Says here toward the end of this video Unique is position sensitive on the Chrony

[Just Duke]

Could I possibly use a tuft of Dacron? Not my video BTW.
http://www.youtube.com/watch?v=5mTfeF4yhc8

[35remington]

Universal by Hodgdon is even worse. Another reason the 45 Auto came out as a much shorter cartridge.

Perhaps some Titegroup is in order. I've had low extreme spreads in velocity with that.

Dacron would certainly lower the velocity spreads. Some don't like it with fast powders in pistol cases. While I have done dacron with faster powder like Unique and W231 for thousands of rounds with no harm whatsoever, I generally prefer to use it with powders of 2400 speed or slower.

I'd try to address the position sensitivity with another powder first.

BTW, what was the charge of Unique? Good speed when the powder was rearward.

[stephenj]

I wouldnt call unique position sensative .
I dont use a chrony but i do use a bunch of unique .

I use it in .45 colt .. works well for me loads dont change pount of impact
No matter how the powder is positioned for me .

He also mentioned what he called the cavernouse (spelling )
.45 colt case .

Well lets talk about a huge case .... i also use unique in my 577-.450
Martini henry .
I use 12 grains with no filler or wadding .... positioning the powder makes zero differance
On target out to 200 yards

I do think id have learned about it being position sensative by now in the truly huge 577-.450
But ... i suspect his chrony numbers ... 1000fps with 40 grains of ffg ?
Anyone else gotten numbers that high ? 850 fps sounds more like where it should be to me

[35remington]

Well......no, he isn't making this up. Position sensitivity happens and I've had it happen with Unique. I've also experienced it with the 38 Special using Unique.

"I dont use a chrony but i do use a bunch of unique."

Stephen, show us chronograph results and then you'll have a better handle on what is happening to you. Point of impact is more related to bullet weight than speed, and both 700 and 900 fps loads may center point of aim since barrel time compensates for speed to some degree. The 900 fps load makes the barrel rise more but the bullet is in the barrel for a shorter time, so things cancel out and point of impact is not affected.

Mine aren't quite as wide in extreme spread as Duke's but they are there, and often exceed 100 fps depending upon how long a case we're talking about.

Trot out the chronograph and be prepared for an eye opener in some instances.

[Just Duke]

Universal by Hodgdon is even worse. Another reason the 45 Auto came out as a much shorter cartridge.

Perhaps some Titegroup is in order. I've had low extreme spreads in velocity with that.

Dacron would certainly lower the velocity spreads. Some don't like it with fast powders in pistol cases. While I have done dacron with faster powder like Unique and W231 for thousands of rounds with no harm whatsoever, I generally prefer to use it with powders of 2400 speed or slower.

I'd try to address the position sensitivity with another powder first.

BTW, what was the charge of Unique? Good speed when the powder was rearward.

We use 8 grains of Unique. We have 4 8 pounders so powder change is impossible along with the fact that it's hard to find powder these days. And I'm broke..

[Just Duke]

Forgot to say this is not my video.

[Just Duke]

Well......no, he isn't making this up. Position sensitivity happens and I've had it happen with Unique. I've also experienced it with the 38 Special using Unique.

"I dont use a chrony but i do use a bunch of unique."

Stephen, show us chronograph results and then you'll have a better handle on what is happening to you. Point of impact is more related to bullet weight than speed, and both 700 and 900 fps loads may center point of aim since barrel time compensates for speed to some degree. The 900 fps load makes the barrel rise more but the bullet is in the barrel for a shorter time, so things cancel out and point of impact is not affected.

Mine aren't quite as wide in extreme spread as Duke's but they are there, and often exceed 100 fps depending upon how long a case we're talking about.

Trot out the chronograph and be prepared for an eye opener in some instances.

So if I used a tuft that held the powder at the back of the case wouldn't that make my loads around 1000fps? The fella in the video says he's using 7.5 grains and I'm using 8 grains.

[jmort]

Unique is not considered to be a "position sensitive" powder.

[stephenj]

35 remington

Ok in the interest of learning a bit i have a question .

In the .45colt i understand what your saying .... makes good sense

But where that logic loses me is when you jump up to a case
With about 4 times the volume of the .45 such as my 577-450

Lets just assume that unique is moderatly position sensative .
Surely i would be seeing some signs of vertical stringing out at 200
And im not ... 12 grains is a spot of powder in the case and i see no signs of anything resembling stringing

[35remington]

I'm not stating absolutes for every instance. I use a charge of 16 grains in a 45-70 with much less position sensitivity.....yet I use a 4.8 grain charge in a 38 case and get much more position sensitivity. What's happening may have to do with rifle versus pistol primer ignition differences, as well as operating pressures.

Point is, don't consider a powder to be "not position sensitive" unless you've tested it for position sensitivity in the load you're using. ALL powders are position sensitive to some degree, even in stubby cases like the 45 ACP and using powders like Bullseye and Red Dot. Velocities are higher even with "less position sensitive powders" when powder is near the primer than when near the bullet, almost always. I can think of no exceptions to this, and I've chronographed a lot of ammo deliberately testing for such a thing. In both short and long cases.

This is to be expected. The question really is not that powders are position sensitive, as all are. The question is how much they're position sensitive. It is more correct to say some are less position sensitive, some are more, but all are position sensitive.

Want to see it in rifle powders? Try a partial caseful of Hodgdon's recommended "60 percent" charge of H4895 and position powder front to back. I get 200 fps variations with cast bullet loads in my 7-30 Waters, for example.

[35remington]

Duke, if you're getting 900 fps with the powder at the back of the case, you'd get that or a bit more with dacron as not only would the powder also be at the back of the case but case volume would be very slightly reduced with the dacron.

In addition, from examining bullets shot with dacron behind them, gas cutting is reduced. In theory, corking up the powder gasses behind the bullet with the gas cutting reducing, gap sealing qualities of dacron will also serve to increase velocities. So other mechanisms besides positioning the powder may be at play and serve to increase velocities a bit as well when dacron is used. The actual weight of dacron is so small that its inclusion in terms of weight alone has little effect. Something else about it is acting on velocities as well.

As always, adding a filler increases the risk. Try other powders first in handguns to reduce position sensitivity.

[rockshooter]

I too have found Unique to be position sensitive, esp with bullets that are light for caliber- thus leaving more space in the case. I have found this to be especially true in .38 sp and .45 Colt.
Loren

[rintinglen]

Only tests I did were with my 158 grain round nose boolits in 38 Special. 5.0 grains of Unique did not show the extreme (150 fps+=20%) variations reported in that video. They were fairly consistent at 850 fps+-20 as I recall, whether nose down and raised up or muzzle up and lowered down. I will say that 5.0 grains under a 358-311 pretty near touches the boolit base, so the loading density is going to be different, with less room to slop around.
I use bamboo filler in my 45/70 when using Unique.

[Mustangpalmer1911]

Kind of a small world. Just yesteday I had my first issues Unique and being position sensitive. Same thing a couple others have said small light bullets. I am playing with 160 grn round balls in my 45 colt ammo. I droped it down to 6 grn to see how it would preform. I had 2 hit the cardboard fine and 4 littlerly puff out and bounce off. My 8 grn loads with the the same ball never failed. I am going to grab some cotten balls on the way home and retest them today.

[Just Duke]

What is the risk of Dacron filler?

[stephenj]

Ringing a barrel on a rifle or a cylinder on a revolver .

I do not use fillers because of this ... but i also dont think a ringed chamber happens.so much when a filler
Is used so much as with improperly used wads ...and even more so withwads made of a material that doesnt compress well or is made of a denser material . ... this is just my opinion
I think you will find many many people disagree with it

A lot of peolple safely use fillers with no issue .. only a few manage to screw it ip
I choose not to do it because i dont have to .

One more thing to think about .....
Say you have a load that normaly gives you 800fps .
Then you add a filler to hold the powder at the back of the case and you now get 900 fps .
As you are getting a higher velocity it stands to reason you are also getting a higher pressure
A load that is perfectly safe by itself may not be with the filler

[44MAG#1]

All powders are positive sensitive to a degree. I have tried a couple of loads recommended on here even with heavy bullets and have found position sensitivity even though the powders were fast (Red Dot) and a couple with Unique. One with HS-6 with the 45 Colt had two different averages over 100 fps apart with the same load depending if the powder was in the front of the case or the back.
It happens when there is more powder space than the powder requires for ease of ignition.
It is easy to find out using a chrono.
I have said this many times but of course I don't know what I am talking about I guess. Or so it seems.

[M-Tecs]

8 grains of Unique under a Lyman 454190 is one of my favorite loads. I loaded my first one in 1969. I don't view it as position sensitive but I have only chronographed it once. It has always grouped well for me so I never worried about it. Same for my trapdoor loads of 10 grains Unique under a 385 cast. I have group tested that load for position sensitivity. How it chono's I don't have a clue, but I couldn't detect any accuracy loss at a 100 yard due to position.

[Scharfschuetze]

Several years ago I ran a few tests to determine position sensitivity in the 45 Colt cartridge. I was a bit surprised at the results.

Revolver: 6" 45 Colt SAA made by Uberti

Loads:

45 Colt
230 grain cast 45 ACP round nose boolit
WW Cases with a moderate roll crimp just over the beginning of the ogive of the boolit
CCI 300 primers
8.0 grains Unique
No filler used

The below results are for 12 shot strings over a PACT chronograph.
The powder was oriented either up or down just prior to each shot so its position was uniform shot to shot.

"Muzzle UP"
Average velocity: 912 fps
Extreme spread: 46
Standard deviation: 17

"Muzzle DOWN"
Average velocity: 597 fps
Extreme Spread: 18
Standard Deviation: 10

"No orientation." Just fired as one normally does
Average velocity: 854 fps
Extreme spread:76
Standard deviation: 34

The results with Winchester 231 were similar, but a bit with a bit less extreme spread between the up and the down positions. My notes indicate "only" a 190 fps difference.

My current thinking is that Hodgdon "Tight Group" powder may offer an improvement for uniformity in voluminous cases. I haven't rerun the 45 Colt tests with it yet, but in the 45/70 it is producing standard deviations that equal the low numbers produced by black powder in the cartridge.

By the way, I still use lots of Unique in several different cartridges with good results, so numbers are numbers and accuracy is accuracy and sometimes we just can't explain what we should be able to explain.

[Larry Gibson]

Unique is not considered to be a "position sensitive" powder.

Some may not consider Unique (and many other fast burning powders) to be "position sensitive" but the video and Scharfschuetzer's simple test here apply demonstrate it is in the 45 Colt cartridge. Many of us who have thoroughly tested Unique in numerous cartridges, rifle and handgun, have found when load density is less than 80% almost any powder is "position sensitive".....some more so than others depending on ease of ignition, load density and bullet weight. While I favor a Dacron filler with many loads I do not use a Dacron filler with any Unique load. I also do not use a filler in any revolver cartridge instead preferring to find a powder/bullet combination more suitable with less "position sensitivity".

I do not recommend a Dacron filler with faster burning powders such as Unique in any cartridge. While the 8.5 gr Unique load under the Keith 255 gr SWC was a favorite 45 Colt load of mine I understood the "position sensitive" issue and was careful to be consistent in cocking the revolver just prior to shooting with the muzzle slightly raised using my two hand shooting technique and cocking the hammer with the left thumb. This gave a mostly consistent performance with that load.

However, I have found little need to throw that much lead down range at one time and have since switched to 185 - 205 gr cast bullets for my .45 Colt loads in my 2 SAAs and M73 Carbine. I mostly use the 200 gr Lee 452-200-RF loaded over 7.3 gr Bullseye for 950 fps out of the SAAs and 1150 fps out of the M73 Carbine. This duplicates original 44-40 ballistics which is fine with me. I have found this load to be less "position sensitive" and an excellent performer to 300 yards.

Larry Gibson