Drams Equivalent

[Dave K]

I have been looking through all my printed material, but I haven't found it yet, so I am going by memory. If I remember correctly (this is scary) Dram Equiv. is not really rated by size of each powder grain, but is determined by the amount of work, a certain amount of any powder will push a set amount of shot. Like for example, if 3 drams of 2F powder, pushes 1 1/8 oz. of shot 1200 fps, that "may" constitute a load. Now if only 2 3/4 drams pushes the same 1 1/8 oz. load, 1200 fps. than it would constitute a "3 dram equiv." So when they went to Nitro and other smokeless powders, it wasn't the amount of powder, it was the speed at which the powder sent the amount of shot out the muzzle, that determined "dram equiv". I hope I made sense of this.

 

[roundball]

"...for example, if 3 drams of 2F powder..."

What you're saying is clear, and I agree with[url] it...in[/url] fact recall stumbling across something like that while surfing in the past myself.

And when all that methodoloogy was developed, established, etc, a determination had to have been established as a foundation for a Dram standard or reference...like in your clip above, you used 2F as your Dram reference...you didn't use 3F.

They had to use a single standard...otherwise, when for example a statement is made "1+1/8oz shot at 1200fps requires a 3 Dram equivalent powder charge"...it would beg the question:
A powder charge equivalent to 3 a Dram charge of what? 1F? 2F? 3F? 4F? 5F? 7F?

A 3 Dram charge of 3F would produce a different velocity than a 3 Dram charge of 2F so to understand precisely what such a statement was referring to, it must be known which powder granulation was being referenced in the "Drams" comment.

My turn to say I hope that was clear...

 

[Dave K]

The more I think about it, the more I confuse myself. I know what you mean, trying to put it to words. It really doesn't matter what type of "F" was used as long as it gave us the 1200 fps of a 1 1/8oz load. But yes! What load, of what powder, did it take to established it to be 3 drams? :hmm: I have another place to ask this question. I will see what answer I get.

 

[Dave K]

Well, I asked the question and seemed to get really the same answers or discussion we had here. A website was posted and it does talk about BP shotshells, but think for this discussion it "may" not be out of line since we are interested in the way BP and the different sizes of powder work. Here is the website and feel free to delete if it is not appropriate here. [url] http://www.tbullock.com/bpsg.html[/url]

 

[roundball]

Well, I asked the question and seemed to get really the same answers or discussion we had here. A website was posted and it does talk about BP shotshells, but think for this discussion it "may" not be out of line since we are interested in the way BP and the different sizes of powder work. Here is the website and feel free to delete if it is not appropriate here. [url] http://www.tbullock.com/bpsg.html[/url]

I tagged it, thanks.

PS:
Don't know if you saw my other post but I'm going to try your suggestion...ordered some .62cal Circle Fly 1/2" lubed fiber cushion wads...planning to slice them in half and try them for a dove shoot this Labor Day...see if I can shoot a while without having to wipe the bore.

 

[Dave K]

I thought I saw that post, but now I can't find it. I use the fiber cushions and I cut them in half and soak them olive oil. Let them drain and store them in a zip lock bag. I can shoot ALL day and never wipe the bore. Never a problem.All day for me has been a lb. of powder through a SxS.

 

[roundball]

I thought I saw that post, but now I can't find it. I use the fiber cushions and I cut them in half and soak them olive oil. Let them drain and store them in a zip lock bag. I can shoot ALL day and never wipe the bore. Never a problem.All day for me has been a lb. of powder through a SxS.

That's what I was hoping to hear...now, these are prelubed by Circle Fly and I don't know if they're soaked through, or just edge lubed but I'll try a round of skeet targets with them before the dove shoot.

(I'll also probably stuff a bag of damp patches in a pocket if I'm going to be a long way from the truck at the dove field just in case)

 

[CoyoteJoe]

No Roundball, you don't get out of your claim that easily. Your assertion that one can substitute 3f for 2f by reducing the charge by 10-15% for similar velocity and pressure is one I have seen only on this forum and usually posted by yourself. The fact that you had a telephone conversation with some employee of Thompson/Center who agrees with you does not make this an "industry standard" guess. That may indeed hold true in certain selected instances but I have already presented data showing that it DOES NOT HOLD TRUE as a generality across the board. Your use of the term "industry standard" infers some degree of credibility which simply can not be supported by any published pressure and velocity data. The fact is that when you vary from published data by substituting a different powder you are experimenting on your own with no idea of the pressure of your load. If you chronographed your loads that would at least represent half of the equation but you still would have no basis to guess as to pressure produced by that load. The fact that some charge weight of 3f produces the same velocity as another charge of 2f does not mean that they produce the same pressure. There are plenty of instances in published data which demonstrate that one powder may produce a given velocity with very different pressure than another powder and certainly there is no "rule of thumb" which can reliably predict the results from substituting powders.
If I were to speculate as to the difference between 2f and 3f for similar velocities I would speculate closer to 25% but that would be my rule-of-thumb and I'd not present it as an "industry standard" but simply as my best guess and I would not even speculate as to pressure produced by either powder.

 

[Dave K]

CoyoteJoe, fps and psi are actually two different topics. Look at any reloading shotshell manual and it will become very apparent that one load can have a very significant less psi and the same fps. Dram equiv., as I understand it, is based on the amount of work a certain amount of powder will do to move a certain amount of load. Kind of like looking at horsepower in an engine.

 

[Joel/Calgary]

Coyote Joe, this 10-15% rule of thumb that one hears nowadays has become a burr under my saddle, too. I've never seen any citation of it that includes data or primary references.

When I got started 35 years ago (with sources dating back a decade or three before that), the common wisdom was to increase the charge by "up to 1/3" when going from 3F to 2F to get the same velocity (equivalent to decreasing the charge by up to 1/4 going from 2F to 3F). It was generally accepted that the 3F charge would likely have higher pressure. Getting the same point of impact is a separate matter - muzzle whip and barrel rise have more involved than just muzzle velocity.

When I looked again at the Lyman and Gun Digest loading manuals (and some other sources), where they compare loads with different granulations of powder by the same manufacturer and vintage, fired in the same gun, I found the charge increase required to get the same velocity (usually had to interpolate a bit, given 10 grain increments often listed) when going from 3F to 2F varied from 15% to 55%. Caliber, projectile, barrel length, etc. certainly cause differences, and the charge increases varied somewhat by the pressure/velocity involved in a given barrel, but by far the majority of the charge increases ranged from 1/4-1/3 (25%-33%). This is equivalent to reducing the charge by 1/5-1/4 (20%-25%) when going from 2F to 3F. When pressures were given, they were always higher with the 3F, and often significantly so, but none that I noticed were excessive with reasonable loads.

I'd dearly love for someone to cite some more systematic comparisons.

Joel

 

[roundball]

I'd dearly love for someone to cite some more systematic comparisons.

That would probably be of additional interest to many of us Joel and I assume with your decades long irritation over the referenced reductrion, you probably keep an eye open for such things more than the average guy...hope you'll share any such credible sources if you encounter them.

I only have 3 references for the 10-15% 2F to 3F reduction rule-of-thumb and I'm fine with them:

1) Countless references to that rule-of-thumb by many ML shooters on various ML forums over the years;

2) Thompson/Center Arms unhesitating agreement;

3) My own use and experiences...and while my 16+ years of muzzleloading are less than some who have more...and my 10,000-12,000 shots are less than some have shot more...it never-the-less provides me with concrete, personal hands experience as a reference dealing with it.

As a result, I have total confidence in the practical utilization of the 10-15% reduction as a means of managing pressure differences between similar loads when substituting 3F in place of 2F, as I've heard it said over the years by others who employ the same practice.

Said another way, the 10-15% 2F to 3F reduction has worked perfectly as I've heard it referenced as a so called industry rule of thumb over the years, and has produced no problems whatsoever.

 

[Joel/Calgary]

That would probably be of additional interest to many of us Joel and I assume with your decades long irritation over the referenced reductrion, you probably keep an eye open for such things more than the average guy...hope you'll share any such credible sources if you encounter them.

As I said, on my most recent review of the matter, the Lyman and the Gun Digest loading manuals were my main sources with chronograph and pressure data for comparison. My copies are buried (again) and I don't know if I'll have time to dig them out and assemble the relevant info any time soon, but there was a reasonable quantity and diversity of data, and it was as I summarized above. Anyone who can find a copy of either can look it up.

I'm starting to get a feeling that we might be having an "apples and oranges" difference. What I'm looking for/at is purely internal ballistics. This is not the same as seeking load substitution to get approximately the same POI and trajectory over real-world distances.

Joel