Target Sports

HANDLOADING: WEIGHTY MATTERS

Created on 27th May 2009

LAURIE HOLLAND calls in the heavies - heavy bullets, that is

LAST MONTH'S Target Sports had just gone to press when the MoD relaxed its threatened 3,800J ME ceiling to 4,500 (3,318ft/lb), lifting the threat to Target and Match Rifle disciplines. The formulae in last month's ‘Handloading Topics' work with the new value, but I've recalculated the maximum allowed MVs for a range of standard bullet weights (Table 1), and it's apparent that all cartridges up to and including 6.5mm calibre are ‘safe', either because nothing in common use produces such velocities, or exceeds the existing 3,275fps MV ceiling.

Larger-cased 7mm and .30 calibre designs, such as the WSMs, still have no difficulty in achieving velocities that exceed the maximum allowed ME with 160gn to 175gn 0.284s or 185gn to 240gn 0.308s respectively in target length barrels, so issues over ‘policing' loads still apply. Actually, this isn't a new obligation, since the MoD placed a burden of proof on civilian range-users that their ammunition wouldn't exceed the 3,275fps MV ceiling and/or the previous, higher ME limit many years ago. This had to be either a copy of the manufacturer's ballistic data for factory products, or a signed statement for handloads providing cartridge name and bullet weight with chronographed MV (or naming the reloading manual whose data was used with estimated MV). In either case, the ME had to be calculated and shown. This requirement was rarely, if ever, enforced, but I wouldn't be surprised if it is now.

Maximum range

Are MV and ME figures reliable indicators of a bullet's extreme range, and therefore whether it might travel far enough to leave the RDA (Range Danger Area) behind the stop-butts? Taking rifle ranges first, many RDAs have probably been inadequate since the pre-WW1 introduction of the 0.303" Mk VII ball cartridge if fired at a high enough muzzle elevation, nor will any ballistics-orientated limit cope with a seriously ‘sideways' angled shot. However, such practices are rightly categorised as negligent discharges, and the near-complete absence of reported bullet strikes outside of range boundaries despite the staggering numbers of rounds fired suggests layouts and firing practices work. (One must also consider two relevant historical factors - the millions of wartime and National Service conscripts that have used these ranges, many of them unwilling recruits and a percentage frightened of handling any firearm to the point of dangerous incompetence; and billions of rounds fired as bursts from medium and general-purpose machine-guns, weapons designed to produce ‘beaten zones' of bullet strikes, and posing a much increased risk of bullet escape from backstops.) MV and ME values do obviously have some relationship to bullet performance and range, but only tell part of the story. For instance, the pre-WW2 US .30-06 service cartridges I mentioned in the last issue had very different ranging abilities, despite the more effective M1 model having a lower MV and only slightly higher ME than the later M2. The difference was of course in their bullets' shapes, the M1 using a high-BC 173gn long-range boattailed design to extend machine-gun effective range.

Absolute range is determined by muzzle elevation; ambient conditions (temperature, humidity, barometric pressure, altitude); muzzle velocity; and bullet characteristics. For any given angle of departure, the key factors are the combination of MV and bullet ballistic performance, and efficient cartridges loaded with high-BC bullets are likely to have enhanced long range capabilities irrespective of their MVs and MEs. Rob Hunter's tactical rifle chambered for the little 6.5 x 47mm Lapua cartridge featured in last month's issue will give a 123gn 0.264" Scenar (claimed BC: 0.547) something in the 2,900 to 3,000fps MV bracket (a modest 2,460ft/lb/3,335J ME), but knocks spots off any 7.62mm/.308W load ballistically thanks to the bullet's high BC. Conversely, .45-70 + P and heavy .444 Marlin loads produce lots of ft/lb ME, but are classic short-range sporting cartridges thanks to their blunt low-BC bullets (Figure 1).

Ultimate ranges

I cannot tell you how far a bullet will travel under optimum conditions - calculating this is no simple matter, even for professional ballisticians with computers and specialised ballistics software. The ordinary shooter cannot ascertain it for two reasons. Firstly, standard external ballistics programs are unsuitable. Then, once the bullet becomes subsonic, air-drag produces quite different (generally lower) characteristics from when it was supersonic, and velocity now drops at a much reduced rate. (In case you think subsonic bullets cannot travel far, remember the humble .22 Long Rifle and its aerodynamically inefficient 40gn bullet that reaches out more than a mile, not to mention famous historic long-range shots with black powder big-bores.) Bryan Litz, who does business as Applied Ballistics, has the necessary software and can calculate an estimated maximum range of any bullet/MV combination on request (W: http://bryanlitz.bravehost.com; E: bsl135@yahoo.com). A factor that affects some bullet designs is trans-sonic velocity zone instability, which sees them suffer increased drag and buffeting as they approach the speed of sound (c. 1,120fps), and their range is likely to be much curtailed as a result.

223 Remington

Let's return to handloading, in this case .223 Remington with heavyweight match bullets that have transformed the little cartridge's performance to put it on a level footing with larger, more powerful designs, in particular .308 Winchester. Heavyweight? Mainly 77gn and 80gn models, although there is a 75gn model included too, and heavier projectiles are now becoming available with 90-grainers from Berger, JLK and Sierra. We've no worries about MoD ME ceilings with any bullet weight as we're producing under 1,500ft/lb (2,033J), less than half the limit, and one cannot get anywhere near 3,275fps MV either with these bullets.

However, before you cheer too loudly at leaving boring old ballistics behind, we cannot escape them completely as we still need to understand what we can or cannot do with the various bullet weights: how they determine usage, MVs and rifling twist rates, a subject that still causes endless confusion with this cartridge.

Multi-purpose

Most bullets fall within one of three weight groupings - 50-55gn; 68-75gn; and 77-80gn, each with different characteristics and performance. Light bullets came first, many preceding the cartridge having been developed for the older .222 Remington with its slightly lower MV and noticeably slower (14T) rifling twist. This applies to most members of a raft of 52gn and 53gn hollow-point match bullets. When the US military adopted the 5.56mm M193 back in 1964, with its 55gn FMJBT bullet, and the M16A1 rifle with a 12" rifling twist to stabilise the projectile to 500m, commercial manufacturers soon adopted the cartridge under the .223 Remington designation and bullet-makers produced new 55gn sporting models to suit, an ongoing process with such (more recent) designs as the Hornady V-Max, Sierra BlitzKing and Nosler Ballistic Tip models. Conversely, with the exception of some Berger Bullets designs and the polycarbonate tipped 52gn Hornady A-Max, little new in the way of match bullets has since appeared in this category, models designed for the .222 Rem performing equally well in the younger cartridge.

As can be seen from the number of ‘varmint' bullets on the market (Table 2), this category is still built around the cartridge's original sporting usage, making it a great 250yd fox number - accurate, flat-shooting and terminally effective. A recent innovation, lightweight (40gn) versions of some of the best projectiles have enhanced this short-range use, 3,600-3,800fps MVs taking the 223 into what was .22-250 Remington ballistics territory not so many years ago. These high-velocity combinations have very flat trajectories to around 300yd but then shed speed rapidly, so performance quickly drops off and wind drift becomes an issue, but that's not a problem for most
users.

A good rifle with 52/53gn match bullet handloads can provide startling performance up to 200yd, even 300yd in settled conditions, making it more than competitive with .308 Winchester while using less powder and cheaper bullets, and offering longer barrel life and lower recoil. Such combinations are deservedly popular in short-range club-level competition, especially where the rifle doubles up for foxing. Good heavy-barrel models like the Remington VS/PSS and Savage Model 12 BVSS/LRPV also do well in 100yd benchrest competition in the factory rifle class. However, heavier bullet .223 loads or more ballistically efficient cartridges provide superior performance at 300yd, even 200yd, as soon as the wind gets tricky.

While 55gn is normally seen as the upper weight ceiling for this bullet category, note there are 60gn to 70gn models from Sierra, Speer and Berger designed to stabilise in a 12T barrel (Tables 2 and 3).

Nevertheless, the next category up weight-wise (62gn Speer and military M855/SS109, plus 68 - 75gn match designs) offers markedly enhanced target shooting performance at 300yd and upwards. The Remington 700PSS (but not the outwardly similar VS) and heavy-barrel Savage models come with a 9" rifling twist rate and will handle these bullets. The good news is that there is little, if any, performance fall-off with 52gn match and 55gn expanding types, so rifles with this barrel twist rate suit lots of different uses for one-rifle owners.

Bullets like the 69gn Sierra Match King make the cartridge 500yd and 600yd-capable without each little puff of wind blowing the bullet out of the black. But note that ‘capable' and ‘optimal' are very different things - a 68-70gn match bullet handload at 3,000fps still needs 40% more wind correction than off-the-shelf 155gn RG Bisley Match at 2,765fps MV from my 24" barrel FN SPR. Put that another way: if a 90º crosswind gusts by 5mph as you squeeze the trigger in a 600yd shot, the 223's bullet is deflected by over 23" compared to the 308's 16.5" - a distance of over an MOA, which is no small beer to the competition shooter.

Heavies

To achieve external ballistics parity with the 155gn bulleted .308W, we have to go up to the heavyweight category, the 75gn and 80gn Hornady A-Max models, 80gn tangent-ogive models from Sierra and Nosler and the long ‘slippery' 80gn VLDs from JLK and Berger Bullets. Note A-Max models with their secant-profile ogives are properly described as VLDs too. An 8T barrel is ideal for the Nosler and Sierra 80s, and while JLK and Berger also quote this twist rate for their products, Accuracy Speaks' Derrick Martin, of AR15 competition rifle building and 223 experimentation fame, says unequivocally that these bullets perform better in a 7" twist rate barrel. 80gn bullets can reach 2,700fps MV from 20"-barrel AR15/M16A2 competition rifles with careful handloading, with another 100fps, and maybe even a little more available from 26" tubes with one or two powders.

What about the 90s? They need a 6½" rifling twist rate at .223 MVs, and American shooters have found it hard work getting 2,500fps out of them without blowing primers. At this MV, there is no benefit over the 80s and the general consensus is that they're much better suited to .22-250 and .22BR, larger capacity cartridges capable of providing 2,900fps plus from target length barrels. Talking barrel lengths, there is little benefit in going above 26" with .223 as the cartridge just doesn't produce enough gas to obtain much benefit at greater lengths.

The 75gn Hornady A-Max has been included with the heavyweights rather than the intermediate group, as it is a long high-BC type that needs a fast rifling twist and should also be seated into the rifling, the resulting COL being well over the cartridge's listed maximum as well as magazine length. With a claimed BC that's marginally higher than the 80gn Sierra MK, and the ability to give it a slightly higher MV, it should be a good long-range performer, which is in fact what I found having used this model successfully at 1,000yd. You'll also notice 77gn models from Sierra, Nosler and Berger listed in a little group of their own in Table 3. Unlike the A-Max, all three are tangent-ogive designs for loading to magazine length COLs (2.25-2.26", depending on the rifle/make of magazine). This weight, allied to bullet length, is as high as you can go without ending up with a bullet seated over-deeply in the case at the standard COL and reducing powder capacity excessively. All three happily make a large jump to the rifling. I know, as I tried the same 77gn Sierra MK loads at mag-length, then seated a full two-tenths of an inch further out for single-loading into the chamber. Although the latter had a minimal (10 thou) jump into the leade, they provided no reduction in group size. These designs were produced to substitute for older 68-75gn types in US Hi-Power Service Rifle 200yd and 300yd rapid-fire stages to further reduce wind-drift. (Ammunition loaded with the Match King has also been used by US special forces troops in the Middle East in an attempt to increase the effective range of short-barrelled M4 carbines and increase their terminal effectiveness. Neither objective was fully achieved according to reports from the field, hence the recent US Army dalliance with 6.8mm Remington SPC.) Can they be used in 9T barrels? ‘Fraid not - Stuart Anselm tried them in his Savage Model 12 BVSS before it was rebuilt into its current F/TR Championship-winning .308W guise, and they wouldn't stabilise even at short range.

Pinch of salt

Table 3 lists the BCs claimed for match bullets by their manufacturers. You'll notice that the light (50-55gn) numbers have values under 0.25: really low nowadays when competition shooters are looking for 0.5-plus and many F-Classers consider 0.6 a reasonable starting point. Yes, but light-bullet .223 gives high MVs doesn't it, so surely that compensates? Unfortunately, only at very short ranges - compare the retained velocity and computed wind drift (10mph crosswind) at 600yd, shown in the last column, for the 52gn Sierra MK launched at the maximum MV allowed on an MoD range or Bisley (3,275fps) against the same company's 80-grainer launched 475fps slower. The big bullet has performed so much better aerodynamically, but the position has been neatly reversed with it travelling 475fps faster at this range, as well as suffering almost exactly half the wind-induced drift of its little brother.

Moreover, one must take many of the claimed BC values with a good healthy dose of scepticism. The aforementioned Derrick Martin once carried out range tests using two chronographs set 500yd apart and 80gn VLDs did not perform as predicted (ie lost more velocity than they should have for the claimed BC), while the 80gn Sierra did better than it should have. That's why I've included muzzle and 600yd figures for the military 5.56 x 45mm 55gn M193 and current 62gn M855 (from the US Army Proving Ground, Aberdeen, Maryland) as a reality check. There is a huge performance gap between the latter's performance and what ballistics programs say the Speer copy of the M855/SS109 should do if its 0.307 BC is correct.

Range-testing ballistic performance only tells you how bullets perform against each other on that day under the prevailing conditions - they may change significantly if run elsewhere or at another time, BC values not being fixed in tablets of stone. So use Table 3 as a guide to relative performance. What it should tell you is that if you use a 223 purely for target shooting and want to be competitive, you must get a rifle with a 7T or 8T barrel and load 80gn bullets.

Next month, I'll finish this examination of the .223's ballistics envelope to explain why nobody uses the cartridge in Target Rifle thanks to the limitations imposed by ‘issued ammunition,' meaning the 62gn L2A2 version of the FN SS109 in this country, as well as comparing handloaded heavy-bullet .223 to the equivalent .308. The two cartridges are frequently pitted against each other at club level and are also the only designs eligible in the TR division of F-Class. With all national F-Class League rounds shot over 800-1,100yd stages, can the little .22 hack it at such ranges and be competitive with the older, bigger .30? (As an initial guide, I've included three popular .308W F-Class handloads in Table 3.) We'll also look at the other components, the choice of primer and case being even more important than usual when one starts loading heavy bullets in this tiny cartridge.