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Thread: Gained 100fps !

  1. #1
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    Gained 100fps !

    So my favourite rifle just got better
    Model 7 7mm08 15 inch with dpt timney trig talley xlows and a bushnell elite 3-9x40
    First load i made up was 41g of 2206h behind a 140NBT which was useable at under a inch wich gave me 2560fps
    41.5 gave me slightly heavy bolt lift

    Decided to tinker as usual and tried some 2208 and got to 43.5g with light eject marks but 43g was very unaccurate.

    At 43.5g with light marks it shoots under 1 inch at 2675fps !! Sorted

    Although the prochrono i borrowed showed a 90fps variance i think it may have not been reading right due to the tight group ?
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    GWH likes this.

  2. #2
    Member stug's Avatar
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    Nice, my 708 has an 18" barrel. I'm using H335 and a 110gr TTSX getting 3000 fps with 45gr.
    2208 is probably the best powder for 140gr, irrespective of barrel length. The lighter the projectile the faster the powder, within reason.
    Neck diameter to case diameter ratio also has an effect. The smaller the neck diameter to the case diameter the slower the powder needed.
    sneeze and llewelyn like this.

  3. #3
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    Cheers @stug shes just waiting in line for one of your stocks now
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  4. #4
    Member stug's Avatar
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    The other projectile to try is the 120/125gr Nosler BT. Weirdly it is actually slighty tougher than the 140NBT. They make them from the same cup, so the 120gr being shorter has thicker walls at the tip.

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  5. #5
    GWH
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    I use CFE223 in my 15" 708. Use to use the 120 NBT at just shy of 2900, but now use the 140 NBT at 2720 fps at about 3/4" @ 100. Going from 120's to 140's extended the range that it holds good energy. Id shoot a deer at 500 yards now if i had too.
    llewelyn and winaa like this.

  6. #6
    Member Beavis's Avatar
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    It is possible to shoot tight groups at 100m, with large ES and SD
    chainsaw, llewelyn and rossi.45 like this.

  7. #7
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    Aye hard to beat the old 43.5gn of 2208 in 7mm08!
    The first two shots (I’m assuming you have written the numbers in sequence from 1st to last) are pretty close only 20 fps difference but then a big jump to 3rd one. Also assume u running with suppressor ? You might find the 3rd outlier is a result of a hot barrel if you’ve fired the 3 shots in quick succession with suppressor and summer temps of 25-28C ? If this is happening then your first 2 shots are probably a better indication of muzzle velocity.
    R93 likes this.

  8. #8
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    @chainsaw yes your correct.
    That was my thinking also so split the difference of the first two

  9. #9
    Member 10-Ring's Avatar
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    To verify good accuracy you should fire at least three or more groups with the same load. Not suggesting you didn't - just saying.
    llewelyn likes this.
    "The 257 Roberts, some people like to call it the .257 Bob. I think these people should be hung in trees where crows can peck at them." - David Petzal

  10. #10
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    Done and done @10-Ring also shot out to 200m and 300m with good grouping from a little model 7 so ready to rock and roll
    10-Ring likes this.

  11. #11
    Member Tikka7mm08's Avatar
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    Model 7: 50gn 2209 Norma brass 120gn BT CCI mag primer sub 0.250moa with Z6i 2-12.

    Stug stock too @stug

    Sent from my SM-G950F using Tapatalk
    llewelyn likes this.

 

 

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