250gr TTSX / .375H&H

Discussion in 'Reloading' started by PHOENIX PHIL, Nov 17, 2012.

  1. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    So as if I haven't put enough time, gas and $$$ into developing loads, I decided to give the 250 TTSX a go in my .375H&H. One problem is the current Barnes manual has no loads for this round listed. So I did some linear interpoloation between the 235 and 270 grain versions of the TSX. I used RL15 listed loads to estimate the max for Varget since their burn rates are similar. I used H4895 listed loads for the same.

    My calculations put max load for Varget at 79gr and for the H4895 at 75gr. Well I didn't even get very close to that with what I loaded up.

    At 77gr of Varget, a little bit of a sticky bolt and just a light extractor mark. At 77.5gr the bolt required effort to open and a very clear extractor mark on the brass.

    At 73gr of H4895, no issues. At 73.5gr the bolt was again getting just a little sticky and a light extractor mark. After the results with Varget, I was inclined to quit there.

    That's the bad news. The good news is the rounds were producing very nice groups. I had a tripod problem and was not able to chrono these rounds. If the manual is in the least bit close for the 235/270 rounds, they should be flying easily above 2700fps and perhaps close to 2800fps.

    I'll be working on this load some more and when I have final numbers I'll post them. But in case anybody is getting started with this round, do be careful. I'm really questioning the Barnes manual. The max load listed for RL15 for the 270gr round is 77gr, so it surprises me that I'm getting high pressure symptoms at 77.5 with the 250gr round.

    One last note, I was loading these such that I was crimping just behind the leading edge of the front groove. I don't remember what the OAL is at this point, to be sure well under the SAAMI length of 3.6".
     
  2. PaulT

    PaulT AH Fanatic

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    G'day Phil.

    I think the powder you refer to as Varget is the Nth American version of what we know Down Under as 2208.

    IF that IS the case proceed with caution as you are way over max.

    I just referred to another reloading manual I have which lists 73gns of 2208 as maximum (giving roughly 3025fps ??? possibly a missprint ?) with the 250gn bullet.
    That would be assuming a standard cup and core bullet which when comparing to the longer (more case consuming copper projies) would take a slightly higher dose than say a Barnes would.

    Best way to find your peak load, I've found, is to record the pattern of increase increments in velocity per grains of powder loaded until the increase in velocity reduces in ratio to the load.

    Best of luck.

    Paul.
     
  3. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Caution and moving DOWN in powder charge are indeed the words of the day. I think you're load data of 73gr as max for Varget (2208, which I also agree is the same) is perhaps a bit conservative. H4895 is a faster powder and 73gr was okay. Without a doubt though, 77.5gr is more than I want to play with.

    I wondered if I had a misprint too, but I looked those loads up again in another Barnes manual when I was working up loads for the 270gr North Forks. North Fork does not have a loading manual so I was comparing various manuals including the Barnes at that time.
     
  4. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Paul,

    I'm going to take back what I said about 73gr of Varget being max. Looking in my Swift manual, the max load for a 250gr A-Frame is 72gr. From what I've seen with this manual is they're a little on the conservative side, but not that much.

    I think I'll work up from 73gr when I load these again. See you in Dallas!
     
  5. PaulT

    PaulT AH Fanatic

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    Phil, as you'd know there is a fair bit of variation from one reloading manual to another.
    Everyone's trying to cover their asses by printing loads they know are conservative in order to avoid possible litigation, but in saying that I wouldn't want to get too carried away either.

    Add to that slight varying differences in chamber dimesions from one rifle make to another and varying degrees of burning rates of the same powder from one keg to another.

    All added together creates a LOT of "blue sky" !

    What your now highlighting is the great Royal Pain in the rear when having to;
    a) establish a good hunting load for a new rifle
    b) re-establish a good hunting load for a rifle when your favourite bullet is no longer available.

    When doing all of this in big bores it is quite an expensive excersice.

    Currently I have two .375's a 458 Lott a .500 wildcat and a .500 NE all of which require some form of testing, loading new loads and or regulating !!

    By the way when you DO find a good load that'll be an extremely versatile weapon.
    .375 with a fast stepping 250gn T.Shok will lend itself to a lot of applications in a lot of environments.


    Look forwards to you dropping by in Dallas.

    Paul.
     
  6. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    I went to the range yesterday and this morning with a number of these loads. The variation across the chronograph is pretty surprising and is really all I have to report at this point. Somewhere along the way the screws in my rear base loosened up, I just love sending $$$ downrange with little return on investment. The last two loads I shot this morning were after I discovered this and retightened. These were with H4895 at 72.2 and 72.4 grains. The groups were okay at about 1.25" or so.

    The interesting part though is the variation in muzzle velocity. At 72gr yesterday I was getting right around 2800 fps. At 73gr, the loads were smoking at around 3040 fps. I was quite surprised to see 200 fps spread over one grain of powder. It was pretty linear with 72.5gr yielding 2890 fps. As would be expect however, there were flyers in the groups with the loose scope base.

    If I can find a good solid grouping load though, I think this will be a great round. We shall see.
     
  7. Bobpuckett

    Bobpuckett GOLD SUPPORTER AH Legend

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    Wow Phil you've really got'm smoken Hodgdon doesn't even recommend over 69gr of H4895 with a 250gr bullet. good luck at the range and keep us informed.
     
  8. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    That's why again I'm questioning the manual. The max load for a 235gr TSX in H4895 is 77grains and makes 2992fps per the manual. So how does 73gr of H4894 in a 270gr TTSX make 3040fps? Granted there's differences in chrono's, barrels and whatever, but that just doesn't make sense.
     
  9. Bobpuckett

    Bobpuckett GOLD SUPPORTER AH Legend

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    :confused: That does make you wonder.
     
  10. huntingbigun

    huntingbigun AH Veteran

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  11. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Good link Bigun! That manual shows perhaps to be a bit old, but the H4895 max load for a 250gr bullet is listed at 72gr. This in turn gives a MV of 2840fps, that's very close to what I was getting, 2800fps.

    It also shows RL15 max at 76.5 which is fitting right in with what I was seeing for Varget.
     
  12. huntingbigun

    huntingbigun AH Veteran

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    I keep all my old books lol, the older books by Barnes were much better than the new one but what is new about that in todays world. lol, another site I belong to for wildcat and newer stuff is this one, well worth the money, have fun I got to start on 338 Lupra ouch want to trade:D

    http://www.loaddata.com/home/index.cfm?CFID=20110780&CFTOKEN=19047959
     
  13. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Uhhhh.....nope! I've got a .416 Rigby for that sort of abuse! :cool:
     

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