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Thread: Why use larger grain BP

  1. #1
    Boolit Buddy
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    Why use larger grain BP

    I know that the larger the grain of BP the slower it burns. However, most shooters with smaller cartridges always talk about wanting to get as much powder behind the boolit as possible. With smaller grain powder, there must be less air space between the grains. Shouldn’t that enable you to get more powder in the same case and more power?

    Dose the slower burning powder accelerate slower giving a better outcome like with smokeless? Do you need the air space between the grains? I’m just wondering and would like to understand more about how BP works.

    Thanks

  2. #2
    Boolit Grand Master

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    I believe with the coarser granulations you get a more consistant stack or fill of powder and more consistant compression. nother thing to remember is most are looking to be in the 1150=1200 fps range and on big cases the coarser granulations tend to run there with the proper compression. Coarser granulation have fewer fines and finer granulations fewer coarse. The fewer fines make fill level more even height. Buffalo Arms has a chart showing granulation size and percentages of other sizes in a lb of a given rating.

  3. #3
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    I’ve heard that Swiss powder is often thought to be better because the are a more similar size. Is that true?

  4. #4
    Boolit Master
    JSnover's Avatar
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    Sometimes I wonder if the slower burn also creates a smoother pressure curve.
    Warning: I know Judo. If you force me to prove it I'll shoot you.

  5. #5
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    Quote Originally Posted by JSnover View Post
    Sometimes I wonder if the slower burn also creates a smoother pressure curve.
    That’s what I wonder too.

  6. #6
    Boolit Master


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    My daughter and I like the coarser grains as you get less efficient burn and more sparks at night shoots!

  7. #7
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    I have a rather new Marlin 336 Cowboy in 38-55. I really need to shoot it more. However for fun and giggles I load up 20 to 30 BP fueled cartridges and they stay away from the rest of the herd. I load Swiss 1 1/2 charge a .60 thick felt or paper wad and low compression with a 245 gr boolit.

    The roar of the holy black igniting and the flame and heavy white smoke will really draw a crowd on the 60 place firing line on a weekend day.. I load up the mag to the max and have at it and in no time a crowd materializes around me and I get peppered with questions. I might go out and get a can of Swiss in a coarser blend. Maybe it will spark more to make a decent display in the sunlight. If that does not work out then they will go into 50-90 Sharps hull and will work with my Winchester 1885.

    I don't mind cleaning this rifle after using black powder as it is soothing to my soul and comforts me. The smell of Hoppes #9 and my jug of Ed's Red along with a hot cup of coffee laced with bourbon and a stack of cookies will fuel my cleaning chores. At the range immediately after firing I drop the expended cartridge cases into a water jug of the gallon size. In the jug is water and a decent concentration of Dawn dishwashing soap. This kinda kills off the corrosion aspects on the cases and keeps the fouling soft and easily removed when I run the cases thru SS pin media, Dawn, Lemishine and water. I make sure to give them a decent rinse and they go into the oven at 125 degrees for an hour. When removed they are wiped down with staight Ballisterol on a soft rag. This just removes any water stain and put a coating on the brass that will impede further degradation of the decent finish on the brass.
    Pax Nobiscum Dan (Crash) Corrigan

    Currently casting, reloading and shooting: 223 Rem, 6.5x55 Sweede, 30 Carbine, 30-06 Springfield, 30-30 WCF, 303 Brit., 7.62x39, 7.92x57 Mauser, .32 Long, 32 H&R Mag, 327 Fed Mag, 380 ACP. 9x19, 38 Spcl, 357 Mag, 38-55 Win, 41 Mag, 44 Spcl., 44 Mag, 45 Colt, 45 ACP, 454 Casull, 457 RB for ROA and 50-90 Sharps. Shooting .22 LR & 12 Gauge seldom and buying ammo for same.

  8. #8
    Boolit Buddy
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    Quote Originally Posted by Crash_Corrigan View Post
    I have a rather new Marlin 336 Cowboy in 38-55. I really need to shoot it more. However for fun and giggles I load up 20 to 30 BP fueled cartridges and they stay away from the rest of the herd. I load Swiss 1 1/2 charge a .60 thick felt or paper wad and low compression with a 245 gr boolit.

    The roar of the holy black igniting and the flame and heavy white smoke will really draw a crowd on the 60 place firing line on a weekend day.. I load up the mag to the max and have at it and in no time a crowd materializes around me and I get peppered with questions. I might go out and get a can of Swiss in a coarser blend. Maybe it will spark more to make a decent display in the sunlight. If that does not work out then they will go into 50-90 Sharps hull and will work with my Winchester 1885.

    I don't mind cleaning this rifle after using black powder as it is soothing to my soul and comforts me. The smell of Hoppes #9 and my jug of Ed's Red along with a hot cup of coffee laced with bourbon and a stack of cookies will fuel my cleaning chores. At the range immediately after firing I drop the expended cartridge cases into a water jug of the gallon size. In the jug is water and a decent concentration of Dawn dishwashing soap. This kinda kills off the corrosion aspects on the cases and keeps the fouling soft and easily removed when I run the cases thru SS pin media, Dawn, Lemishine and water. I make sure to give them a decent rinse and they go into the oven at 125 degrees for an hour. When removed they are wiped down with staight Ballisterol on a soft rag. This just removes any water stain and put a coating on the brass that will impede further degradation of the decent finish on the brass.
    What type of a greese cookie do you use if any? Thanks.

  9. #9
    Boolit Master
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    The only reason to use different granulations is to maximize accuracy, minimize fouling, and maybe to reduce recoil.

    Sometimes Fg can work very well, even in small cartridges like the .32-40.

    In my .45-2.6" paper patch rifle I only use Swiss Fg. In my .45-2.4" paper patch rifle I can use either Fg or 1.5Fg granulation as long as it's Swiss powder. Goex Fg seems to have a slower pressure build up so it only works with a lube cookie in my rifle.

    Chris.

  10. #10
    And for a same volume of powder, the coarser granulation will weigh more...

  11. #11
    Boolit Master
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    Quote Originally Posted by Gunlaker View Post
    The only reason to use different granulations is to maximize accuracy, minimize fouling, and maybe to reduce recoil.

    Sometimes Fg can work very well, even in small cartridges like the .32-40.

    In my .45-2.6" paper patch rifle I only use Swiss Fg. In my .45-2.4" paper patch rifle I can use either Fg or 1.5Fg granulation as long as it's Swiss powder. Goex Fg seems to have a slower pressure build up so it only works with a lube cookie in my rifle.

    Chris.
    major reason for coarser granulation is to reduce peak pressure in older firearms (in particular)

  12. #12
    Boolit Master
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    Quote Originally Posted by martinibelgian View Post
    And for a same volume of powder, the coarser granulation will weigh more...
    Thats a theory - sounds right - has not been my experience over many years - not any appreciable difference anyways
    I think that we have "compensating errors" at play here ---larger airspaces between coarser heavier grains - finer powder settles better - end result = no appreciable difference.

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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