Target Sports

HANDLOADING PART TWO: THE .30 CARBINE

Created on 14th May 2009

Last time LAURIE HOLLAND tested this popular cartridge; this month he's looking at loading it

Let's move onto loading our little World War II rimless number, trying jacketed and cast lead bullets. If we kick off with the mechanical operations, we note that this ‘rifle cartridge' is treated like a pistol design using a three- or four-die set with case-mouth expansion (‘belling') carried out as an intermediate step between resizing and powder charging/bullet seating. Most reloading tool makers offer three-die kits incorporating a carbide sizer die to reduce workload and remove the need for lubrication. In case you're wondering about the fourth die, that's an optional standalone taper crimp - the case-mouth headspaces on a chamber ledge like semi-auto pistol designs, so a roll-crimp is unacceptable.

Tapered

The .30 Carbine case shares another characteristic with semi-auto pistol types, notably 9mm Parabellum and .45ACP, with its tapered body. Carbide sizer dies have a tungsten carbide ring glued into the bottom of the die-body, thereby reducing everything to a single diameter and converting our tapered case into a cylinder. While this seems to cause no great problem in 9mm/.45, it may produce excessive diameter reduction in the lower part of the longer .30C case. I also found the Lee sizer die produced a large (to my mind excessively so) reduction of the case-body, requiring a considerable amount of mouth-belling to let the bullet be finger-seated.

Throw in a rather slack chamber in the rifle and there was substantial case expansion on firing, especially towards the rear above the web. I became aware of this when I resized my fired factory ammo brass - a surprising amount of effort was needed to resize the relatively thin walls on a powerful single-stage press. Such full-length sized cases would then re-expand up to 10/1000" when fired with full-pressure loads. Subsequent resizing back down again will do little to provide a concentric cartridge fit in the chamber, and still less for case life. The answer is to back the sizer die off to reduce the length of case-body affected. In fact, with light loads I would unscrew the die in the press until only the top section that holds the bullet is sized, although one would need to test a sample of such ‘neck-sized' cases in the rifle chamber before completion to ensure they still chamber freely. Incidentally, mention of the AL30C's ‘slack' chamber is not a criticism of Armalon: standard chamber dimensions are geared to military rifles that have to function with any old ammo and/or when badly fouled.

Length and Crimp

With the case headspacing on its mouth its length is important for accuracy, and in some circumstances safety. Manuals stress that the maximum allowed length of 1.290" must not be exceeded, nor reduced below the ‘trim-to' value. In normal circumstances the case will be shorter than the chamber. On pressing the trigger the firing pin will push the cartridge forward until the case-mouth hits the chamber ledge. The greater the amount of forward movement the more firing pin energy will be absorbed, and if cases have significantly different lengths we may get inconsistent strikes. Even when all cartridges fire instantly, tests show that this invariably produces pressure and velocity variations. It's important to measure cases after resizing, not in the as-fired condition. PMC cases ran around 1.275" out of the rifle, but grew 10/1000" with part-sizing and mouthbelling. Fortunately their consistency in this regard was good, which couldn't be said of that obtained by firing factory FNM cartridges, given that they had a 10 thou. length range and most were shorter. Batching or trimming these cases to keep lengths within a smaller range might improve accuracy. In practice, this probably had little effect on performance as the AL30C's Enfield Number 4-based action delivered lots of firing pin energy, judging by the heavily indented primer cups.

As noted, if a crimp is used it must be of the taper variety - and US sources strongly advise doing it as a separate step from bullet seating. The Lee seater die incorporates a taper crimp facility, but I found that 0.308" diameter bullets were a tight fit, requiring more effort to seat than was probably good for accuracy. The lead bullets were of still larger diameter and the pressure required to push them into the case saw the seater stem produce a deep indentation on the soft metal. So there was no need for a crimp in my ammunition and I left well alone.

110gn jacketed

The above may give the impression this is a difficult cartridge to load, but not so - you just need to keep one or two things in mind for best results and decent case life. With my having 100 rounds of factory FNM 110gn RNFMJ cartridges for initial rifle testing and nearly all published handloading data for 110gn jacketed bullets, it seemed logical to start with this type and see what the AL30C would do at 100yd. My objective was five-round groups under the 2" mark. I might have felt dispirited after using the FNM fodder, with 10-round groups ranging from just over the desired performance to double that (most were around 3") but I was confident handloads would improve matters. The FNM rounds had averaged 1,947fps MV and strings gave spreads that varied between 53 and 80fps.

Sierra's data for the cartridge is more comprehensive than most but even so it only consists of two bullets (really only one, as they are FMJ and SP versions of a single 110gn round-nose jacketed design) matched with eight powders. Of these, one (Norma R123) is unavailable here and another (Accurate Arms No.9) only found with difficulty. Two (Hodgdon H110 and Winchester 296) are actually different production lots of the same powder manufactured in the St. Marks Powder Company's Florida factory. With Accurate Arms 1680 really too slow-burning for this cartridge, you're now down to half the original figure - Alliant 2400, Hodgdon H110, IMR-4227, and Vihtavuori N110. I had a tin of the IMR powder available but running Sierra's maximum load of 15.4gn through QuickLOAD showed it would be heavily compressed - so then there were three! Sierra's maximum for H110 and N110 seems conservative at 13.8gn and 12.3gn respectively compared to the powder manufacturers' recommendations of 15.0gn and 14.0gn, albeit with different makes of 110gn bullets.

Anyway, I still had three suitable powders to try behind the Sierra 110gn RNFMJ - 2400, H110 and N110 - and worked up to Sierra's maximum loads in 0.3gn steps. H110 gave a range of group sizes - the best just below 2", the worst double that, all producing sooted cases and lower velocity than Sierra had predicted. The Viht powder grouped markedly better straight away, with 12gn producing the best group of 1.5" at just over 1,700fps and the five charge weights averaging 1.8". (The 12gn load actually put four bullets into a single 4/10" group, spoilt by one off to the side.) MVs were spot on too, with Sierra's maximum charge of 12.3gn producing 1,787fps compared to the predicted 1,800fps. Both powders produced large MV variations, ranging from a smallest spread of 38fps to a worst case of 123fps! Sooted cases suggested the H110 charges were too low, this being a powder that needs to run at or just below full-throttle to perform properly. Hodgdon used to advise that its maximum H110 loads should be reduced by 3% to obtain a starting load, in this case to 14.5gn. This seemed to be pushing things a bit so I carried on working loads up, but this time in 0.2gn steps starting at 14.2gn and groups reduced to 1.75" to 2.75". Best results in this rifle were obtained with 14.4 and 14.6gn for MVs around 1,850fps that also produced smaller velocity spreads. Moving to 2400, a starting load of 12.2gn was tried rising initially in 0.4gn, later 0.3gn, steps to Sierra's top load of 13.6gn. The best 100yd group with this bullet, at a shade over the inch, was 13.3gn and the four groups that covered 12.6 to 13.6gn charges averaged 1.77", so my sub 2" objective was comfortably achieved with all three powders.

N105

QuickLOAD PC software is invaluable for planning new loads, especially if one wishes to try combinations without factory data - although it's wise to remember that it is only a computer modelling programme and real-life combinations sometimes give a noticeably different performance from that predicted. Just apply some common sense and caution. Having said all this, QuickLOAD suggested Vihtavuori N105 might suit this application. This powder is faster-burning than N110 and lies between Alliant Blue Dot and 2400 in Vihtavuori's burning rate comparison chart. Starting deliberately low and still with the 110gn Sierra, initial loads were nothing special but charges between 10 and 10.5gn gave excellent results in the 1¼" to 1½" range. Unfortunately I wasn't able to chronograph these loads but QuickLOAD predicts that 10.5gn will give around 1,970fps at 42,290psi pressure. However, the programme seemed to serially overestimate velocities (and hence pressures) with this cartridge, so they're likely to be lower than this. I'll stress that these are not pressure barrel-tested loads and so readers should only try N105 at their own risk starting with very low loads (around 9gn).

123gn Lapua

Sticking with QuickLOAD, it also let me try Lapua's 123gn S405 pointed FMJ, modelling various charge ranges with Alliant 2400. QuickLOAD lists this bullet as 0.311" diameter in its database, which would raise pressures compared to equivalent loads with 0.308" projectiles, but they mike a shade over 0.310". Nevertheless I started off very low at 7.2gn, which was predicted to produce 1,256fps at a mere 13,500psi, and worked up to 9gn in very small steps, which should have given me around 1,520fps. On the range it was obvious that QuickLOAD had overestimated pressures and velocities with this bullet. Supersonic velocities were not produced until the charge weight reached 8.2gn. The very low velocity loads didn't group - this desirable feature appeared at 7.8gn, with an unimpressive 5" on the paper. (Nevertheless the subsonic loads were fun to shoot, with no recoil and such a soft report that earmuffs weren't needed even on a covered firing point.) Group size reduced as charges and MVs rose, with my top load this time of 9gn (1,354fps) producing 1.4". Even better was 8.8gn, which gave my smallest of all group with the AL30C at 1" precisely. A second batch of 2400 loads running from 9.4 to 10.5gn produced 1.6 to 1.9" groups up to 10gn, opening up after that to 2½". Unfortunately the weather stopped me chronographing these loads, but with a full-grain weight rise adding 268fps to the lower loads 10gn would likely produce around 1,600fps. Incidentally, that massive MV rise for a single-grain weight of powder tells you something - the importance of working charges up in small (0.2 or 0.3gn) steps in this cartridge.

These cartridges had bullets seated to a COAL of 1.86", nearly 2/10 above the normal value, and had to be single-loaded into the chamber. I'll stress here that this bullet must never be seated to the standard 1.68" in order to use the magazine. They still won't feed, but more importantly the effective reduction in case capacity will increase pressures. QuickLOAD estimates pressures produced by my 10.5gn top charge would jump by 43% simply through seating the S405 0.18" deeper! Again, I'll stress that these are not pressure barrel-tested loads and readers should only try these bullets at their own risk, starting with very low powder charges. I should also mention that the generous military .30C chamber dimensions are an advantage when it comes to using oversize bullets, whether 0.310" jacketed or our next subject, lead bullets, which will usually give best results when sized one or two thou. above the standard jacketed bullet diameter. With plenty of room around the cartridge there were no worries about over-fat cartridge dimensions as there would be in a tightly chambered match rifle.

Lead

Bob Clark at the Southern Gun Company supplied a collection of cast lead bullets - 0.309"-diameter 115gn plain base examples from GM in Leeds. Their shape copies that of the 110gn jacketed design closely: two 125gn designs with a blunter nose of unstated origin, one plain-base and the other gas-checked. Some batches sized to 0.309", others a thou. larger. Such bullets give a great degree of freedom in powder choice, with nearly every pistol powder potentially usable. With the AL30C's 1-10" twist-rate and sharp rifling, leading becomes a hazard, so velocities have to be kept down with the plain base bullets. This suggests the fast-burning powders one might use in light .38 Special and .357 Magnum loads, but gas-checked bullets can be driven harder allowing larger charges of slower burners. There were two problems - lack of published loads data and lack of time as the carbine was now overdue its return to Armalon Ltd. While the jacketed bullets had been shot over 100yd, lead bullet loads were tested at 50m (55yd). Again, my aim was sub-2", experience showing that such groups at this distance translate to a single hole at 25m.

More time with QuickLOAD suggested powders in the Alliant Bullseye to Unique range should work, with charges running to 4.5gn. I had two newcomers to try too, the super-bulky IMR ‘Trail Boss' and Vihtavuori N32C ‘Tin Star'. Playing safe initially, maximum loads were kept to 4gn, rising in 0.2gn steps from a starting charge of 3.2gn for Alliant Unique, IMR Trail Boss and Vihtavuori N32C ‘Tin Star' as well as good old-fashioned N320. This was with the 115gn plain-base GM hard-cast bullet. Only N320 exceeded 1,100fps with the 4gn top load - all were mild and pressures were obviously low. Alliant Bullseye and Hodgdon Titegroup, powders that have always given me top performance in mild lead bullet .357 Magnum loads were now tried with charges that reached 4.5gn. This took MVs up a bit to 1,224 and 1,282 respectively, neither showing any pressure signs nor wayward lead streaks in the barrel. Of the six Titegroup produced the most consistent results by far, all five charge weights grouping between 2-2½". The others produced the odd equivalent group, but also a fair number between 3-4". Only one group out of the 30 fired achieved my sub-2" target, 3.4gn of N320 giving 1½" at 1,015fps MV - but since three of the other four exceeded 3" then this may have been just a fluke.

Now running out of time, I was unable to try the 125gn plain-base RN types but had a final fling with the 125gn gas-checked models. The aim was to see how high I could push MVs, as well as finding out if they would group at mid-to-high velocities. With only one range session left I broke my own rules, raising charges of the powders I had selected, Alliant Power Pistol and Blue Dot, in full-grain steps. High MVs were obtained alright, the 7-11gn Blue Dot charge range rising from 1,202 to 1,863fps and the 6-10gn Power Pistol range 1,365 to 1,865fps. The latter combination produced excellent accuracy with lower charges, 6 and 7gn running at 1.3" and 1.1" respectively - the smallest lead bullet groups obtained overall. A charge of 8gn gave a still respectable 2.1" but the next increase expanded the pattern on the paper to over 6" and the top load of 10gn didn't group at all, cases also showing signs of distress with substantial expansion ahead of the web. Blue dot also did well in the three lower loads: 7gn, 8gn, and 9gn produced 2" groups, the highest running at 1,577fps. After that things went downhill, with 4-5" groups. So gas-checked bullets can be driven at 1,500fps, even a bit more, with good accuracy. Again there were no indications of barrel leading. However, 8gn of Power Pistol and 9gn of Blue Dot must be regarded as the absolute maximum with these or similar bullets. Also, these powders and charges should not be used with plain-base cast lead bullets as serious leading is a near certainty.

Conclusions? In a good rifle .30C handloads will match, and with enough load development beat, .357 Magnum accuracy while offering more shooting opportunities up to longer ranges with the right bullet choice. It will never be a long-range cartridge - 200yd is as far as you would sensibly use it even with jacketed bullets - but there is potential, especially between 25 and 100yd.

While my 50m low-velocity lead bullet results were no great shakes, the rate of achievement with these initial loads was superior to that of the comparable stages trying .357 Magnum in lever-action rifles. In particular, results obtained with 125gn gas-checked bullets and only two powders were encouraging.

IMPORTANT NOTICE

These components and loads performed safely in the test rifle but this cannot be guaranteed for other firearms. Good handloading procedures should be used, working loads up from low starting levels while looking for signs of excessive pressure. Note that loads using Vihtavuori N105 powder and .310" Lapua S405 FMJ bullets are not pressure-barrel tested and readers use them entirely at their own discretion and risk.