Laurie

I'm in agreement with both Vince and Jim (Gun Pimp & Firedoc) re the superiority of the 6BR in this role, and the relative ease / modest cost of having the bolt-face enlarged. (My first BR started as a 223 rifle with a much larger bolt-face enlargement needed.) I'd be a tad wary of the ARC. I spent some time and effort researching this design after its launch. and It's certainly a very capable design ballistically with remarkable performance for the case size/capacity. It is designed with heavy 6mm bullets in mind with a suitably long chamber throat and one turn in 7.5-inch rifling pitch rate specified as the SAAMI standards. However, like other such recent designs with the 7.62X39 / PPC / Grendel 0.447-inch dia. case-head, its factory target market appears to be primarily the US AR-15 shooter rather than PRS, BR, or prone match disciplines. Chambers and hence reamers are meant for this kind of firearm and use, and although in essence the cartridge is a fast-twist 6PPC 'improved', (or a stolen and slightly modified version of Robert Whitley's successful 6mmAR necked-down Grendel wildcat cartridge), there is much more to creating a BR quality rifle than simply a good case shape. So before committing yourself, look closely at who is making chamber reamers and their dimensions. I've no idea how many custom 6ARC rifles have been built in the UK, but would reckon that at best it'll be a handful. Not many gunsmiths will even hold a reamer as a result. Conversely, the gunsmithing world abounds with BR reamers and small-clearance chamber designs optimised for precision shooting disciplines. The same sort of issue applies to brass specs and its manufacturing quality / consistency. I'd be very surprised indeed if the Hornady brass is up to Lapua, Norma, or the specialist US case makers' 6BR standards, and IME Hornady case-heads are often on the 'soft' side. The Hornady ARC case also has a huge disadvantage too which would simply rule it out for me. The small diameter flash-hole (1.5mm vs the older standard of 2mm) is an integral element of the PPC / BR / 6,5X47mm Lapua precision mix when combined with small primer ignition. Hornady reportedly turns out its ARC cases with the large 2mm flash-hole. Had I followed up with my early interest in the ARC, I'd have bought Lapua 6.5 Grendel cases and reformed them - but Lapua suspended Grendel case production in the Ukraine invasion fall-out, and who knows if it has resumed - or ever will. In the current US supply situation for both factory ammunition and components, the ARC was introduced at a bad time, and as comments about it have dried up pretty well completely over the last year or two, it may be only just hanging onto life. A couple of US gunsmiths worked up long-barrel ARC bolt-actions mostly using the little Howa Mini-action, designed for low recoiling long-range varmint and plate / plinking etc use where they apparently do quite well. It has gone very quiet on that front however, and I'm not sure just how much real interest was generated.

Nick, the S&B SR did well in my small rifle primers tests in 308 Win 'Palma' brass with an N150 based load. https://www.targetshooter.co.uk/?p=2662 (In the previous large rifle primer tests in 308, S&B was the overall 'winner') David, the Magtech 7 1/2 was the overall winner in the aforementioned SR tests in 308 Win. It's my choice in my 6BR Lawton / Benchmark Benchrest 'Light Gun' too and has given me good results with a 107gn SMK / N150 load. Its only downside IME is that the cup seems to be slightly softer brass than the CCI-450 / BR4, so is more prone to crater.

Peter Sarony (Armalon Ltd) made them for years. Armalon's Facebook page is still live, so it seems to still be in business. He bought Parker-Hale's barrel hammer forging machinery when P-H went bust, rebuilt it over the years including the crucial electronic controls and set it up on a former military base IIRC at Bampton in Oxon. (He makes barrels in many other calibres and for other rifle models too.)

If you like Sierra MatchKings, I suggest you look at Henry Krank's website where 77s (including the rare as hens' teeth TMK version) and 80s are in stock in 100 and 500-ct boxes currently. Krank does a very efficient mail order service at a reasonable carriage price. Don't hang around as these bullets usually go out of stock rather quickly! So far as suitable powders go, Target Shooter free online ezine http://www.targetshooter.co.uk has a series of articles under the 'Reach-Out' heading looking at Reach-compliant alternatives to H4895 and VarGet using 223 with the 77gn SMK in a 7-twist F-Class rifle as the range test tool. Many of these powders tested have become scarce or completely unobtainable, but exceptions include Ramshot TAC and Wild Boar, Lovex S062 and the Lovex ball powders, but much more widely available N135, N140/540. Even though shops temporarily run out of Viht grades, the UK distributor Hannams Reloading continues to receive large shipments every few months, so it may be a case of getting an order in with a local retailer for the next shipment. Tested here: http://www.targetshooter.co.uk/?p=3934 http://www.targetshooter.co.uk/?p=3856 Alliant and Reload Swiss seem to continue with very occasional small deliveries of a limited number of grades, so you might be lucky locally, but frankly I doubt if we'll see much of these grades in the near or even foreseeable future. Even if the Ukraine war were to finish tomorrow, the western European security situation has irrevocably changed and governments are ordering smallarms ammunition stocks at a rate not seen since the USSR collapsed and the cold war ended. Moreover, there is now a general endemic shortage of propellant manufacturing capacity in the West and huge barriers to new entrants (health & safety costs, local community opposition, high-risk business cases due to lack of guaranteed demand), so nobody will be building new factories anytime soon if ever. Alliant now seems a hopeless case with very little if anything being delivered to the handloading market. Both of its extruded powder suppliers are in Europe - Eurenco Bofors in Sweden and Nitrochemie Wimmis in Switzerland, the Reload Swiss manufacturer, and both are heavily committed to government military orders for the foreseeable future. To rub salt into the wound, this part of Alliant ATK is now owned by Vista International, a classic Gouge, Take the Profits & Run venture capital firm which is a) up for sale and b) wrote earlier this month wrote to all of its distributors that Alliant powder prices will rise by 10% on 01.01.24 including those ordered under the old prices. What a bl**dy cheek - we can't supply you with what you order, but if we can it'll cost you +10%!

The order doesn't apply to some 40 countries that are members of an arms (re) export-control agreement with the US. I'd be astonished if the UK and most if not all EU countries aren't in that group. From commentary elsewhere, it seems that South American and Asian countries make up the bulk of those affected by this order.

I can't say what people are using, but Viht developed N565 specifically for the 338LM with 250gn bullets. https://www.vihtavuori.com/powder/n565-high-energy-powder/

N160 works very well in these rifles with the 140gn SMK. I used 44gn N160 for many years in an M1896 with excellent results. Start at ~41gn and work up. I'm pretty sure N150 will work too. The new N555 is extremely well suited to the cartridge and 140s. Alliant Re19 and 22 work well, and I'd expect the newish Re23 to as well - but cost and availability? Lovex S065 and 70 are good powders in this combination. The faster burning Lovex S062 isn't far removed from your original IMR-4895. Lovex's manufacturer Explosia provides data for all three powders in the cartridge with 139/140gn bullets. I've not tried it in 6.5X55, but Reload Swiss RS62 works superbly in similar applications. There are RS62 data for the 6.5x55/140 SMK on RS UK's website (www.propellants.co.uk)

Don't get rid of them. Light loads will be fine unless your bolt/firing pin fit is really poor, and even then it'll probably just be mild cratering which looks unsightly but doesn't cause any problems. I'm using up several hundred weak-cup CCI-400s, Rem 6 1/2s and especially a large lot of the original Russian copper colour PMC SRs made by Murom in a 6.5 Grendel Howa 'Mini' 1500. It has a small diameter pin which is a reasonable fit for a factory rifle, and loads that are running a tad over 50,000 psi if QuickLOAD is believed don't see any problems in this respect other than a liveable with level of cratering. It's only when I tip the powder can over-much and hit somewhere around 53,500/54,000 psi that things start to turn nasty. Let your rifle and the fired primer conditions tell you when to stop or back of a bit. Have a look at the pic of fired Rem 6 1/2 primers here in 308 Win small primer 'Palma' brass loads http://www.targetshooter.co.uk/?p=2621 None blanked, but those examples are very heavily cratered and right 'on the edge'. In normal load development, I'd rate the loads too high pressure for this primer model, and either change primer model to an SRM/BR or reduce the powder charge significantly. In the final part of this SR primer test series, here: http://www.targetshooter.co.uk/?p=2662 if you scroll down towards the end, there are pics of different small rifle primers fired in my onetime 'hot' long-range 308 Win Palma brass FTR load. I almost got away with it with weaker models as the rifle had a Stolle Atlas action with small dia. pin and fairly close bolt-face fit (but not the perfect fit you get on some custom actions). Only one example of the soft PMC SR blanked. (Note too the difference in appearance between primer appearance despite these cartridges having an otherwise identical components combination. It's impossible to gauge pressures from primer condition when switching primer makes and models around, (but possible with extensive experience of a single model in a particular rifle with experience and cross-checking MVs against QuickLOAD predicted values and their accompanying estimated pressures).

The CCI-400 and Rem 6 1/2 were originally designed for the .22 Hornet, .218 Bee and similar. In addition to these being relatively low pressure cartridges, they needed rather 'soft' (read 'thin') cups as in poorer times than now many rifles were built on converted rimfires, old Martini Cadet and similar actions with weaker and lighter mainsprings/strikers. When Remington introduced the .222 Rem in 1950, a ~50,000 psi cartridge, the 6 1/2 was deemed too weak and the first SR 'magnum', the No. 7 1/2 was introduced to cope with the higher pressure. As with most SR 'magnums', it was no 'hotter' than the standard model, but had a thicker brass cup - 25 thou' vs 20 thou'. (The later / current 7 1/2 BR is more aggressive having been introduced alongside the .17 Rem cartridge that needed a higher brisance primer with some powders.) In the 223, it's always better to use the thicker cup models, although you can 'get away with it' with weaker designs depending on 1) the pressure you handload too. (In a standard shortish freebore chamber the 77 SMK + 24gn Viht N140 would likely be approaching full pressures, rather less with a Wylde or longer freebore chamber.) ........... and 2) the nature of the action and how much clearance there is between the firing pin and its hole in the bolt-face. A loose fit facilitates cratering, and at higher pressures 'blanking' where the metal disk of the pin indentation in the primer cup detaches and either ends up inside the primer or in some action designs is blown back into the bolt body. (The latter happens with ARs and similar with a floating firing pin and no firing pin retaining spring, also thin-cup primers aren't a great idea in such actions anyway, as there is a small risk of a slamfire caused by the pin's momentum as the bolt slams closed under spring power. This is why there are special military spec primers such as the CCI-41 for such rifles.) Cup thickness is as follows for US models 20 thou' ............ CCI-400; Rem 6 1/2 21 thou' ............ Winchester WSR 22.5 thou' ........ Federal 205 and 205M 25 thou' ........... CCI-450 and BR4; Rem 7 1/2 and 7 1/2BR European primers vary. The original Russian Murom / PMC SR primer (KVB-223) with the bright copper colour metal was very thin/soft and blanked easily. The last of the KVB-223s available here before the import ban on Russian stuff was sold as the 'SR Competition' and is sturdier, but can still be blanked with a not massively hot a load in the 223. (I sometimes wonder if this is a procurement or production QC issue rather than the design as it occurs randomly.) The KVB-5,56 and later KVB-223M are both tough primers, the former with a mild explosive pellet, the latter more powerful to cope with some modern ball type powders that need 'warmer' ignition. Fiocchi, PPU, and S&B seem fairly sturdy, but the S&B marque has both 'SR' and '5.56' versions, the 5.56 obviously made to a military spec. Can't comment on Ginex as never seen any, likewise the RUAG/RWS/GECO (same thing; different labels). However as Nitrochemie uses RWS in its 223 RS40/77 loads data with a max pressure over 58,000 psi, it must be robust. South American CBC Magtech 7 1/2s are as the identification number denotes, a 'magnum' type with a thick cup. IME, it's a tad 'softer' though than the equivalent Remington or CCI SRM / BRs, but is fine in most 223 bolt-actions, and the late 'Bradders' both sold them to his AR shooting customers, and used them himself in CSR loads. (Excellent primers and FAR better value than any US model if you come across any, but strangely they're not 'rated' by most British handloaders.) If you ever come across 20th century Vihtavuori primers in the old blue and orange packaging, these are the weakest of the weak and blank very easily indeed. (Viht is restarting primer production next year or maybe the year after as a result of the current western European security crisis allied to Finland's accession to NATO that sees it switching from LRP 7.62X39 to SRP 5.56 and one assumes that when its primers eventually reappear for sale to handloaders the SR versions will be 'tough' models.)

All LR primers have same thickness cups (0.027"). The cup differences only apply to SR and the reasons are historic, weak-cup models such as the CCI-400 and Rem 6 1/2 originally intended for the low-pressure .22 Hornet, .218 Bee and similar in less affluent times when many rifles chambered for such cartridges used the small centrefire Martini actions, modified rimfires etc. Whilst there is no apparent direct relationship between the name and explosive pellet formulation in the SRs, some LRMs have very different ingredients from the standard version (eg Fed 215 vs 210) and are often far more 'aggressive' (greater brisance) to handle very large powders charges, cope with extreme cold conditions, consistently ignite large charges of some ball powder grades.

A Guardian article apparently. https://www.thestalkingdirectory.co.uk/threads/the-guardian-on-the-gun-lobby.267236/

Yes, N140 and RS52 are fairly versatile (in common with nearly all tubular powders in that burn rate category), but it is more an issue of the three cartridges' case capacity to bore ratios, which are much closer than you might imagine. The usual way to measure / categorise the ratio is to use capacity as measured in grains water weight and available either by measuring yourself using a fired and unsized case with the spent primer still in situ, or an approximate value as supplied by QuickLOAD or GRT, and dividing it by the area of the bore in square inches. This is the primary determinant of the optimal powder for that cartridge, a secondary one being bullet weight. 308 ratio value is c. 750 (56gn water capacity divided by 0.075 sq in. bore area) 6BR runs at around 820 I can't be bothered looking up 22 Valkyrie's case capacity, but the slightly smaller 223 Rem runs at around 780 with my brass and rifle chamber, so is likely a tad over 800. These lie, in the nature of this metric, very close, so need similar powder characteristics, hence RS52 and N140 work very well in all of them. As examples of quite different cartridges, .30BR runs at 527 and 30-30WCF at 587, so use faster burners to suit a low ratio; 7mm Rem Mag and 7mmWSM are both at 1,300 and need much slower burning magnum rifle powders to optimise performance. That 1300 figure is traditionally also taken as the dividing line for a cartridge being a true over bore-capacity design. Anything much higher reduces efficiency in terms of return on each grain weight of powder employed as well as going from being a 'barrel-burner' to being a serious barrel-burner. It is not cartridge size per se that dictates powder needs. An easy way to see that is to look at a cartridge family based on a single case but necked up/down to different bore sizes and look at the powders advised in a reloading manual, and which produce the highest MVs. The most adapted design in current use is the 308 Win, since adopted in 6mm, 6.5mm, 7mm, .33 and .35 bores/bullets factory versions, and a few more wildcats too, but all 'same size' cartridges. 243 Win uses 'slower' powders than 308 Win which in turn uses 'slower' powders than .33 Federal for a typical bullet weight in each calibre.

I've used CBC's Magtech primers off and on in both rifle and pistol cartridges in both sizes for over 30 years. They work fine, are strong enough in their brass cups to avoid excessive cratering, blanking and suchlike. The 9 1/2 LR isn't an outstanding model for match ammunition, but neither is it the worst choice by far. http://www.targetshooter.co.uk/?p=1471 CBC is a major (Brazilian) company in both recreational and military ammunition markets. The USA used to see their stuff much more than us, but Viking Arms has been importing it for as long as I can remember, and that's who still supplies us with Magtech primers as well as cartridges. The primers have always been good value compared to the North American brands, but their biggest problem has been a lack of direct sailings from South America to Europe, and ships' masters have the final say on carrying explosives on any trip. Consignments of primers can therefore sit in a Sao Paolo warehouse for months after leaving the factory gate before they get a ride. Whilst the 9 1/2 is an OK but not exceptional performer IME, the SR 7 1/2, can be outstanding. I use it in my 'Light Gun' 6BR bench rifle ammunition and have had some excellent 600 yard groups. Its cup is a tad 'soft' compared to say the CCI-450. The late 'Bradders', AR-15 rifle builder and keen CSR competitor was a proponent of this model, sold them through his business Bradley Arms, and used them in his own very successful competition shooting.

It has a similar burn rate to VarGet. Whether it is a Great alternative to VarGet, well we'll have to see. It has an RRP of £70/lb I'm told and VarGet will be a very hard act to follow. Few if any ball-powder technology propellants have the flexibility of the best of the tubular/extruded types or give as consistent a performance in the very demanding roles of target and precision shooting. Military and hunting ammunition are very different uses and this type can often be better. Temperature stability, or lack of it, has been one of the types' Achilles heels and the General Dynamics St. Marks StaBALL range is claimed to finally overcome it, hence the StaBALL name. (Hodgdon now undertakes Winchester canister powders' bottling and distribution, as well as having used St. Marks products since its early days branded as Hodgdon Spherical grades - H335, BLC(2), H380, H414 Li'l Gun, CFE grades etc, etc. Hodgdon's marketing people are pushing the new St. Marks / Winchester powders like crazy at least partly in hope of transferring across some of the demand for their ADI 'Extreme' extruded grades that they have no hope of satisfying. StaBALL Match is being promoted as a VarGet replacement, and StaBALL 6.5 likewise but for H4350, another ADI product whose demand Hodgdon cannot satisfy.

You couldn't be further out here. It is manufactured by ADI (Australian Defence Industries) part of the multinational Thales engineering and defence French based multinational, in New South Wales, sold as ADI AR-2208 in the Antipodes, used in ADI manufactured rifle ammunition, and exported in bulk to the Hodgdon Powder Company in the US for the entire Americas, north and south, under the VarGet name. Far from manufacture having been stopped, the US market has been unable to get enough of the stuff for many years and American shooting forums regularly host posts saying words to the effect of "Varget is now in stock at .........." ADI will almost certainly eventually reformulate its extruded rifle propellants range to eliminate DNT, but there is no requirement to do this immediately as only the lunatics in the EU hierarchy have the desire to eliminate every potentially harmful substance in every chemical product. (Propellants and explosives are a tiny part of REACH which overall took 10 years of research, consultation among member states and drawing up/implemeting regulations sector by sector covering everything with chemicals from paint and washing-up detergents to herbicides, agricultural products and industrial chemicals (which is why RoseClear and suchlike don't work on your roses half as well as they used to). As an aside, the original official EU online explanation of Project REACH and its rationale and implementation listed these regulations being a plus for European chemical manufacturers as it would discourage imports and protect domestic manufacturers. That 'benefit' was removed from the website within weeks - I wonder why!

The GT's case capacity is much closer to that of the 6Dasher than the Creedmoor. I don't know what Hornady and Alpha production cases have ended up as, with pre production examples holding c.45gn water and reformed Lapua 6.5X47mm 43.4gn. George Gardiner of GAP and Alpha were looking to make production brass with the lower capacity value and a beefed-up case-head and web area. 6 Dasher is c.41gn and 6 Creedmoor c.51gn. So the 'Gay Tiger' will have a longer barrel life and significantly reduced recoil over the Creedmoor all other things being equal. The 6-6.5X47L wildcat lies between the GT and Creedmoor in this respect. The GT reportedly shoots very well, and also reportedly fulfils the prime objective of feeding 100% reliably from standard unmodified 308 magazines. With factory adoption, it should be a winner against the Dasher were the latter still in the position of being a wildcat that needed reforming and fire or hydro forming in the chamber. But, with good factory Dasher brass now (sometimes) available and 'fixes' to cure its onetime magazine feed issues, the GT benefits may no longer apply. Should Hornady's winning streak with introductions continue, the GT will almost certainly come out as the cheaper, easier option. But with the current turmoil in the US ammunition and components supply chain, who knows? Ironically, one of the BR/Dasher/6.5X47 etc 'pluses', (strong and efficient small primer brass) has been working against them with the acute shortage of Small Rifle primers in the USA, and the ludicrous prices some suppliers of the few around have demanded. The Creedmoors, 260 Rem etc with the option of Large Primer brass have had a significant advantage as a result which may or may not prove to be temporary. I've been attracted to the GT too, but I'd wait to see how the brass supply options and availability work out before spending serious money on a new build, or even a rebarrel. Also, nobody knows just how any newcomer will work out in competition terms until it's been around a while and the 'serious players' in any discipline have adopted (or rejected) it. How flexible is it in handloading recipes? With today's (and I'm 100% sure not at all short-lived) powder shortages and massive price hikes for some grades, a wide and tolerant appetite is a huge advantage. 15 or so years ago, the 6-6.6X47L wildcat was going to be the next big thing and there were prophesies it'd overtake the parent 6.5mm version. It didn't for various reasons. That story is repeated again and again. (6.5X47L itself was developed by Lapua to supplant the 6BR Norma in 300M ISSF 3-position shooting, and was a flop in this role in real life!) There are plenty of REACH-compliant alternatives to VarGet. I've tested some eight or nine for Target Shooter Online over the last couple of years with the results available free. With the GT's capacity to bore ratio value, Viht N150/550 will likely work very well, possibly N140/540 too.

https://www.opticswarehouse.co.uk/sightron-sii-36x42-sfp-brd-moa-non-ir-rifle-scope

No he won't. N135 is a low bulk density propellant and its performance is therefore severely limited in the 223 case with a 77gn HPBT such as the Sierra MK seated to 2.26" for magazine feed which I'd assume @John MHis using. Viht's max load of 22.5gn N135 with the 77gn SMK is becoming fairly heavily compressed. N140/540; RS50/52; Re15/Norma 203-B will give higher MVs at lower pressures than N135 in this combination. Viht developed N135 a long time ago specifically for the standard Lapua 7.62X51mm NATO ball round military load with 144-150gn short bearing surface and OAL FMJBT bullet.

Magazines are allowed in situ, but the rifle must be single-loaded in both disciplines in which case the mag acts as a platform. (This was the case for generations of Service Rifle and TR of course with the Enfield No.4 rifle.) If your rifle will feed a cartridge placed on top of the mag/feed lips, you don't have a problem. Certainly a well designed and fitting 'sled' helps if you go into BR seriously as quick, smooth loading is very desirable. If it's PSSA Diggle matches, you're looking at, magazine fed 'tactical' type rifle users have their own F sub-class, F-Military, which is heavily subscribed. (That makes four classes in these matches in the calendar - Target Rifle; F-Open; F/TR; F-Military.) F-Mil. F-Mil restrictions are: To clarify FTR, F open & Target Rifle are run generally in line with Bisley rules, the Diggle f Military rules are as follows :- 1. Any centre fire calibre can be used up to & including .338 2. There are no restrictions on the weight of the rifle used. 3. Folding Bipods (Harris style) must be capable of being deployed within 10 seconds & must be no wider than 8 inches when stowed. i.e. No fixed Bipods. 4. Back bags are to be of soft bean bag type. Bag riders & leather back bags are not permitted. 5. Muzzle devices i.e. Breaks & suppressors are optional. 6. Barrel tuners are not permitted. If you still want a sled, this outfit may be able to help. (I got one for a Howa Mini 1500 Oryx from them recently) https://riflemags.co.uk

Good question! In your shoes, I'd try both in this rifle (the HPS) and see how they shoot. You'll likely find the HPS rifle very short-throated, the chamber having been cut with one of the TR/Fullbore reamers such as the old 'Bisley 150' chamber or whatever its more modern equivalent is. In your rifle, I know having had Dolphin do several rebarrelings for me in various cartridges, Mik usually uses a minimum-freebore reamer, then 'throats' it as a second operation to suit the customer's intended bullet, so you'll likely find somewhat greater freebore. But again, you'll have to see. Returning to the pros & cons of the various bullets, the old 155 SMK is relatively low BC (0.214 average G7), but its great 'pro' is that it is an exceptionally stable design as speed drops into the trans, then subsonic speeds. That is another reason why it has been adopted by the NRA for its ammo given that many TR rifles in use will struggle to keep their bullets supersonic at 1,000 yards especially in colder weather conditions. The Scenar is higher BC, but interestingly, Bryan Litz gives two BCs for the design (Ballistic Performance of Rifle Bullets 3rd edition). The 'cooking' Scenar gets 0.236 average; the Scenar-L 0.221, not a great deal better than the antediluvian SMK. This puzzled me as I'd thought the 'L' was identical to the ordinary Scenar, except for a guaranteed improvement in production quality / consistency. However, according to Litz's bullet measurements / drawings, Lapua made some shape changes here, to nose and tail sections. IIRC, Lapua dropped the older 155gn plain-Scenar version some years ago, and they've all been the 'L' variety in this weight in recent times, so it depends what you actually have. (If both, don't mix them in an ammo lot 😀 !) Run them through the Berger Ballistics Solver and at 3,000 fps MV for Bisley on a 'standard' day (29.92 inches HG at sea level; 59-deg F air temp), you get at 1,000 yards (theoretically): Older SMK (0.214 BC): ............ 1,181 fps / 10.56 inches movement per 1 mph 90-deg wind change Scenar-L (0.221 BC) ................ 1,225 fps / 10.04 inches etc Scenar (0.236 BC) .................. 1,315 fps / 9.07 inches etc However, that's on the basis of perfect bullet stabilisation from the imparted rifling spin. Berger's Twist Rate Calculator predicts the Scenars will see a ~9% actual BC reduction with a 13-inch twist under the same external conditions at 3,000 fps MV to 0.215 for the Scenar and 0.202 for the Scenar-L. So the older Scenar has no BC benefit over the SMK, and the Scenar-L is actually worse. (The SMK is perfectly stabilised so retains its nominal 0.214.) So, theoretically anyway, irrespective of which design groups better at 1K in a 13-twist, the SMK sees no extra windage effect over the old Scenar, and outperforms the newer 'L' variant. Clever man though Bryan Litz is, this may all be b*ll*x in real life on Stickledown, Altcar, Diggle, and Blair, but the evidence suggests the old 155 SMK may be the better choice in your other half's rifle on a number of counts. If she ever tries the two models side by side at 1,000, I'd love to hear the results.

A 13 twist as on your wife's rifle is decidedly 'slow' for the 155gn Scenar which is an exceptionally long bullet for its weight. At a tad over 1.290" bullet OAL, it is the longest 308 bullet in its weight class by quite a margin. The Berger stability calculator gives it an Sg of 1.19 at 3,000 fps MV in standard ballistic conditions (1.5 optimal). Yes, I know people have long used 155 Scenars in 308 TR / Fullbore / Palma rifles with this twist rate, but performance can deteriorate markedly beyond 800 yards with this degree of spin. The 13 rate is ideal for the much shorter original 155gn SMK (#2155) which is one reason (and a very good reason too) why the NRA specified this bullet in its contract ammo. Your rifle's 11 twist rate is ideal for this bullet. I used to use N150 a lot with 155s in 308, as the combination often gives superb precision, but it's difficult to get enough of it into a Lapua case for 3,000 fps level MVs. I never tried N550 with this bullet weight, but suspect that (despite what Viht says in its powder descriptions) it is considerably slower burning than the single-based 150, and therefore won't develop full working pressures with the bullet weight. When talking single-shot competition rifles, top loads are often very heavily influenced by the chamber throat length the gunsmith gives it. TR and similar rifles are normally chambered with very short 'freebores' which reduce maximum charges, if nothing else because of the effect on physical powder capacity in the case. Always worth trying it though!

See how 25.0gn N540 performed for me in my F-Class rig with the 77gn Sierra MK http://www.targetshooter.co.uk/?p=3856

Again, I can't see how Viht gets its load in Lapua brass and the quoted 2.26" COAL with the 75 ELD-M. N135 is a lower density powder than N140. QuickLOAD (which is pretty accurate on fill-ratios) calculates 100% case-fill at just over 21gn in my Lapua cases (30.5gn water capacity fireformed). Using a reasonable length small-bore drop tube, you can pack around another 1gn into the case, but I just don't see how you'd ever achieve the quoted maximum of 24.4gn. The 75gn ELD-M is a long bullet with 0.55" inside the case when seated to that overall length. That sees 0.35" of bullet intruding into the powder space below the neck on this small and already constrained case. I loaded the cartridge up to 24.0gn N135 with the 77gn SMK (BUT that seated right out at 2.400-inch for the custom long-freebore chamber). That was both a heavily compressed and HOT load that gave over 3,000 fps in the 30-inch barrel. QuickLOAD calculated PMax of a hair under 60,000 psi to achieve the velocity I got with 24gn of this powder. I wouldn't load up to this level in my rifle despite the extra freebore never mind Viht's still higher figure.

The Viht N140 data include the compressed load notation. Id say it is - and how! I doubt if you'd get 26.2gn in a Lapua case with the 75 ELD-M at 2.260" COAL! There are two issues here. The first is a generic one over chamber form, specifically freebore and throat angle. US loading manuals (with the exception of Sierra's 'AR-15 Loads Data' invariably use the findings from industry-spec test barrels and and chambered to the very restrictive SAAMI specs with a mere 25 thou' freebore and a steep (short) leade. This creates way higher pressures than most people's factory rifle barrels, and even more so commonly found Wylde, 5.56 and even longer freebore chambers. Have a look in here: https://www.luckygunner.com/labs/5-56-vs-223/ As well as being an interesting read in itself, read the section on chambers specifically. Note in particular the author's words: .223 Remington ammunition is pressure tested in what is called a “SAAMI Minimum Spec” chamber – that is, a “worst case scenario” chamber in this regard, made to the smallest dimensions, which would result in the highest pressures with any given ammunition. In reality, the likelihood of encountering such a chamber outside a testing lab is incredibly small. Many .223 Remington chambers will see maximum chamber pressures which are several thousand pounds per square inch (PSI) lower than those seen in SAAMI test barrels. Hornady will undoubtedly use exactly such a SAAMI barrel and chamber. Viht as a CIP member will use that organisation's specs and the CIP pressure measuring method and ceilings which aren't directly comparable. (US companies are working to 55,000 psi MAP measured on the case-body mid point and CIP 62,366 psi on the case-neck (same methodology and pressure ceiling as NATO uses for the 5.56X45mm). So, there's a bit of apples and pears here. Case-fill levels aside, some of Viht's recent additions have been to my mind and experience 'dubious' to put it euphemistically. See: http://www.targetshooter.co.uk/?p=3856 with the 77gn SMK in Lapua brass (same as the Viht data). BUT note that my rifle uses a non-custom chamber with a very much longer freebore allowing a 2.400" 77gn SMK COAL (2.500-inch plus with the longer-nose ELD and its acetyl tip). Using QuickLOAD to model loads, it allows near 1gn higher charges than a standard SAAMI COAL and chamber. So my max 25.0gn N140 would be closer to 24.0gn in a standard barrel/chamber. QuickLOAD was right on the money with its predicted MV for my rifle's set-up and its 30-inch barrel at 2,996 fps predicted vs 3,007 fps actual from the 25gn N140, but says it produces ~59,000 psi in achieving it. Viht's 25.5gn for the Sierra 77gn TMK and 26.2gn N140 for the ELD therefore look 'dodgy' to put it mildly. However, I reckon handloaders are pretty safe as I don't believe you'd manage to get those weights of powder into the case anyway, and certainly not seat a bullet to magazine length in most rifles.

I think that's listed here too, Vince. https://ukvarminting.com/topic/58763-savage-mod-12-ftr-308-barrel-for-sale/#comment-424484 but @GunnerOne has sent a PM to the OP, so it may have already gone.