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Thread: Velocity, opinions please.

  1. #1

    Velocity, opinions please.

    I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

    Regards and thanks in advance

    Mike

    155 sierra match king
    Last edited by mudlark; 06-10-2015 at 09:32.

  2. #2
    My Nosler manual shows 2645 fps with 42.5grns of n140. That is their most accurate load, but 2887 fps was achieved with 46.5grns, so you are not loading to the maximum.

  3. #3
    none of my loads are close to book data

    bought a diesel volkswagen lately? same deal!


    IMO it only makes any difference when out past 800+ yds when the bullet MAY become unstable as it slow down past supersonic speeds

    My 300WM (.30cal bullets obviously) are much slower than book data at a factory max load
    My .308 loads were only up around and slightly over book data when I was running a 29" barrel compared to the powder makers 24" test barrel!!


    at 600 yds it won't make a jot of difference
    accuracy is what matters

  4. #4
    The Viht book max is 44.2max. Bewsher that the answer I was hoping for thanks

  5. #5
    The Viht 'book figures' are very low for ammo to be used in industry standard 0.300" bore / 0.3080" groove dia. barrels, and seem to be held down maybe over concerns over cartridges to be used in 'tight-barrel' rifles which can make a significant difference (Minus 2-3gn with most powders in a Paramount TR rifle I have with an older spec Lothar Walther 1-14" twist barrel).

    Most TR and FTR shooters even at club level run N140 somewhere between 46 and 47gn with either of the 155 SMKs and other popular 155s. However, if you don't shoot beyond 600 yards and your current load performs well, don't fix something that's not broke! At 44gn, your barrel will last a long, long time especially as N140 is a reasonably cool burning propellant.

    (Owners of older Enfield Number 4 TR rifles should stick to the Viht max and stay below that even if they have a heavy original Enfield match barrel still on - they had really tight internal dimensions.)
    Last edited by Laurie; 06-10-2015 at 11:33.

  6. #6
    It's only too slow if it doesn't suit your needs.
    You should try shooting a larger sample next time. Four rounds is far too small a sample.~Muir

  7. #7
    Quote Originally Posted by mudlark View Post
    I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

    Regards and thanks in advance

    Mike

    155 sierra match king
    Also worth noting temperature during testing as its surprising just how much a rise or fall of 10 degrees Celsius can have on powder burn rate and muzzle velocity. Some powders can be affected to the tune of 3.5fps depending on cartridge and load, per every one degree change (ie a one degree rise gives a 3.5fps rise in velocity). For long range (out past 600m) shooting in colder conditions, this might have a greater effect on accuracy requiring an increase in load or a change of powder to one less susceptible to temperature changes. Some powders might be less susceptible but even those might see a 1 to 1.5fps change per degree change. It's important when looking at all of these figures then that you reference them to standard environmental data. Some manufacturers will state velocities based on an ambient 20 degrees C for example.

    For your loads tested, I don't know what the temperature was on the day or where the cartridges were stored, but for argument's sake it might have been 12 degrees, then at 22 degrees, your 2580fps could well become 2600 and at 2 degrees, you might expect a drop the other way. From your measurements, your loads seem ok for your needs so I wouldn't let it bother you too much and just carry on doing what you're doing.
    Last edited by ChesterP; 06-10-2015 at 15:18.

  8. #8
    Quote Originally Posted by mudlark View Post
    I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

    Regards and thanks in advance

    Mike

    155 sierra match king
    Silly boy - you were happy before in blissful ignorance. On the basis of six rounds you have pretty consistent velocity and by your own admission an accurate load. But by pursuing too much information you have let a niggling doubt which won't go away. Does the load work - of course it does.

    I made the mistake of thinking I had a good load for my 7x65R - pretty accurate and deer fall over. but then I borrow ed Bushers chronograph and found that my bullets are only doing 2,500 fps and not the 2,600 fps and velocity variation of 60 fps. I am still using the same load but I need now to get out and work up a better load - why oh why did I enquire too much????

  9. #9
    Heym beat me too it, your published velocities are pretty consistent which shows your reloading is consistent. Don't worry if they're down on book speeds, as these are often not realistic. If they're accurate and doing the job they're intended for, I'd leave it alone.

  10. #10
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    As above, if you have a load you like, don't chronograph it.

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