Velocity change with powder position in 44 mag.

[earlmck]

I had some loads to test today, all light cast bullet loads with light charges of Green Dot powder. Set my chrony up on the camera tripod out in front of the table so I could chronograph while I shot for group.

On the first string I was perking along with a fairly decent velocity spread going when I stood up to reposition my chair. That next shot chronographed about 125 fps slower than the others had been going. I belatedly realized I had shot that one after having pointed the barrel down so that the powder would be positioned up near the front of the case by the bullet. So after that I paid attention to getting all the shots off after raising the gun up so powder was for sure back by the primer.

Then after each string of 5 shots I would shoot one shot where the barrel was tipped down to put the powder to the front. It seemed to me these "down" shots were running at least 100 fps slower than the shots from the "up" position. No big surprise, we all know small charges of powder leave you with a position-sensitive load.

For my last string I went ahead and did 5 shots where the powder was positioned at the "down" position. The load was the 205 grain Lee RNFP sized .431, 7.2 grains Green Dot powder, Federal small pistol magnum primer (which I had used with the thought that the magnum primer might reduce the position-sensitivity of this light load). The "up" shots went 1184 +/- 19 fps; The "down" shots went 1087 +/- 17 fps. If I mixed the two sets of data to give a 10 shot string I ended up with 1136 +/- 54 fps. (Rossi levergun, 24" bbl).

I thought this was interesting that the forward-positioned powder charge had virtually the same shot consistency; it was just 100 fps slower than the rear-positioned charges. And the group? Yep, the forward-positioned charges gave me virtually the same (even a slightly better) group than the rear-positioned.

My previous assumtion was that you would get a considerably greater SD with forward-positioned powder and a poorer group. The things you find when you put your assumptions to the test!

[AJMD429]

I found a website with lots of "powder position" and "ambient temperature" data on it about ten years ago, but haven't been able to find it. There were probably 20-30 of the more popular cartridges listed, with data from the poster's own chronograph, so it wasn't a 'commercial' site.

I know the military studies the temperature stuff, and suppose they load so that their powder choice will nearly-fill the case, but sure haven't seen any other published "powder position" data. As I recall, SOME of the powders, even with partial-fill loads, were NOT position-sensitive, but others were.

[Malamute]

Very interesting, though doesn't surprise me too much. Ive experienced noticeable changes in sound of report with different angle of the barrel when shooting various varmints. One round ball load in 45-70 with I believe 6 1/2 grs Unique and no Dacron positioning material pooted out the barrel and bounced off a fair sized rattlesnakes head. It seemed to annoy him. Shooting upwards at grouse it was fine. I went back to using the Dacron fluff positioning material for all my extra-light loads after that. Have also had very noticeable vertical stringing when shooting lighter bullets in 45 Colt with mild/moderate charges compared to full weight bullets. Probably wouldn't ever notice it up close, but at 200 or so it was very noticeable.

[AJMD429]

Some articles I found, but haven't had time to read yet...

• http://www.handgunsandammunition.com/re ... ocity.html
  
  http://reloadingtips.com/pages/powder-position.htm
  
  http://forum.accurateshooter.com/thread ... e.3892103/
  
  http://www.thehighroad.org/archive/inde ... 36204.html

[earlmck]

Interesting reading, Doc. From reading your first reference it looks like the article we need is Ken Ohler's in Shooting times, 4/07 which I didn't have any luck finding.

I was most interested that the "reloading tips" fellow found no position sensitivity at all with 40 to 45% density Unique or Bullseye but did find a bit with an 80% load of slower powder. I'm sure after his tests he is convinced that there is no such phenomenon. And he did such a comprehensive job of testing, with 10 shots each and with positions back, forward, and level. At least he says he did: this kid is thinking "dry lab" since this is so opposite of my own and others findings.

I looked at my post again an noticed an error -- I said I used Federal small pistol magnum primers in my 44 mag loads. Obviously those would not stay in a large pistol style case. No, I used those Fed spm primers in the 454 Casull I was also shooting yesterday. The 44 mag got CCI Lpm primers.

With the 454 Casull I didn't do a string with powder postitioned forward (didn't have enough loads) but for two different loads from it I did shoot one round with the powder forward-positioned and those were both somewhat more than 100 fps slower than the rear-positioned chronograph string was averaging.

I remember that a few years ago I chronographed one my 30/30 loads using 5744 with loads positioned forward vs. back (5744 is one of those powders supposed to be less position-sensitive). I can't find a record of my findings but I do remember that there was a noticeable difference, though I'm pretty sure it was not anything like 100 fps. That particular load of 18 grains 5744/170 grain FNGC bullet is about a 60% load density and is one of my old stand-bys and always shoots well. I'll have to test it again sometime and record the results this time.

[6pt-sika]

I had issue or I thought I had issue with the powder position in cast bullet 45-70 loads using SR4759 about 15 years ago . A lot of what I read said use some type of filler and a lot of other stuff I read said if you used the polymer filler they suggested more then likely you'd have a build up ring from this stuff melting .

SO I used SR4759 without any polymer filler and as you mentioned I would always try and lean the case back for powder positioning . And later after reading Venturino I went to XMP5744 and had no problems . Truth of the matter is , I never had problems with the position of SR4759 I was just told I did .

For my part with 44 MAG loads cast jacketed or otherwise I generally load the case full with H-110 or W296 so I've not had or seen what you asked about . And since I got away from XMP5744/SR4759 I've not had problems in the 45-70 or 444 be them actual or perceived . With H322 , RL-7 and IMR8208 you can do quite a bit with 444 or 45-70 cast loads .

[Griff]

I get velocity fluctuations with light loads in the 45Colt under about 40% of available volume. A couple of common powders give variance with more capacity filled, most less. Light bullets and light powder charges exacerbate the problem; go figure; you're increasing the capacity with most light for cartridge bullets.

[southfork]

So why Green Dot powder? What are the good points of that particular powder in 44 magnum loads for a '92 Rossi? I have recently purchased a Rossi 44 magnum, that's why I ask. I'm trying decide what powder to use when I starting reloading for mine.

[earlmck]

So why Green Dot powder? What are the good points of that particular powder in 44 magnum loads for a '92 Rossi? I have recently purchased a Rossi 44 magnum, that's why I ask. I'm trying decide what powder to use when I starting reloading for mine.

The attraction to Green Dot powder for me is that I still have 9# of the stuff remaining out of a 25# keg I bought about 40 years ago. And it is about the right burning speed for making light cast bullet loads from a number of different cartridges. It is not the powder to use if you are going to load normal power loads from a 44 magnum. There are waay better powders out there for that (H110, Lil' Gun, 2400, Blue Dot, and many others). It is not even the powder I'd buy for my light cast loads if I were going to buy new stuff, as it doesn't drop well from a powder measure and there are others which would do much better that way. And I'm not even sure that my old Hercules-manufactured Green Dot is very closely related to the new stuff made by Alliant.

[crs]

So, Earl, do we live with the phenomenon, or just simply compress all loads?

[earlmck]

So, Earl, do we live with the phenomenon, or just simply compress all loads?

I'm still working on that one, crs. I think it mostly isn't a big thing for me and my trusty Green Dot loads because 98% of the time I end up with the powder in the "powder back" position just from the way I handle the gun. And did you catch my later thread http://www.levergunscommunity.com/viewt ... =1&t=65564 where it looks like both Unique and Universal may be non-position sensitive (at least in a 30/30 sized case using CCI 200 primers)?

More investigation to come...