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Thread: Varying powder column heights. Need help/advice

  1. #1

    Varying powder column heights. Need help/advice

    The way I have been charging my .45-70 case were as follows. Throw the initial charge into a pan, place the pan on the Gempro 250 and trickle up to correct weight. The place my case on a electric engraving pen turn on the vibrator and slowly pour the powder int the funnel that’s on the case. I then measure the powder column height from mouth to a thin plastic “wad” that sit on the powder. If it not deep enough I vibrate again ‘till it is the correct height. Yes, very slow, but the column height is very close to nominal plus or minus .004 thou. The past few days I made up a vibrating drop tube gizmo. I now can easily get 83 grains of Swiss 1 1/5 in an unfired Starline .45x70 case, so I’m getting more compaction with the vibrator/Drop tube set up. The problem now is the height variation can easily exceed plus or minus .012 thou. The top funnel has a metering hole that is .061”, Smaller and the powder clogs on occasion, larger and the powder column variation increases further. I have a screen just inside the top funnel that I think helps cut down on poring variations. I hold the case in touch with the drop tube, it has an inverted cone the the case mouth rests against. Then I pour the powder into the top funnel and turn the vibrator on for a mental count of 8. With this procedure I get the plus or minus .012 inches. The way it stands now, if I set the COL to the nominal height my seating can go to .012 compression to .012 air space. Any hot ideas about cutting down on the variations in powder height ?
    What are you fellows getting for powder column variation? Should I be worried about this as in decreased accuracy. I’m thinking I may not see any change in group size inside of 600 yards but then I don’t have the experience to make any sort of WAG.
    As an aside I’m going to pick up a RCBS Chargemaster Lite tomorrow and my Gem Pro 250 still drifts so I constantly need to re zero.
    Thanks Folks

  2. #2
    Boolit Master
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    After I insert the wad, I use a powder compression die to make them all the same depth. That means the powder will be compressed slightly more.
    Last edited by upnorthwis; 09-17-2018 at 10:47 AM.
    The only amendment the Democrats support is the 5th.

  3. #3
    Boolit Master

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    3 What your seeing is some settling of the fines in the powder as its ran thru the measure. Not usually enough to matter but it does change how the powder weighs and settles in the case. More of the finer granuals settles and sits closer together leaving column lower slightly. Powder can be screened to remove more of the fines if needed.

    I trickle slowly thru a 36" drop tube into case, hand set a .060 rubber fiber wad onto the powder then compress to depth with a die. this takes the variation out of the powder column.

    To test set aside 10 rounds with perfect powder column heights and 10 rounds that vary the max amount. Shoot them for group and chronograph see what they tell you its does.

  4. #4
    Boolit Master
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    Here is how my mentor, Doug Knoell told me he did the powder loading. First figure overall length with the bullet you plan to use and take 1 to 3 thousands off from when it touches the lands. When the load was being worked up the amount of compression would vary but OAL was always the exact same. I finally figured that 68 grains of Goex FFG (volume equivalent) was what worked best out to 800 yards (longest I could shoot) so I loaded the powder with short drop tube, put in the wad (milk carton) and compressed until I got to the OAL I needed. I would pull the bullet and put in the news paper wad and put bullet back in and measure. Each load was then done this way and each OAL was measured to insure correct powder compression.


    Now you need to know I never won any cartridge matches BUT 'ol Doug Knoell won quite a few!
    John

  5. #5
    I neglected to mention that the same charge is run through the vibrator/drop tube and that is what is giving me the wide variation of powder column height (PCH). That should, I think, take care of any “fines” that may be in that one charge. Sometimes I’ll get a few PCH that only varies by a few thousandths then, for some unknown reason, I get much larger swings in PCH. I’m trying to find out why I’m getting those swings in PCH with the vibrator/droptube contraption I made. I think I may try just the drop tube with some screen baffles and see what happens. BTW Oldracer, these are bore riding PP bullets.
    Thanks Richard

  6. #6
    Boolit Master

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    Quote Originally Posted by flatsguide View Post
    ... As an aside I’m going to pick up a RCBS Chargemaster Lite tomorrow and my Gem Pro 250 still drifts so I constantly need to re zero.
    Thanks Folks
    had the chargemaster when i was doing smokeless, is it good for bp?

    IMO, the gempro 250 is still the Best .02 grain scale, but yep it's delicate and can be finicky, but when it works it's super fast and accurate. make sure it's on a separate table to isolate vibrations. and it's also very sensitive to air movement. when you first turn it on, walk away and let it sit a bit, get acclimated to the surroundings. if immediately, or after a few seconds, it increments some tenth grains on its own, turn it off, and back on. once it's holding zero, yer good to go but still observe vibrations and air movement. when mine burns out, as did my first after about 6 years, i'll buy another, it's that good (at least to me). another .02 grain scale is the jennings mack 20, lots cheaper than the gempro, dunno if it's still being offered, i have one as an immediate back up, which is a backup to an rcbs analog scale

  7. #7
    Boolit Master
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    Humm Richard, I would imagine that the OAL might be longer since the nose of the bullet is further in? My 5 muzzle loader slug guns shoot both paper patched and grease groove and are all bore riding bullets so I an familiar with that. In any case as I mentioned OAL is the important thing. The other thing I saw here is every one is talking powder weight and I was taught to measure volume weather in a cartridge or in my muzzle loaders.
    John

  8. #8
    Boolit Master

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    My gem pro 250 also came with a anti vibration mat for it to sit on that helps it some. mine does good on maintaining zero.

    My early rcbs auto dispenser trickler unit and separate scales had a warning not to use BP in it. But also would take a long time for it to dispense a 70-80 grn charge complete.

  9. #9
    Oldracer, I’ve always used volume in my muzzle loaders in the past, but for no other reason than most, if not all of the competitive shooters, weigh each load from what I gather. Also there is a lot of emphasis on powder compression or lack of it; that tell me that it is also important to have a consistent PCH and I’m trying to minimize that variable. I am very new at BPCR loading/shooting and lack the knowledge on what is or is not important to obtain the best accuracy possible out of the rifle (Getting the best accuracy out of the nut behind the gun is another matter entirely, lol.).
    Country Gent, RFD ,
    My Gempro250 uses the anti vibration pad but still after being on for a couple of days the tare drifts by a few tenths pretty soon after zeroing it out. So I’m re-zeroing often. I’ll try cycling it on and off.
    I just got the RSBS Chargemaster Lite I hope it will throw 80 gns a black in thirty to forty seconds or so.
    Thanks guys.
    Richard

  10. #10
    Boolit Master Dan Cash's Avatar
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    Doing all of this makes me think you seldom actually shoot anything.
    To paraphrase Ronald Reagan, the trouble with many shooting experts is not that they're ignorant; its just that they know so much that isn't so.

  11. #11
    Boolit Master

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    On my older version you could drop a charge light by 5 grns or so in the pan and then hit the start button it trickled up the last little bit quickly. 5 grns or so it started with the high speed tube running and finished with the slow tube. Much closer on the drop and it only ran the slow tube taking longer. I would check the instructions manual for warning against using BP in it

  12. #12
    You are absolutely right Dan! I seldom get to shoot anything, but somehow I did managed to shoot my way into third place last month at a NRA Silouette shoot , only the second time really shooting this rifle in “anger”. So you are spot on when you say “makes me think...” With your insight, possibly, you could help me out with this PCH problem I’m having. You would really be doing me a favor by solving this, along with any other “words of wisdom” you care to share and then this eighty year old guy could get out and shoot more often.
    Regards, Richard

  13. #13
    Country Gent,
    Thanks for that info...I’ll give that a try on my Chargemaster.

    The wa4ning about BP is probably lawyer speak. Have you seen this? Interesting.
    http://www.ctmuzzleloaders.com/ctml_...ks/sparks.html
    Thanks Richard

  14. #14
    Boolit Master

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    i used my chargemaster strictly for smokeless and when that white powder passing fancy of 4 or 5 decades ended, i sold it off right quick. it is not meant for black powder, despite my belief in the bp sparking tests. i'm also of a mind to keep things as simple as possible, whilst achieving good results. i've used many Many different powder weighing and charging methods, and the easiest/quickest for me is using lee scoops into a brass pan sitting on the gempro 250. i've made some really tiny scoops out of .22rf brass and bamboo skewers and it didn't take long for me to get really accurate at using these measures along with the scale. but, to each their own, it's all good.

  15. #15
    Boolit Master
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    Quote Originally Posted by oldracer View Post
    Humm Richard, I would imagine that the OAL might be longer since the nose of the bullet is further in? My 5 muzzle loader slug guns shoot both paper patched and grease groove and are all bore riding bullets so I an familiar with that. In any case as I mentioned OAL is the important thing. The other thing I saw here is every one is talking powder weight and I was taught to measure volume weather in a cartridge or in my muzzle loaders.
    John
    Me being strictly a hobbyist (competitive) and my only BPCR a C Sharps 1874 /45/70 I wonder if OAL is that important in my PP chamber ?Seems my issue is also powder comp (it varies slightly),I use a cheap RCBS Range master 750 and trickle manually to get finished weights . As far as OAL I figure when I seat the load (JIM443530E),2 wraps 9 LB that boolit seats the same in that PP chamber every time (close), my thinking crimp is not an issue as it so light (my thumb is weak) Ed

  16. #16
    Edward, I use the same bullet that you use and am getting around 1.3” groups at one hundred. Like rfd I use a Gempro250 so getting accurate charges are not the problem just the inconsistent powder column heights. As someone suggested I need to find out if variations of powder charge by plus or minus .015” really make a difference or is it lost in the noise. Anyway I really enjoy tinkering and loading good ammo is part of the fun as rfd says.
    Thanks Richard

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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