POWDER POSITION, RELATIVE TO PRESSURE

Recently in a thread, someone commented about an article about powder postition, with Unique under 110 g slugs, in a Contender wired with a strain gauge.

Some of the spring cleaning I've been doing is going through the old gun rags, clipping for reference, and getting them down the road. The article mentioned in the thead was in the April 2007 Shooting Times, by Ken Oehler.

Mr. Oehler outlined that SAMMI procedures state that cartridges to be tested should be placed oriented and handled in a way to orient the powder against the primer. This point was brought home while working some loads of Unique over 110 slugs, that were between .38 Spc and .357 Mag pressure levels, in .38 Spc brass.

It was discovered that the powder forward position yeilded 16,000 psi. The powder positioned to the rear yeilded 26,000 psi, with a 300 fps velocity difference....

The short conclusion, little things can matter, and powder density in the case is a real consideration. In the choice of powders, some advertise insensitvities to powder location in the case, some make no mention of it. While many of us would like to have the time and resourses to pressure check our loads, it is not a reality for most.

When in doubt, do more research, contact manufacter's, whatever. We owe it to those around us (literally, they may catch the flying pieces), to be safe.

I have kept up with Ken's work. The exact info you mentioned is why I have always prefferred to have a load that fills the case to the base of the bullet if at all possible. I recall reading something about the uniformity of ammo if the powder was up against the primer way back in the 1970's. I was just into reloading then, and was using 3.2 grns of Bullseye with a 148 grn W/C. I used pillow fiberfill on top of my charges to keep the powder against the primer. I was following loading info of that era. Uniformity is one key to accuracy AND safety.

Absolutely contender. Consistency is a reward unto itself.

That sounded preachy

I have used Dacron, rice, cream of wheat and vegatable wads and even a small wad of tissue to keep the powder where it belongs. On the other hand I have built duplex loads for H/gun and shot M-80's out of a 12 ga to scare crows towards me. Consistency--I try.

When shooting light to moderate loads of HP-38/W231 and Universal at the range I have noticed a difference in recoil depending on powder position. I didn't have a chronograph at the time but I am sure the difference in velocity was considerable. It is always a good idea to point the barrel up before shooting light loads I guess.

Jimbo ,that`s the reason I stopped useing ww231/hp-38 .

I use Hodgdon`s Clay line of powders , The CLAYS is the most position insensitive powder I`ve ever shot !!

I use Titegroup for light loads since it's advertised as being less position sensitive.

Unique is so position sensitive that its useless in the .38 Special. It does work well in the 9X19 as it nearly fills the case. Accurate #5 is the best powder I've ever used in the .38, I'm planning to give Titegroup a try also.

If ya ever get the chance & if any are left in ya area watch an old bullseye shooter ,he`ll point the handgun straight up & lower it to the target ever so gently .

To keep the powder next to the primer !

Just try it over the chrony , straight up vs. straight down with the same load of unique or bullseye powder.

I first noticed position sensitivity when using IMR SR 7625 (similar burn rate to Unique) and 130 grain cast bullets in a .357, a worst case scenario-long narrow case with a short bullet. Shot to shot differences were easily felt. Longer (heavier) bullets fixed the problem. I'm sticking with SR 7625 in the .357.

With my .45 Colt carbine and light loads with 200 grain SWC's and Clays, the pressure difference between muzzle up and muzzle down was enough to seal the case to the chamber and engrave the primer with breach marks when tipping the gun up before the shot.
Muzzle down or random positions would not seal the chamber resulting in sooty cases and primers with no marks. I switched to Trail Boss for the Colt and won't be going back to Clays for light loads.

Mobuck said:

I use Titegroup for light loads since it's advertised as being less position sensitive.

Click to expand...

I made some .308 subsonic using both Trailboss and Titegroup. Trailboss filled the case, Titegroup was 9 grains kicking around in the case. I shot 30 rounds of the Titegroup, tilting down, then flat then up before shooting through the chrony. Then 10 rounds of the Trailboss. The Titegroup had less spread than the Trailboss! SD was 109 compared to 169! The variation in the Titegroup was due more to some cold shots because other shooters wanted to go down range. Titegroup didn't care where it was in the case!

Warthog

PS The load I am now using for my wife is Hornady 208 gr with 9 grains of Titegroup gives 1085 fps out of my .308 with a 1 in 10" 24" barrel.

Warthog,

I guess Titegroup lives up to the Hodgdon's claim of not being position sensitive!

Yeah, Titegroup is pretty good. I used to use it in my light 100 yard silhouette .357 loads with a stubby 140 LFP. A lot of empty case with that combination. I never had a chance to chrono it, but accuracy was always good at the 100 yard line.

That 'bump' to a gun's heel before firing settles the charge to the rear.

Titegroup was developed specifically to alleviate position sensitivity AND to reduce ejecta.
It excels at both.



There are many characteristics of powders that make them our favorites, or hated enemies.
I use WAP and Power Pistol and N350 and 3N37 and Universal instead of Unique. Ay?

FergusonTO35 said:

Unique is so position sensitive that its useless in the .38 Special. It does work well in the 9X19 as it nearly fills the case. Accurate #5 is the best powder I've ever used in the .38, I'm planning to give Titegroup a try also.

Click to expand...

To take that at face value would seem to indicate that Unique would be even MORE useless in the likes of the 44Spl and 45LC....which in turn, would seem to indicate that what has been the go-to smokeless powder for them three cartridges for how long now?....about 100years?...has suddenly been proven to be what?...useless?

Surely, I've missed your point....huh?

DGW

FergusonTO35 said:

Unique is so position sensitive that its useless in the .38 Special. It does work well in the 9X19 as it nearly fills the case. Accurate #5 is the best powder I've ever used in the .38, I'm planning to give Titegroup a try also.

Click to expand...

THIS IS SO INCORRECT AS TO BORDER UPON THE SILLY !!!
UNIQUE is nothing short of superb in the 38SPL. So is AA5, as you say, but nothing will surpass INFALLIBLE in the 38SPL and this propellent uses the same identical loading data as UNIQUE.

I too had to question the above quote about Unique. MANY years ago,,, it was THE powder choice for 45 ACP in the 1911. I found it to be good enought to use it for my USPSA match ammo in 45 ACP. I have for years. ANd with the MANY times I've had my ammo chronographed at matches,,, and by me,, it has shown to be quite consistant. I use 5.6 grns of Unique under a 230 grn plated bullet. I get very good results,, and since it's the "chronomen" who test my guns at matches,,, it's not me or anything special I or we do to make the position of the powder a factor.

Unique might be worthless, but it sure works for me!
Another worthless one, W231, also performs with no problems.
My favorites in .357 Mag with cast bullets.

Unique works great in the 38 special or 38/44. You just have to load it up to what it was originally loaded to. In my 38/44's I routinely shoot 6.5 grns with a 158 and it works perfectly. Very accurate. In a 38 special I back that down to 5 to 5.5 grns and never had to worry about position of the powder.