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Totally weird.

Discussion in 'Handloading and Reloading' started by Kachok, Feb 28, 2013.

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  1. Kachok

    Kachok Member

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    OK so I just got back from the range as you can tell from my last thread, I have been trying very very hard to get my M70 308 FTW to group well with 165s like it does with 150s since I have never used 150s for hunting (not in 30 cal anyway), well today I tried something off the cuff and loaded 180gr SGK over W748 just to see, WOW a .515" group with the first three shots! My jaw about hit the floor! So it shoots 1/2" with 150s, 1/2" with 180s but 1.5" is the best I can do with 165s?!? I asked the reloading guru in the shop and he has never seen anything like that either, had the 180s not grouped I could have chalked it up to the slow twist but this one has me scratching my head, and yes I have tried just about every 165gr bullet/powder combo you could imagine within reason, RL15, Varget, H380, Big Game, 748, BL-C(2), Speers, Sierras, Hornadys, Noslers.....etc, anyone have any ideas?
     
  2. c.latrans

    c.latrans Member

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    You have tried 165's other than SGK?
     
  3. Kachok

    Kachok Member

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    Yep Nosler BTs, Hornady SST, and Speer BTSP. Oh and I tried the SGKs in SP and HP versions.
     
  4. c.latrans

    c.latrans Member

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    Probably witchcraft....have you ticked anybody off? Funny stuff happens, doesn't it?!
     
  5. Kachok

    Kachok Member

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    And to make this whole story even less believable the POI of my 180gr loads is over an inch higher then my factory 150gr core-lokt zero, even the mid load was higher, I don't think barrel harmonics could do that to all powder charges, and I am pretty sure I am not hitting 2850fps+ with 180s that would be a stretch for the 06 on a good day.
     
  6. Kachok

    Kachok Member

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    Published velocity for 46.5gr of W748 and a 180 SP is only 2610fps, I should be about an inch low, and no I did not hang the target upside down. No pressure signs even at max but it did kick rather stout, nothing like any 180gr 308 I ever shot, dang I need a chronograph.
     
  7. Rollis R. Karvellis

    Rollis R. Karvellis Member

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    The muzzle has more time to rise before the bullet leaves it.
     
  8. Kachok

    Kachok Member

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    Then why do factory 180s hit low? My 180gr Core-Lokt hand loads hit WAY low with a max dose of IMR4350 too.
     
  9. James2

    James2 Member

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    As soon as a bullets starts to move into the barrel, the recoil begins. Recoil that raises the barrel as we well know. Heavier bullet = heavier recoil = more barrel raise. No surprise it may hit a bit higher. This has little to do with velocity nor trajectory, but is a simple matter of how high the barrel kicked up before the bullet left.

    Sorry, no theory on the poor groups on the 165s. I would not worry too much about it. Buy what the rifle likes.
     
  10. Kachok

    Kachok Member

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    Oh I am, already working up my next batch of 150s and 180s, I am not too worried about it, but I would like to know what I am missing for future reference. I have seen guns that like the heavy bullet and not the light and vice versa, but never one that likes heavy/light and nothing in between.
     
  11. TNBilly

    TNBilly Member

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    Hate to say it but Quickload calls 46.5gr of W748 an overload running about 70k. You can't get the pressure in bounds unless you're seating out to 3".
     
  12. Kachok

    Kachok Member

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    Not according to the fine folks at Hodgdon.
    180 GR. SPR SP Winchester 748 .308" 2.800" 46.5 2610 48,500 CUP
    I would think I would see pressure signs at 70k, but then again that thing did kick like it meant business too.
    I have shot factory 180gr Power points through that rifle and they did not feel anything like that, nor did they hit that high, if I remember correctly they are supposed to be 2600fps too.
     
  13. chris in va

    chris in va Member

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    Um, better check that formula again.

    My Lyman manual shows a 178gr A-max 748 40.0-45.0max at 2662 and 60,500psi. I think you had a dangerous overcharge.
     
  14. Kachok

    Kachok Member

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    Wow really? Why would Hodgdon post that load if it were dangerous? I am shooting CCI primers don't they show excessive pressure pretty well? I looked the brass and primer over thoroughly, no crater or primer flow and no extractor marks though it is a CRF action so I am not sure if that is the same.
     
  15. Lost Sheep

    Lost Sheep Member

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    I don't think so. CCI primers are reputed to be made of harder metal than other brands, thus would not flow a whole lot.

    About the accuracy thing. Don't discount the effects of barrel harmonics. Also, seating depth can make a difference. A chronograph would probably help you analyze things. Might not help accuracy, but it sure is fun to have the extra information.

    Good luck

    Lost Sheep
     
  16. kingmt

    kingmt Member

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    Your not going to see barrel clime in a rifle. You would never shoot .5" groups if it did.
     
  17. gamestalker

    gamestalker member

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    Without a chronograph the best we can do is guess. As for reading primers, it isn't a real reliable means of identifying high pressures. If anything, primers are easier to identify low pressures. But you did say there were no extractor marks on the case head, so based on your observations alone you are probably OK regarding pressures.
    As for accuracy swings, some rifles like what they like. As for those 180's having a higher POI, it contradicts ballistics?
    GS
     
  18. Ky Larry

    Ky Larry Member

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    I have a CZ-550 Varmint. It shoots 140gr and 155gr Noslers and 165gr Hornady S.P's under an inch at 100yrds with IMR-3031 and TAC. I haven't shot any 180gr bullets.
     
  19. Kachok

    Kachok Member

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    That is what I said, but I would swear on a stack of bibles it is true, I probably would not believe it had I not shot it myself. The other 180gr loads did not kick that stout and all impacted low, that one kicked like a compressed load 30-06 and grouped high, using Leopold rings/mounts and a Buckmaster scope I highly doubt anything got thrown off zero, my 44gr Varget 150s where hitting just like they usually do. Anyways I need to invest in a chrono of my own so I can check this stuff, while I like the way that load shot, and I don't mind the extra kick I need to do a little homework before trying that one again since everyone thinks it is dangerous.
    I have had an overpressure load in that rifle once, flattend the primer like a train ran over it and was leaking around the edges, sadly that was not even near a max load Varget is a funny thing.
     
  20. joneb

    joneb Member

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    Only in your sick twisted skull.
    As high as the heavens are above the earth, are my ways higher than yours says the Lord.
     
  21. Kachok

    Kachok Member

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    OK doing a little research and it turns out that load might very well be quite hot despite being a published load from a reputable company and lacking of visible pressure signs, also might have been quite a but faster then I thought, Sierra's max load it 43.6gr at 2600fps seeing as I was running almost three grains more then that I could have very well been in the 2700fps range which while that does not explain the 1" higher POI it gets me halfway there.
    I am going to have to error on the side of caution and abandon that one :( darn I thought I had a real winner there, back to the drawing board I guess. Anyone else know a good 180gr powder? My normal Nosler pet loads is letting me down on 308, while I am sure it would be accurate and I don't need 3000fps speeds I was hoping for a little more then 2400fps.
     
  22. MtnCreek

    MtnCreek Member

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    Varget w/ 180gr Nosler BT has been accurate for me, but the 165 seems to performs better on deer IMO.

    For 165gr Noslet BT, both Varget and 4895 have given good results. Best loads w/ Varget are pretty hot. Best loads w/ 4895 are slower, but a little more accurate. Most deer that I’ve shot have been inside 100yds, so I guess it doesn’t matter much either way.
     
  23. dagger dog

    dagger dog Member

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    Kachok,

    " The whip may be extreme enough that the barrel will move both above and below the zero line while the bullet is still in the barrel. The starting movement while usually down, can be either up or down and measurements show that 7 to 15 minutes of angle is common"

    This paragraph is the last one on page 58 of 4 pages on barrel whip from ;

    UNDERSTANDING FIREARM BALLISTICS
    Basic to Advanced Ballistics
    Simplified,Illustrated & Expanded

    By Robert A. Rinker

    Buffalo Arms has this book on sale in their close out section.

    It's a great book and can answer questions most experianced handdloader reloader-shooters can ask.
     
    Last edited: Mar 1, 2013
  24. Kachok

    Kachok Member

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    Something other then Varget perhaps? To be honest that stuff scares the goomba out of me, I won't load it over my starting charge with 150s because it made for the worst pressure spike I have ever seen on a mid ranged load! Same rifle, and if it is not flattening out a primer at 70k psi I would hate to think of how much pressure it took to flow those primers like that and cause them to leak. Maybe I just have a bad batch of Varget, but with a starting load it does shoot 150gr Speers and SSTs very well, and the POI is right in line with the factory zero.
     
  25. MtnCreek

    MtnCreek Member

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    I wonder if there was something else going on with your Varget load. IME, Varget gives a steady pressure increase and thrives at the upper end of published data. I've pushed some loads a little beyond data and still had good accuracy.

    Another powder I've used a lot recently is 8208. I started using it because I wanted a good metering extruded powder in around that rate. I've pretty much replaced all my .223 loads to use it. It does a good job w/ 168 / 178 gr bullets in .308, but did not deliver the velocity that Varget did.
     
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