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Thread: Why does one load make my primers so flat with BP

  1. #21
    Boolit Buddy
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    Quote Originally Posted by bigted View Post
    Id be very proud to hear your IMR 4198 loads. I have heard that you can compress this powder and rel #7 like black powder. Any truth to this?
    No. You are using a 40% by weight equivalent of 4198 to BP. It wound up being about 26 grains of 4198 for the load I was using. This left a very large amount of empty space in the cartridge, which resulted in radically different performance if you first tilted the gun either up or down before firing: With the cartridge pointed down, the powder was by the bullet and had very poor ignition. With the gun first pointed up, the powder was next to the primer and shot fairly well.
    I wound up stuffing a small roll of toilet paper over the powder column and then seating the bullet over this.
    Now I'm getting good ignition, and fairly consistent performance.
    I don't think it's a good idea to compress smokeless powder. There may be instances where this is OK, but I know with voluminous powders like Trail Boss, this radically changes their ignition timing and pressure curve, resulting in drastically raised pressures.
    This is NOT what you want when using guns dersigned for BP, especially 150 year old originals.. You want to mimic the performance (pressure curve and timing) of 2F or so BP...

    -Tom

  2. #22
    Boolit Master Lead pot's Avatar
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    Quote Originally Posted by bigted View Post
    Not so in my experience concerning super compressed loads of BP.

    What i have found upon taking them back apart is that the compressed powder column does not compress clear thru the whole charge. What i found is the top quarter to half was so tight i needed my picks to uncompress and remove the charge from the weapon ... but below this i find my powder to be lose still and not crushed like the top half gets like.

    This leads me to believe that the bottom of the charge gets plenty of fire from standard primers. Way easy to lite and immediate smoke and fire

    This is my experience with 38-55, 45-70, 45 Colt, and 357 mag as well as 43 spanish and 38 WCF.
    Here you go Ted.
    This is what compressed black powder looks like from .050" tp .500"


    Click image for larger version. 

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  3. #23
    Boolit Master
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    Leadpot, thanks for the show n tell. I have never used 1/2 inch of compression and find your pictures to varify my experience, the bottom of my compressed loads seem to remain fairly lose and my conclusion is therefore kinda shown in your photo as being lose enough for the spark from my regular primers to penetrate and cause a generally good ignition. As the boolit moves out of the case, the volume gets larger quickly and the pressure drops as the bulk of the compressed "plug" ignites.

    In my understanding ( if correct) the powder [ black ] is much harder to cause such pressure as to flatten a primer. Altho i will not present a "cause" for the op's flattened primers as i have not experienced this myself.
    WHEN ALL IS SAID AND DONE...MORE WILL BE SAID THEN DONE

  4. #24
    Boolit Master Lead pot's Avatar
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    Ted I have never seen pressure signs with a black powder rounds even with my .45-120 or the .50-90 using 118 gr of 3F and a 720 gr bullet using regular large rifle primers or Magnum for that matter.

  5. #25
    Boolit Master
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    This reflects my findings as well. In my humble experience, i have never seen flattened primers indicating pressure when loading black. I also have a 45-120 and i have loaded it with 135 grains 2Fg and no pressure signs. My heavy 55 grain loads in my 38-55 do not do so either. I have compressed 40 grains of both 2Fg and 3Fg into 45 Colt cases under a 255 grain Lee and lotza recoil but again, no flattened primers that would indicate pressure.

    I wonder about the primer channel. This maybe could allow a flattened primer shooting a well compressed black load with a enlarged primer channel.
    WHEN ALL IS SAID AND DONE...MORE WILL BE SAID THEN DONE

  6. #26
    Boolit Buddy
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    Quote Originally Posted by Lead pot View Post
    Here you go Ted.
    This is what compressed black powder looks like from .050" tp .500"


    Click image for larger version. 

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    Further to that .. I have dug the powder charge out of some loads for my 45/75 and find the variation in compression down the charge from neck to base even more different in the bottle neck case than in a straight side case (45/70) --- could be part of why the bottle necks have a rep for being more difficult to get shooting right?

  7. #27
    Boolit Buddy
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    I have observed the same uneven compression of black powder in my 45 Colt cases.
    The powder was packed much looser at the bottom of the powder column, but it was still very very crowded the granuals were packed close touching just not compression welded together like the powder granules at the top of the powder column. The looser packed BP at the bottom does not compare to a virtually empty 45 Colt case when charged with just 9.0 grains of smokeless Hodgdon CFE-Pistol powder. In the smokeless scenario the primer flame jet flashes through the hole completely unobstructed as the powder is most likely up near the bullet base or laying flat on the bottom of the case. The near empty case provides a volume of space for the bulk of the primer fame jet to be absorbed into, there by reducing the back pressure force that slams the primer back against the recoil shield. In the smokeless case the primer back slam is gentle, in the BP case the back slam is much more violent with a near total reflection of primer gas pressure.
    I suspect that is what’s causing my primers fired in BP charged cases to be flat with very slight edge riveting, whereas the primers fired in smokeless cases still have rounded edges.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check