compressing black powder

[oldracer]

I asked a question similar to this a while back as I am just starting out with the black powder cartridge shooting. I was curious as to the compression and got many of the same answers you have so far. I was also referred to the fall 2009 issue of Black Powder Cartridge magazine and the excellent article on various amounts of compression with ALL the various makers of black powder and what the effects would be on velocity, std velocity deviation, etc, etc. The author did a huge amount of tests and found the amount of compression varied little as to velocity effects and likewise on accuracy. What he did note as important was compressing the powder after a good trickle into the case, using a good wad and checking to make sure the powder did not swell out any before the bullet was seated. The author also noted to make a constant and smooth motion when compressing the powder in a single stroke which is what I do.

Over the past few months I have been using a homemade compression die just like yours and setting it so the powder is compressed just so the bullet is 0.002 off the lands for both flat nose and pointed. So far I am using 68gn of FFG and load by volume and just check the weight every 10 rounds or so. I have found the the weight varies up/down slightly over 50 or 60 loads but not enough to worry. I did also notice that the "70" measure on my muzzle loader powder measure (volume) does not equal 70gn by weight and also leave a slight amount of room in the case so I am happy with that.

As for final size, I do not think there is any chance of danger as long as the cases are lubed well as this is what is done with my handgun cases, especially the 357 magnum cases as they get a nice bump from the wadcutters being seated.

[KCSO]

In 1888 the British put 70 grains of black in a un formed 303 case, compressed it enough to then size the case and seat a 215 grain bullet over the load. Now I don't know how much pressure they used but no home press will come close to that. I sure wouldn't worry about your compression.

[bigted]

kewl...thought this had gone to rest but i gladly accept the new posts on compressing the bp. i have gotten over my ebeee-jebees when i compress now and actually i do compress with 1 smooth stroke...just seems like the rite thing to do. my compression ranges from just a small bit...maybe an 1/8th of an inch and goes up to quite a lot [i think] of compression...something like .465 of an inch but then i have a felt wad over powder as well so this goes pretty smooth and im getting great dependable ignition with all loads...gotta wait for spring for a good accuracy test.

[RMulhern]

Good idea to have the interior of your cases 'squeaky clean' when heavily compressing!

[oldracer]

Is there a chance we could have a "sticky" about powder compression? Maybe also one on seating the bullets, sizing and possibly crimping? It would have helped me to have one point of reference to read through about what works, doesn't work and the "mystery" stuff that works for some and not others. As I noted above, in the back issues of the black powder magazine there were articles that said one thing and then later another that said another..........

[RMulhern]

Ask folks how to plant corn....and you'll get maybe 100 different answers!!

[giz189]

Just to add another idea from another source, I read from another pp black powder user that he thought a bit more compression than usual, like maybe .500 as compared to .250 gives cleaner burning. Can't say myself right now, but I may try in the near future.

[gunplumber]

these are compressed .2 of an inch to make room for a grease cookie underneath, my grease groove boolits are compressed .35 of an inch to seat with the first driving band touching the rifling. both are on top of 70 gr by weight of 2f goex.

[RMulhern]

Good looking PP! If my eyes aren't deceiving me....on the nearest ones lying flat.....are those crimped??

[boommer]

they all look crimped, from the sheen of the cases

[gunplumber]

just enough that the boolit wont fall out, i can still move it with very little finger pressure.

[bigted]

VERY COOL! i love that pp look and when i catch up with the other "ideas" i have and schetch out my accuracy field tests ill be trying this pp with bp. they just look rite. what boolit are those again?

[giz189]

How in the dadgum heck do all you guys keep that pretty white paper so darn clean?

[montana_charlie]

How in the dadgum heck do all you guys keep that pretty white paper so darn clean?

By the time the over-powder wad is used to compress the charge, all of the 'dirty jobs' have been completed. From then on, clean hands and clean environment assures quality patching.

It helps that there is no exposed 'lube' to mess things up...

CM

[WARD O]

Some say Swiss powder does not like compression near as much as Goex for example. If you are seeking accuracy, you might try varying the compression with any particular load (vary the charge.)

As far as BP powder measures being on the mark, I have found that comparisons of the same volumn, same brand, same granulation size, but different lots may show a marked variation in weight - likely due to moisture content?

Ward

[gunplumber]

those boolits are .441 500 gr pp pure lead cup base from buffalo arms

[giz189]

By the time the over-powder wad is used to compress the charge, all of the 'dirty jobs' have been completed. From then on, clean hands and clean environment assures quality patching.

It helps that there is no exposed 'lube' to mess things up...

CM

Hey Charlie, I guess I am just gonna have to start washing my hands more often.

[trap4570]

In my minds eye - I can't see a consistent shot to shot velocity from over compressed powder. If anything it would crush the grains and change the burning rate.

[kokomokid]

Have you ever pulled one apart after it goes crunch with moderate compression? Ther will be some almost dust on goex FFG.

[bigted]

that makes sense as i hear the crunch as well on my heavily compressed loads. ill have to do some accuracy tests as to how much compression before accuracy goes south.

this is all slow going for me as im limited to how much i can shoot with the chilly weather. im willing but its hard to scrub a barrel with frozen "juice" and the froze juice dosnt soak a patch very well either. i dont have a warm place to shoot yet but im working on it. so as of now the longer range shooting with black powder will have to wait for spring.