Is cleanliness more from pressure or complete burn

Discussion in '10mm Reloading Forum' started by OhioGlockMan, Feb 14, 2013.


  1. Ok I got thinking about how so many people post on here that they get a really dirty burn and/or flakes of unburnt powder in barrel and action of gun when the pressure is low. I got thinking about this issue when reloading shotgun shells with our favorite 10mm powder, blue dot. The 12 gauge only operates at like 10,000 PSI, ultra low pressure compared to our 10mm loadings, yet the inside of the barrel is very clean after shooting shells with blue dot, appears to burn real clean overall and no flakes of unburnt powder anywhere. It seems to me that you could have a real high pressure loading with really short barrel and get the dirtyness in that case, right? I'm just curious to hear thoughts from you all on this issue.
     

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  3. _The_Shadow

    _The_Shadow Ret. Fireman

    4,498
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    Shot gun primers are very strong as compared to the pistol primers, the Brisance of the 209 yields better ignition. I have seen some unburned flakes in some of my 12 ga loads but I can argue with there performance.

    I do sometimes go for a magnum primers for the 10mm because I think think the full case needs better ignition even if I drop the charge slightly to accomadate for the primer's strength.
     

  4. Taterhead

    Taterhead Counting Beans

    3,284
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    A lot of powders clean up with pressure. Pressure and a good burn are typically correlated. Blue Dot is a great example of a powder that is filthy dirty at modest pressures, but spotlessly clean at closer to max pressures. For a given cartridge, the slowest burning powders tend to burn cleanest at higher pressures. That is why when I download, I use a quicker burning powder.

    I, admittedly, have nothing to add regarding shotshell loading since I have no experience there.
     
  5. Shadow and Taterhead,

    I'm just very curious if this clean burning has more to do with the powder being fully burnt more then it does pressure, the thing that got me thinking about the shotgun thing is its only operating at 10,000 psi but the long barrel lets it burn completely. The slow burning powders use much larger amounts of powder, so for a given barrel length less will get burnt, that quickload software is very good at predicting the percentage of powder burnt and when u put in a longer barrel more burns. Another thing that got me wondering is I;ve seen people post on here about how they shoot their hot blue dot loads out of the factory length barrels and get flakes of unburnt powder but in the 6 inch aftermarket barrel they don't get that at all. I'm very curious now if you had a carbine length barrel and used one of these slow powders at a reduced pressure loading if it would be clean just simply because it had enough barrel length, I'm going to try this with my 357 carbine and a reduced level charge of 2400
     
  6. _The_Shadow

    _The_Shadow Ret. Fireman

    4,498
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    One thing I think also helps, is that the flakes are touching or slightly compressed to achieve ignition of all the flakes which in turn adds to complete and cleaner burn.

    This igniting of all the flakes probably what leads to cleaner burn, here is a thought, if the charge is not as compressed, the primer may blow the flakes around and start bullet movement before they all ignite. Leaving some dirtier conditions and unignited flakes.

    Even the shotgun shell with today's compressible wads help hold the charge in place.
     
  7. well how is the .45 auto and .38 special able to get a clean burn then? I mean some loads burn dirty and some real clean, but both operate at real low pressures, and both generally have a lot of airspace, epecially the 38
     
  8. _The_Shadow

    _The_Shadow Ret. Fireman

    4,498
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    OhioGlockMan, mainly I'm referring to Blue Dot only in the above statement, the Blue Dot loads I use in the 45 ACP and 38's are full or slightly compressed loadings that I use.

    However the faster burning powders do offer advantages to using less powder and also designed to burn cleaner for the most part.

    Some primers seem to be dirty burning, as is evident by the reloading process...

    Cast bullets can add to the dirty conditions as lubes can leave some deposits.
     

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