Si-Snipe Posted December 18, 2012 Report Share Posted December 18, 2012 Perhaps looking to change from 6.5x47 on my rebarrel and thought I'd have a look at the options. I'd have to go a long way to beat 140g Amax (0.6 BC - Litz confirmed) at 2800 fps without throwing shovels of powder into a larger case. Any thoughts on 7mm-08 for long range targets and plinking etc with 162 Amax? Cheers Si Link to comment Share on other sites More sharing options...
Swamp Donkey Posted December 18, 2012 Report Share Posted December 18, 2012 Get baldie to build you one of his 'super hmr's ' they'll take out an elephant at 4 miles Link to comment Share on other sites More sharing options...
Chris-NZ Posted December 19, 2012 Report Share Posted December 19, 2012 I'd think the ballistic advantage would be negligible Si. You'd have to step up to a bigger boiler room to make real inroads. I'd leave it as is if it were me (I've got both but the 7-08's a hunting rig) Chris-NZ Link to comment Share on other sites More sharing options...
baldie Posted December 19, 2012 Report Share Posted December 19, 2012 Get baldie to build you one of his 'super hmr's ' they'll take out an elephant at 4 miles Somehow i sense the irony was lost on you..... Here,s a quick pick of a 7mm-08 that i built not long back. The owner has shot several tiny groups with it, this one being the best. 5 rounds at 400 yards for around an inch. Link to comment Share on other sites More sharing options...
jcampbellsmith Posted December 19, 2012 Report Share Posted December 19, 2012 Perhaps looking to change from 6.5x47 on my rebarrel.... Si. Would you care to shed some light on why you are thinking of changing? Thanks JCS Link to comment Share on other sites More sharing options...
tackb Posted December 19, 2012 Report Share Posted December 19, 2012 I considered this as the 162amax really appealed (being a big amax fan)but upon investigation the advantage wasn't really there over my 260 with the 140 amax. I feel that you need a bigger case to realise the 162 amax's full potential ? Link to comment Share on other sites More sharing options...
6.5shooter Posted December 19, 2012 Report Share Posted December 19, 2012 If you are leaving 6.5mm to go 7mm make it worth youre while and expense and go 7mm wsm. 6.5x284 is another good option but 6.5x47 sheer accuracy is hard to whack in not too difficult conditions. Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 Si. Would you care to shed some light on why you are thinking of changing? Thanks JCS Just for a change really. Looking around at all the options but as suggested already in this thread the 6.5x47 is difficult to beat for a few reasons, barrel life, accuracy, efficiency, low recoil, ballistics (especially with 140g Amax) mega strong brass (23 reloads and no change in pp or accuracy)........ That's it I'm staying put! Link to comment Share on other sites More sharing options...
Chris-NZ Posted December 19, 2012 Report Share Posted December 19, 2012 A smart move, ma man For sheer tack-driving ability, I'd never sell my 47. In fact, if I was forced to choose one medium power chambering for everything, that'd be it Chris-NZ Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 My new barrel must shoot the 140 Amax. It's the best all round bullet for long range IMO. It was a huge margin better at 900 yards when I compared them to the 123 Amax and very good on varmints. Link to comment Share on other sites More sharing options...
dannywayoflife Posted December 19, 2012 Report Share Posted December 19, 2012 Is the BC of the 140 Amax .6? I thought it was .55? Can the 162 Amax work well in the 7-08 at mag length? Link to comment Share on other sites More sharing options...
rabbit fingers Posted December 19, 2012 Report Share Posted December 19, 2012 Multi g1 bc's 0.626-3000 0.602-2500 0.583-2000 0.525-1500 0.520-0 They work down to 12-1300fps then accuracy goes to pot anyway because I've found they don't go through the transonic velocity area and remain stable. Link to comment Share on other sites More sharing options...
dannywayoflife Posted December 19, 2012 Report Share Posted December 19, 2012 That is an impressive BC! Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 Page 3 of this link shows the real world figures tested by Brian Litz. We've found Brian's BC figures are very close to what we are seeing in the field. http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA554683 Entering multi BC figures into the calculator and matching them into the observed drop in the field has shown us that the BC although decreases as the velocity drops (as with all projectiles) the 140 still retains a much higher BC than the 123g Amax. Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 Rabbit fingers has done extensive testing with the 140's and has superb knowledge of it. He's the man. Link to comment Share on other sites More sharing options...
dannywayoflife Posted December 19, 2012 Report Share Posted December 19, 2012 Thanks for that si I've just saved the link in my iBooks I'll have a proper read later. I'm hoping when I start loading my own in the new year I can get the 140Amax working in my 6.5x55:-) Link to comment Share on other sites More sharing options...
Laurie Posted December 19, 2012 Report Share Posted December 19, 2012 Any thoughts on 7mm-08 for long range targets and plinking etc with 162 Amax? [si] Now that .260 Rem has been miraculously 'discovered', I reckon 7-08 has taken its place as the most overlooked common cartridge around. Logically, anything .260 can do, the 7mm version should do as well as or better ballistically. 7mm bullets have long been regarded as the optimal calibre for ballistic efficiency. Well, that's the theory. If you look at the bullets on the market, the applecart is upset a bit by the existence of some outstandingly efficient 6.5s from Cauterucio, Hoover and Berger with i7 form factors as low as 0.888 (136gn Hoover). Yes, maybe difficult to get at who knows what price, but Berger makes its more commonly available 140gn 264 VLD with an outstanding 0.918. The best commonly available 7mm bullet listed in Litz's book is the new 180gn Hybrid at 0.924. However, I'm not sure if the 260 / 7mm-08 case is large enough to give best results with a 180gn bullet. 162-168gn bullets seem better suited to the design. The 168 Berger VLD has an i7 of 0.942, a fantastic value and one that Litz / Berger has only just achieved with the new breed of .30 cal heavy Hybrids as a comparison, but still higher drag / lower efficiency than that 6.5 140's 0.918. Running a QuickLOAD Charge-Run table for a 28-inch barrel, 60,000 psi max pressure, and COALs set for a chamber allowing one calibre of bullet shank seating depth gives top theoretical MVs of just over 2,900 fps with 260 / 140 and 100 fps less with 7-08 / 168. With a lot of potential loads in the 2,850 - 2,900 fps ballpark, I ran the 260 at an MV of 2,875 and the 7mm at 2,775 through a ballistics table over 1,000 yards. As others have suggested, there's very little in it, but the 260/140 VLD combination comes out a little ahead in terms of retained velocity and wind drift. In practical terms it would come down to individual barrels, actions and rifles as to what velocities were produced by the most accurate high-MV loads. This exercisxe also assumes that your 260 Rem barrel performs well with the 140 VLD - if it doesn't and you have to use a higher i7 / lower BC equivalent, you lose the ballistic benefits offered by that one outstanding bullet and the balance would potentially tip marginally to the 7mm. I must admit this finding surprised me as I expected the advantage of whichever of the pair came out best to be small, but the results to favour the 7mm-08. But ... it's not just ballistics as there are the issues of precision, recoil, and barrel life. With no experience of the 7mm, I can't comment on it v the 260 for the first of these, but I assume it will group at least as well. Recoil will be marginally heavier, but in a heavy rifle built for range use and shot in F-Class mode supported, I don't see it being an issue. That leaves barrel life where the 7mm should give a significant benefit over its same case / same charges through a smaller bore 6.5mm sibling. 2,500 rounds v 2,000? Maybe 3,000 rounds barrel life? Again, I've no experience, but it must be significant. Overall though, for competitive long-range shooting, 7mm appears to make a lot more sense with a larger case round, either .284 Win or as I notice in current US F Class competition winners' circles, the increasingly common appearance of the 'old fashioned' but apparently very effective .280 Remington. Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 These are the BC figures I have found in the 123 Amax shot from my barrel. My 123 MV is 2900 fps and the 140 Amax were doing 2800 fps but my barrel doesn't seem to like the 140's hence the re-barrel but its had 2500 shots through anyway. BC Min. Velocity Max. Velocity 0.490 2400 3000 0.460 1800 2400 0.440 1200 1800 0.420 0 1200 Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 Somehow i sense the irony was lost on you..... Here,s a quick pick of a 7mm-08 that i built not long back. The owner has shot several tiny groups with it, this one being the best. 5 rounds at 400 yards for around an inch. Dave that's no good - I can do groups like that at 100 yards. Link to comment Share on other sites More sharing options...
Laurie Posted December 19, 2012 Report Share Posted December 19, 2012 Si, I've slowly come around to the view that the smaller 6.5s are best suited to 120-130gn bullets especially if magazine operation is needed. 6.5X47 Lapua is very popular 'down-under' in long-range F in single-shot rifles and a lot of these guys get the 140s to shoot well and at surprisingly high velocities. I reckon they're really pushing the design though and will certainly pay for the performance in barrel wear. Litz doesn't list average G7 BC for the 123gn AMax, but I doubt if it's too far away from the 123gn Lapua Scenar which he found was 0.265. The 7mm Hornady 162gn AMax is 0.307. Working on the minus 100 fps assumption for a 160-170gn seven against a 140 six and a half, you'd likely run the 162s somewhere around 2,700-2,750 fps in 7mm-08 with a same length barrel. 0.265 G7 BC / 2,900 fps MV = 1,382 fps retained vel at 1,000; 7.8-MOA drift in 10 mph wind @ 90-deg 0.307 G7 BC / 2,700 fps MV = 1,413 fps .....................; 7.15-MOA 0.307 G7 BC / 2,750 fps MV = 1,449 fps .....................; 6.9-MOA So you should see some benefit in 7mm-08 ballistically at any rate Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 Si, I've slowly come around to the view that the smaller 6.5s are best suited to 120-130gn bullets especially if magazine operation is needed. 6.5X47 Lapua is very popular 'down-under' in long-range F in single-shot rifles and a lot of these guys get the 140s to shoot well and at surprisingly high velocities. I reckon they're really pushing the design though and will certainly pay for the performance in barrel wear. Litz doesn't list average G7 BC for the 123gn AMax, but I doubt if it's too far away from the 123gn Lapua Scenar which he found was 0.265. The 7mm Hornady 162gn AMax is 0.307. Working on the minus 100 fps assumption for a 160-170gn seven against a 140 six and a half, you'd likely run the 162s somewhere around 2,700-2,750 fps in 7mm-08 with a same length barrel. 0.265 G7 BC / 2,900 fps MV = 1,382 fps retained vel at 1,000; 7.8-MOA drift in 10 mph wind @ 90-deg 0.307 G7 BC / 2,700 fps MV = 1,413 fps .....................; 7.15-MOA 0.307 G7 BC / 2,750 fps MV = 1,449 fps .....................; 6.9-MOA So you should see some benefit in 7mm-08 ballistically at any rate Hi Laurie Thanks for the info. I don't agree regarding barrel wear though. I shot probably 1200 140g Amax at 2900 fps using RL17 (without pressure signs) plus a further 1300 rounds using 123 Scenar and Amax using RL15. My barrel is still well sub 0.5MOA with 123g Amax at a count of 2500. The 140 loads I used fit and fed fine from the AI mag so don't see any problem mag wise using the 140's? Cheers Si Link to comment Share on other sites More sharing options...
Chris-NZ Posted December 19, 2012 Report Share Posted December 19, 2012 That's a pretty impressive barrel life Si given RL17 is known as the barrel maker's friend What make of barrel? Chris-NZ Link to comment Share on other sites More sharing options...
Si-Snipe Posted December 19, 2012 Author Report Share Posted December 19, 2012 That's a pretty impressive barrel life Si given RL17 is known as the barrel maker's friend What make of barrel? Chris-NZ It's a Trueflite Chris. Link to comment Share on other sites More sharing options...
baldie Posted December 19, 2012 Report Share Posted December 19, 2012 Thats even more amazing Si, because truflite steel is relativly soft....personally i think thats what makes them so damn good. The steel is soft, but beautiful quality. Anyone who,s machined one will say the same. Link to comment Share on other sites More sharing options...
Laurie Posted December 19, 2012 Report Share Posted December 19, 2012 You built many 7-08s Dave? (Oh, and those you've built, what were they to be used for?) Link to comment Share on other sites More sharing options...
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