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About Laurie

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  • Birthday 10/05/1949

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    F-Class, BR, and any form of target shooting that involves a scoped rifle, but doesn't require shooting offhand

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  1. Hmmmm .......!! Your load is 3.6gn above Viht's maximum, a full 10%. Viht data can be conservative, particularly for N140 in 308 Win, but I'd be loathe to advise people to simply assume that must also apply to the Creedmoor. Just be aware that the Lapua small primer 6.5X47/308 Palma/6BR/ 6.5 Creedmoor case-head rarely shows any signs of excessive pressure until it reaches blown-primer level, and that's likely on the wrong side of 70,000 psi. QuickLOAD suggests your load is OK in fact - but to be honest I simply don't trust the program for the various smaller 6.5s for various reasons. However, it also says that whilst pressures are OK, they'll only produce 2,647 fps from a 24-inch barrel. To get the 139 up to 2,800 fps takes a tad over 67,000 psi with this powder. That might or might not be so, but it wouldn't surprise me overmuch. Use of 65,000 psi + handloads is pretty common with this group of small primer cases, but there are no free lunches and sometimes things that are OK can suddenly stop being so in this situation. (That's exactly what I found with the 6.5X47L and the 123gn Scenar and N150.)
  2. Head Space Head Ache

    A 'comparator' bushing is NOT a headspace gauge! As the name suggests, it is for comparing a resized case to one that is fireformed and therefore (more or less) matches the chamber. IME experience, the diameters of the Stoney-Point / Hornady case and bullet bushings sometimes vary considerably from each other of the same nominal size / calibre, so much so that if you have more than one example of a calibre bullet comparator bushing, you have to mark them and ensure you use the same one each time for a particular job. The idea is to ideally start with new brass in your rifle which as the Gun Pimp says usually has a little too much clearance. (Not always though - the Stalking Directory forum has more than a few complaints of factory PPU ammunition giving tight chambering through a small amount of negative headspace, usually in 243 Win and often in T3s.) After firing, the comparator is used to get a reading on the case shoulder (or properly, several case shoulders) as you've done - then it is used to set the sizer die up in the press so that the shoulder is 'bumped' back 0.001-0.002" for a conventional turnbolt bolt-action rifle. If this (measurement plus die setting) is done correctly, the case will fit the chamber easily but incur minimum case-body stretch on firing. You need to find out why the round won't fit your chamber and sort it. Headspace is one of several possible causes and isn't guaranteed to be the culprit. You don't say for instance whether it is a case previously fired in another rifle - sometimes you cannot full-length size a case fired in a slack chamber down to fit that of a tightly chambered job, but it can be over-long COAL and other problems. A sticking case leaves witness marks on the brass or bullet - where are they on your cartridge that won't chamber?
  3. Viht N150, N550, and N160 will all work with this combination (6.5 Creedmoor + 136-143gn bullets). I had excellent results (small groups and ES) with N160 in Norma (large primer) brass with the old low BC and budget Nosler 140gn Custom Competition HPBT, but MVs are lower than with H4350/IMR-4451. 4451 worked well too and in my rifle needed slightly higher charges than H4350 for the same MVs. (Given the ongoing H4350 shortages in the USA, IMR-4451 has become a favourite stand-in for H4350 and many US Creedmoor shooters whether match shooters or deerhunters have switched to it full-time having become fed up with continual H4350 shortages. The PRS Blog people did a side by side test a while back and found it's more temperature affected than H4350 and generally the top PRS competitors using 6 and 6.5 Creedmoor have stuck with H4350 just making sure they buy large amounts at whatever price is demanded.) I've not tried N150/550 in the Creedmoor, but I would expect N550 to be very well matched and give high MVs, albeit at the expense of barrel life if loaded up to the limit. N150 is a little on the fast-burning side and (like N160) has a considerably lower energy content than H4350, IMR-4451, or RS60/62, so again MVs will be at best adequate. Note that whilst Viht provides loads data for the powder with the 139gn Scenar, the MVs are well down on N160 and even more so N550. http://www.vihtavuori.com/en/reloading-data/rifle-reloading/6-5-creedmoor.html (Note too that Viht load data is for the Lapua small primer case, and while I have no way of knowing how hot or conservative the company's maximum loads are, they may be too high pressure for some makes of large primer Creedmoor brass given that the small primer and 1.5mm flash-hole reduce pressures considerably in most cartridges compared to LR primers and 2mm flash-holes.) I've also found a tendency for N150 to produce a pressure spike if you go a little too far in the small / mid-size 6.5s, so if you use it be careful as you approach maximum listed loads with small charge weight increases especially in large primer brass. Note too there are quite large discrepancies between Creedmoor case capacities which affect pressures - Hornady cases (very variable in themselves between production lots) have greater capacity than Norma, and I would expect (but can't confirm) Lapua. The new Lapua small primer case is not only very strong, but the small primer and flash-hole set-up reduce the pressures produced from any given charge weight, and maximum loads would therefore tend to be higher. Unfortunately, recent loads data-sets from US sources have little or no use of Viht powders. I understand that use of the powders has dropped off a lot 'over there' due to a combination of poor supplies in many states and compared to IMR/Hodgdon high prices - the exact opposite of our situation. So Lyman, Hornady and Sierra have no Viht powder options in their recently produced and issued 6.5 Creedmoor data. With Lapua having bought into the USA in a big way recently - buying Berger Bullets and it has set up a new wholly owned US distribution company called Capstone Precision Group commissioning a new large purpose-built distribution centre for all Nammo brands at Capstone, Missouri which went live at the end of 2017. So, this situation may improve in the future. (A bit of a minefield here!)
  4. IMR-4451 has been available here for nearly two years now and is a standard Edgar Brothers product line, so order through any gunshop that does the Hodgdon / IMR range. It's not a version of H4350 as it is manufactured by a different company (General Dynamics v Thales / ADI), in a different continent even (Canada as opposed to Australia). It is a very good alternative to IMR and H4350. It is mildly high-energy (as seems to be common amongst recent introductions), is less temperature affected than IMR-4350 but more so than H4350, and has an anti copper fouling additive. It is short-cut so suits mechanical powder measures very well. Also consider Reload Swiss RS62, a very stable single-based tubular product which also does the same job as the 4350s and 4451, but which is longer grained than H4350/IMR-4451. Hodgdon doesn't have data for 77s in 22-250 (nobody does I should think), but does for the 70gn Speer SP on its online database for both H4350 and IMR-4451 letting you see how they behave in relative terms for a heavy bullet http://www.hodgdonreloading.com/data/rifle IME, having compared many Hodgdon loads for the pair, 4451 maxima bracket H4350 depending on cartridge, some m marginally lower, some marginally higher. .22-250 with the 70gn Speer is one of those with both powders given a 34.0gn starting load, but 4451 given a maximum of 37.5gn against H4350's 36.0gn, but this is reversed for the 60gn Hornady VMax, but that may be due to compressed charges and how much the case will hold for this pair.
  5. Humane Dispatch Pistols Sect (5) ?

    They are S5 from an import, distribution and sale point of view, but are bought and owned by the deerstalking (or other) purchaser on a normal S1 variation. (Yes !!!! explain any logic in this.) What that means is that the buyer having got his / her variation can only buy the revolver from an S5 dealer face to face. If you don't have an S5 dealer near you, you have to travel to the seller's premises. (I saw a case some years back where the buyer lived north of Aberdeen and the vendor was York Guns Ltd with the little Bond Arms 2-chamber 'Derringer' type pistols that YGL imported and sold for humane despatch - the buyer had to travel down specially to buy it.) If transported to another S5 dealer to make a transaction nearer you, this has to be under very onerous (hence expensive) S5 carriage arrangements on top of the dealer's fee. I assume that where it is a private sale from an S1 holder to another with an S1 variation, this is OK not needing an S5 RFD involved - but I'll wait for advice on that one given the nature of the legislation / guidance in this dog's breakfast. Most forces put other restrictions on the use and nature of firearm too - a common one at one time was four out of six chambers permanently blocked off in a revolver. There were some legal challenges to this some years back, so I'm not sure if this is as common as it once was. It has recently been said on other forums that semi-auto pistols with restricted capacity magazines are about to be regulated out of their current acceptable S5/S1 status too becoming S5 permanently, so who knows on that one.
  6. 6BRA

    ".......... inside an inch at 300yds" which we'll take as the absolute maximum to achieve that (0.99") equates to 0.315-MOA for the centre to centre dispersion. (MOA here is the key unit - as in all ballistics calculations.) So, one assumes that as you've not actually shot any sub one-inch groups at this distance that you're looking for 0.33-inch groups at 100 yard groups, still 0.315-MOA. Easey-peasey, we can all shoot just under third of an inch groups at 100 (now what's that common shooting forum phrase? ah, yes .........) all day long. Actually, consistently shooting groups that average 0.33" at 100, isn't as easy as many believe. ........ and we're talking five round groups. If we're shooting 3-round 0.33" groups, statistical analysis says that you have to multiply the group size by 1.28 to get the equivalent value for five shots, reducing that 0.33" to 0.27" if it's only a threesome. BUT .......... shooting a 0.315-MOA group at 100, or 300, yards doesn't equate to the same performance in MOA at other distances. Dispersion tends to change in a true linear manner according to distance in identical external conditions. The amount has been calculated as being 0.023-MOA per 100 yards change in the shooting distance. So, to achieve the equivalent of shooting 0.99" at 300 (0.315-MOA), one has to achieve 0.315 minus 0.046 = 0.269-MOA at 100. 0.269-MOA = 0.281 inches at 100, doable with a very high quality rifle / ammunition combination but actually getting pretty hard to achieve serially averaging several groups. It's marginally better than many top F-Class shooters actually achieve with their custom kit in load development. The Gun Pimp says that under an inch at 300 is 'usually competitive' at 1,000. Using the 0.023-MOA / 100 yards formula, we get 0.315 + (7 X 0.023) = 0.476-MOA at 1,000. As 1,000 yards is 10.46-MOA, actual estimated group size is therefore 0.476 X 10.46 = 4.98 inches centre to centre, or just under 5 inches. And that's certainly where starting to be competitive comes in - the number of sub 5-inch groups shot over the UKBRA 6-match 1,000 yard annual series at Diggle is actually rather small. However, that just under 5-inches figure is without the effect of the notorious Diggle wind changes, not to mention the occasional bit of mirage upsetting aiming, not to mention small amounts of barrel heat produced mirage that can inject vertical even without the shooter seeing a visible mirage through the scope. That's why there aren't that many sub 5-inch groups shot there, so the 'under an inch at 300' is just a useful rule of thumb to know you have something that mechanically might be competitive, but shooter skill, experience and let's be honest luck too come into the equation, not to mention what Atlantic weather systems give you on the day. On some days, anything significantly under 10-inches is good. Mentioning luck, plain old luck is a factor, BUT luck never, ever runs over the course of shooting four groups - I know that from bitter experience!!) So where do these various factors I've quoted come from? Modern Advancements in Long range Shooting Volume II by Bryan LItz and they are based on analysis of very large numbers of groups fired in competition on US ranges as well as Applied Ballistics LLC's own range tests. As Bryan Litz explains there is no such thing as 100% consistently balanced and identical bullets short of machining each and every example to CNC machine standards from very high grade billets - and the greater the distance, the greater the small but significant inbuilt dispersion even with the best of today's off the shelf match bullets.
  7. I'm 100% sure that is the case. Also, it's interesting how it is military pressure that is driving advances in propellant R&D and manufacture towards so-called 'copper eraser' types, presumably to allow rough, nearly shot out barrels to keep going under adverse conditions. Or ... maybe to cope better with barrels that are internally 'rough' from new?
  8. 6BRA

    Yes Al and Les, strong and variable winds at Diggle always inject verticals, bad enough when it's a westerly / south-westerly up the range but much worse when it's a north-easterly coming down the re-entry above and to the left of the butts (as forecast for this weekend). Blair Atholl is also well known for this issue with some conditions (blown right = blown low too; blown left = POI left + high), but at least it is almost predictable there. I tried for many a year (in F-Class) at Diggle to compensate for this factor aiming high or low alongside the windage change as appropriate, but gave it up as a bad job in the end. For every time that I got it right, there was at least one occasion where the high/low aimed shot went exactly to the aimed elevation even though the anticipated lateral windage element had appeared. In the end, I came to the conclusion that the least bad solution was a rifle/load holding very good verticals and just worry about the windage alone, as always keeping an eye (on the plotting sheet) for elevation drift in the course of the match and allowing for that as needed. There are obviously very strange effects at work in the Diggle Ranges valley - air movements appear to bounce around the valley sides and the sheer hillside behind the butts. Even on apparently dead still days with no mirage, rogue elevations appear - I've seen this on a couple of occasions when the range is hosting GB F-Class Association national league rounds with many of Europe's best long-range competition shooters in play at 1,000 yards - scores that one would expect to be 100 with maybe 18 or 19 V-Bulls for the top few end up as 98s and 99s with 10 to 15 V's, the dropped points and moves out of the V usually down to elevation variations. Watching from behind the firing line and scanning along the targets with binos, this often shows as a pattern with every shot being slightly high or low as targets are pulled and marked over just two or three minutes. This leaves the shooter who has just leaked into the 4-ring at 12 o'clock say with a problem as to what to do on the subsequent shot - ignoring the poor one is usually the best course (but this isn't guaranteed).
  9. Powder for 243 107gr SMK

    There aren't any home-based 'go to loads' as so few people in the UK use the 243 with a fast-twist barrel and 105gn + bullets for range use. If you're not worried about barrel life, Reload Swiss RS70 and Viht N560 will give very high MVs, over 3,100 fps at max loads. N165 is a much cooler burning powder, but will likely cost you 150 fps or so. Of the remaining 'US powders', post-Reach, the new IMR-7977magnum powder looks a very good choice and is in the UK now. IMR-4955 is a 4831 equivalent and should arrive here soon and there is a new super-slow magnum grade 8133 just announced which we won't see until at least 2019 I'd think. Hodgdon has loads for the trio and the 107gn SMK on its menu driven online reloading center. Alliant Re22 should be suitable too and is Reach compliant, but again may be rather hard on barrels if run 'hot'.
  10. Loads for 300 RSAUM

    Bullet weights?
  11. You have your targets handed back to you at the end of the day too, so you have no doubt as to just how your rifle shot, whether the loads held elevation well etc. (After shooting each group, the butts crew also mark and briefly display the extreme shots so you have an ongoing idea of how well - or badly - you're doing as you go along.)
  12. Hornaday eld match bullets

    Yes, but not by as much as was previously believed and disseminated in Litz's early editions of Applied Ballistics for Long Range Shooting where a range of potential improvement of 3 to 7% was quoted. (Degree of meplat diameter reduction allied to calibre with small calibres gaining the most.) Bryan Litz's book Ballistic Performance of Rifle Bullets has just been republished in its much expanded 3rd edition (around 950 bullet models now covered in all calibres from .17 to .510" bar 7.7mm (.303) and 8mm), and interestingly it has some models in their old unpointed form retested in new and shiny 'pointed' versions side by side. This has turned out to be interesting in two unrelated ways. First, you cannot always do a simple side by side comparison for Sierra MatchKings for pointing alone. It becomes apparent when you look at the bullet drawings and dimensions that Sierra has taken the opportunity to indulge in some basic redesign work while at it, so there is more to what causes measurement changes than 'pointing 'alone. (The same applies to the Sierra TMKs in some cases. Some such as the 168 and 175gn .308 TMKs are completely new designs and will behave very differently in the chamber / barrel as well as in their external ballistics to their still available blunt tangent ogive SMK predecessors. Some such as the 6mm 95gn SMK and TMK share an identical form bar the tip.) So one has to find examples where the basics are unchanged leaving just pointing. One such is the 0.224" 90gn SMK where the original's 0.062" dia. meplat has been reduced to a most impressive 0.045". (Few home 'pointers' can get down to that size.) The drag related G7 Form Factor has reduced from 0.999 to 0.991 which in turn increases the average G7 BC from 0.257 to 0.259, an increase that's not going to be noticeable on the range. Bearing in mind that Litz says there is a one or two percent error tolerance in his methodology, that could mean that in real life there might be a small BC increase to a nil increase or even a reduction depending on which way the parameters worked here. Litz looks at bullet tip trimming and pointing both separately and in concert as a section in Modern Advancements in Long Range Shooting Vol. II and BC benefits range from nil to at most 3% in BC terms IIRC, although there may be benefits in reducing BC variations between individual bullets giving better elevation consistency at long ranges. As I said, the other interesting feature to come out is that of a bit of quiet redesign of some models. The antediluvian 0.224" 80gn SMK in its new 'pointed' form is not otherwise identical to its older unpointed cousin. About the only things that remains the same are bullet OAL and the 9-deg tail angle, with minor but useful changes / improvements to shank length and nose shape it having a slightly longer radius 'pointier' front end so its form factor reduces from 1.030 to 0.968 and BC increases from 0.221 to 0.235, a useful 6+% improvement. This is achieved at the expense of a 'sharper' transition from parallel shank to nose sections changing it from a true tangent design to one that will be a bit fussier re its position to the lands. So, if you take the new model and simply load it as per the older version, the results will likely change and more likely for the worse at that.
  13. 6BRA

    Most bipods are far inferior to a front-rest for shooting off a bench though. The wider F-Class bipods are actually wider than the benches and don't fit. Any reasonably wide bipod moves you over to a central position behind the bench and away from the correct / natural seated position in the rear cut-out section. That's not to say it can't be done and there have been many good groups shot off bipods at Diggle, but it does make life harder than it need be or ideally would be - a self-imposed handicap. Depending on what you have in mind rifle wise remember weights too. F-Open allows up to 22lb all-in weight (including any bipod used) and this takes you into HG Benchrest class. Until the Lenton family, Bald Headed Geordie, and Big Al started using real 'Heavy Guns', this was what most HG competitors used, an F/O rifle. A typical F/O rifle chambered for effective cartridges in that discipline such as the 284 now struggles against 6BRs, Dashers etc in proper 40lb + HGs. Good fun and it tells you how well your F-Class rifle and ammunition really perform when the conditions are mellow, but these rifles move about on the bench too much under recoil and that slows down your rate of fire and also makes it harder to stay on the required pinpoint precision aim. (That is the primary purpose of having a truly heavy rifle. Whilst a small part of the extra mass is about the final bit of enhancement of the precision potential, most of it is there to have gravity tie the rifle down to the bench as much as possible.) Conversely, keeping to Light Gun (17lb) restricts the utility of the rifle in F-Class unless you're planning on a light, short-barrel piece chambered for a light recoiling 6 or 6.5mm cartridge for mid-range matches. I prefer a bipod these days to a front-rest for F-Open for all cartridges not just light recoiling numbers. When I say 'bipod' though, I mean really wide footprint and stable numbers of 2/3 metre or so, the main trio being the Tier-One 'Carbon', Dolphin AB, and Shooting Shed 'Stotteben' - all unsuitable for Diggle's benches. To get around that and have a front-rest friendly 3-inch wide forend you can have a recessed Anshutz accessory rail inletted into the forend bottom, or do what I do with my dual-use F/O and BR HG rigs - have them built in a Dolphin or other modular stock and switch between F/O and F/TR forends as required depending on the competition.
  14. Have a look at the copy of the two pages from an old 'American Rifleman' (the US NRA magazine) on bullet diameter effects on barrel life and precision (group sizes) using the 7.62X54R with loads just under 40,000 psi. The barrel life is stupendous! (14,000 rounds before groups start to enlarge and a total usable life of 23,000 rounds.) http://forum.accurateshooter.com/threads/243-barrel-life.3934900/page-2 (Scroll down to Post #38 with the embedded pages) The Gun Pimp and I discussed this afterwards. I'd ascribed most of the barrel longevity to low pressure / heat effects and presumably a cool burning propellant, but Vince points out how hard a good chrome moly barrel is too and doubts that our modern soft 416 grade 'stainless' barrels would last anything like as long even with these loads.
  15. 6BRA

    These classifications apply to mid/long-range BR only. There is a third type/class we don't see here for 'rail guns', ie return to battery types which only bear a passing resemblance to a conventional rifle. For 100/200 yard BR (100 only in the UK, there not being any suitable 200 yard ranges in use to date), a completely different and much more restrictive set of equipment rules apply, and then it depends which of the US BR governing bodies' rules are used. I think we (UKBRA) use IBS rules, but mole-e30 or The Gun Pimp can quote chapter and verse here. In this case, the three classes are Light and Heavy Varmint (as per US / international rules) and then there is a home-grown sporter class as an entry class for non PPC BR custom rifle owners. As in L-R BR competitors aren't restricted to any one cartridge or limited range of cartridges, but the 6PPC in its many variants is almost universally used in the two 'Varmint' categories as nobody has devised a 'better mousetrap' yet.

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