer, leaving only pests and small game. But a good .17 or .22 rimfire is usually more effective in this role at .30C-friendly distances, and the cartridge is no match at all for .222 or .223 Remington in ‘varmint-shooting' especially at the 200yd mark.

So that leaves its military role. With its 20-year service record and participation in three major wars, still turning up in bush conflicts today, surely it must have been successful? Former users are split on the matter, depending on whether they just carried a carbine or actually fought with it! To be fair, the little rifle did exactly what it said on the tin, or rather in the US Army tender specifications - if only the authorities had restricted it to support troops and heavy weapons crews as originally intended. The consequence of using a small calibre pistol-type cartridge in a primary combat role was extremely low lethality and poor disabling performance on determined, dangerous opponents such as the WWII Japanese soldier. This was thanks to the small calibre compounded by an ogive shape that produced a relatively small-diameter, sharp nose. The shape was needed to obtain reliable feed and is also why the cartridge doesn't work overly well in some sporting applications, as most 110gn RN soft-point bullets stick with the FMJ RN shape and don't expand at .30C terminal velocities except in very short-range hits. Speer recommends designs with lots of exposed lead such as its semi-jacketed 100gn ‘Plinker' and 110gn Hollow-Point, but notes they won't work reliably in many carbines unless the feed ramp is polished.

So, with this list of inadequacies, why is the carbine and its cartridge so popular? Obviously, Americans were influenced by their government's quarter-century-long sale of surplus guns and ammunition at giveaway prices, but there is more to it than that. The carbine is easy to carry and great fun to shoot, making it a popular ‘walking rifle' or plinking gun in those countries with lots of space and few regulations - for example the USA, Australia and New Zealand - even if much of the shooting will be at tin. It can also be a very satisfactory short-range target rifle when competing against its fellows. I'm told this is the case in Germany where many clubs run individual and team carbine competitions, many shot indoors over the winter months. Interest in using the carbine competitively in its home country has taken off too, with clubs, state rifle associations and the CMP (Civilian Marksmanship Program) running hugely popular competitions restricted to the two M1s - rifle and carbine.

Characteristics

Let's move onto the cartridge, its characteristics, components and loading data. When I put some .30C cartridges alongside far more commonly seen .357 Magnum examples, I was surprised at just how similar they are. Sure, the .30C is rimless while the .357 revolver number has a marked rim, and the ‘30' has a slimmer case and bullet, but these differences are less obvious than envisaged. This is probably because of the similarity in their lengths, the cases being identical and nominal COALs varying by less than a tenth of an inch (see Table One). QuickLOAD gives the .30C 22.5gn water capacity with a Sierra 110gn FMJ seated to the standard OAL, compared to 26.9gn for the .357 with an equivalent 158gn JSP, so it has around 15% less powder capacity. This is relevant as maximum loads use similar amounts of the available room in both designs, generally around 90% with very small-grained or ball powders, rising to 100% with Vihtavuori N110 and Hodgdon H4227. Why compare them? The .357 Magnum is the default choice for most Gallery Rifle shooters, so this has to be the benchmark to measure the .30C against.

Looking further at the two cartridges' specifications dispelled some assumptions. It's regularly said that as a rifle cartridge the .30C operates at much higher pressures than equivalent pistol numbers. (It is specified for small rifle primers, unlike magnum revolver cartridges that use pistol types.) In fact there isn't that much of a difference, the CIP giving the .30C a MAP of 320 MPa (46,400 psi) and the .357 only 6% less at 300 MPa (43,500 psi), both using the Piezo measurement system. I'd always thought as the .30C provides better external ballistics at the longer ranges the pair might be used over (100yd or thereabouts), with its smaller calibre, more streamlined bullet, and higher MV. But again, running the figures (using Sierra's Infinity VI programme this time) only gives the carbine a marginal advantage using the top MVs in the new Speer No. 14 Manual (see Table Two). Moreover, both models lose nearly identical amounts of velocity and energy (in percentage terms) over 100yd, showing the .30C's better-shaped bullet confers no ballistic advantage due to its low sectional density arising from the 110gn weight.

However, the balance of advantage is actually more in the .30C's favour as it will be used in rifles with front-locking actions, unlike the .357's rear-locking leverguns. Most manuals warn that maximum loads ruin cases quickly in such rifles, and accuracy is usually disappointing when one stresses the case and action to this extent. So I ran the comparison again with the .357 restricted to Speer's starting load that drops the MV by 174fps, and the .30C now has a useful 100yd performance advantage. Both see a lot of wind-induced movement in a 5mph crosswind at this range, but the .30C bullet is now moved nearly half an inch less.

Components

As already noted, the standard bullet is a 110gn round-nose. This is what you get in factory loads, either in full metal jacket form to duplicate the military cartridge or as a round-nose soft-point for vermin and small game. Spire or sharply pointed bullets cannot be used in the M1 carbine (or its magazine, as employed in the Armalon AL30C) unless rounds are fed singly into the chamber. Bullets that weigh more than 110gn may produce rounds that are over-length, don't fit the carbine magazine or are seated deeply in the case. They present another hazard to semi-auto carbine users with a gas-port only a couple of inches ahead of the chamber - their greater inertia, hence slower acceleration down the barrel, alters the pressure/barrel-time relationship, producing higher port pressures which will damage the action in extreme cases. As with all gas-operated weapons, the carbine needs ammunition that produces pressures within clearly defined limits - too low and the bolt ‘short-strokes'; too much and the action operates over-violently. So, the six cartridge manufacturers that produce .30C ammunition all load 110gn jacketed bullets within a small range of claimed MVs (1,990 to 2,001fps).

There is plenty of loads data around - all powder manufacturers list the cartridge and of the bullet manufacturers you'll find data in the Hornady, Sierra and Speer manuals. They're often the shortest data section in the book (a result of the small bullet choice), likewise there are relatively few powders that meet the carbine's gas-pressure requirements, all of them magnum pistol or fast-burning rifle types such as Alliant 2400, H4227 and Viht N110. For the same reason, listed charges produce performance near the top end of the velocity range, starting loads normally producing 1,600-1,700fps and maximum loads 1,800-1,900fps. Cast lead bullet data is thin on the ground, only Lyman providing it and noting that loads may not operate carbine actions. The problem here is that sufficiently high pressures and velocities are likely to produce barrel-leading and/or cause a build-up of lead particles and lubricant in the gas system.

Manual

None of the above, apart from barrel-leading, is likely to trouble .30C users here, of course, as we're limited to manually operated rifles so don't have to worry about over-low pressures. We can therefore use any combination of powder and 0.308" diameter bullet we fancy, as long as the resulting cartridge fits the magazine, feeds and pushes the bullet out of the muzzle. If we're prepared to single-load, we can exceed the 1.68" COAL too, allowing us to use heavier, longer and pointed bullets. Unfortunately, due to yet more legislative constraints, we cannot try any of the accurate 125-135gn varmint and small game single-shot pistol bullets produced by the American bullet companies, as they're expanding designs. There is, however, a reasonably priced pointed FMJ in this weight category - Lapua's 123gn produced in 0.309" diameter (designation: S495) and 0.310" (S405), intended for 7.62x39mm cartridges and a good quality gilding metal/lead core version of the Soviet AK bullet. Cheaper S&B steel jacketed 0.310" alternatives are sometimes available too. The S405 is available here, and although slightly oversize can be used safely provided loads are worked up cautiously. How heavy can you go with jacketed bullets if over-length cartridges are acceptable? A keen .30C user who owns an AL30C and Southern Gun Co LAC30 advised that he has loaded the exceptionally long Lapua 155gn Scenar with good results, so 144-155gn FMJBTs and match bullets are ‘on' if desired, albeit at low MVs. (This only applies to the Armalon and SGC rifles which employ a faster rifling twist than .30C revolvers or the original M1 carbine, a 1-20" twist rate being standard which will only stabilise short bullets.)

When it comes to using cast lead bullets, there are 115gn RN plain-base and 125gn (plain-base and gas-checked) models available. All produce standard COAL rounds for magazine operation. Home-casters have a better choice as there are bullet-moulds for many suitable designs on the market. Using lead bullets puts the .30C on a par with the .38 Special/.357 Magnum in terms of flexibility with a wide choice of pistol powders and the ability to choose charges that produce all sorts of loads from subsonic 25m cartridges up to medium-velocity examples that should perform at 100yd. As with cast bullet .357 loads they are economical - in fact more so as you need less expensive lead and tin in the lighter bullet.

You might have to shop around a bit to find components, especially cast lead bullets, but they are available, and while Sierra 110gn FMJ RNs are widely available I've noticed some dealers stock cheaper Remington examples too. Tim Hannam provides ‘Relcom' (Remington) unprimed cases, while York Guns has PMC examples. Alternatively, you can start with York Guns' FNM or Henry Krank's PPU factory cartridges to get your brass. Small rifle primers are no problem of course - I used Russian-manufactured PMC examples throughout in my handloads, their relatively soft cups not an issue in this low-pressure (by rifle standards) number. So, the .30C apparently offers short-range target shooters the same benefits as .357 Magnum when used in a carbine: cast lead bullets, light recoil, great flexibility through handloading and economy. Further pluses are that the rimless case is designed for box magazines offering much faster reloads and higher capacity (15 and 30-round) than any levergun for action events. There is a better choice of non-expanding jacketed bullets for high-velocity loads used at longer ranges than for the .357 - and if single-loading is acceptable, markedly heavier and more ballistically efficient models, even if the ballistics come nowhere near those of .223 Remington or 7.62X39mm. The remaining question is - how does the .30C compare accuracy-wise to the .357 in a carbine at Gallery Rifle ranges? I'll move onto the mechanics of cartridge-loading next month to try to answer that question.