38spl, swaged 158gr LRN and Unique, Powder position sensitive ?

[Swede 45]

Well, here in Sweden, american powders are rare, but I found a pound of Unique at a small dealer..
I have never loaded anything with this, or any other american powder, so I´d gave it a try..
I also got a good price on some .38 boolits from Sellier & Bellot. It´s their (swaged ?) 158 gr LRN coated in some plastic lube. A combo, I thought!

I checked Alliants webpage for data, and they state 4.7 as max (-10% as start) for a 158gr Speer LSWC at 1.44 c.o.l and 815f/sec.
(5.2 as max for a +P load for the same boolit.)
I loaded up some tests at 4.4gr and 4.6gr (what my set lee disks throws)
CCI SP and sorted brass..
C.o.l at 1.52 inch (factory lenght on that boolit is 1.54) and a tapercrimp since the boolit doesn´t have any crimp groove.

At the range I got huge spread of vel.. the 4.4 load was between 460 to 700 f/sec.. what :???: ?!
The 4.6 load was between 662 and 770 f/sec.

I also had some of the 4.4 loads with a light rollcrimp into the boolit, (originally a mistake while setting the tapercrimp) and I shot some of those too.. better velocities, but still some spread..
I shot some of those crimped 4.4´s by setting the powder either forward (velocity at 688f/sec +- 10f/s), or back by tipping muzzle upwards/down for each shot and got 735f/s +-10f/s
variation.

So, this raises a few Qs:
Is Unique so sensitive on crimp and position in the case ?
Is Unique hard to meter well? (Usually when I get velocity variations, I can find the cause in light loads. I threw some 5x single charges, and checked them out on my balance scale one by one.. pretty even. And also threw 10 charges into one, and weighted and devided by 10.. pretty close to the single charges.)
Does Unique burn badly ? (noticed my chrono had some powderflakes to it, 6 feet from the muzzle)
Will velocities/burn even out if i go 5:ish ?
Is Unique a poor choice for soft loads? Will I be better off to push this into the +P range or swap powder ?

Gun: 4" Ruger GP100
Accuracy was best with the crimped 4.4 with the powder set back in case.. 2 inch group at 25 meters.
All loads shot in strings of 6

S&B states 997 f/sec out of a 7½ barrel for that boolit in their factoryload, so I guess I can push that bullet a bit faster, but I want a softshooting targetload with accuracy as the main factor..

I have never experienced a load that is so position sensitive.. I usually uses Vithavouri 310, 320 or 340 for all my loads, and get velocities with very low deviations without positioning the powder by doing the barrel shake dance ! :roll:

[bhn22]

Unique is at it's best at near maximum loadings. It burns cleaner and seems more efficient. It does meter poorly through some measures. One of my "go to" loads for many years was 5.0 gr of Unique under a cast semi-wadcutter in 38 Spl.

[35remington]

"I shot some of those crimped 4.4´s by setting the powder either forward (velocity at 688f/sec +- 10f/s), or back by tipping muzzle upwards/down for each shot and got 735f/s +-10f/s
variation."

Actually, that's quite good in extreme variation using Unique. 50 f/s variation is my targeted "ideal" with extremes in powder position in the 38 Special case, and that's about where you're at. Usually I do somewhat worse than that with similar charges.

Hodgdon Universal is much worse!

Afraid it's the nature of the beast with large airspace cases like the 38 Special in a lot of loadings, not just with Unique. The bell tolls for many powders in the roomy 38 Special case. The low pressures the 38 operates under doesn't help.

Now that you're aware of it as a potential problem, you can take steps to avoid extremes in powder position by how you handle the gun before firing it. It's not that great a cross to bear.

Simply do not fire the gun from a muzzle down and raise to fire procedure. Rather, tip it up a bit before the shot. Since subsequent shots string the powder out horizontally and the variations in velocity are much less pronounced when the powder is in this position rather than all at the front, the gun's muzzle need be tipped up only once per cylinder.

Since I have a number of standard pressure only 38's, on those fairly rare occasions when I use a SWC and Unique I'll go to the full 4.7 grain charge to fill the case more completely and therefore reduce the potential variation.

FWIW, Herco is slightly lighter than Unique for the same volume and comparable velocities are obtained with about 0.3 grain more powder. It's another way to fill the case a bit more. These two powders are the same basic formulation.....Herco is just a tad slower.

The more powder you put in the case, within pressure limits, the lower the velocity spreads from powder position will be. If you have a revolver rated for Plus P 5.2 grains is your huckleberry.

For good ballistic consistency from the 38 Special case, nothing beats a deeply seated wadcutter. Most of my shooting uses that bullet, most often lately with Ed Harris's "full charge" wadcutter load of 3.5 grains Bullseye. This is the top end of standard pressures. If using Unique around 4.1 grains is the limit for standard pressure loads with wadcutters conventionally seated to the crimp groove.

I would suggest the 460 f/s reading was a chronograph error, probably the screens triggered by the blast wave. Back up your screens a bit, maybe.

[Scharfschuetze]

Several years ago I ran a few tests with different powders in the 45 Colt. Each powder charge was fired twice; the first string with the powder positioned forward and a second string with the powder positioned to the rear. The 45 case is a rather extreme vehicle for this, but I wanted to compare various pistol powders and how velocities varied depending on position.

The short story is that all the powders exhibited quite a difference between front and rear positioning in the big case. The Unique loads showed about a 150 fps difference between the two positions. Extreme spread of each string was fairly good though. 231 also exhibited a fairly wide variation in its position as did Clays and Herco. I have to run this test again with Tightgroup powder as it has proven to be less position sensitive in the rounds that I've used it in so far.

Unique is still a great powder for the old 38 Special, but as noted above, it's at its best at near a maximum load or +P loads. Still, faced with your limited choice of powder in Sweden, it's a very usable powder, not only in revolvers and pistols, but in light rifle loads as well.

[DrCaveman]

A great load for me, in my gp100 6", is 5 grains unique behind the lee 158 rnfp. Probably very similar to your bullet, and a nice clean accurate load.

Ill bet the 5.2 grain load mentioned is pretty good too, but i havent had great luck pushing unique beyond its comfort zone. I get leading when it is too hot, seen it in 44 mag and 45 colt loads. If im pushing for that much velocity, i step down in burn speed a little

But 5 grains seems to be a pretty sweet spot for unique in 38 spl behind 158 grain pills

[DrCaveman]

Reading back over the OP, maybe swaged is a bit soft for the 5 grain load. I use wheel weights or 50/50 WW/pure lead. If those swaged are dead soft, black powder is the ticket!

Among VV powders, i heard tin star is pretty good for low velocity, consistent loads

But...to backtrack, ill once again state the sweetness of 5 grains with my boolit in a 38 case. It is the best use of unique that i have found, with 8-9 grains in a 45 colt a close second best. Ive also tried it in 30-30, 30-06, 45-70, 460 magnum, 44 magnum, and 9mm, with the final results i just mentioned.

[Swede 45]

Thanks for the input.. I´ll do some more testing and comparison against Vitha powders..

And, no the 460 reading was not a chrono error.. It had a way softer recoil and sound to that round.. either by a light charge or somehow a poor crimp?
And the +-10 vel variations on the powder positioned rounds was in m/sec to my notes, (my error in translation)..that is a spread of 65 f/s.
Usually I have very uniform velocities with my standard powders.. without doing the barrelshake dance! :smile:

[44man]

It is also hard to maintain even case tension with soft boolits and a taper crimp. You will never know if airspace is changing shot to shot from boolit movement.
Unique has always worked well for me. You might try a little Dacron.

[Swede 45]

44man: yeah.. i got the best accuracy and most "even" velocities with the rollcrimped ones..but still to much variation for my taste.
I will keep the rollcrimp in my upcoming tests..
That boolit has a quite slick coating.. and prolly, a taper doesnt hold them in place?

[jonp]

I shot a bunch of Unique with a boolit and jwords of that weight through a GP100, a Ruger Blackhawk and a SW Model 19 with various charges under it. I never noticed Unique to be that position sensitive but I'm not the best handgunner in the world

[35remington]

460 is low even for powder in the front of the case. I'd look to some other cause.

[cowboy]

Howdy, from the desert southwest.
You are on the right path, and obviously put some thought into this. I have used Unique in the past, but got away from it as I did have inconsistent metering with it in my powder measure. Have had a solution to that by using a vibrating device used to calm fussy infants secured to my powder measure when using powders that are otherwise difficult to get consistent weights with. Unique is a bit slower than some of the other powders I like, so absolutely yes, roll crimp. Ditto on Unique working better in greater than small to middle sized charges- it likes to get pressured up for better combustion, so use something closer to max, but work up your load for best results.