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Thread: 6.5x47 - load development

  1. #1

    6.5x47 - load development

    After experiencing a number of problems relating to my 6.5x47 blowing the back off the primers I decided enough was enough and it was time for a bit of Research & Development.

    Having looked at a number of possible causes and taking on the advice of the members here, I popped down to Brock & Norris to see what could be done.

    Mike is an expert in the field of all things that go bang and no doubt he would be able to find a solution.
    So both I and Dan534 (who is also getting a 6.5x47 in the same Accuracy International AE platform)
    packed are kit and headed off to Shropshire.

    Once we arrived I explained the issues in more detail with Mike and after inspecting and stripping the gun a number of possibility's were ruled out.

    It appeared the firing pin was fully intact, fully functional and not to long - so that was not hitting the primers to hard.

    The internals of the rifle were as they should be so all OK there.

    The most likely cause of the primers was overpressure, now although my original load - 38.5gr RL 15, 123gr Senar & CCI 450 small rifle magnum primer, works well in some rifles it isn't always going to be the case in every rifle. Each rifle is unique and individual and although the barrel might be cut with the same tools that make many others guns. Each one will have its own accuracy nodes and perform ever so slightly differently from the next.

    Mike then measured the barrel length, checked the seating depth and other gun measurements. He then started the full process of case prep, carefully checking each individual case, resizing, measuring and double checking to ensure uniformity through out.

    After batching up all the cases, Mike ran a number of known accuracy nodes with different powders through "Quick Load V 3.4" to get the starting points for the test loads.

    First up was Vit N150, according to Quick load the place to start was 38.5gr, so following on from this the first 5 rounds were reloaded, measured and double checked. This process was then repeated for IMR @ 40.7gr, H4350 @ 40.7gr & RL15 @ 37.1gr.

    According to "Quick Load" the powders should be producing the following:-

    Vit N150 = 2831fps

    IMR = 2868fps

    H 4350 = 2862fps

    RL15 = 2886fps

    All the test rounds were seated at 2.102 to the ogive.

    With all bullets being 123gr Lapua Senars.

    Primers being CCI 450s.

    After the heading down to the range (measured at 98m) with the test ammo, the gun was set up along with the chrono.

    The Met data was recorded:-

    Temp = 23.4 C

    Station Pressure = 1012mb

    Humidity 67.4 %

    Once set up and we then fired off each group in order, the results are as follows:-

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    IMR was ruled out strait away.
    Chrono data:-

    1. 2917 fps
    2. 2918 fps
    3. 2931 fps
    4. 2942 fps
    5. 2941 fps

    Average 2929 fps

    Extreme spread 24 fps

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    H4350 seemed ok - although a adjustment of seating depth + or - could tighten up the group.
    Chrono data:-

    1. 2907 fps
    2. 2901 fps
    3. 2884 fps
    4. 2895 fps
    5. 2898 fps

    Average 2897 fps

    Extreme spread 23 fps

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    Vit N150 groups could be made tighter with + or - of powder. Adjusting seating depth would also improve.
    Chrono data:-

    1. 2986 fps
    2. 3014 fps
    3. 2996 fps
    4. 2994 fps
    5. 3004 fps

    Average 2998 fps

    Extreme spread 28 fps

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    RL 15 group also good but adjusting seating depth and powder would also assist.
    Chrono data:-

    1. 2915 fps
    2. 2919 fps
    3. 2911 fps
    4. 2920 fps
    5. 2933 fps

    Average 2919 fps

    Extreme spread 18 fps

    The results were interesting, they showed a number of different things, primarily that my barrel was tight in comparison to not only "Quick Loads" virtual barrel. But also tight compared to a good friend of mine who has a very similar gun, all be it the AW version in 6.5X47.

    The reason for the overpressure could be put down to my original load of 38.5gr RL15 being to hot (to much powder at to higher burn rate) for my gun - resulting in the blown primers. Also of note, the more powder in a case does not always mean more fps, but does on occasion mean overpressure.

    One key difference on all the powders I tested was that none of them showed any pressure signs and the primers were not damaged.

    There are, as one would expect differences between Quick loads predictions and the real world data collected:-

    Quick Load - Vit N150 = 2831 fps
    Real world - Vit N150 = 2998 fps

    167 fps difference.

    Quick load - IMR = 2868 fps
    Real world - IMR = 2929 fps

    61 fps difference.

    Quick Load - H 4350 = 2862 fps
    Real World - H 4350 = 2897 fps

    35 fps difference.

    Quick Load - RL15 = 2886 fps
    Real World - RL15 = 2919 fps

    33 fps difference.

    Moving forward I intend to play around with the RL 15 powder, I will look to possibly increase 0.2gr increments and adjust seating depth to get the best I can from this impressive little round.

    I hope this has been of interest.

    Kind Regards


  2. #2
    Hi Rob

    I think the 6.5x47 is a little pressure sensitive. I ran into pressure issues before reaching the velocities that others have reached but diidnt suffer from pierced primers. I have up to now been using N140 (37 grains) which is similar to Re 15 in burning rate with good results. At this point I am getting slight cratering of the primers so dont want to go any higher. Varget also seems to do very well in this cartridge (I personally havent tried it yet). One issue with Re 15 to bear in mind is that it can be a little variable with climatic conditions and between lots. If you are on the edge pressure wise it could be enough to tip you over the edge. When I get chance to try the varget I wil let you know how I get n


  3. #3
    Rob, that is interesting. I have observed in my custom barrelled 260rem that I am achieving near book max velocity with a 20" barrel and loads which stop about 1.5gr short of max. If I go near book max loads in this rifle I start getting very nasty pressure signs, flattened and in some case blow primers, extractor marks etc.

    It also confirms my general view of the 6.5x47L. Guys are making great claims for it's velocity potential - some claims are just plain outrageous. The 47L is no doubt a very good design, but it must be operating on the ragged edge of sensible pressures to achieve the velocities claimed for it.

    2900fps with a 123gr bullet is an excellent return for under 40gr of powder in that small case.

    You might try loads of 41-43gr of Reloder 17 of you can lay hands on some.
    Last edited by Claret_Dabbler; 04-07-2011 at 08:57.

    Just because you are paranoid, doesn't mean they aren't out to get you......

  4. #4
    I have a 6.5*47 built by Riflecraft on a blueprinted Rem 700 action with a Pac Nor 26" barrel. Wanted to use 130 Scirocco's but couldn't make them fly straight using R15, R17 or IMR 4350. Switched to a Nosler 120 grain which was instantly much better. Using R15 with CCI Benchrest primers my final load was 39.1 grains. Average speed 2967 with a spread of just 9. Group size is just over 0.5" which is good enough for me. I'm sure someone better could close that down given the time and the inclination if they wanted to use it for paper. Bullet seated 10 though into the lands. No pressure signs ever seen. Most I have taken it to is 39.4 grains of R15 but the groups started to open up so i came back down. My target was 2950 giving +/- 1" to 200 yards. I'm sure I have been lucky, none of the other guns have been that easy to find a good load for.

    Shot, Roe, Red and Sika with it. Great terminal performance. They go down hard and damage isn't bad. I don't use a mod so it's great to carry about. I do use a mod on the other guns but this one just isn't that loud in the field. Head phones on the range. Other guns are now gathering a bit of dust, apart from the fox rifle, but that's another story.
    So much to learn and so little time left

  5. #5
    I also now have one of these little beauties built by Andrew Hendricks it is one he built for himself ,when I gave him the spec I wanted ,he smiled and said he had just built one the same apart from a bit of tarty bling ie 1/2 fluted barrel.
    Any way I dont have acess to some of the testing facilities some have so I read these forums and learn from others mistakes and bath in their glory.At the moment I am using 120gr nosler 36gr varget 20 thou from lands I have no idea of speed or pressure but there are no signs of excess pressure,and they drop 50mm at 200m when I zero at 125m. The group at 125m is 5 shots inside a 20pence piece which is good enough for this kiwi hunter. Lifted a fallow buck fawn off its feet yesterday shoulder shot at 220m ,so I say it still has a punch at that range. This may not be as scientific as many who write on here,but my job is to use it for what its built for and this little beauty has paid for itself in less than one season.

  6. #6
    A good friend received his custom 6.5x47Lapua in September and began his load development. Very early on it became apparent he was hitting pressure problems and first suspected the firing pin in his GBR bolt/action.
    His barrel is 24" Shilen with 1 - 8" twist.
    His selected bullet the 129gn Hornady SST.
    After discussion with GBR in Northwich, where no problems were found with his action, it was discovered the published cartridge case OAL
    Lapua, trim-to length 46,80 mm (1.843”) is the max the case should be - and not the trimmed length. So, at this cartridge case length in a blueprinted barrel/action, there's no additional room left in the breech for expansion - hence we believe, early pressure signs show.
    Since learning this, his cases are now trimmed to 1.833" and his load with selected bullet at 37.2gns Rel.15 with the 129gn SST
    is extremely accurate with no further signs of pressure. Chrono'd at 2830fps.

    If your barrel has a 1 in 8 twist, you may discover it works better with the heavier bullet......123gn may be a little light for your barrel.
    Last edited by deeangeo; 31-12-2011 at 23:10.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Zeiss 8x56, 110gn Nosler Accubond = Game Over!

  7. #7
    Dean, that is interesting and also further enforces my views on custom rifles.

    When you build a rifle to tight minimum spec tolerances, the dividing line between safe and unsafe pressures can be very thin. Combine a tight barrel, a minimum spec chamber and a blue printed action and you will get good velocity, often book max at less than book max powder charges. In my case, the 260 is doing c.2900 fps with a 20" barrel and 43.2gr Rel17. Book max velocity is 2930fps with about 44.5gr of Rel17.

    However, any deviation from a known good safe load will result in a sudden pressure spike. A 0.5gr increment in powder will result in blown primers, I have to keep the brass trimmed to minimum length, and the bullet back out of the lands.

    If you are shooting a factory rifle with a standard loose-ish chamber and a decent length of led, you will get a slow build up of pressure which a competent reloader should easily spot. Likewise, if you are shooting a 222rem or a 6.5x55, load data is very conservative and you will have to work hard to get into trouble. Contrast all that to the 6.5x47Lapua, which is spec'ed already at the ragged edge of pressure, combine that with the custom minimum spec rifle, you could get in a lot of trouble very quickly.

    Just because you are paranoid, doesn't mean they aren't out to get you......

  8. #8
    mine is away at the proof house - i have varget and 120gn noslers and 123gn amax to start with, just about to load up some running in/development rounds - i was thinking of starting at 37gn - 20 thou off - is that too high?

  9. #9
    Not the first time I have heard of primer problems with the 6.5x47 in the Acccuracy International rifle, which may be rifle specific. This may be of interest

  10. #10
    When my friend had his selected barrel & action assembled together – (Incidentally, by a very reputable & knowledgeable gunsmith) neither my friend nor I, thought on, to check the ‘Actual’ chamber measurements. We just presumed the Trim-to-length dimension on the Vihtavouri load data site, was what should be done.

    It was only when primer/pressure problems arose very quickly in the trial period of load development, that the Lapua dimensions I posted earlier were discovered to be the actual chamber dimensions in my friends barrel.
    It seemed to follow therefore that the trim to length dimension needed to be shorter.

    We opted for the standard .010" reduction in case OAL and immediately saw a significant change in cartridge behaviour.

    As stated, originally we suspected the action/bolt was not quite right, but having investigated this thoroughly, we looked at the OAL case length in much greater detail.

    The load currently in use is both accurate and consistent, with terminal bullet performance at usual hunting ranges completely satisfactory.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Zeiss 8x56, 110gn Nosler Accubond = Game Over!

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