Compressed Loads: Need Schooling Please

Discussion in 'Reloading' started by Kwesi, Feb 26, 2017.

  1. Kwesi

    Kwesi

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    To the best of my knowledge I've never loaded any compressed loads. At least the manuals did not list them as a "c". OTOH even Hornady's 8th edition doesn't even list 14.9 as compressed (I'll assume that it is!) After following a few threads on loading AA9 with 180 200 XTP's I'm confused. I laddered up using virgin Nickel Starline 10mm brass @ 12.6, 12.8 and 13.0 grains ( 1.260) which is well below Hornady's max load of 14.9gr. Other manuals suggest a much lower max.

    Now to the confusion: some have stated that 13.0 is a compressed load and in the same post referenced that the HP petals were a bit crushed in the seating process. Are these two unrelated statements OR are they suggesting that the deformed petals suggest a compressed load?

    I'm using a Redding Micrometer Competition Seating Die with zero deformation as it seats on the ogive. How does one determine that a load is compressed?

    One other question: after applying the taper crimp the rounds COAL increased .001-.002. Why? I pulled a test round to see if there were any signs of over crimping but the base of the bullet did not have any pinching.
    Thanks!
     
  2. WeeWilly

    WeeWilly

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    I am not sure there is a formal definition of compressed, other than if after being settled, the powder volume in the case is more than the case capacity after the bullet is seated to your target OAL.

    Deformation of the bullet when seating is a pretty good sign you are compressing the powder.
     

  3. Kwesi

    Kwesi

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    So are you eyeballing the settled powder level to where you expect the base to seat?
     
  4. Taterhead

    Taterhead

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    You could measure the distance from the top of a settled charge to the case mouth. Then calculate the length of the part of the bullet that is seated in the case. That would be case length + bullet length - COL. Compare the values.
     
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  5. fredj338

    fredj338

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    If you are loading slow powders like aa#9, i wouldnt sweat compression. Most of my rifle loads run on compressed loads of slower powder. With heavy for caliber bullets in handguns & slower powders, you are almost always compressing some. Even my 9mm minor loads running 147gr LRN is very slightly compressed.
    The bullet moving slightly on crimping isnt odd especially if you seat & crimp in one step.
     
  6. Kwesi

    Kwesi

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    Thanks! I seat & Crimp in separate dies.
     
  7. Kwesi

    Kwesi

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    Duplicate post
     
  8. WeeWilly

    WeeWilly

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    Frankly, I never really paid any attention, but you certainly can determine where into the case the seated bullet ends, just make a dummy round. Or settle the powder, mark the side of the case then seat the bullet. If the crease the bullets base leaves is below the line, you know you compressed it.

    I never really understood the whole fascination (or fear) some people have of compressing powder. I have never had a single bad thing happen when I had compressed a load (other than meplat deformation on a bullet in extreme cases with rifle).

    I am compressing a 380 load right now, I have been working on using Unique. I literally have a full case, right up to the rim, so I know it is compressing the powder when I seat the bullet, I am guessing it must be 20% compressed.

    I bet every single shotshell I ever loaded compressed the powder to the extent it could be compressed (ball doesn't compress all that well).

    I suppose alarm bells go off in people's heads when they see a "C" next to a load weight, kind of like, "why are they telling me this?, it must be bad!", when all they were trying to tell you is that a crunching sound when seating the bullet is normal for that load. :)
     
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  9. fredj338

    fredj338

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    The fear of compression of powder comes from all those warnings about seating a bullet too deep & raising pressures. It is all powder dependent. I wouldnt want to compress RedDot in a 9mm, but unique is almost always 100%+ compressed.
    Btw, flattening of the bullet nose can also be thicker brass.
     
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  10. Kwesi

    Kwesi

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    So what causes the bullet COAL to increase .001-.002? Possibly Nickel vs regular virgin brass?
     
  11. fredj338

    fredj338

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    That is insignificant, the bullet nose profile can vary that much. Mixed brass also contributes to little changes in OAl. If you are deforming the nose half the thickness of a sheet of paper, who cares. DOn't over think this Kwesi
     
  12. Kwesi

    Kwesi

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    Thanks fred. Curiosity.
     
  13. A6Gator

    A6Gator

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    You're right. The open class guys I know who shoot 9 major do it pretty much all the time. Driving a 124gr pill at around 1370fps takes a lot of powder!