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About gbal

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  • Birthday 09/24/1943

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  1. Viht 133-probably the most popular informed choice of powder from the shooters who really do put accuracy first (100&200 yard Bench Rest). gbal
  2. gbal

    223 52gr Amax and 223 50gr vmax

    SAAMI spec brass case length for the 223 Rem cartridge is 1.760 inches. Cartridfge Over Alll Length (COAL) doesn't tell you much-though it has to be longer than your magazine size,if you want to use the magazine.Cartridge Base To Ogive is more informative wrt 'bullet jump'/seating depth,and is a superior measure anyway-bullets simply vary in length (but much less in ogive) from the same box. Read Bryan Litz (Chief Ballistician at Berger Bullets) article comparing COAL and CBTO (on Brger Bullets site).OF course,for. A given COAL/CBTO that is a measure in that rifle-other chambers and throats especially may well differ-and indeed it's common to 'chase the lands'-ie load bullet further out (COAL longer) as the throat erodes,to maintain the same bullet jump to the start of the (now eroder ) rifling. Any given COAL can only be a very general guide for your rifle-and you need to get a comparator (have a look at the Hornady/Sinclair one,with special threaded cartridge case) and measure your "COAL" for your rifle and bullet,and seat the bullet to the desired CBTO. Someone else's measures for their gear (powder included) isn't a measure of your gear(and for powder,may give higher/unsafe pressures-check the. Book maximum,and don't exceed that-and work up to it in small steps-maybe .2g).It'sall really individual to your set up-as are the measurements-you and your comparator 'compare' but do not neccessarily give absolute/everyone agrees measures-the precision of the measure tool,and the users' sensitivity come into -"just touching the lands" depends in part on finger sensitivity-your fingers may not be identical to someone else's,and that can vary seating depth readings by a few thou, for the same loaded round. Note too,seating depth changes pressure,as it changes the 'space' in the case the powder has to expand into initially-so be aware around max charges-and of course,different ( 223) brass has differnt total capacity (measured by volume of water) due to brass thickness etc.Do not 'cram' ( copress) powder into your cases to get to someone else's alleged 'safe' load. The /max'book values are what they are for a reason-safety.Another 50 fps MV won't transform your rifles performance (more likely reduce accuracy) so don't be tempted to over max velocity. The 223 isn't a long range cartridge,but is just fine to mid range (say 500y) at sub max powder/bullet loadings,and you may score reasonably with it,on mid size targets/gongs etc.Heavier bullets will do better,but your (slow?) rifling twist may not be suitable for them contrasted with the 52/53g Hornadys you mention.V133 should be a good powder-go for accuracy,not velocity.....a miss at any warp speed is still a miss! gbal
  3. The more competitive the competition,and thecloserthe distance gets to 1000y,the more the balance swings to the better 7mm cartridges. For club/pure enjoyment/ reactive gongs.....and sub 750y informal shooting, with multiple shots,the best of the 6.5s are probably easier to shoot enjoyably. Ballistics balanced against recoil. In a heavy rifle (20lb), it's close,between my two -7Shehane and 6.5x55 Ackley....but goes as above...chips down,Shehane. gbal
  4. You could add in the Berger 180VLD,and more tolerant 180 Hybrid especially. BC of course changes drop and drift-ony you can decide if differnces matter- there are no comparable data for Shehane-as it's a wildcat etc,but soma SAAMI 7rem mag data will give a good idea of drop/drift at sightly lower than Shehane mvs(about 75 fps):these are all at 800y, but will hold pro rata at your prefered 600 and 9ooy,closely enough to give a fair idea of BC&MV 206/effects in a 7mm (10 mph wind),and 175g (hunting) bullets drop/drift in inches: 7RemMag:Fed 175 g Trophy bonded BC .407 @2860 mv. 206/72 Fed 175 Hi Shok. Soft Point. BC .428 @2860. 181/64 Rem 175 Core LOkt SP BC .428@ 2860 181/64 Win 175 PowrLokt PSP. BC .428@ 2860 181/64 Nosler 175 Part BC .519 @ 2800. 168/51 Increasing velocity and BC effects: ((7mmRem UltraMag. Rem 175 Swift BC .548@3025. 137/42 Weatherby 7Mag 175 SP BC.462@3070. 146/46 gbal
  5. 7rem mag 175g BC .428 @2860fps 200 zero;Fed/Rem/Win hunting bullets/SAAMI loads,all quote 1000y drop of 354 inches. Just for comparison,175g BC .519 Nosler @2800fps,drop at 1000y is 318 inches. With a 100y zero,drop would be a bit more,of course.Ditto lower BC or MV. Norma 150g BC .537 @3166 200y zero comes in 234 inches lowat 1000y Fed 150g SGK BC .435 @3110fps is 286inches low at 1000y. 7STW 140 Nos BT BC .485 @3300fps...200zero....at 1000y is 228 inches low 7STW 160 Sierra BT BC .622 @3250.......1000y 202 inches low Lazzeroni 7MM 140g Nos Part BC.560 @ 3750fps ........1000y 168 inches low. 7RSAUM 160g Nos Part BC .475 @2850 ..327";160gBC.531 @2850 ...300" gbal
  6. How much elevation do you think the 'howlin' wind caused....wind drift,yes...and there will be some elevation too- but there are several factors that differentiate the gear too......would the vertical component of a cross wind be the big factor-and if so,how could your 7 Rem Mag cope less well?The AICS stock is probably a lot less important than the 284 win ballistics-which we don't know.....and March 8-80 scope is way better for the application,as is the Nesika action and probably the barrel-you don't give your rifle specs on these important factors. Maybe the shooter read the wind better-that can't be bought,but the superior equipment otherwise can be duplicated,maybe even improved on. Maybe a howlin wind isn't the best test... and a one off is always a limited reason to throw money at a perceived shortcoming. Consider,It might be a Shehane next time. gbal
  7. Canine precision match chamberings (PPC sired) include the following. Waldog and Talldog. The Velo Dog is obsolete and definitely not PPC,nor KC,nor PC. The 22 CHeetah,of course,is quite properly a Wildcat,While the 9.53 Hellcat is legitimately well bred proprietary Lazzeroni -who also ofers a veritable aviary: 6.71 Blackbird;7.21Firebird;7.82 Warbird,9.09 Eagle;;7.21 Firehawk; but the 7.21 Tomahawk continues the long tradition of classification challenges,and could well be with the 6.17 Spitfire; 6.17 Flash;2; 6.53 Scramjet; 450 Assegai; and 12.04 Bibamufu-the serious human artifacts range. There are Whispers of others,as well as one off Mavericks (10.7),and the 300 Pegasus and 8.59 Titan are not mythical. The 577 Tyrannosaur isn't extinct,so has it's own place as alpha predator tool. The sky is not the limit,either....8.59 Galaxy; 9.53 Saturn; and 10.57 Meteor. gbal
  8. gbal

    Diggle Benchrest Success

    Nick,I think Al has already given a summary answer. Once a 'barrel has gone'-and that means different things,depending on your precision criteria,then it can only be restored (a bit) if the reason for it's decline is removed/reduced. Crown damage can be effectively dealt with,by a recrown.If it's close to muzzle rifling damage,the barrel can be corrrespondingly shortened and recrowned. But most of the damage is at the chamber end-and is unavoidable -very hot gassesunder pressure (crown damage is typically clumsy cleaning etc)Even so,it can be mitigated by cutting back a few inches and rechambering (a more expensive proceedure). That may well give some extended and acceptable barrel life-but at 25 + ? MV fps lost per inch removed ,it will also mean losing 100fps minimum MV,and that is quite a price to pay in competitive long range target shooting,even if precision were restored (no guarantee).Of course,if you start with a longer barrel,you might have some inches to play with. It may be more tempting for a varminter,as absolute precision must haves are a bit less demanding and ranges less extreme.but how do you cost out a "miss" -at any level-bearing very much in mind that relatively fine differences in precision of the rig/ammo may not be the weakest link as distance increases. gbal
  9. gbal

    Scope Calibration

    Some indivudually brief comments: Bradders -scope calibration is a precision issue,you don't have to readit oreven worry about it-good luck with your Precision (22rf?) Rifle ideas..."if I can get it off the ground"- one good way to get any rifle (except a black one-concession,not confrontation) ) off the ground,is to use a bipod (look it up). Chanonry,yes thanks for that-of course it is-as I suggested 'theoretical' was a weasel word for Matt to use (my quote of Yogi was just an attempt to lighten the discussion up a bit). Terry, I think more or less on the same page-and especially wrt to your reply to Avian-all these alleged potential misleading errorsare likely removed prior to a competent shooter doing the firing test. (And see below for some detail). Gluv...well, read on a bit.... OK. NO-one has actually given areplicable account of how a non firing scope calibration test would be done. I think it's possible-subject to what follows-but liable to human error (it would take an optomatrist to clarify,let alone measure such error. I see the rifle with bubble clamped frirmly,and aimed at some horizontal mark on the paper at a measured distance away (100y- if you prefer,in all of this,substitute metres/mils etc-the principles and proceeduresarethe same).There willl have to be a clear bottom horizontal for the scope crosshair to be aligned with - easy enough. Clicksarethen wound on upwards...lets say 20 moa worth as per scope makers claims...and the cross hairs now aligned with....ah what- a set of very recisely scribed horizontals ? Around the 20 moa elevation area (let say 20-22 inches-but how thick are these lines-they will have to be clearly visible and discerniblefrom each other(acuity) and sufficiently thin seperable to allow fine alignment ( 5% error is unacceptable,so maybe 2% needed to pass the scope as useable.See below what that means,but i'd take 1moa as about an inch at 100y,so .1 means lines separated by only .1 inch....I just don't know if such would be visible enough(or what magnification would do it-quite high,i'd think.)If so,then the proceedure has limited application to only such scopes.Perhaps someone could obligewith specifics,as I am no expert on visual acuity so assessed. All this done,of course,the actual vertical produced by the known clicks can be measured,as in the TT test,with similar accuracy of measurement. A wind on of windage (say 10 moa) for both methods allows the windage calibration-not neccessarily the same as vertical...but of course in the optical no fire it will need some very accurate vertical lines about 9-12 inches to the side.Fire TT just needs a shot/group-no need for lines. OK,please let's have the details of the optical method,dealing with acuity etc .Itseems in principle doable-though I've never seen/reado it being done. The basic box test is often done and reported,including by UKV members who test scpes. Basic :fire a shot,click up say 20 moa,fire again,click 20 right (orL) fire a shot,click down 20 moa,fire a shot,and click left (or R) lef 20 and fire a shot-a good tracing scope should allow the first and last shotsto be touching/overlapping.Measuring just what is the actual distance between appropriate shots gives some measure for calibration. O course,groups could be shot. But this raises the issue of rig (rifle and ammo precision,and shooter 'accuracy'....indeed,several have raised this issue...but consider: A decent Bench Rest rig will shoot .25 at 100y,as an aggregate for 25 shots,in standard Diggle conditions (some wind). THe larger component of what is a small dispersion is horizontal(wind induced) but there may be some vertical errorfrom all the alleged raft of possibles.Lets say .1 moa,and that is under less than very good conditions.I hope it's clear that testing for scope calibrationneeds very good conditions. So all the alleged errors wil not exceed .1moa. ( accepted some shootersanr rigs not that consistent-but then such will not do any test so well,and moreover,their real shooting will be confounded by far more error sourcesthan small scope issues). So we have a shooter error under .1 moa....nothing is going to be perfect (I'm not sure human eyes are that acute for the optical non fire version) a .1 moa shooter error seemsacceptable in a test wich would be higjly successful with a 25 calibration error. 5% is too much (with 30 moa up for 1000y shooting,5% error is 1.5moa,about 15 inches (and too much?) but 1% error is only 3 inches-about as good as one might hope for (perfection being zero inches). OK,the thrust of all this is that the TAll Target live fire test is NOT prone to unacceptable erorof the sort alleged.I doubt that the optical would be either,though differnt issues might arise. Tall test is both fuly specified and fit for purpose . Checking vertical tracink is a nice bonus (though a less likely mechanical error,hard to otherwise diagnose (as wind blows to the sides too in real field/comp shooting). Sorry,all this should already be adequate,but LItz eg is in it's third edition,since 2015 publication-I have never seen any criticism of the Tall Test methodology.The box test is similar enough,and has been in use longer-again,never seen any criticism.No criticism does not mean immune,just that so far,no-one has in any public way. If there are viable alternatives,preferably as human error free,and as practicable-hooray- I'm all for several measures (if they correlate highly,as they must,if valid)-just as several dictionaries can help with labels.I'll stick with LItz,but it matters not-the concepts do,and for he is the clearest theoretically,and useful /pragmatic ,and is explicit about each.He also shoots very well,especially at very long range,where all this really matters. One "refinement",I buy into the clear distinction between precision (engineering of the rifle and ammo) and accuracy (what the shooter' skill brings to hitting the target)-ignoring/confusing this is a major source of profound mischief,but I'd see ancilliaries ( rests,triggers and especially scopes here) as engineered hardware that enables the skilled shooter to bring out more such precision in actual accurate performances. Sorry it's so long- Saturday indulgence. There is more in Litz (pp432) for them as wants to know,though that includeds maths and equations-absolutely a virtue where valid (as on 431 pages;-at a pinch I'll add the dedication one that says ..."and 2+2 is always 4", because were it otherwise, we'd be in big trouble,up that famous creek,without a bipod ....or 'heaven' as Bradders would construe it. Your choice,but remember it's a hobby,whether done well,or modally.... :-) gbal
  10. gbal

    Scope Calibration

    OK,Matt-won't the zero ing check (the first live fire group,)show whether all these shooter error variables are actually occuring ....IF the scope's vertical is out,the lateral will only gradually emerge as more vertical is dialled in-hard to see why the horizontal would be incremental/ accumulate if it's the same raft of shooter errors.** Alternately,how do you -separately from the TT test-check for lateral using a different method,immune from this raft of shooter error,some of which may be present as likely for the vertical test,when done? ** ie IF the horizontal gradually emerges as vertical clicks are dialled in, does it not begin to look like a consistent incremental internal scope fault in vertical tracking? I was going to check all my aperture sights,but I've lost the will . And since the aperture's adjustment mechanisms are actually exposed,it's not neccessary to actually shoot the rifle-so where is the fun in that? :-) g PS Avian,without firing,how do you check for the second possible manufacture error-the scope does not track true vertical(so shots are increasingly dislaced sideways;this is indendent of whether the calibration is accurate (one click really is 1/4 moa,as marked) As suggested ,a pure optical test may be fine for checking click values-though Litz et al just shoot carefully-as it does both tests at the same time. Ditto the 'box test etc...clickmout and reverse.....first and last shots should touch (perfection would be same hole).
  11. gbal

    Scope Calibration

    I see the difference.My point is that the advantage of doing a TallTarget Test with live firing to check calibration is that this will ,at the same time-which isn't the same as 'conflating' the concepts-check for any cant induced by internal misalignment of the scope crosshairs with the click mechanism. SO live firing test for optical calibration is one method-but so is justan optical alignment check without live firiing.BUt only the first method can also check for internal cant induced horizontal error. SO the tall target test firing has two outcomes,and is worth doing,especially in the absence of an alternative check for the second possible ''can't error. "Two birdswith one stone' sort of,or at least with two or three groups of 5 shotswith vertical clicks aaround 10 moa bewteen them. Optical alone will check calibration-but not the second issue.Holes on paper in the rightbplaces is probably good for confidence too,but not essential.The downside to not shooting a TT test ,is unresolved doubt about the possible,though not common,horizontal error.Of course,if you don't know about it,no worries-unless you get such a scope. "Don't take it for granted that the crosshairs move actually as advertised.Don't take it for granted that the crosshairs are actually level,and track exactly vertical" (Litz,as in his Tall Target Test video-I'm happy to be conflated with him on this point.) :-) I suspect some/many don't even do the tall target test to check click calibration,and are then puzzled by elevation errors, and attribute it to error in their ballistic solver. Shame,there is an easy check. 'Separate and sequential'-OK,but the live fire Tall Target test is 'synoptic"....ie it provides data on both;so why not do it. Seems sensible,as there does not seem a convenient 'separate but sequential' vertical tracking test' I suppose you could do the tall target without firing (calibration) and the tall target with firing (vertical alignment)....OK,you'd also have some correlational/comparative data on the two assessments of calibration. But don't do them on the same page...LItz writes "The tall target test outlined previously for calibrating adjustments can also be used to confirm that the scope is tracking straight up....the tall target test (may ) reveal a tracking error",but I admit,with a carefully placed photo,it's printed on the last few part lines on one page,and the top couple of lines on the next. As Litz conflates it "the good news is that the problem of uncertain sight adjustments can be fixed with one trip to the range.Here's how to do it...' (The tall target live firing test). Let's leave it at that,since the actual proceedure is very clear,and should answer both uncertainties ...err...simultaneously. g
  12. gbal

    Scope Calibration

    Matt -Can optical calibration as you described it actually identify cant? It seems able to calibrate the actual scope click values at least as well as can be discriminated by eye by comparing the horizontal cross hair to the ruler markings used on the vertical. (Are the claimed -what you describe as 'theoretical-' 1/4 moa click(s) actually moving 1/4 moa ( or just something close to 1/4 moa;and is any discrepancy consistent over the adjustment range (or does it get less close to 1/4 moa at extremes?) I think "cant' determination perhaps gets to a higher order checking of the scope.Most shooters don't need/want cant -the situation that obtains when the scope's vertical is not straight up/down,but which will induce some unintentional horizontal. (The formula for estimating has already been given) Best for Long Range shooting is a perfectly level rifle,so that the vertical and horizontal ascope adjustments are independent.Cant is eliminated via a simple sight level-the familiar bubble indicator,fixed to scope (etc) where the shooter can easlity check visually.Instalation is done by holding the scope's vertical crosshair fixed in relation to a reference plumb line,and the bubble level is fitted to read level. The tall targer test-as per the litz video- can confirm/not that the scope is tracking true vertical (as well as checking calibration,of course-the main objective). But this will only work IF the the crosshairs actually move straight up/down. BUT if the vertical crosshair in the scopee is installed at manufacture at a slight angle to the mechanism that moves the crosshairs (the clicker) there ill be a tracking problem.Such ar not very common,but even the best make scopes sometimes perform modestly on test (the PR blog had poor results from a March,and a new spec S&B las year).The tall target test can reveal any such issues,so it's worth doing-by firing a tall target test to calibrate,and simultaneously check for cant. Effects of course increase with real shooting range (100y "should"not be an issue-but rabbits have been shot over/under by 2 inches at 500y,despite meticulous shooting solution inputs-but no calibration correction. (Intentional cant,which some shooters use,is fine,so long as the sights are level,and 'forced' cant-from an awkward position eg,can be allowed for via the 'cant rule of thumb' formula. Bottom take away line-best to never take anything for granted,whatever it 'says on the tin',if it can be measured with confidence and accuracy-and actually,fairly easily here,if you get a wind free half hour. gbal .
  13. gbal

    New brass

    With quality new brass (and 'nothing shoots like new brass"),if it feels to you that it is doing some good,then do it. If not convinced,see last point below. Neck sizing is so much easier (I'm getting too old for sticky fingers),and should sort the neck dings-I doubt the case body will have any,or to any effect. When only going plinking (ie .5 moa will do nicely) I just load a round as normal,and hope that it will " fire formed " pretty well around the neck etc. Catch-I'd modify the trimming-if 99 were within .1 spec,and one was sub SAAMI,I'd just keep that one for 'sighter" and load the rest as is.You probably would too-99 considtent on spec and no trimming for me beats 100 trimmed to marginal sub spec.. We all set criteria a little flexibly,I suppose.-as ever,is it a world cchampionship event,or a tin can rattle (and how good are the weakest links elsewhere in the chain?) gbal
  14. gbal

    Scope Calibration

    Mark, the classic male relationship weakness ....."Cant explain" Matt,yes despite complex ANOVA designs I broadly prefer the one variable change at a time,where possible/convenient. BUt I note from the video posted earlier in the thread,Bryan Litz sems to think shots on target can help both. It may be that the use of 'cant'to incluse/be a non vertical orentation of the scope crosshair is a tad misleading (as UK use can include shooter induced 'tilt/cant' of the rifle (and therfore vertical in scope) away from strict horizontal/neutral.Indeed some targeteers deliberately add cant to counteract ...well,quantifiable aspects of the devils work using other variables,whether spin/shooter position etc etc. Whatever,the main point was that 'optical' might well give answers to calibration (does xmoa (ormil) dialed in by clicking actually give the desired ccorrection on target,and does it do so reliably every time and return to zero when freversed),but can a non firing method check for cant (bullets impact to the side,without any horizontal clicking). If not,then somefiring will be needed-ssparately perhaps,but I'm not sure I see how any other variables will be removed from 'cant' firing,that were there in the 'vertical tracking'test? Seem to me always best to check-at least- by actual firing,for almost any sighting/load issue and applied 'solution'....holes in the paper afre the proof of the cooking,as it were. Otherwise,we could all get someone (I'd favour Mr Litz) to do the math(s),and just not shoot at all,confident that perfect centered hits were assured,so did not actually need to be fired. If only......we could still have math(s) as a hobby,given a reliable and caliibrated ballistics wizzard to do them....hmmmm.... "In theory,theory and practice are the same,but in practice they may not be"...Yogi Bear(a)...time to rechamber in 30 Boo Boo,lest the uncontrolled Valkyries attack. The optical approach has merit of course,with a suitably fine measuring rule,and is relatively weather immune,and much reduces the noise of human error.And of course as ever,consider wrt target size-just count the hits/misses (though a proper WEZ analysis will be more revealing,and cost a lot less in ammo)-though isn't a hundred plus shots what the well read,cellared and armed hobbyist should welcome? :-) My trust in maths (plural,just in case all math are not equal) is great,but as said,something reassuring about holes in the predicted and desired places (noise is inaudible!) atb,on all these gentleman's essentials! g
  15. gbal

    Scope Calibration

    Matt, . You could indeed do a vertical calibration of the scope optically as described. But would this indicate whether any cant was present-cant of course displacing shots to the side of the vertical plumbed measure line used to calibrate the scope clicks. Shooting does that too,though of course adds shooting system variance,if any,to the whole process.At the BR level,that won't be much,with sub .25 moa groups for 5 shots. Cant effect isn't negligible-ball park at 1000y,say 300" adjustment to be zeroed,then each 1 degree of cant will displace the poi some 5 inches horizontally to poa. At 600y,with 5 degrees of cant, needing 13 moa elevation,you'd hit nearly 9 inches to the side (and nearly half an inch low). (Rule of thumb calculation for horizontal displacement : elevation needed to hit target at the distance,plus 3moa (or 1 mil) multiplied by the sine of the cant angle. So that's (13+3xsin5) which is 1.4moa or 8.8 inches .Vertical is (13+3xcos5) which is 15.94 moa,ie .06 moa low (.4inches). So If your scope is 'canted' out of true vertical,you'd want to know and correct it. Holes on paper may also have some psychological clout/reassurance;and we're supposed to enjoy shooting. If we can't :-) do it adequately,perhaps better we know,with improvement an option,rather than blaming the gear. gbal

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