Powder Position

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  • Last Post 11 July 2015
billglaze posted this 09 July 2015

Just a little note for those that may be curious about the Powder Position affecting cartridge performance. Just for the fun of it, I loaded up a batch of .308 cartridges with the same 15 gr. of 3031  powder, same primers, all rounds loaded as identically as I could make them. Half I fired with the powder as far back as I could get it, and still leave the rifle in position on the bench rest.  The other half were fired with the cartridges tapped on the bullet end, to get the powder as far forward as possible. Powder to rear:    Avg. Vel. 1164 E.S. 46 S.D.14                                                   Powder to front:  Avg. Vel 1132  E.S. 53 S.D. 16 Interestingly, the slower group had a center 3/4” below the faster group. Also, both groups had 2-5 shots of the 10 (each) that went into 1". The rear powder grouped an even 2", the powder in front grouped 2-1/4".  BHN for all bullets was 20. I don't know if this information can be used, but it scratches an itch I've had for a long time about any difference in powder placement.  There is a difference.  These results are, if not definitive, at least indicative. Bill    

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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onondaga posted this 09 July 2015

http://castbulletassoc.org/view_user.php?id=5098>billglaze Thanks for the testing.

You can get that velocity in .308 with the TiteGroup you mentioned you are starting to like. TiteGroup should not have any position sensitivity at that load level in .308  .

Gary

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45ACPete posted this 09 July 2015

What about something in between? That is, rotating the cartridge with a level gun, thus distributing the powder evenly from to rear. It's what I do, mostly.

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billglaze posted this 10 July 2015

Just a guess, but what you do probably would lend consistency to performance, which is exactly opposite to what I was trying to do. I was trying to accentuate the difference, if any, in powder position by going to the extremes. I proved, at least to myself, that there is, in fact, a measurable difference between the two powder positions. We won't even get into sample size, performance of different cartridges, powders, bullet weights etc. etc. I'm aware there are a zillion variables, as to amount of difference. I just wanted to see if there was a quantifiable difference. There is. Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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billglaze posted this 10 July 2015

Gary, just as an aside I have loaded light loads in the .308 with Tite Group, and what you say seems to pan out.  5 grs. gives me decent grouping, and very low velocity, as well as good chrono numbers.  (I'm too lazy to go down 3 floors and look at my notes to get a solid number. (blush))Anyhow, John and some of the other shooters reports got me started on using some faster powders, and, so far, so good.  My new batch of 22's dropped out of the mould at a BHN of 11; a little soft for my taste.  I'm thinking of water-dropping next time, but I've got some questions about the process.  More questions later.  Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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John Alexander posted this 10 July 2015

Bill, Nice test. However, I don't think you have shot enough shots to say “There is a difference". The velocity difference is only about 2.5% and the group difference only about 12 %.

Two more ten shot groups with each position, making a total of 30 consecutive shots for each position would be a lot more persuasive -- IF the difference stayed the same.  Even that many probably wouldn't convince Joe but it would be a much stronger argument. John

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Brodie posted this 10 July 2015

I think that John has a point.  If you are going to say something a bout powder position you should be able to back it up statistically.  Also, you omitted the possibility of ignition lag.  Some powders when positioned improperly do not ignite instantly.  Of course this affects accuracy to a degree.  You might look into that if you want to say anything conclusive or important about powder positioning. Brodie

B.E.Brickey

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billglaze posted this 10 July 2015

I believe I alluded to the fact that statistically the sample was too small to be conclusive.  That is certainly the case.  I just ran this small test for my own edification; I would have probably been better off not to post something so vague and inconclusive.However, I did prove, if only to myself, that position of the powder does make some kind of difference.  At least in this one specific example. Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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frnkeore posted this 10 July 2015

Something that I think would be benefial to this test, is to include a test with the ammo shot the same way as you would normally shoot it in match conditions.

Frank

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John Alexander posted this 10 July 2015

Bill, I'm glad that you posted your test. It was a good contribution and we could use more. Your results seem to me to say -- it is fairly likely that there is a difference with the powder positioned fore and aft -- it also says that it is fairly likely that the differences are small instead of large.

Keep up the good work and when you get that Swift shooting 415 into moa ten shot groups as often as not then a lot of us are going to have to rethink the possibilities of short cast bullets in all calibers. If Ken doesn't beat you to it with his soft short heeled bullets like the 22 rfs.

John

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Brodie posted this 11 July 2015

All teasing about Statistic's Fanatics aside, I think what you have posted has merit.  It suggests that the position of the powder has some bearing on ignition.  At least that is the way I have always found it to be.  Ever since I used to load a 300gr. half jacket in front of about 45gr. of 2400.  It was an accurate load once I started to use a filler.  Without the filler the bullets printed all over the place because you were never sure when it would go off after pulling the trigger.  Brodie

B.E.Brickey

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billglaze posted this 11 July 2015

Just one more thing about this subject: although I didn't post individual velocities, (too boring) I will say that the slowest round of the “faster” group, was still faster than the fastest round of the “slower” group. You now have your algebra word problem for today's homework!

Brodie, the first time I had heard about a “filler” was ca. 1947, when a few High-Power shooters were talking about it at a Smallbore Match. These shooters were shooting Springfields and were using cast bullets for their 200 yd. stages. They were shooting the old Lyman “Squib” bullet of 169 grs. Using small charges, they were apparently not getting uniform ignition. So, that was te first time that I had heard about Cream of Wheat as a filler. Inasmuch as I was still about 4 years from beginning reloading, I never heard how it worked out. Only thing I knew: The Hardholders wouldn't be satisfied with second-best. And, they kept shooting that bullet, (known then as the 311169.)

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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Brodie posted this 11 July 2015

Bill, I only mentioned the cream of wheat to point out that keeping the powder against the primer in a bunch made all the difference in that load. Like you said I've run across the problem several times, but am unwilling to use COW as a fill even in an 06 case for fear of a pressure spike. I have not tried the new stuff Gary uses yet. Brodie

B.E.Brickey

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joeb33050 posted this 11 July 2015

Or

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Tom Acheson posted this 11 July 2015

Is there a connection here as to why military “factory” loads have powder formulated so that the top of the powder column is at the base of the seated bullet? Is the military “fearful” of the inconsistencies of powder position?

Tom

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Ken Campbell Iowa posted this 11 July 2015

old coot ... your 45 gr. of 2400 might do just as well without the filler .... or was that in a 50 bmg ? heh, that woke me up from my morning nap ...

ken

oh, and my can of that newfangled ballistic products powdered plastic is about 20 years old ... don't wanna just jump into the latest craze ... i think we casters kinda like the slower rythm of change ...

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OU812 posted this 11 July 2015

2400 works very well in my 223, but is very position sensitive. I get good grouping if I raise the barrel between shots (lots of work) to position powder. Without raising barrel I get vertical stringing (wider velocity spread).   13-14 bhn works best in my rifle.

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billglaze posted this 11 July 2015

Joeb, thanks for that extremely comprehensive table of powder positioning. This thing has gone far beyond what I envisioned it to be. It was to be just a small test to answer a simple question: Can/does powder positioning make a difference? I wondered if my careful efforts to tap the cartridge, base down, on the bench, and then to handle it carefully as it's inserted into the rifle, ever paid off. I answered it to my satisfaction: yes, care pays off. As it usually does in most things. So, I posted it as a small, casual bit of possible interest. Seems it took off from there.
(And, out of curiosity and not a little bit of awe, where does Joe get all this information?)

As far as the Government getting involved in powder position, I remember reading in the Rifleman that the M14 round, (the T65 if memory serves) came about when someone working at Springfield noticed 1/2” of airspace in the .30/06 between the powder and the bullet base, and decided to remedy that condition by shortening the case. Probably apocryphl and a in-house joke. Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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joeb33050 posted this 11 July 2015

billglaze wrote: Joeb, thanks for that extremely comprehensive table of powder positioning. This thing has gone far beyond what I envisioned it to be. It was to be just a small test to answer a simple question: Can/does powder positioning make a difference? I wondered if my careful efforts to tap the cartridge, base down, on the bench, and then to handle it carefully as it's inserted into the rifle, ever paid off. I answered it to my satisfaction: yes, care pays off. As it usually does in most things. So, I posted it as a small, casual bit of possible interest. Seems it took off from there.
(And, out of curiosity and not a little bit of awe, where does Joe get all this information?)

As far as the Government getting involved in powder position, I remember reading in the Rifleman that the M14 round, (the T65 if memory serves) came about when someone working at Springfield noticed 1/2” of airspace in the .30/06 between the powder and the bullet base, and decided to remedy that condition by shortening the case. Probably apocryphl and a in-house joke. BillI'd like to see this/my test continued. I got shut down at the range, they wouldn't let me move the rifle as described.I found that I could not: 1 move/prepare rifle, 2. chronograph and 3. shoot accurately at the same time. 

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Brodie posted this 11 July 2015

Ken, No it was a 300gr. half jacket in a .458 Win. Loading without a filler produced momentary hang fires. At least there was some lag between pulling the trigger and actual firing of the weapon. It made for a very inaccurate load. The same bullet with a case full of IMR 4198 was the greatest load I have ever used to gather mistletoe. One of those half jackets at whatever the velocity was into a branch the size of you thigh and it came right down. Brodie

B.E.Brickey

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