Dram vs. Power factor

[Garmil]

I've been shopping shells a bunch looking for an affordable light recoil load for 3 gun.

What is a Better way to compare sa shells power to one another?

Power factor or dram equivalent?

It gets confusing when some 3 dram loads have a lower power factor than other 2.75 dram loads.

Regarding knockdown power and recoil what is the best way to put them in order of least to most powerful? And can those 2 things be independent of one another or are they proportional for the most part?

Thanks for any insight on this.

[thermobollocks]

Grab a box each of what they have and shoot it.

[Flatland Shooter]

Once broken in, your MKA 1919 will really like Remington STS and Winchester AA for matches. For practice, save a few bucks and use Remington Gun Club shells.

After a few magazines, you should be able to cycle 1200 fps 1-1/8 oz loads reliably. After a while, and possibly the addition of a low power recoil spring, the 1145 fps shells should work.

Even though I shoot mostly the 1145 fps rounds, I keep a box of 1200 fps shells for tougher steel and a few 1300 fps shells with #6 shot for spinners.

Bill

Edited October 27, 2015 by Flatland Shooter

[Garmil]

Thanks Bill that helps my decision. Still curious about the technical side of it though.

[Flatland Shooter]

As it appears on a box of shotgun shells, the "dram" is the weight of blackpowder necessary for a set velocity.

If memory serves me. 1-1/8 ounce shot at 1145 fps would require around a 2-3/4 dram load of black powder. A 3 dram load will get the pellets going at 1200 fps.

Some shells show the dram number, some show just fps, and some show both.

[Garmil]

Yeah but there are

1oz 1250 fps 3 dram 1250pf

1 1/8 oz 1145 2.75 dram 1288pf

So less powder for more pf?

[P.E. Kelley]

Power Factor is expressed as bullet weight in grains (times) velocity in feet per second (divided) by 1000

1oz 1250 fps 3 dram 1250pf is actually 546.875 power factor

1 1/8 oz 1145 2.75 dram 1288pf is actually 563.554 power factor

Dram Equivalent is (as previously posted) the blackpower charge that would net a velocity value.

[Garmil]

Yeah I didn't do the conversion just showing that the lower dram had a higher pf.

I was under the impression that dram equivalent was the amount of black powder the shell would have in general. Making the 3 dram more powerful but in this case it's less.

[P.E. Kelley]

Yeah I didn't do the conversion just showing that the lower dram had a higher pf.

I was under the impression that dram equivalent was the amount of black powder the shell would have in general. Making the 3 dram more powerful but in this case it's less.

You are close. Higher dram more VELOCITY not power. Even that is payload dependent.

Within the SAME payloads higher Dram is higher velocity.

1 1/8oz. @ 1145fps is a 2 3/4 dram load

1 1/8oz. @ 1200fps is a 3 dram load

1 1/8oz @ 1255fps is a 3 1/4 dram load

1 1/8oz @ 1300fps is a 3 1/2 dram load

Dram (or DRAM Equivalents) is an antiquated measure based on the amount of black powder (in drams) it takes to propel a certain mass of shot at a specific velocity.

Edited October 28, 2015 by P.E. Kelley

[Garmil]

Ok makes sense with the same shot weight.

Sounds like power factor is the better way to judge how much power then.

[openclassterror]

It is, but on a lot of shells you have to do the math because the PF numbers are not on the box. Also, depending on barrel length, back boring, forcing cone length, etc, your shotgun may not produce the published figures. A lot of chronos don't reliably read on shot because the wad/ shot string can cause false triggers. So a lot of this is just "by guess and by golly". Kinda like me shooting at flying clays.

Edited because I can't spell "chronos", apparently.

Edited October 29, 2015 by openclassterror

[StealthyBlagga]

Power factor is MASS x VELOCITY, which is the formula for MOMENTUM. For knocking down steel, it is a reasonable number, and easy for people to understand and calculate. Increasing mass or velocity will deliver a corresponding increase in Power Factor/Momentum.

Another, perhaps more important parameter, is the amount of shot that actually hits the targets. This is why it is so important to pattern your shotgun with your chosen loads at different distances with different chokes, and to make an informed choke choice for each stage.

[kurtm]

I'll drink to that...... with approximately 8 drams, which would be about an ounce of pure golden sippin liquor.

A dram as we know it in shotgun ammo is about a teaspoon full of #2 Black Powder, Goex anyone?