Sometimes what you think is not what it is.

I have long been of the opinion that Unique in old BP cases is sensitive to powder position. Have observed high and low strikes depending on how the rifle is mounted with other shooters and was able to make my 32/20 group high or low depending on way the gun was handled

Working with a 38/40, caliber is new to me.  Mostly fire forming brass while waiting for a MVA tang sight to arrive.  Old data gives the factory black powder load with a 180 gr lead bullet 1330 fps.

Have been using NRA's recommended load, 8 grs of Unique published velocity 1330.  They also have loads for 4227 16 grs & 4959 16.2  same 1330 velocity.

Other day loaded up three cases to the NRA recommended 1330 ft loads. Unique 4227 & 4759 and measured powder height in the case.  Then measured total available in the empty case less bullet seating depth  Surprising outcome

Unique uses about 25 % of case capacity. 4227 29 % and 4759 as expected a lot more. 51 %   What surprised me was the small difference in bulk 4227 to Unique loads supposed to produce the same velocity.

it's entirely possible vertical stringing due to powder position will happen with 4227, just I never observed it. Other question is will 4759 string any less. 50 % is still not full and no doubt burns different depending on how the rifle is handled.

Other thing is you can double charge Unique but can double charge 4227 too.  However looking at double charged cases either powder it would take a careless loader to make that mistake.  They are obviously overfilled.  4759 you can double charge too.  Two throws of the measure bullet will still easily seat on top of the powder.

Real lesson is mount the gun same way every time no matter what powder you use.

Boats

Best thing is know it all, no doubts and don't worry about understanding anything

Boats

I did some experiments on powder position vs. MV, and have the EXCEL data and WORD report files if anyone wants them. This with Unique, SR4759 and IMR4227 in 30-30 and 45-70. The range master shut me down, no lifting of the muzzle.
joeb33050@yahoo.com
joe b.

I have a Borchardt with a George Schoyen barrel in 38-55 It shoots well but has the tendency to pucker cases at the mouth unless I bell the case mouth for each shot. I shot it at a match in Asheville and sat next to Charlie Dell. Charlie asked why I belled the case mouth for each shot as I was shooting breech seated. I told him about the case pucker and he said that I should orient the powder to the front of the case with a wad in the mouth. I tried it put a cork wad in the mouth after loading the powder and tipped it down then put it in the chamber. It worked like a charm. No more pucker. I did have to increase the powder charge .4 of a grain to get the velocity back up to where it wanted to group. I still shoot the rifle this way. I use 4227 with this rifle. 

40 Rod

Quote:
Boats, if before shooting nitro powder that doesn't fill the case or is position sensitive ... "Muzzle Up!"
It will position the powder against the primer flash hole - to reduce avg velocity and SD's

So, on a single shot other than a Martini which by necessity loads with the case mouth pointed roughly down, just very carefully slide the case into the chamber after pointing the case mouth towards the sky...it won't magically slide all the powder towards the muzzle unless you point the muzzle down before firing.   

David

Afraid muzzle up is going away at all ranges. I had to re-learn that high power high then screw it down into position mount. Been using it a very long time perhaps 40 years and it was hard to change.  Our Club Small bore Silhouette matches have to watch competitors all the time who still like to raise high and come down on the target.

However fact of the matter is load the rifle level put the muzzle down on a rest (I use Proktetors window bag) put the butt in your shoulder and raise to level is just as good, perhaps better, uses less energy.  Probably the most important thing about shooting any position, offhand, prone, or even bench rest is mount the same way every time. More important that the small component changes we talk so much about.

Powder position front back or held in place with a wad is way less important than position consistency. If your mount and hold is consistent powder position will be too.

Boats

POWDER POSITION SENSITIVITY


TESTING CONDITIONS
     POWDER FRONT-hold the rifle with cartridge chambered at ~ a 45 degree angle down and slap the side of the rifle three times, then put it carefully on the rest.
     POWDER LEVEL-put the rifle with cartridge chambered on the rest and slap the side of the rifle ten times.
     POWDER REAR-hold the rifle with cartridge chambered at ~ a 45 degree or greater angle up and slap the side of the rifle three times, then put it carefully on the rest.
     DACRON WAD-I recommend cotton but use Dacron wads. I use as small a wad as possible, a teased wad about dime to penny size, tamped down on top of the powder with a pencil.
I try to chronograph a minimum of 15 of each condition, shooting at 100 yards over my PACT chronograph.
I record all results on an EXCEL workbook called "POWDER POSITION SENSITIVITY". (See the EXCEL workbook for all the information about the loads and results.)
An excerpt/summary from this file is given below:

ALL UNIQUE AND SR4759 DRIBBLED TO WEIGHT

30-30 31141 M54 WIN
2/6/08 UNIQUE 7.0 FRONT 1195, LEVEL 1214
4/9/08 UNIQUE 7.0 LEVEL 1163, REAR 1175
2/20/08 UNIQUE 8.5 FRONT 1346, LEVEL 1365, WAD 1378
4/9/08 UNIQUE 8.5 LEVEL 1337, REAR 1368
2/20/08 UNIQUE 10 FRONT 1502, LEVEL 1519
4/9/08 UNIQUE 10 LEVEL 1491, REAR 1478
3/12/08 IMR4227 14.5 FRONT 1353, LEVEL 1347, WAD 1453
3/12/08 IMR4227 14.5 FRONT 1357, LEVEL 1357, WAD 1454 REM 2.5
3/26/08 IMR4227 14.5 REAR 1457
4/9/08 IMR422 14.5 LEVEL 1392, REAR 1451
4/16/08 IMR4227 14.5 REAR 1424, WAD 1422

45-70 457193 C. SHARPS
2/27/08 UNIQUE 14 LEVEL 1195, WAD 1240
4/16/08 UNIQUE 14 LEVEL 1173, REAR 1216
2/27/08 SR4759 22 LEVEL 1128, WAD 1310
4/16/08 SR4759 22 LEVEL 1195, REAR 1241

ased on this testing it seems that the following are/may be true:
Accuracy variation has to do with the ratio of powder volume to case volume. Small quantities of powder in big cases show big variations in velocities as powder position varies.
The standard deviation