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brown dog

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  1. brown dog

    Book - Rifle Accuracy Facts

    Dave, I've been pondering whether to put a few books up for sale. I've got a copy. Sat on the shelf for years. Drop me a PM if it's of interest. This has prompted me to dig out a bunch of other books!
  2. What a painful argument. A whole lot of people arguing about a feqqin Velcro patch. Personally, I'm with Cetirizine. I'd be very surprised if the Black Rifle lot lied. ...but it's just a feqqin patch, who gives a feq? The fellow in the photos would laugh his tits off at the utter pointlessness.
  3. brown dog

    G22A2

    From this month's European Security and Defence Journal:
  4. brown dog

    Velocity plateaus in load testing: Why?

    If we really think we're empirically measuring deflagration characteristics being chemically changed due to tiny pressure changes that the charge doesn't 'know' it's experiencing until the pressure peak is reached - I'd have thought changed charge temp (a much bigger burn rate effector, to my brain) will likely throw the whole experiment for a ball of chalk! It'll be interesting to see the outcome 😊
  5. brown dog

    Velocity plateaus in load testing: Why?

    Written with amusing irony, but that about nails my view. I simply struggle to accept, given the huge error budget in small arms internal ballistics, how a pressure driven (by a half grain change) theoretical change to propellant chemical burn rate characteristics being postulated here -which would be absolutely miniscule in comparison to the scale of all the other factors - would be empirically observable. Any non linear observation between increasing charge and increasing vel could be down to - well, just about anything. And with the sample sizes being shown, I suspect we're just seeing single points in the normal distribution of vels at each charge weight - and taking them as centre points. I've not seen a graph plot yet that I would accept wasn't showing random variance. With a few points randomly aligning to show what the viewer's brain wants to see. Has anyone here repeated this process on discrete occasions and been able to reproduce results? [As a melancholic aside: Just occurred to me that GBal would have loved this thread and been all over it!]
  6. brown dog

    Velocity plateaus in load testing: Why?

    I'm really struggling with the idea that, working at safe pressures, fractions of a grain changes to charge weight cause significant enough changes to pressure that the propellant has an empirically observable change to the characteristics of its burn rate - but you're saying that's indeed the case?
  7. brown dog

    Velocity plateaus in load testing: Why?

    This has to be one of the most technically thought-provoking threads on here for a long while. 😊Good stuff
  8. brown dog

    Velocity plateaus in load testing: Why?

    " explanation is that unlike OCW, Satterlee concentrates on optimal bullet velocity (not charge weight, as powders will vary batch to batch) because the results are pressure dependant. Using different powders, he has achieved the same results with the same bullet provided the results are matched in velocity. " Isn't that the same as saying: In a particular rifle, with a particular bullet, once I find an accurate load, any load giving the same mv with that bullet in that gun will also be accurate ...and it doesn't get affected by which powder I use. (?) (So he's simply describing matching barrel-time) (?)
  9. brown dog

    Velocity plateaus in load testing: Why?

    Yes, and any move towards or away from the commencement of rifling will also change shot start pressure. I'm still of the opinion that charge weight (as opposed to particle burn rate) velocity plateaux are bunkum (banjo?)physics at normal pressures. But I'll be interested to read Shuggy's take on my preceding post.
  10. brown dog

    Velocity plateaus in load testing: Why?

    Shuggy, Are you not conflating the possible plateau effects on the deflagration rate of individual particles of propellant caused by additives affecting different stages of the particle's burn differently, (or even variance of through-burn particle burn rate by differing extrusion shape (piobert's law etc - increasing, steady or decreasing surface area during burn)) with a theory here, which purports that small changes to charge weight cause plateaux? As you know, we shape pressure/velocity curves with additives and varied extrusion shapes - spaghetti, macaroni, star, multicore etc , some combinations will increase rate of pressure generation continuously, some will decrease it continuously etc. I'm not surehow those burn characteristics are related to small changescharge weight, with all else broadly constant. The plateau effect being postulated in Satterlee, relates to small changes to charge weight and not rates of particle deflagration - to my mind -given that we're not talking about massive pressure excursions- Satterlee's plateaux are an unrelated idea (?) [Edit to add afterthought, thinking on this over a mug of tea: If, as is the norm, shot exit is taking place after all-burnt has occurred, additive or extrusion related changes to particle burn rate must surely be irrelevant (?) and they'll only be seen in projectile performance in terms of mv attainable within a given pressure (?). ]
  11. brown dog

    Velocity plateaus in load testing: Why?

    The reason quickload doesn't show mid curve velocities plateauing with increasing charge weight, will be because, excepting empirical small-sample experimental and statistical error, it won't be happening. This is like a school physics experiment where students measure how far a toy car rolls off a ramp and draw a graph of the results. As they raise the end of the ramp one book at a time, the graphed outcome will (should) show that the car will go further for each height raise - more energy in, more car velocity. End of. - but not all the graphs produced will show that. A sneeze, a push, aruler error, whatever will mean some get the expected graph, and some don't. But the science doesn't change. I just googled Satterlee's theory: "The following quote from Scott summarizes a key observation with load development, “Im not sure it is optimal charge weight at all but optimal velocity for the bullet weight that determines barrel harmonics. The reason I say this is because I can get the exact same great results in a velocity node using seven different powders. As long as I keep the bullet going the same velocity from powder to powder I get the same result. Powder charge may be slightly different but as long as I’m in the velocity happy place for that bullet and my cartridge, powder is secondary.” " Some confused concepts in there. He's describing a bullet velocity sweet spot. And relating it to harmonics. And saying that harmonic sweet spot can be hit with a number of different powders. And because of that, he's relabelling OCW as optimal bullet vel. Umm. I think? So, back to this:
  12. brown dog

    Velocity plateaus in load testing: Why?

    Yes, and OCW makes physical and chemical sense: The link between barrel time and harmonics is a cause of nodes at the target that's easy to account for. I haven't read about 'saterlee' beyond this thread; but, as per the OP's question, I'd be interested in hearing why the postulated vel plateaux are thought to be happening. (I acknowledge Andrew's point about diminishing returns at the upper ends, but I believe this Saterlee is postulating mid curve vel nodes, akin to OCW nodes...and these make no physical/chemical sense.) For example, artillery and mortar ammunition generally has charge increments. Nowhere do the velocities 'plateaux' as the increments are increased. More chemical power means greater vel. More grunt, more speed. What's the vel plateau theory?
  13. brown dog

    Velocity plateaus in load testing: Why?

    To the original question: I've only ever heard of OCW in the context of harmonics etc, and that makes total ballistic sense to me. The multiple 'velocity plateaux' concept is a new one on me; which makes no sense. My kneejerk would be to wonder if it's a process defined/developed by someone who didn't quite understand OCW?
  14. brown dog

    The Fix from Q

    Bloomin' awesome! - really taken with the concept behind that rifle.
  15. brown dog

    3D Prints

    Eye opening stuff! - I know nothing about these capabilities.
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