compressing black powder

[Lead pot]

Michael

I have something I will share with you guys on compressing powder.
I shoot a lot in the winter and I noticed a lot of powder melting holes in the fresh snow cover after shooting many rounds.
This made me wonder just how much powder passes through the barrel unburned so I doug out some 4" PVC pipe I had laying around in the pipe rack left over from my plumbing days so I coupled two 20" lengths together and taped the far end and shot through the pipes to collect the unburned powder. I lost the figures do to a computer crash so I cant give the exact grains unburned but it was considerable.
I'm like you selecting a longer case to increase the powder load using the least amount of compression. A uncompressed powder load burns more efficient and all powder has different levels like sine waves that cross a center line. Most generally the best accuracy comes with the least compression. The OE powder does best with less then .200" compressed in my calibers I shoot. I don't like to use a .45-70 thinking I need more powder in it to reach the 1K by heavy compressing it I just go to the .45-90 or the .44-2-5/8 or the .44-100 Rem straight.
When you look at the pictures of what a compressed powder load looks like from .100",.200", .300", .400" .500", and .600" you can see that the efficiency of the burn should drop. Shooting over a chronograph the drop of velocity also decreases as compression increases after a point. The cleaner burn you see looking down the bore with the increased compression I think is from the hard compressed unburned powder pellet scrapping the bore of it's fouling and not the burning efficiency.

When you compress the powder, the front gets compressed more then the bottom. The third photo is a close up with the .500" and .600 thousand compression.
Just something to look at. Kurt

[BrentD]

I am not a big fan of a lot of compression. My loads have just enough to even out the powder column and support the bullet. I think some of us that finger seat bullets may want to consider that the powder has a second purpose and that is holding the bullet in it's position as it is inserted into the barrel. If it is too loose back there, some de facto and variable compression may be occurring. This may be more important for a snugly fit bore-diameter bullet or someone that engraves a groove diameter bullet when loading.

I have also noticed what Kurt mentions where heavy compression is used, so I avoid "too much of a good thing". In then end, I do just fine with 82 grs of Swiss 1.5 and that reaches all the way to 1000 yds in my .45-70. I haven't tried lesser mounts that would leave the bullet totally unsupported. Someone else can try that.

[Kenny Wasserburger]

In my own personal experiences, anything over .280 with Swiss for compression was a waste. In Goex Fg anything over .385-.400 was the point of deminished returns much the same with the Olde Eynsford. My personal results are increased powder charges and the resulting compression gave me more velocity up to the afore mentioned amounts of compression. I am not discounting Kirk's melted snow or residue in the PVC, my question was it powder melting the snow, or ejected fouling? I agree that a lot of something is being ejected from the barrel, if it is unhurt powder way is it melting the snow? The stuff inside the PVC trap may prove out the statements. A most interesting conservation.

KW

[Lead pot]

Melting the snow might be the wrong explanation. I should have said settled in the snow maybe.
The collected residue was unburned powder and what I would call fouling and bullet lube that spun off the GG. When when I was done separating the stuff I weight what was powder (I don't remember what the weight was) and lite it and it flashed.

As far as the point of diminished returns. I have looked for it in my .45-3-1/4 and have never seen it over the chronograph. I have seen reduced velocities with full compressed loads in the 3-1/4 but never with no increase.
I think you would need a heavy barreled slug gun that you can get more powder in to see how much it would take to see no gains.

[Kenny Wasserburger]

As far as the point of diminished returns. I have looked for it in my .45-3-1/4 and have never seen it over the chronograph. I have seen reduced velocities with full compressed loads in the 3-1/4 but never with no increase.

I am sorry, but if you got reduced velocities, then you reached the point of deminished returns? Your statement makes no sense to me.

KW

[Lead pot]

Typo that should have been decrease instead of increase.
I have seen reduced velocities with full compressed loads in the 3-1/4 but never with decrease in velocities

[Doc Highwall]

Kenny, when you say .280 with Swiss for compression, is this from the case mouth/top of powder column with your 45-110 because that same amount of compression of .280 from the mouth/top of powder column of a 45-70 would be an even greater compression. I want to make sure I understand exactly what you mean so I can actually put it to use.

[Toymaker]

Although it applies to muzzle loaders, there was an article in the NMLRA MuzzleBlasts magazine some time back that demonstrated black powder is most efficient when compressed to 65 pounds. I spent a lot of time with the bathroom scale practicing pushing down on my ramrod to get 65 pounds of pressure.
I'd have to say that the same likely applies to compressing the powder in a cartridge.
My Lyman 457-193, 405 grain bullet over 70 grains FFg gets 0.28 inch compression. 68 grains gives me better accuracy and the depth of the compression die is unchanged. OAL is 2.687 inches.
With a Hoch 500 grain Semi-Spritzer (1.32 in long, 0.459 in dia.) over 70 grains FFg the compression was 0.24 inch. OAL is 2.683 inches.

[Toymaker]

I found Lead Pot's pictures to be very interesting. I drop my FFg down a 36 inch drop tube into the case; insert a cardboard wad and compress the powder 0.28 inch. I compress slowly. Then a newspaper disk goes in and I hand fit the bullet on top.
I clearly remember one time a primer didn't go off. When I got home from the match I picked the bullet out of the case by hand and used a needle awl to remove the newspaper and cardboard disks. The powder wouldn't pour out so I used the awl to carefully pick/chip the powder column out of the case. It was compacted tightly from top to bottom.
I thought perhaps the powder had gotten wet. I had a cartridge left over from the match so I disassembled it also and found the same conditions. It was compressed, as uniformly as I could see, from top to bottom.

[Kenny Wasserburger]

Doc,
i compress .280 in my 38-50 that's after drop tubing the powder placing a wad on top of the dropped charge then compress .280. I never use swiss in my 110. I do the same method in my 110 drop the powder place my wad on the powder then measure the depth of the wad from the case mouth, the amount of compression is from this depth first measured. I keep very extensive records of powder lots and the amount of compression used. The amount of powder used by wt varies due to differing bulk density of lot to lot. The volume remains the same, but the wt changes. I have come up with a pretty good method, it works with Goex and Ole Eynsford quite well. But does involve compressed loads.
Kenny W.

[Doc Highwall]

Kenny, as I understand it, if the wad is .100 below the case mouth when you drop it on top of the powder charge, you then compress it .280 which is now .380 below the case mouth.
Thank you for explaining it.

[Kenny Wasserburger]

Yes Doc you got it.

KW

[country gent]

I measure the compression the same way and it is the easiest way I have found. One book said making a dowel 1.000 long and using it to measure from case head for compression a real pain as now your handling 3 diffrent things. I drop powder in with a drop tube. Seat a wad by hand with a seating punch down onto powder charge to make sure its square and right then compress to wanted depth. One other plus to doing this is the measurement is a direct dimension to the amount of bullet in the case. On grease grooves bullets measureing the base to crimp groove or where the case mouth ends on the bullet allows you to adjust the stack ip of powder and wads closely.

[Doc Highwall]

I was thinking of doing it a different way. First I would find out the maximum O.A.L. that would fit into my rifle then minus the length of the bullet, with that measurement I would then set the compression die to that height above the shell holder.

Example I load my 45-90 to a O.A.L. of 3.300" and my Brooks bullet is 1.432" so the dimension from the base of the cartridge to the bullet base is 1.868", now if I set the compression die to 1.868" above the shell holder. I know I need to fill the case up to the 1.868" mark minimum with powder. Now I would start with this as a minimum powder load and start to add powder say in 5 grain increments and compress it. I would then shoot this over a chronograph and record all information including group size till I found the lowest extreme spread and smallest group. Then what ever the powder charge ended up being I would be able to measure the dropped powder height to the compressed powder height and then know how much compression I have.

[Don McDowell]

But doing it that way how do you determine if its the seating depth causing large groups, or the amount of powder in the case?

[Doc Highwall]

It would just be a place to start followed by seating depth/or ogive distance from the lands. I suspect that the bullet would be no more than .060" off the lands but I know that the only real way to know for sure is by what the target says.

I have thought of this as well and if I had to seat the bullet deeper I could reduce the powder charge. I have found with most of my white powder guns that .060 was the most I have ever had to back off the lands.

[Don McDowell]

With the BACO 549535M3 bullet I'm seating it with 2 lube grooves showing and using 81 grs of Eynsford 1.5f, this CPA is lappin those up like candy and shooting extremely well at 800-1000 yds.

[country gent]

I have 45-70, 45-90 and 40-65 cases made up into collet style necks ( 1 split to allow a spring tension this works even better with a case that needs annealing) i left roughly 3/8" of the neck and cut a window below it also. On grease grooves this allow you to chamber the round and seat the bullet to depth in the case spring tension holds it and you can measure the case mouth to base of bullet dimension easily with calipers. I split the neck with a dremil .030 cuttoff wheel then the window with the same the split runs down one side of the window.

[Doc Highwall]

I have the Stoney Point tool now made by Hornady with the modified cases for O.A.L. and I also measure the ogive at bore diameter where it contacts the lead of the rifling.

I have been doing load development with the powder charge being the variable first, then playing with seating depth second and I usually start with the bullet just touching the lands. After I determine the the most promising powder charge I go back to the range with that same powder charge and different seating depths in steps of .005" increments to determine what seating depth is best, followed be a very minor change of powder charge.

The black powder will have to be modified slightly due to the fact that the powder charge will be compressed an additional .005" with each step.

[MikeA]

I'm compressing mine by bullet seating only, along with a drop tube. I bought a compression die but haven't used it yet. It is .405" compressed unless I want one lube groove to stick out. Part of this thread is calming to know I can lift my house and alarming because I'm compressing it more than you guys on the thread. My bullet is the Lee mold 459/500/3r.